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Thread: Anyone else had a HUGE MV drop w/ H4350

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    Anyone else had a HUGE MV drop w/ H4350

    Was just curious if anyone is seeing velocities drop like crazy in really cold weather using H4350? I run H1000, and Retumbo alot but it's always been less than 1 fps per degree ( shot last week and was NO change due to weather with Retumbo ). With this lot of h4350 I'm seeing a drop from an 80 degree day at 2805 fps to a 46 degree day to 2724 fps. You think it's just the lot of powder?? I'm pretty disappointed in this batch... It's like a damn Reloader powder. Opinions please...
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    likely the batch of powder - good reason to buy powder in quantity and avoid lot variations - since you now hate this powder, the good news is lots of folks would be willing to relieve you of your misery
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    Quote Originally Posted by George63 View Post
    likely the batch of powder - good reason to buy powder in quantity and avoid lot variations - since you now hate this powder, the good news is lots of folks would be willing to relieve you of your misery
    Lol... All 12#'s of it!!
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    I don't know how many shots you have on your barrel but I had a big MV drop with Varget and it was do to throat erosion.


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    It's a GAP Crusader with 1100 rounds down the tube. 6.5 creedmor Id say its not even close to being burnt out because it still shoots REALLY TIGHT at 1,000 yards
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    Stew, One of my 6,5x47's experienced a steady drop after around 1100 rds, to about 75fps. at 1600 rds, set the barrel back, and poured the powder to it to get it back to where it was, see how long it lasts. Accurate through the whole thing, just add more up!

    Barrels are funny, 3 of my last 4 new barrels, experienced a velocity jump after 60-75 rds, then stabilized, poi change came with it though, without having to re-work load. Of coarse the one barrel that would have really benefited from a jump stayed tight!

    I'd be disappointed in my powder choice if it was a lot to lot issue.

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    Quote Originally Posted by milo 2.0 View Post
    Stew, One of my 6,5x47's experienced a steady drop after around 1100 rds, to about 75fps. at 1600 rds, set the barrel back, and poured the powder to it to get it back to where it was, see how long it lasts. Accurate through the whole thing, just add more up!

    Barrels are funny, 3 of my last 4 new barrels, experienced a velocity jump after 60-75 rds, then stabilized, poi change came with it though, without having to re-work load. Of coarse the one barrel that would have really benefited from a jump stayed tight!

    I'd be disappointed in my powder choice if it was a lot to lot issue.
    Miles, I have a buddy with a borescope. I'll get him to take a look at it and see if the barrel headed South
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    Quote Originally Posted by Aimsmall55 View Post
    Miles, I have a buddy with a borescope. I'll get him to take a look at it and see if the barrel headed South
    I'll bet the you could get another 2k accurate rds out of it, just up the charge!! Just because there is a loss of pressure, or velocity, doesn't mean the gun won't shoot, heck, you're probably just getting the rough edges off the rifling!!

    I think I remember, PGS, from Montana having the same issue with a gap 260, he just keeps adding more powder, and his gun has way over 3k, and still shoots nicer groups than most of us can.
    Last edited by milo 2.0; 12-08-2013 at 09:12 AM.

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    What's the lot number on the H4350 in question?
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    Quote Originally Posted by gvanhyning View Post
    I don't know how many shots you have on your barrel but I had a big MV drop with Varget and it was do to throat erosion.


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    Same here but with H-4831. Barrel was about done.

    OP, if you are using a cheap chrony it could be lying to you as well.
    Last edited by steve123; 12-08-2013 at 09:42 AM.

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    Did you change the manufacture of primers or the cases you were using ? If not sounds like an issue with that lot of powder.It might make sense to check velocity again with your chronograph than borrow another chronograph from a friend and see if there are major differences.

    Regards,Mike

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    I have had a similar experience with an 8lb jug of IMR-4064. I don't know how old it was when I bought it, but I have only owned it for about 2 years and it has been stored indoors the whole time I owned it.

    I just recently noticed that my groups started opening up, and decided to start my investegation by running a few across the chrono. I found that I lost 80fps, which took me out of the sweet spot of my barrel. After checking all other obvious factors with the rifle, I felt confident that my particular lot of powder just lost potency.

    I decided to obtain some fresher 4064 to see if I could get my old tried and true charge weight to produce the MV I had gotten before. BINGO! My groups and my MV came right back as before. Problem solved.

