horsemen61
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Sounds like your getting it figured out op
Extraction problem
- Thread starter Nature Boy
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Cut your loads and keep cutting till the over pressure symptoms go away. I could not find the bullet you were using, but I used 41.5 grs H4895 with a 168 match bullet. You changed powder lots, maybe you were lucky with your old powder lot, but this lot, is causing you problems.
WelshShooter
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Could the base of the case near the headstamp be too tight in the chamber (ie similar to instances where people use small base full length sizing dies). As this part of the case is not typically annealed, it could be springing back and sticking in your chamber.
Does it feel any different when you're feeding these rounds into your rifle when pushing down on the bolt, or does it feel the same as any other round you shoot?
Does it feel any different when you're feeding these rounds into your rifle when pushing down on the bolt, or does it feel the same as any other round you shoot?
OP
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Nature Boy
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I’m sure it’s a combination of several things.
My daughter shot it yesterday in an F Class match with me and my son. She had no issues with extraction using the brass with 3 firings and the 43.0 load.
Unfortunately, I dumped the brass with 6 cycles into the scrap bucket so I can’t measure the case heads and be certain I got a sample from that batch
I used that batch for load development and practice. I’m sure some of it saw some hot loads. Primer pockets we nearing the end of their usability so the case heads could have been enlarged enough to case extraction problems.
I’ve probably been overly optimistic about case life when running loads on the upper end. I’ll definitely be watching more closely
My daughter shot it yesterday in an F Class match with me and my son. She had no issues with extraction using the brass with 3 firings and the 43.0 load.
Unfortunately, I dumped the brass with 6 cycles into the scrap bucket so I can’t measure the case heads and be certain I got a sample from that batch
I used that batch for load development and practice. I’m sure some of it saw some hot loads. Primer pockets we nearing the end of their usability so the case heads could have been enlarged enough to case extraction problems.
I’ve probably been overly optimistic about case life when running loads on the upper end. I’ll definitely be watching more closely
horsemen61
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Well op it’s like they say no free lunch sucks it happened but at least your getting it fixed up the problem that is
Had to smile a little at that.
I would still double check all dimensions in the sizing process, although end of life may very well be all that it is. If it is, I am guessing it's in the case head area.
243winxb
Member
Was brass cleaned with stainless steel pins? Cases sized with wax?
Zinc removed , waxed, sticky.
Zinc removed , waxed, sticky.
Nature Boy said:
It sucks to have to throw away a piece of quality brass. I met the Shell Shock Technologies folks out at Centre Firearms Co., Inc. during this year's SHOT Show and their stainless steel and aluminum cases might be the future. The case head is aluminum and the body is stainless steel. They've been developing rifle cases for standard US military cartridges since clearly that's where the money is, but eventually we might see rifle "brass" for reloaders with near infinite life.
OP
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Nature Boy
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Almost everyone shooting .308 in F/TR are using palma brass with small primer pockets for the benefit of longer case life. I would have also switched if I didn’t have so many federal large rifle match primers in my inventory. It took me a long time to accumulate those and I’m trying to use them up. I may have to be resigned to the fact that 4 or 5 reloads is all I’m going to get
Are they running bushed firing pins with those SRP pockets? I have a few hundred Lapua SRP 6.5 CM cases that I plan on using soon for my AI AW (currently using Hornady brass), but the firing pin might pierce the primers. The AXMC has a different firing pin arrangement to reduce the chances of that happening which seems to work well since I haven't had a problem with hot 6.5x47mm Lapua loads with five different primer brands.
I remember reading that the SRP .308 Win brass was very temperature sensitive. It was good over a narrow range but somewhat unpredictable outside of that range. Maybe the size of the flash hole was a factor too. Not sure if that still holds true of if I've got my wires crossed.
I remember reading that the SRP .308 Win brass was very temperature sensitive. It was good over a narrow range but somewhat unpredictable outside of that range. Maybe the size of the flash hole was a factor too. Not sure if that still holds true of if I've got my wires crossed.
OP
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Nature Boy
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Are they running bushed firing pins with those SRP pockets? I have a few hundred Lapua SRP 6.5 CM cases that I plan on using soon for my AI AW (currently using Hornady brass), but the firing pin might pierce the primers. The AXMC has a different firing pin arrangement to reduce the chances of that happening which seems to work well since I haven't had a problem with hot 6.5x47mm Lapua loads with five different primer brands.
I remember reading that the SRP .308 Win brass was very temperature sensitive. It was good over a narrow range but somewhat unpredictable outside of that range. Maybe the size of the flash hole was a factor too. Not sure if that still holds true of if I've got my wires crossed.
It would be rifle/bolt dependent. As you note, your AXMC would work with SRPs. I believe my Mausingfield would as well but my FN SPR would need to be bushed or I’m sure I’d be blanking SRPs if I ran competition loads in them.
As far as the difference in performance between LRP and SRP, there are enough guys running SRPs successfully that I would assume the difference is negligible. They are also running much hotter loads than I do. The bullet of choice for F/TR is the Berger 200g and they’re pushing them as speeds close to what I’m running the 185g Hybrids. If I tried that with LRP Lapua .308 brass I would expect my case life would be one and done.
That’s life in the fast lane of competition shooting I guess. Thankfully prize money is so lucrative. I won the F Open group this weekend and got a whole $11 dollars for the effort.
243winxb
Member
After prove-out was completed, an experiment was conducted to determine what effect the spit-
hole area had on the primer force output. It was hypothesized that if the gas flow was choked
through the spit-hole, then the pressure within the primer pocket would increase. For this
experiment the spit-hole diameter was reduced from the mil-spec 0.078 in to 0.055 in. As
figure 4 illustrates, this reduction in area increased the force exerted on the primer cup by 20
times when compared to the no. 34 primer output. https://apps.dtic.mil/docs/citations/ADA599210
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