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Join the contest SubscribeBerger 109’s measure at .2435Even at 2450 in a 7.5 twist, I got perfectly round holes. I'd say you have something else going on there - especially if that caliper measurement is right. What do other 6mm bullets measure on your calipers?
....how many instances of occurrence and is any muzzle device in use?
...I didn't catch that .240 measurement earlier, sounds like you are going to have to go thru your inventory to look for undersized bullets if its happening that frequently...Berger 109’s measure at .2435
It’s happening at about 1 every 5-10 rounds.
I was hoping there was a bad batch going around and I didn’t some how dick up my barrel.
Tested without my brake with the same results. Crown looks good.
It’s starting to look like there’s a bad lot out there. On the 6gt forum someone identified a possible culprit. The gas ring is oversized and inconsistent. I found this to be true on my lot as well. I have reached out to other members that have reported problems ranging from flyers to keyholes and exploding bullets. I won’t be surprised at all if they share this lot as well.I've been running that same lot number in my Dasher with a 7.7 twist (might be 7.5?) at 6300 feet. I've been chasing my tail a little bit with unexplained flyers. I've not seen keyholes, though. I have 1500 more of a different lot that I've not opened yet. I've got loads ready to test. I'm going to push them faster and seat deeper and see if I find something better.
...yes, I've used a Lee bullet sizer to resize some Hornady VMAX 123gn AK bullets to .308 for use in my 300BLK back in the last supply shortage, they are one of my more accurate bullets. I lubed them up with my alcohol/lanolin mix and they went thru like butter. I had tested them "as is" and "resized", they had to be seated at different depths due to the "touch point" of the ogives and pressure was reached faster on the "as is" bullets. I did not encounter any "spring-back" when checked months later...Don't laugh, this is an honest question. Is there some sort of tool that pushes a bullet through and sizes the outside? They exist for cast lead bullets, but I've not heard of them for jacketed bullets. It would seem that if we can point bullets we could just as easily uniform the outside dimensions.
I once had some 109s my barrel didn't like and I asked Berger about the "pressure ring" on this particular lot of bullets I was using. They said a pressure ring is the result of the manufacturing process and not a design feature, at least not in Berger bullets. He said it was very difficult to control as well.
I assume the AK bullets are boat tail? How did you push them through the sizer? It seems like they would need a pusher that matched the boat tail shape?...yes, I've used a Lee bullet sizer to resize some Hornady VMAX 123gn AK bullets to .308 for use in my 300BLK back in the last supply shortage, they are one of my more accurate bullets. I lubed them up with my alcohol/lanolin mix and they went thru like butter. I had tested them "as is" and "resized", they had to be seated at different depths due to the "touch point" of the ogives and pressure was reached faster on the "as is" bullets. I did not encounter any "spring-back" when checked months later...
Link to a representative image of unit I used... https://www.titanreloading.com/prod...reloading-equipment/lee-lube-and-sizing-kits/
If you are talking to me I can't say with any authority. From what I picked up talking to Bob at Berger is that a "pressure ring" can occur due to the different materials and machinery used.I.E. tolerances. It wasn't designed in, but would just happen. It sounded, and I'm reading between the lines, that when it happened it wasn't a big deal until it got beyond their acceptable amount. Once that happened they stop producing them and changed something in the process to get the pressure ring down to what they considered acceptable or removed completely.So… there is supposed to be NO variation in diameter in the shank?
I assume the AK bullets are boat tail? How did you push them through the sizer? It seems like they would need a pusher that matched the boat tail shape?
I imagine it's worth a shot. I wouldn't think that I'd actually be resizing the bullet, just touching up the pressure ring area. I don't think that would be enough to deform the boat tail or separate the lead from the jacket? That would likely be disastrous at 300,000 RPM....no, they were flat base bullets. Back then Hornady had a couple of bullets for them, FMJ, SP, Vmax, SST and the "Zombie" (which was essentially a Vmax/SST with neon green tip). The nominal diameter was .310 so resizing took them down .020, I would imagine same could be done with the 112 Burners you have. The ram the bullets sit on is flat so even a boat-tail could be used. The ogive actually helps to center the bullet and it should only affect the oversized area you identified, not the full bullet body...
...for me the approximate cost of $20 dollars was a minimal amount that I could walk away from if it didn't work out, but I could also just use it for my pistol reloading, especially since my ancient Star lube/sizer for .45ACP was lost in a moving shuffle...