    I would have to say that I am a little disappointed in that my remaining 3lbs of 4064 out of my old lot is pretty much useless, considering how hard powder is to come by lately. I even tried stepping up the charge weight to get my original MV back in an effort to use up the remaining powder, but my groups were not there despite getting MV back up. A fresh batch of 4064 was the only answer to my lost speed and accuracy.

    For powder purchases in the future, I am considering only buying 8 each of 1 lb containers from the same lot. My amateur theory is that powder may stay a little fresher over time in an unopened container. This way, I will only be exposing 1lb of powder at a time to the air while I use it. Time will tell.
    Last edited by gigamortis; 12-08-2013 at 10:52 AM.

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    Quote Originally Posted by thrusty View Post
    What's the lot number on the H4350 in question?
    I have it on all my ammo boxes , which are all at my camp where the "magic" happens
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    Quote Originally Posted by gigamortis View Post
    I have had a similar experience with an 8lb jug of IMR-4064. I don't know how old it was when I bought it, but I have only owned it for about 2 years and it has been stored indoors the whole time I owned it.

    I just recently noticed that my groups started opening up, and decided to start my investegation by running a few across the chrono. I found that I lost 80fps, which took me out of the sweet spot of my barrel. After checking all other obvious factors with the rifle, I felt confident that my particular lot of powder just lost potency.

    I decided to obtain some fresher 4064 to see if I could get my old tried and true charge weight to produce the MV I had gotten before. BINGO! My groups and my MV came right back as before. Problem solved.

    I would have to say that I am a little disappointed in that my remaining 3lbs of 4064 out of my old lot is pretty much useless, considering how hard powder is to come by lately. I even tried stepping up the charge weight to get my original MV back in an effort to use up the remaining powder, but my groups were not there despite getting MV back up. A fresh batch of 4064 was the only answer to my lost speed and accuracy.

    For powder purchases in the future, I am considering only buying 8 each of 1 lb containers from the same lot. My amateur theory is that powder may stay a little fresher over time in an unopened container. This way, I will only be exposing 1lb of powder at a time to the air while I use it. Time will tell.

    I did buy one pound cans .. 12 of them. All same lot. Primers... 2 or 3 lots used (fgm210m) but always VERY close fps wise. I was looking threw my log book and I ran across a day in March where it was 29 Degrees. I had been shooting in the mid sixties to seventies previously and ALWAYS at an AR500 plate I had set up at 520 yards from the bench. My previous dope was 9 moa, but when the cold hit it went to 10.2 moa. So now that I went back and looked..... It all makes sense
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    I had a bottle of RL-19 that seemed to have lost a lot of its "potency," and a buddy suggested it was due to increased moisture content. If the powder absorbs humidity, over time, a given charge weight will contain less powder and more water. Which has nothing to do with powder potency, more like a case "reversible" contamination due to water content.

    So I put a packet of silica gel desiccant in the bottle and left it a couple of days, then tested it again. MV with the same charge weight had jumped ~70 fps. So I started checking it every day. I tested until the 7th day after adding the desiccant but the MV stopped increasing after 5. When it was done, the same charge weight was shooting 150 fps faster. It even was faster than my logs showed it had been when that bottle was fresh-opened, which I'm guessing indicates it came from the factory with a small amount of moisture in it, which the desiccant removed.

    I have read that a little moisture actually is good for the powder, but never a reasonable explanation as to what that good it is, or why. And I lack the means to control moisture so there's only "a little," all I can do is everything or nothing, suck it all out or let it go unchecked. So now I put a packet of silica gel desiccant in every new bottle and leave it sit a week before I load from it, then test a light load to gauge its potency fully-dry. When a bottle runs out, I "recharge" each silica gel desiccant packet by putting it in a hot oven for a couple of hours, then it's ready to go in the next new bottle. So far, I haven't noticed any drawbacks to this process, and my loads definitely are more consistent, all the way to the bottom of the bottle.

    Regarding potency, gunpowder was created to be a highly reactive compound, to the extreme. It even reacts with the very air around it, starting the instant it's manufactured, so its potency does decay over time, at a rate largely determined by ambient temperature. But with modern powders, the rate of decay is very, very slow. If I remember these numbers correctly, DoD discards single base powders after 45 years in storage and double base after 20 (or maybe it was 40 and 25?). And AFAIK their storage bunkers are not climate controlled, so I would imagine gunpowder stored in your home should fare even better.

