Tips for Benchrest accuracy from PRS style rifle

tsonda

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OK, Let me tell you what I'm doing, Then I would like to hear some tips to improve our accuracy. My 11yo and 9yo are shooting a match that is scored more like a benchrest or Fclass match. 500 yard and 750 yards. In that points are awarded for more center hits on a steel plate. I'm trying to find out what I can do to build better ammo to do the job to the best of our abilities.

Currently shooting a 23" barreled 6mm Dasher 1:7.5 twist on Impact action suppressed. Have to shoot prone off a bipod, we have a Harris. Currently running 105 Hybrids over Varget at 2915. Accuracy node is more important to me than speed. Top distance at the moment is 750yards.

Lapua brass- I don't anneal, overall what is my benefit here?
105 Hybrids- Will custom bullets like Vapor trails or Barts Bullets help much? I don't measure and sort my bullets (I've already ordered some and got on list to try)
I hand weigh every charge on a tuned OHAUS. Not sure what else I can do here.
Match rounds I try to sort by feel of resistance when seating bullet.
I don't have a very good chrono. I chrono and then tweak in my Ballistic APP. (I'm assuming this could really help by finding lower SD's)

Things I've thought of-
Cleaning inside of necks (I've heard steel wool, graphite)?
Moly coating bullets?
Custom bullets?
Different style bullet, flat base. Not sure what I'll lose in the wind here with BC. I know I've read of some Benchrest guys not shooting Boattails
Neck turning, I really don't want to do this if possible.
Sorting brass, I currently don't
Trying different primers? I currently use CCI 450's

Thanks for any advice.
 

Precision Underground

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Annealing will make the cases accurate for more loads and extend the life of the brass. Once it gets hardened it will become inconsistent. So you don't HAVE to anneal but you will have to throw out the brass a lot sooner if you don't.

What kind of accuracy are you getting now? I don't do anything special other than be consistent while doing the basics and my ammo shoots .3 - .5 from a bipod in the dirt when I shoot groups (rarely). I'd say using the right bullet/powder combo for the barrel and just being consistent in what you do is much more important than trying to find something "else" do do to make accurate ammo.
 

LawnMM

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Buy a chronograph. IMO you should develop your load first by chronograph, then by accuracy of the load.

Why you may ask? But OCW...but ladder test...but...but...

You could have a quarter minute group at 100yds, if your SD is 30 and ES is 60 your consistency downrange at 600-1k is going to start being a problem. Particularly on a benchrest type target rather than a big steel target that can eat up some of the velocity error.

Start with a load that looks good on the Chrono, then see if you like the group size. If you subscribe to the whole barrel timing theory with ladders and OCW where we want the bullet to exit the muzzle while the vibration wave in the barrel is farthest away this should resonate.

If the bullet exits as the shockwave is present at the muzzle, so the theory goes, you get poor accuracy as the muzzle is vibrating on bullet exit.

I don't believe, absent a mechanical issue with the chambering job, barrel material, etc. that it's possible to achieve a consistent, low SD/ES load that doesn't shoot well. Consistency begets a tight shooting rifle.

Now if the chamber isn't concentric and bullets are jumping into the bore at angles or your crown is fucked up sure, but soley on the basis of the load, consistency matters.

Think about OCW tests. You're looking for bullet impacts on target with low vertical dispersion. What's the primary cause of vertical dispersion? At distance, it's variance in muzzle velocity.

I'm not saying don't check for accuracy, I've worked up a consistent load on Chrono that wouldn't group well. It was a factory Remington barrel. Shit chamber job. Rebarreled and had the action worked on, now it's a hammer.

The point is, don't waste time on group size at 100yds only to realize later your SD/ES suck and you're starting over.



Edited to add annealing is a waste of time and money unless you're well over ten reloads on the brass.
 

tsonda

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When we shoot groups at a 100 we are in the same range as you. .3 to .5 for 5 shots. I also realize just improving my windcalling could help a lot as well!
 

Sheldon N

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How small is the center score ring of the steel plate? Or to phrase the question in a different way, how tight does the vertical dispersion need to be at 750 yards? Second question, when you shoot... where are you most often missing? Is it left/right or vertical?

A well developed Dasher load on a PRS gun should be able to hold vertical of 3-4 inches or so at 750 yards without any fancy benchrest processes.

How does your gun shoot when you put it on paper at 750 yards on a calm day?
 

tsonda

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vertically at distance we are usually holding around .5 MOA. But I hear ya, I've spent thousands on rifles and optics and I've cheaped out on a Chrono. I figured that would be one of the suggestions. Thanks
 

tsonda

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Its rarely calm at my house. But on the better wind of days will hold .5 MOA at 750 of vertical dispersion. Center ring of target is 1.5"
 

EchoDeltaSierra

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Sheldon N

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My 0.02 on what you could do to place better.

