Primer pockets ?

[rsbhunter]

Have a friend that used my 6mm Norma brass Dasher reamer to chamber a 26" bartlien blank. At the same time, another friend did an identical barrel, with the same reamer, etc. The first guy is having problems with the Norma primer pockets being trashed after 3 loadings. Load is 108 Bergers with 32.0 Varget , Berger 108 Bt, CCI450. I tried 32.5 gr Varget loads with105 hybrids and 108gr hpbt bergers a got slight pressure signs...so in my rifle I shoot either 31.0 or 31.5gr Varget. All rifles using Norma new brass...I am up to 8 loadings on some brass, and there holding up. Any idea's why his brass is trashed after 3 loadings, when others aren't? Thanks for any info....rsbhunter

 

[SKWERLZ]

Same lot of brass?
Same lot of powder?

 

[rsbhunter]

No,different lots of brass in each case, same with powder..(different lot)..rsbhunter

 

[NZ_Fclass]

Different scales? Different bullet jam? Headspace?

 

[rsbhunter]

Both "other" barrels were chambered and headspaced by my gunsmith, Denny Powell. Used same go gauge. Friend texted saying he is now cleaning barrel with Kroil and JB. Going to let me know after new ladder test....will keep everyone posted on results, rsbhunter

 

[swd]

No,different lots of brass in each case, same with powder..(different lot)..rsbhunter

Probably this. Varget can vary quite a bit lot to lot.

 

[Clancy]

You have to hit that brass easy for a firing or two. If you lightly fireformed your cases and your friend didn’t, that’s probably why you’re not having trouble.

 

[rsbhunter]

I believe I did medium loads at least on the first firing....I've realized that just because "everybody" loads 32.5gr of Varget with 105gr or 109gr, it doesn't mean it is "the" load for your rifle...rsbhunter

 

[Clancy]

I believe I did medium loads at least on the first firing....I've realized that just because "everybody" loads 32.5gr of Varget with 105gr or 109gr, it doesn't mean it is "the" load for your rifle...rsbhunter

I don’t know anyone that shoots 32.5 with a 109, and very few with a 105.

32.2 with a 105 is a popular yet very warm load in Lapua brass that needs to be worked up to.

In Norma, it’s no wonder he lost pockets.

 

[rsbhunter]

Well, the PRS guy's think enough of the 32.5 load with 105gr that it's the most popular load , according to the prs website...and, if you read enough forum's about the Dasher, you'll see loads up to 33.0 gr! Not that I have a need to push it that hard, but for some it's doable....and as for norma brass, it's not Lapua, but I've gotten 8 loadings out of it so far, and it's holding up so far...rsb

 

[Webster]

Have a friend that used my 6mm Norma brass Dasher reamer to chamber a 26" bartlien blank. At the same time, another friend did an identical barrel, with the same reamer, etc. The first guy is having problems with the Norma primer pockets being trashed after 3 loadings. Load is 108 Bergers with 32.0 Varget , Berger 108 Bt, CCI450. I tried 32.5 gr Varget loads with105 hybrids and 108gr hpbt bergers a got slight pressure signs...so in my rifle I shoot either 31.0 or 31.5gr Varget. All rifles using Norma new brass...I am up to 8 loadings on some brass, and there holding up. Any idea's why his brass is trashed after 3 loadings, when others aren't? Thanks for any info....rsbhunter

The Berger manual ilst 31.3 Gr of Varget for a max load with 105 or 108 gr bullets. Pressure is the only thing that can damage primer pockets. No idea why his gun is different. Don't have any idea if sizing to much would be a problem? Measure some of your cases and his at the .200" line above the case head and see if he is expanding the cases a lot. Backing off on powder always helps. Group size is all that matters.

 

[Keefe300]

I saved this picture from this site from years ago. Can’t remember who posted it but it shows not all brass is the same. Internal volume of the Norma dasher brass will be less than fire formed Lapua brass.



I have also experienced that the 108 Berger will pressure out sooner than say a 105 hybrid. Also what do the bullets measure at the pressure ring, is his barrel a tighter fit, carbon ring, chamber oversized at 200 line, etc. there are other things that can lead to pressure or lack there of and loose primer pockets.

 

[rsbhunter]

Well, the mystery is solved..carbon ring!. I always ask first if they have checked for a carbon ring when someone has "sudden" pressure signs with a load that was fine originally. Funny thing is, 98% say, no, it's not that, I cleaned it. Then you talk them into using a 25 cal bronze brush on a short rod and turn the brush in the throat, inserted about 1/8"-1/4" . Next thing they say is, wow, thought I had cleaned it out. Everyone needs to spend about $75.00 and buy a borescope! I guess alot of guy's expect to see a mass of black carbon mountains sticking up from the mouth/leade area of the barrel...when actually its just a dull area that looks rough. Anyway, problem solved..Maybe we can get a sticky with pictures of what a carbon ring looks like, and a barrel thathad it removed. I'll post pictures after my next match...it's not a bad carbon ring, but I usually have the start of one after 50-60 rounds. rsbhunter

 

[rsbhunter]

Actually just got on utube, and there are a couple great videos showing the carbon ring... shows the area people need to look at when inspecting for carbon ring...rsbhunter