    All of which leads me to suggest maybe your powder hasn't so much lost potency as it has gained "water weight." Somewhere around the house, you've probably got a couple of old silica gel packets that came out of a bottle of aspirin or an iPhone or even a pair of sneakers. You could test the theory by putting enough powder for a few loads in some air tight container, like tupperware, along with the silica gel packet, and leaving it a few days, then testing it. Those "free" packets that come in so many things we buy won't suck up a lot of water, which is why I'd recommend you do an experiment on a small scale. And since that gel packet probably already is used up, it would stand a better chance of working if you'd "recharge" it first by putting it in a hot oven (I've seen everything recommended from 250°-300°F) for a couple of hours. But be aware most of those packets are sealed with hot glue, so that high of a temperature probably will cause them to come un-glued. I use larger semi-industrial sized packets that I've sewn shut with cotton thread.

    And especially if you've adjusted your charge weight up over time, be wary for the potential of creating an overpressure with that dried-out powder.
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    Quote Originally Posted by Fred_C_Dobbs View Post
    I had a bottle of RL-19 that seemed to have lost a lot of its "potency," and a buddy suggested it was due to increased moisture content. If the powder absorbs humidity, over time, a given charge weight will contain less powder and more water. Which has nothing to do with powder potency, more like a case "reversible" contamination due to water content.

    So I put a packet of silica gel desiccant in the bottle and left it a couple of days, then tested it again. MV with the same charge weight had jumped ~70 fps. So I started checking it every day. I tested until the 7th day after adding the desiccant but the MV stopped increasing after 5. When it was done, the same charge weight was shooting 150 fps faster. It even was faster than my logs showed it had been when that bottle was fresh-opened, which I'm guessing indicates it came from the factory with a small amount of moisture in it, which the desiccant removed.

    I have read that a little moisture actually is good for the powder, but never a reasonable explanation as to what that good it is, or why. And I lack the means to control moisture so there's only "a little," all I can do is everything or nothing, suck it all out or let it go unchecked. So now I put a packet of silica gel desiccant in every new bottle and leave it sit a week before I load from it, then test a light load to gauge its potency fully-dry. When a bottle runs out, I "recharge" each silica gel desiccant packet by putting it in a hot oven for a couple of hours, then it's ready to go in the next new bottle. So far, I haven't noticed any drawbacks to this process, and my loads definitely are more consistent, all the way to the bottom of the bottle.

    Regarding potency, gunpowder was created to be a highly reactive compound, to the extreme. It even reacts with the very air around it, starting the instant it's manufactured, so its potency does decay over time, at a rate largely determined by ambient temperature. But with modern powders, the rate of decay is very, very slow. If I remember these numbers correctly, DoD discards single base powders after 45 years in storage and double base after 20 (or maybe it was 40 and 25?). And AFAIK their storage bunkers are not climate controlled, so I would imagine gunpowder stored in your home should fare even better.

    All of which leads me to suggest maybe your powder hasn't so much lost potency as it has gained "water weight." Somewhere around the house, you've probably got a couple of old silica gel packets that came out of a bottle of aspirin or an iPhone or even a pair of sneakers. You could test the theory by putting enough powder for a few loads in some air tight container, like tupperware, along with the silica gel packet, and leaving it a few days, then testing it. Those "free" packets that come in so many things we buy won't suck up a lot of water, which is why I'd recommend you do an experiment on a small scale. And since that gel packet probably already is used up, it would stand a better chance of working if you'd "recharge" it first by putting it in a hot oven (I've seen everything recommended from 250°-300°F) for a couple of hours. But be aware most of those packets are sealed with hot glue, so that high of a temperature probably will cause them to come un-glued. I use larger semi-industrial sized packets that I've sewn shut with cotton thread.

    And especially if you've adjusted your charge weight up over time, be wary for the potential of creating an overpressure with that dried-out powder.

    Thank you so much for that suggestion. I've never heard of that before. One question .... Can I pull loaded rounds and use that powder with the same chance of correcting the problem as straight from the can?? Also what is the powder weight to silica packet ratio?? Thanks again
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    I was was just going to mention moisture and Fred beat me to it . As powder gains moisture it gets heavier but it can change the burn characteristics possibly making it produce lower velocities.. Couple this with it weighing more you will actually add less powder by volume in the case if you're setting up your loads to the same charge weight that you normally do...I store my powder and primers in airtight coolers or a refrigerator...only open them when I have to..is this all necessary? I don't know but it makes me feel better

    Quote Originally Posted by Fred_C_Dobbs View Post
    I had a bottle of RL-19 that seemed to have lost a lot of its "potency," and a buddy suggested it was due to increased moisture content. If the powder absorbs humidity, over time, a given charge weight will contain less powder and more water. Which has nothing to do with powder potency, more like a case "reversible" contamination due to water content.