...really only one way to find outI imagine it's worth a shot. I wouldn't think that I'd actually be resizing the bullet, just touching up the pressure ring area. I don't think that would be enough to deform the boat tail or separate the lead from the jacket? That would likely be disastrous at 300,000 RPM.
Thanks for making me paranoid.
Lot # 7276476-8
Shank - - - Pressure ring
0.2435" - - - .2440" (x10, SD = 0 over the 10 I measured...)
I've shot ~2000 of these and still have ~500 more of this same lot and they have been great for me. I just got 2000 more all from the same (but different) lot, but I haven't seen anything (besides this thread) to get into them and start measuring them...
EDIT: @Gtscotty I haven't experienced/felt anything wonky while seating bullets, and my bullets stay put ...but I anneal every firing/loading with an AMP, FL size followed by a mandrel, and am pretty OCD with my brass prep in my quest for consistent neck tension... not sure if any of that is different from how you do it.
I'm annealing every time as well, I am just using FL collet dies instead of a mandrel. How much neck tension are you using?
Sorry, brain fart, I meant to type "FL bushing dies" not collet dies, RCBS Matchmaster to be specific. I'm not doing double sizing or anything like that, just size with the bushing die, clean the necks, charge and seat.~.002 -.0025" (.268" bushing, followed by .241" mandrel)
Strange, if anything I'd think I'd be worse off than you because I'm running necked-up 22-250 Rem brass with shorter than normal necks..?
Lapua doesn't make LRP 6CM brass, so I made it myself (I just ran the mandrel through them, loaded and shot them... and FYI/FWIW they shoot great even while fire-forming). After 4 firings they're still only scratching SAAMI minimum now at ~1.90-1.88" (haven't trimmed them, and may never have to).
I'm also jumping a bunch (~.100" off the lands, CBTO is 2.145" using the Hornady comparator), so I'm seating the pressure ring past the neck/shoulder junction.
When you say "FL collet dies" do you mean a FL die followed by a Lee collet die..? and, If so, is the collet die's mandrel stock/standard at .242"..?
Just spitballing here: but there might be a chance that the extra .001 thou of neck tension I'm using (if you're using a .242" mandrel) is the difference... or, and this is a super long shot: I've heard some say using a Lee collet die after a FL die can be a little weird here and there since, done that way, one is effectively/literally sizing the shoulder/neck twice in a row, which some say isn't the best, since it's introducing a tiny bit of work hardening and undoing the slightest bit of what you just made right during annealing, and possibly introduces slight concentricity errors... but that's kind of wading deep enough out into the weeds to drown.
Yeah, 6GT and 6CM are different, but I think it's weird that I'm not seeing the same issues if the pressure ring is "oversizing" the necks during seating...
View attachment 7735422
Sorry, brain fart, I meant to type "FL bushing dies" not collet dies, RCBS Matchmaster to be specific. I'm not doing double sizing or anything like that, just size with the bushing die, clean the necks, charge and seat.
Just curious what your jump is? Was thinking if you’re very close to the lands that maybe the effect of stretching the neck may be less? That is if the pressure ring is possibly causing a tension problem as mentioned in an earlier post?Thanks for making me paranoid.
Lot # 7276476-8
Shank - - - Pressure ring
0.2435" - - - .2440" (x10, SD = 0 over the 10 I measured...)
I've shot ~2000 of these and still have ~500 more of this same lot and they have been great for me. I just got 2000 more all from the same (but different) lot, but I haven't seen anything (besides this thread) to get into them and start measuring them...
EDIT: @Gtscotty I haven't experienced/felt anything wonky while seating bullets, and my bullets stay put ...but I anneal every firing/loading with an AMP, FL size followed by a mandrel, and am pretty OCD with my brass prep in my quest for consistent neck tension... not sure if any of that is different from how you do it.
Just curious what your jump is? Was thinking if you’re very close to the lands that maybe the effect of stretching the neck may be less? That is if the pressure ring is possibly causing a tension problem as mentioned in an earlier post?
Maybe the big jump does the same?
What lot number? Did you contact barnes about the issue? I'm curious how barnes will deal with the situation.I had 5 blow up at the last match I shot them in...I went back to D-Tac's the following weekend with no problems. 6XC @ 2820, 7 twist