Wind, wind wind is number one. Doesn't matter if your gun shoots 0.5 MOA or 0.2 MOA if you can't call the wind. This dwarfs everything else.

For bullets, Bart's or Vapor trails will shoot smaller than Hybrids. There's a reason the benchrest guys shoot custom bullets almost exclusively and you don't hear much about world records being set with Hybrids these days. I would say you can probably get away with shooting hybrids for this application though. Sorting the bullets will help, even a simple length sort is pretty easy and will tighten up your vertical at distance. My understanding is that US AMU uses length sorting, that's what I've settled on too as a good balance between attention to detail vs overboard OCD.

As far as loading to a chronograph data, that is not what benchrest guys do. Benchrest loading by the vast majority of top BR shooters is done through meticulous testing, on paper, at distance, in favorable conditions to see what produces the best repeatable results. Lots of work goes into it. The process is usually pretty simple... start with a powder charge weight traditional ladder test, look for the area where vertical remains as flat as possible across sequential charges. Repeat test to confirm and use that as the powder charge node. Then test things like seating depth, primers, neck tension, to see if you can tighten the groups up further. All the OCW and chronograph and 100 yard test methods are just trying to guess at the truth - which is defined by downrange impacts on paper which doesn't lie. And the biggest judge is lack of vertical dispersion.

I wouldn't nerd out too deep though. Get a good load that will hold vertical the size of your bullseye, then spend the rest of your efforts on getting better at wind.
 

Precision Underground

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Buy a chronograph. IMO you should develop your load first by chronograph, then by accuracy of the load.

Why you may ask? But OCW...but ladder test...but...but...

You could have a quarter minute group at 100yds, if your SD is 30 and ES is 60 your consistency downrange at 600-1k is going to start being a problem. Particularly on a benchrest type target rather than a big steel target that can eat up some of the velocity error.

Start with a load that looks good on the Chrono, then see if you like the group size. If you subscribe to the whole barrel timing theory with ladders and OCW where we want the bullet to exit the muzzle while the vibration wave in the barrel is farthest away this should resonate.

If the bullet exits as the shockwave is present at the muzzle, so the theory goes, you get poor accuracy as the muzzle is vibrating on bullet exit.

I don't believe, absent a mechanical issue with the chambering job, barrel material, etc. that it's possible to achieve a consistent, low SD/ES load that doesn't shoot well. Consistency begets a tight shooting rifle.

Now if the chamber isn't concentric and bullets are jumping into the bore at angles or your crown is fucked up sure, but soley on the basis of the load, consistency matters.

Think about OCW tests. You're looking for bullet impacts on target with low vertical dispersion. What's the primary cause of vertical dispersion? At distance, it's variance in muzzle velocity.

I'm not saying don't check for accuracy, I've worked up a consistent load on Chrono that wouldn't group well. It was a factory Remington barrel. Shit chamber job. Rebarreled and had the action worked on, now it's a hammer.

The point is, don't waste time on group size at 100yds only to realize later your SD/ES suck and you're starting over.



Edited to add annealing is a waste of time and money unless you're well over ten reloads on the brass.
Annealing frequency is absolutely dependent on how much the brass is worked with each firing and subsequent sizing. There is no way to put a number on how often any brass will need annealing without knowing how much the brass is being worked and how it is being resized.
 

tsonda

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Thanks for all the info. I'm always learning and trying to learn more.

Sheldon if length sorting bullets what is a good deviation to stay within?? And like you said I don't want to nerd out too much, I just don't have the time for it.
 

Sheldon N

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Sheldon if length sorting bullets what is a good deviation to stay within?? And like you said I don't want to nerd out too much, I just don't have the time for it.
I just put out like 5-6 bins and sorted through a big lot of 2k bullets in an evening or two watching TV. I was sorting 105 Hybrids, all same lot, and used windows that were roughly 2.5 thou wide. The middle two lots will have the most bullets by far, then less bullets in the next highest/lowest, then an even smaller pile in the "outlier" bins for long and short. I still use them all, just group them and shoot the same lengths together.

You could certainly go "finer" increments, but then you'd just have more piles to manage.
 

LawnMM

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Annealing frequency is absolutely dependent on how much the brass is worked with each firing and subsequent sizing. There is no way to put a number on how often any brass will need annealing without knowing how much the brass is being worked and how it is being resized.
Pretty sure most folks are bumping 0.002 but if you're tripling that, sure, go ahead and anneal away. The machines are expensive and at least when the Applied Ballistics folks tested it, zero difference in annealing every other, every firing, or not at all in excess of ten firings in terms of accuracy.