    So I put a packet of silica gel desiccant in the bottle and left it a couple of days, then tested it again. MV with the same charge weight had jumped ~70 fps. So I started checking it every day. I tested until the 7th day after adding the desiccant but the MV stopped increasing after 5. When it was done, the same charge weight was shooting 150 fps faster. It even was faster than my logs showed it had been when that bottle was fresh-opened, which I'm guessing indicates it came from the factory with a small amount of moisture in it, which the desiccant removed.

    I have read that a little moisture actually is good for the powder, but never a reasonable explanation as to what that good it is, or why. And I lack the means to control moisture so there's only "a little," all I can do is everything or nothing, suck it all out or let it go unchecked. So now I put a packet of silica gel desiccant in every new bottle and leave it sit a week before I load from it, then test a light load to gauge its potency fully-dry. When a bottle runs out, I "recharge" each silica gel desiccant packet by putting it in a hot oven for a couple of hours, then it's ready to go in the next new bottle. So far, I haven't noticed any drawbacks to this process, and my loads definitely are more consistent, all the way to the bottom of the bottle.

    Regarding potency, gunpowder was created to be a highly reactive compound, to the extreme. It even reacts with the very air around it, starting the instant it's manufactured, so its potency does decay over time, at a rate largely determined by ambient temperature. But with modern powders, the rate of decay is very, very slow. If I remember these numbers correctly, DoD discards single base powders after 45 years in storage and double base after 20 (or maybe it was 40 and 25?). And AFAIK their storage bunkers are not climate controlled, so I would imagine gunpowder stored in your home should fare even better.

    All of which leads me to suggest maybe your powder hasn't so much lost potency as it has gained "water weight." Somewhere around the house, you've probably got a couple of old silica gel packets that came out of a bottle of aspirin or an iPhone or even a pair of sneakers. You could test the theory by putting enough powder for a few loads in some air tight container, like tupperware, along with the silica gel packet, and leaving it a few days, then testing it. Those "free" packets that come in so many things we buy won't suck up a lot of water, which is why I'd recommend you do an experiment on a small scale. And since that gel packet probably already is used up, it would stand a better chance of working if you'd "recharge" it first by putting it in a hot oven (I've seen everything recommended from 250°-300°F) for a couple of hours. But be aware most of those packets are sealed with hot glue, so that high of a temperature probably will cause them to come un-glued. I use larger semi-industrial sized packets that I've sewn shut with cotton thread.

    And especially if you've adjusted your charge weight up over time, be wary for the potential of creating an overpressure with that dried-out powder.

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    Excellent info here, but let me say this:

    The 20+ year old unopened cans of IMR4064 and IMR4831 I bought this summer performs *right there* with ~1 year old stuff I've got.

    A friend gave me a 1/2 can of Hercules Reloder 15 at least 20 years old. I had it in my basement sitting alongside a nearly new, but opened bottle. One day I decided to shoot old/new to see if I could measure/shoot the difference. I couldn't. I assume after a while, the humidity/water content of the two lots equalized.

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    brother was here form NC this week end and wanted to go out and shoot my creed well it was -15 with -39 windchill not ideal but went out any ways. Don't know what the velocity drop was but everything was low from what my chart was. went back out and shot today at a balmy 5 above and things were back to normal.

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    Before I went on my mule deer hunt I set some rounds loaded with H4350 in a deep freeze set at 0 for 4 hours. Velocity drop from rounds at 65 degrees was right around 10-15fps... surprized me so I plan on doing it again. Maybe this time with a cold gun now that winter has arrived.
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    Fred, thanks for enlightening us on the moisture angle. Being as my powder and loading bench is indoors in climate control, I would have never considered the possibility of moisture contamination. Before I throw out my remaining 3lbs of older 4064, I will try some desiccant for a couple of weeks to see if this powder wakes back up.

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    I had a batch of ammo I loaded up in 243 this spring and was getting 3160-3175 with a 105 berger. I ran out of the powder and got some new stuff and now my gun is running 3050-3060 with the exact same load. I think they has some hotter stuff, I now mix all of my powder.

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    Quote Originally Posted by Aimsmall55 View Post
    Thank you so much for that suggestion. I've never heard of that before. One question .... Can I pull loaded rounds and use that powder with the same chance of correcting the problem as straight from the can?? Also what is the powder weight to silica packet ratio?? Thanks again
    I see no reason you couldn't (or shouldn't) pull the powder from rounds you've already loaded, which would make sense if you don't like how they've worked out.

