Need help solving this

natchomamma

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Im getting this primer swipe when I close the bolt on my MPA. Ant ideas what is causing this? It is not happening all all of my handholds.
 

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pbatesaz

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New brass or previously fired? Primers are fully seated and primer pockets are not excessively dirty or loose fitting primers? Head spacing is correct and bolt not closing hard? Bolt face is smooth?
 

Mordamer

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This is generally caused by primers being seated proud by a smidgen. Measure case length with calipers before and after seating a primer and you'll find out how proud they are.

Possible causes:
1. Primer seater equipment or method sucks. Squeeze harder.
2. Primer pocket in brass not deep enough. They sell primer pocket uniformers that cut the pocket to the right depth. I have never had this problem with good brass.
3. Primers are out of spec. Throw them in a fire and move on with life.
4. Primer pockets might be dirty. Running a uniformer in will clean them up.
 
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natchomamma

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This is generally caused by primers being seated proud by a smidgen. Measure case length with calipers before and after seating a primer and you'll find out how proud they are.

Possible causes:
1. Primer seater equipment or method sucks. Squeeze harder.
2. Primer pocket in brass not deep enough. They sell primer pocket uniformers that cut the pocket to the right depth. I have never had this problem with good brass.
3. Primers are out of spec. Throw them in a fire and move on with life.
4. Primer pockets might be dirty. Running a uniformer in will clean them up.

Thanks. I'll check these things.

These are once fired Hornady brass
I wet temple them with stainless media so they are clean including primer pockets
I did check primer seating on the ones that were scraping and could not seat them more. I also loaded a few more and made sure I was seating them fully, but still found some that were scraping.
I'm only scraping on some of my handholds. Have not noticed this on factory Hornady ammo.
 

pbatesaz

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It is possible that once the bolt is closed a slightly protruding primer would be pushed into the pocket. So when you look at the affected cartridges they seem to be OK. Normally the primer would be seated ever so slightly below the edge of the pocket. You might take a straight edge and check the seating of all of the primers before chambering them. An interesting situation to be sure.
 

MtnCreek

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The factory ammo probably has more head clearance than your reloads. It is likely not all of your reloads have the same head clearance. It makes sense that only some of the cartridges would be pushed back against the boltface enough to mark the primer.

Take a dental pick (or fingernail) and see if there's a high area around the firing pin hole.

If you need to work on pockets, Lyman uniformer is what I use and have no complaints about it.
 

natchomamma

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IMG_6495.jpg

It is flat. I have some I loaded with cci primers. Let me see if I have the same problem with those too.
 

spife7980

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Measure your primer pocket. Measure your primer to the tops of the anvils to the base. Measure your primer from the top of the cup to the base. Measure how far below flush your primer is seated.

The answer is in your hands, you just need to measure it.
 

natchomamma

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Measure your primer pocket. Measure your primer to the tops of the anvils to the base. Measure your primer from the top of the cup to the base. Measure how far below flush your primer is seated.

The answer is in your hands, you just need to measure it.
I tried a case with and without a primer in the chamber and it was still tight when I close the bolt.
 

natchomamma

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Ok I think I know what the problem is. The bottom of my case has a bulge. See the ring in the pic. After sizing it it is .004 larger than a brand new Hornady case. I just don't know why it's like this. Not enough lube when sizing? Bad dies? Signs of pressure from a previous load?

IMG_6498.JPG
 

RegionRat

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Not every die will size the body down by the web. Often, what they call a Small Base Die will have tighter dimensions and affect the lower part of the case body, but regular dies may not.

I’m assuming you only bump the size about a few thousandths using a body die or a FL Size die or similar?

If your sized case will allow an easy bolt closure, that bulge is just cosmetic. Test to see if a sized case will cycle easily before you address the bulge.

Those marks on the primer are usually caused by one or a combination of debris around the firing pin hole or the primer isn’t completely seated, or both. In theory, that primer sits more than 0.002” below the case head so it can’t get touched unless it is in the wrong place or the bolt face has issues.
 

natchomamma

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Jul 4, 2019
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Not every die will size the body down by the web. Often, what they call a Small Base Die will have tighter dimensions and affect the lower part of the case body, but regular dies may not.

I’m assuming you only bump the size about a few thousandths using a body die or a FL Size die or similar?

If your sized case will allow an easy bolt closure, that bulge is just cosmetic. Test to see if a sized case will cycle easily before you address the bulge.

Those marks on the primer are usually caused by one or a combination of debris around the firing pin hole or the primer isn’t completely seated, or both. In theory, that primer sits more than 0.002” below the case head so it can’t get touched unless it is in the wrong place or the bolt face has issues.

The bulge cases create resistance when closing the bolt. With a new factory case the bolt will close much easier.
 

RegionRat

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The bulge cases create resistance when closing the bolt. With a new factory case the bolt will close much easier.
Then we have a problem cause that will only get worse with cycles. The advice given in that video about having the guy that cuts the chamber or reamer make the dies is often good advice.

Who cut your chamber? Can he make you a set of dies?
 

natchomamma

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Then we have a problem cause that will only get worse with cycles. The advice given in that video about having the guy that cuts the chamber or reamer make the dies is often good advice.

Who cut your chamber? Can he make you a set of dies?
Have a masterpiece arms 6.5 creedmoor rifle. It has their barrel and a Curtis Axiom action.
 

Milo 2.5

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View attachment 7129540

It is flat. I have some I loaded with cci primers. Let me see if I have the same problem with those too.
Why don't you clean the bolt face, some solvent and a toothbrush will do. Your ejector plunger may sit proud, that'll scrape the shit out of brass, and in your case, being some don't, all brass not the same dimension. You may have some brass buildup on the underside of the plunger if you know how to pull it and clean that too.
 

natchomamma

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I'm not head spacing the brass (bumping the shoulder?) Im just running it thru my Hornady full size die and calling it good. I wonder if this is my whole problem..... :unsure: Did I mention I'm not an expert at rifle reloading.... (yet).
 

natchomamma

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I think I solved my problem. I had the die touching the shell plate, but evidently did not have the die low enough to cam over. Once I readjusted it I resized a few of the suspect cases and they cycle freely now. (y)
 

RegionRat

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Glad that worked out.

If you can find a mentor, you will learn all this much faster. Clearly you can read and watch videos, but a mentor with experience watching you process is way more valuable up front.
 

MarinePMI

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Just to add: This sounds more like you just have a tight chamber (a good thing really).

As to swipe, I have noticed that Frontier (Hornady's brass company) does have a habit of letting cases out with a dished (concave) case head from time to time. This will give the impression of bolt swipe, but in reality is just the case head flattening out against the bolt face upon initial firing. I have most notably seen this on .17 Hornet brass when it first came out, and am also seeing it on the new Valkyrie brass.

I doubt that is the case here, but wanted to bring it up for awareness sake. Frontier can make some nice inexpensive brass, but they have also let some crappy stuff slide out from time to time as well...
 
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natchomamma

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Glad that worked out.

If you can find a mentor, you will learn all this much faster. Clearly you can read and watch videos, but a mentor with experience watching you process is way more valuable up front.
This is the hot ticket. Took your advice and found one of the top shooters near me willing to share knowledge. Solved my problem. I was not bumping the shoulder back enough. Learned how to set my sizing die for my specific chamber today. (y) (y) Plus some other tips and tricks.