Lapua .220 brass enlarged primer pockets

P

P. Octo

Member
For the past couple of years, several shooters in Europe have found that they had enlarged primer pockets only a few shots after fireforming Lapua .220 into 6PPC. With normal loads of 133, normal seating depth etc., I am talking about experienced competitive shooters.
Have you heard about it, is it due to a bad batch of .220 cases?
The primers litterally fall out, and, apart from one case where we chronographed the rounds and found the velocity way higher than expected due to a different batch of 133, examination of the fired cases show no signs of over pressure. For instance, fireforming load of 1.60g (24.7gr) behind a FB 68gr, second and third loads of 1.88g (29gr), bullets seated out to square marks. Reloading for the 4th time you find the primers at the bottom of the cartridge box!
Looking forward to your feedback on this.
 
I think that you have answered your own question with the shot that you chronographed. It sounds to me like there is a powder issue. For one reason or another the particular lot of powder is out of spec. I would go back and do more chronographing, comparing that powder lot with others from different years. If the results are as I would expect, my next move would be a conversation with the powder manufacturer. In the past I have heard that different lots of 133 may have varied in speed by volume but were pretty close when compared weight for weight.
 
Thanks for your reply. We did pay attention to the lot numbers, so we don't think this was a factor in the latest instances (last week) as the recorded average velocity was a conservative 3240 ft/s. We do suspect a temporary problem with the brass: that's why I was wondering if anybody had experienced the same problem.
 
220 Russian brass

P. Octo said:
Thanks for your reply. We did pay attention to the lot numbers, so we don't think this was a factor in the latest instances (last week) as the recorded average velocity was a conservative 3240 ft/s. We do suspect a temporary problem with the brass: that's why I was wondering if anybody had experienced the same problem.
Click to expand...

Philippe what year and origin of your purchase?
 
There were some brass about 4 years ago that acted like that. Haven´t heard anything about it the past couple years.

Even with the old brown box brass, there were differences between the lots!
 
Though it is hard to get definite answers, it seems that the brass in question had been bought between 4 and 2 years ago. The people I contacted were sure, though, that it wasn't recent lots.
 
now of 3 others that got the same poblem lapua 220 russians is bought about 4 years yes
but i got the same problem with 6x47 lapua brass (bought new less then a year ago ) primer is lose after 2-3 times of reloading
(30x44 with 40.5 gr N133 and 115 gr bullets)
if i use lapua 308 brass with large primer i do not have the problem in my 30x44
 
By the end of the 2016 season my 6 lots of match Lapua brass all had loose primer pockets but most were shot in loads that chronographed about 3550 at 21 feet. (these loads DO go through the paper). When this happens I switch to Wolf SRM primers. These Wolf primers I have are 0.0005" larger diameter and 0.005" shorter than GM 205's.

Some of the shooters I know are shooting firing pin springs so backed off they can flip the bolt open with just one finger. These Wolf primers will not fire consistently with a backed off spring. I use the Tubb double wound springs that test about 25 pounds so no problem with the Wolfs.

You guys may also be shooting a primer that is on the small side on the diameter.


.
 
If brass from a different lot doesn't do that...then it's the brass. Same load, same primer, same bullet....would just about have to be the brass.
 
Thank you all for your input: it does reinforce my pre-conceived idea. BTW, I should have mentionned that the primers used were Federal M205 GM.
 
Every time I have had problems with primer pockets mysteriously becoming tight or loose and it wasn't a load problem, here is what I found.

Take a new piece of brass from the lot and lay a straight ground edge across the bottom of the case. A convex case will tighten the primer pocket when fired. A concave case will loosen when fired.

May not be the problem but it's always worth checking. I check every box/lot of cases now before wasting my time neck turning and fireforming.

Hovis
 
HovisKM said:
Every time I have had problems with primer pockets mysteriously becoming tight or loose and it wasn't a load problem, here is what I found.

Take a new piece of brass from the lot and lay a straight ground edge across the bottom of the case. A convex case will tighten the primer pocket when fired. A concave case will loosen when fired.

May not be the problem but it's always worth checking. I check every box/lot of cases now before wasting my time neck turning and fireforming.

Hovis
Click to expand...

Hovis, I'm not sure if you can recall, but about 8 years ago, some shooters were experiencing primer pockets getting really tight on Lapua 220 Russian. I did what you did, and found the cases to have a considerable covex on the face. Primers would get so tight they would crush going in. I went so far as to make a fixture to face the cases square. That cured the problem, But then, The problem disappeared as new lots of brass came out.
 
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