    I don't know how much desiccant is "enough," but I've deliberately tried to use too much. I put 1 oz in 8-lb bottles and 1/2 oz in 1-lb bottles, and I only ever open an 8-lb bottle long enough to refill a 1-pounder. Then I do all my loading from the smaller bottles. I'm using a bunch of 1-oz silica gel packets from Cheaper Than Dirt that I'd bought years ago that were busy taking up space. Some of them I cut in half and then sewed closed to make the 1/2-oz packets.

    I've asked everybody who'll talk to me who I thought might be knowledgeable on the matter whether the powder granules swell from the moisture, or if it affects the burn characteristics. The answer to both was 'no.' Which was one reason this was not a problem before shooters measured powder with scales because the energy contained in a certain sized scoop of powder is always the same, regardless of "water weight."
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    That's interesting....... Thanks for the info Fred....

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    Know your speed , bump the charge as needed. No big deal
    practice with a purpose


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    Quote Originally Posted by procovert45 View Post
    Know your speed , bump the charge as needed. No big deal
    The problem with that plan is that it requires that every time you reload, you shoot over a chrono for no reason other than testing MV. And if your MV has changed, you have to adjust charge weight and test again. And repeat until you've hit the mark. And if you began with a compressed charge, you are limited in just how much bumping you can do before tempting fate.

    With my method, I de-hydrate once when the powder is new, test MV and adjust charge weight, then I can count on a consistent MV all the way to the bottom of the jug.

    I do load development by OBT so I have no problem with the principle of loading to a MV. But I'm generally drawn to "once and done" fixes, which is what I see my "desiccant in a bottle" as.
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    Quote Originally Posted by Fred_C_Dobbs View Post
    The problem with that plan is that it requires that every time you reload, you shoot over a chrono for no reason other than testing MV. And if your MV has changed, you have to adjust charge weight and test again. And repeat until you've hit the mark. And if you began with a compressed charge, you are limited in just how much bumping you can do before tempting fate.

    With my method, I de-hydrate once when the powder is new, test MV and adjust charge weight, then I can count on a consistent MV all the way to the bottom of the jug.

    I do load development by OBT so I have no problem with the principle of loading to a MV. But I'm generally drawn to "once and done" fixes, which is what I see my "desiccant in a bottle" as.
    most people that shoot tactical matches. load in lots of 250-300 rds , and you can be sure those rounds are chrono'd and or shot real world at distance to speed check

    most guys on here know how to pick powder/chamber combos and are not loading compressed loads

    as your barrel wears over several rds particularly with the 6's that are so popular you will have to chase lands and INCREASE POWDER to maintain speed

    when you use jugs and jugs of powder you will see speed differences and have to increase or decrease charge to stay same



    but im sure you already knew all this. the desiccant is a good thing though
    Last edited by JByrd; 12-11-2013 at 07:02 PM.
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  28. #28
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    I ran a temp sensitivity test with H4350 in my 260 Rem last weekend. It was about -5 degrees outside. I loaded up a number of different charge weights. I left half the ammo outside for a good 30 minutes so it was between -5 and 0 degrees. The other ammo sat in my car and was around 70 degrees. I would load up a mag in my car, run out to the rifle, and put the rounds down range within a few seconds. I made sure the warm rounds did not have time to cool off. To my surprise, there was almost NO difference in velocity of the rounds. There were a couple random rounds that had a 20 fps difference, but the majority were in the 5-10 fps difference range.

    I'll also chime in and say that I've used 4 different lots of IMR 4064 over the last year and I've seen no measurable difference between the lots. It is much more temp sensitive than H4350, but it is a very predictable swing in velocity across all the lots.

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    What have been your findings on this?

    EDIT - I am referring to your 4064 data on fps per degree.

    Quote Originally Posted by afate45 View Post
    It is much more temp sensitive than H4350, but it is a very predictable swing in velocity across all the lots.

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    I ran some loads over the chrono this weekend and they'd dropped about 25fps from the last time i chronoed them at about 70*.

    6.5CM
    140 Amax
    41.2gr of H4350

    Back in April/May with 70* weather they chronoed in at 2601 but this past saturday in 22* weather they clocked in at 2576.

    All ammo was loaded at the same time back in April when i first got my CM. So same brass, powder, primer, bullet lot. Yet a 25fps differance. So what is that roughly 1/2FPS per 1 degree?

