6 BRA: heavy carbon(?) on Alpha case neck

[gunsandgunsmithing]

3 more pics

Yep, the pin tip shows some damage and I strongly suspect the pin hole is the root cause of your problems. @carlsbad

 

[Mauser06]

I have nearly 500 pieces of Alpha I can't use. Just doesn't work in my chamber. I had pressure signs at very low charges. I was piercing 450s at normal BRA loads (2900 give or take with Varget)


I've gone to Lapua brass and I haven't had an issue since.


Also, check your firing pin. They seem to be the failure point of an Impact. I rather replace a firing pin than anything else go bad. My firing pin hole is still good...yours definitely looks like it may have chipped away. Really shouldn't be an issue though. Kinda like how Square barrel crowns are damaged. The sharp 90 degree corners can chip off easily.


I'd get a couple pieces of Lapua brass and see if there's a difference. Fire them 3 or 4x.


I'm betting by the time you get 2-4 firings onnthe Alpha you'll be popping a lot of primers and have a super sticky bolt. Alpha lost a customer with this mess. I'm also seeing the same issues show with their Dasher brass through shooting friends.

Basically if you don't use their reamer prints, you probably aren't gunna be happy using their brass for some of these cartridges.

 

[Keefe300]

Shooting my 1st BR family of cartridges & I’m getting heavy carbon deposits on Alpha 6 BRA case necks.
Kreiger 28” 218/243 .272 .104 M24. Impact 737r. New Alpha brass neck turned to .012. Loaded cartridge neck OD = .267 with 105 Scenar-Ls.
I shot my 1st 92 with a light load of 29.5 Varget. I got heavy deposits on all these. I was jumping 20 thou. Never any deposits on shoulder or case body. My thoughts were the Alpha brass is very tough, jumping 20 thou with 2-1/2 thou clearance around the circumference of the neck that it may not be sealing quick enough to prevent some gas entering the void. My thoughts were to increase the pressure to where I would be shooting long term & see if that stops it. I loaded 20 rds in .2 gr increments from 30-31.8 to see if I found pressure. I never saw pressure. There were a couple where with looking real hard there was a “faint” trace of the ejector.
I’m about to load some more at 30.8 Varget to shoot. I‘m posting this to see if someone has an explanation for so much deposit on the neck area.
Note: before cleaning I looked with scope. The chamber, throat, & leade were very clean with minimal copper on rifling. There was a little of this gook in the neck area. I clean when I shoot. The cleaning regimen depends on how much I shot. I’m used to a little carbon, but not this much. I’ve been shooting & reloading for a very long time for hunting & precision. I’ve only been shooting the small cartridges for a short time. I did forget to mention that in addition to the light charge of 29.5 Varget I only had 1 thou neck tension. These last 20 were loaded with 3. Checked with pin gauges. I do realize the rd count is low.
Thanks for any & all help, Lynn

I did have a bolt quit cocking at 31.4 & don’t know why. I pulled a bolt out of another rifle & finished. When home I pulled the bolt apart, just looked at it, & cleaned a little. I didn’t see anything wrong with the bolt & it worked fine when I put it back together. I just measured the fired cases at the .200 line. They were .470-.471. I mention this because I just read thread where Alex & others discussed problems with Alpha brass. I may have a bigger problem than dirty necks.
Fired necks = .271 - .2715

You are on the right track with your thinking. The neck clearance you have coupled with a lower pressure charge weight will cause what you are seeing with the carbon on the necks. I have experienced this first hand during testing and fire forming. I say low pressure charge weights because 29.3-29.7 grains of Varget is my normal range for a 6BR shooting the 105 class bullets.

Also the other issues you are thinking of with the Alpha brass fitment in your chamber coupled with the heavy bolt lift etc are also valid and you shared some information from Alpha that backs up your suspicions and findings. It also explained what many shooters are experiencing.

Alpha brass does perform well but I have found that chamber/reamer specs and fitment must be on the tighter side.

I will be interested in your testing after having your barrel chambered with the Alpha reamer.

 

[Lynn313]

All, I created this post to get help figuring out why I was getting so much carbon on my necks & it morphed into other potential problems. I sent the barrel to my gunsmith. It was originally purchased from a big store on thier Black Friday sale. My gunsmith didn’t do the original work. It came with the barrel on sale.

please see pic & note from my gunsmith. He has already cut the chamber off and rechambered it with an Alpha reamer. If you look at his pin measurements I think the Alpha brass should have been sealing. So I don’t know why I had some heavy bolt lift at light loads. There is a ring at the .090” mark from the base of the chamber. I can’t believe it came that way as I usually inspect very thoroughly & also check initial CBTO on the bullets I’m using before I screw the barrel on. It sure seems like I would have caught it.

Something else is I just found out that it is a .236 groove. The barrel I 1st ordered was a Bartlein 237/243 5r. The muzzle threads were so buggered I couldn’t use it. I figured they let an apprentice do it. They didn’t argue at all & asked me if I would take a Kreiger as they were out of Bartlein. I said yes and thought it would be a 237 groove. They got the Kreiger to me in record time trying to makeup for thier mistake. My gunsmith told me today that it is a .236. I’ve no experience in what difference to expect with a 236 in pressure & speed.

 

[Jet]

Don't sweat the 236 bore. That barrel will shoot just fine.

 

[Lynn313]

Don't sweat the 236 bore. That barrel will shoot just fine.

I have a case of Lapua 105 Scenar-Ls I’m going to start with. I love the consistency of them & they are slightly undersize. If they don’t work I’ll try my 109 & 105 Bergers.
I think the main thing is I will have confidence in the barrel now that my gunsmith has rechambered it with the Alpha reamer. There is no doubt if I had known more I would have went with Lapua brass. Alpha can be great, but it’s like a box of chocolates you never know what you are going to get.