I do agree with Lash in that neck tension is important. My brass goes through a bushing neck die every time as the last step prior to loading.

I've yet to see any concrete evidence that annealing on a regular basis does anything other than hit your wallet and free time. There is supporting evidence of the opposite, that it's irrelevant in low cycle cases under ten firings.
 
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ken4570tc in WY

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I scanned the advice and didn't see any suggestions on bullet coating or dry neck lube. So here's my two cents worth. Most shooters are running naked bullets and those that don't have largely abandoned moly in favor of WS2 or HBN. Moly was found to build up and shorten barrel life. Under an electron microscope, sub micron moly looks a lot like broken glass. The sharp edges lock up and keep building up. Both the WS2 and HBN don't have that issue since they more resemble small round balls. When impact coating with 0.6 micron WS2, the material wouldn't build up beyond one layer deep, you could still make out the bullet jacket color. HBN is a much cleaner dry lube to work with. It's a white powder that leaves a clear finish and is considered to have lower toxicity than the sulfides. Because of the lower toxicity it is approved for use in the cosmetics industry. That being said, always wear a dust mask when handling the loose material. The human body/lungs don't do well with repeated exposure to fine particulates.
 
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camotoe

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Buy lapua brass. Custom bullets don't need sorting. Try different powders and primers. Reloader17 and h4895 are good. Neck turn and annealing are not necessary at this level . Leave inside necks dirty
 

camotoe

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The carbon on the inside of the neck will cut down on bullet weld. Think of it as free neck lube
 

spartan67

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Tsonda. Congrats on getting your 9, and 11 year old kids into shooting! Just remember its all about keeping the Kids happy, and interested in it. If they are, dont sweat the small stuff! Enjoy the range time while you can!
 
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Lynn Jr

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Don't anneal leave the necks dirty and custom bullets do work. A 107 Sierra is good to around 0.230 inch aggregates while the customs CAN cut that in half.
Some barrels have bullets they prefer.
You won't find many 600 1000 yard Benchrest Shooter using a flatbased 6mm bullet.
I shoot the 187 BIB flatbased bullets in my 300 WSM but no flatbased in my Dashers or BR's.
With a 23 inch barrel your velocity sounds correct as most Benchrest Shooters will be using 28-32 inch barrels at 3025-3050 FPS.
If your SD is 30 and your ES is 60 something is very very wrong with your gun if it's a Dasher. Your ES is what determines the vertical in your groups and it should be under 15 FPS and your SD should be single digit.
Tell us what reamer specs you have for freebore if you know?
Powder charge to the kernel is #1
Seating depth with a comparator to 0.001 is #2
Bullets is #3
when it comes to accuracy.
And never mention Benchrest as it upsets alot of posters here.
 
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brianf

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Don't anneal leave the necks dirty and custom bullets do work. A 107 Sierra is good to around 0.230 inch aggregates while the customs CAN cut that in half.
Some barrels have bullets they prefer.
You won't find many 600 1000 yard Benchrest Shooter using a flatbased 6mm bullet.
I shoot the 187 BIB flatbased bullets in my 300 WSM but no flatbased in my Dashers or BR's.
With a 23 inch barrel your velocity sounds correct as most Benchrest Shooters will be using 28-32 inch barrels at 3025-3050 FPS.
If your SD is 30 and your ES is 60 something is very very wrong with your gun if it's a Dasher. Your ES is what determines the vertical in your groups and it should be under 15 FPS and your SD should be single digit.
Tell us what reamer specs you have for freebore if you know?
Powder charge to the kernel is #1
Seating depth with a comparator to 0.001 is #2
Bullets is #3
when it comes to accuracy.
And never mention Benchrest as it upsets alot of posters here.

He asked for it...welcome to the rabbit hole for benchrest accuracy
 

supercorndogs

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Pretty sure most folks are bumping 0.002 but if you're tripling that, sure, go ahead and anneal away. The machines are expensive and at least when the Applied Ballistics folks tested it, zero difference in annealing every other, every firing, or not at all in excess of ten firings in terms of accuracy.

I do agree with Lash in that neck tension is important. My brass goes through a bushing neck die every time as the last step prior to loading.

I've yet to see any concrete evidence that annealing on a regular basis does anything other than hit your wallet and free time. There is supporting evidence of the opposite, that it's irrelevant in low cycle cases. {under ten firings.}
Is that what that means? I.E. Low cycle cases means cases with less than ten firings?