    Also, that same load didn't shoot as tight as usual. Of course that was probably just the loose nut driving the rifle.

    I don't have my databook in front of me, to tell exact temperatures, so i'm just going off memory. If I'm way off I'll update as needed when i get home.

  31. #31
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    Quote Originally Posted by j-dubya View Post
    What have been your findings on this?

    EDIT - I am referring to your 4064 data on fps per degree.

    About 1 fps per degree

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    Quote Originally Posted by bornhunter04 View Post
    I ran some loads over the chrono this weekend and they'd dropped about 25fps from the last time i chronoed them at about 70*.

    6.5CM
    140 Amax
    41.2gr of H4350

    Back in April/May with 70* weather they chronoed in at 2601 but this past saturday in 22* weather they clocked in at 2576.

    All ammo was loaded at the same time back in April when i first got my CM. So same brass, powder, primer, bullet lot. Yet a 25fps differance. So what is that roughly 1/2FPS per 1 degree?

    Also, that same load didn't shoot as tight as usual. Of course that was probably just the loose nut driving the rifle.

    I don't have my databook in front of me, to tell exact temperatures, so i'm just going off memory. If I'm way off I'll update as needed when i get home.
    How many rounds do you have through your 6.5CM and what Chrono were you using? Was your dope off at distance?

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    Quote Originally Posted by Fred_C_Dobbs View Post
    The problem with that plan is that it requires that every time you reload, you shoot over a chrono for no reason other than testing MV. And if your MV has changed, you have to adjust charge weight and test again. And repeat until you've hit the mark. And if you began with a compressed charge, you are limited in just how much bumping you can do before tempting fate.

    With my method, I de-hydrate once when the powder is new, test MV and adjust charge weight, then I can count on a consistent MV all the way to the bottom of the jug.

    I do load development by OBT so I have no problem with the principle of loading to a MV. But I'm generally drawn to "once and done" fixes, which is what I see my "desiccant in a bottle" as.
    How much FPS increase do you see with desiccant vs non-desiccant?

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    Quote Originally Posted by steve123 View Post
    How many rounds do you have through your 6.5CM and what Chrono were you using? Was your dope off at distance?

    the first chrono was run in the first 100 rounds and these last ones were run through about 100 rounds later. ive got about 250 down the pipe. no chance to run them out to distance yet.

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    Quote Originally Posted by bornhunter04 View Post
    the first chrono was run in the first 100 rounds and these last ones were run through about 100 rounds later. ive got about 250 down the pipe. no chance to run them out to distance yet.
    The reason why I asked is there are other variables involved that fit into the ..."all that's wrong with the world" category...you know, things we don't like to happen that bite us anyway.

    Chrono giving false and or inconsistent readings, especially the cheap ones.

    Digital scales doing the same thing.

    Different lot #'s of powder with slightly different burn rates. Especially when buying 1 pound bottles.

    Temperature change.

    And now the moister content thing that Fred mentioned which I hadn't considered before.

    Maybe you were holding the rifle a little softer. Just kidding on that one, LOL.

    The best way to find out whether there is a problem is to see if your dope has changed at distance.

    Usually with a new barrel the velocity increases when the barrel is worked in. Mine has gained 25 fps since new and it's colder than it was when I worked up the load, 200 rounds through it now.

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    Oh yeah I agree with what your saying.

    My guess is it's 1 of 2 things. either the temperature affected it, or the chrono was giving a false reading. It is a cheaper chrono so that's possibly the culprit. But all other variables were accounted for, like i said, same powder (i.e same 1lb can, same bullet lot, all loaded at the same time. Everything held the same, even used the same Chrono, so it's either the powder slowed down a little bit or the chrono was giving a false reading. I think i'll be sure and put back a few of these loads to run over the chrono at a future time, wait until it warms up to about the same temp as my first reading and then run them again, just to see if there's any change. of course i'll have even more rounds down the barrel by then but still worth a shot.

    I find the moisture absorption of the powder very interesting. Will maybe need to try this for myself.

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    Well, I haven't gotten my hands on any silica packs but I did do this. I took the same lot of powder and added one half grain powder. So I was at 42.6 now I'm at 43.1.... And my numbers are absolutely identical.
    Would this be wear of the barrel or just the powder itself getting old and moisty.
    I've said this before I'm no expert on these matters but given the fact that more powder equaled the same muzzle velocity as before it got cold, I would think that it may be a flip of the coin. Barrel maybe, powder probably
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