First time post here. Looking for brass suggestions for my 6bra rifle which I had built last year. Unfortunately like many 6bra owners, I have experienced pressure signs using the Alpha brass. It appears my chamber simply won't work with the unique brass dimensions and qualities of the Alpha brass. This rifle was chambered specifically for Alpha brass with a .274 no turn neck and .120 FB. However, the reamer used (PTG #100290) measures .4715 at the .200 line. This is causing the bolt thrust covered in previous threads and discussed by Mr. Wheeler. So my question is do I simply switch over to Lapua or Peterson 6br brass and fireform or do I think in terms of having a new chamber cut/new barrel? I appreciate any insight or suggestions you guys can provide me.
Suggestions for my 6bra - no more Alpha brass
- Thread starter gilmanguy
- Start date
Making sure the die is sizing the brass properly at the 200 line would be a first approach. Swapping over to either Lapua or Peterson would be second. One or the other or both probably will take care of the issue.
Brass being sized at the .200 line isn't the issue. If I understand correctly, Alpha brass is designed to only work in a chamber cut to a max of .4712 at the .200 line. My chamber is .4715+ I know others have had problems in their 6bra rifles with the Alpha brass, wondering what solution they arrived at? Wondering if Peterson or Lapua brass will work with the larger .274 neck I am running?
Keefe300
Gold $$ Contributor
I can’t speak to Peterson brass as I have not tried it. Lapua brass will serve you well, you will be around 3.5-4 thou neck clearance with the .274 neck of your current reamer. If memory serves me correctly .270 was the measured outside neck diameter with a 105 Berger hybrid seated into a Lapua 6BR case. This was blue box brass from around 2016, and the hybrids were from the same era.
R.Morehouse
Gold $$ Contributor
So far, I have 8 firings on the Alpha Dasher brass. The pockets are great and it anneals and sizes as well as the Lapua I have used, without the FFing.....Sorry to hear about the troubles with the BRA brass some seem to be having.......But all Alpha brass certainly is not garbage.......
Regards
Rick
Regards
Rick
Keefe300
Gold $$ Contributor
To Rick’s point above, I have been using Alpha brass for my wildcats for a few years now and it has treated me well. Since they are wildcats, I changed my .200 line to .470 and never looked back.
You nailed it on the head earlier talking about the .200 line.
The Alpha brass that I have measured is .4675-.4680 measured with a micrometer. Lapua brass is more like .4685-.4690.
That being said the Lapua brass expands less to go from .4685 to .4715 than the Alpha going from .4675 to .4715. It may only be a thou different from one to the other but that difference coupled with a harder head equals less expansion. Less expansion equals less grip on the chamber walls, which equals more bolt thrust.
Rick’s experience with the Dasher shows this a little more. A standard Dasher has a .200 line of .4707, so it is smaller than the BR variants at .4714 or more.
Also to note case lube left on the case can also cause similar issues, and or exaggerate current issues. So you can also try another test and use non chlorinated brake clean and wipe off a couple of cases so they feel squeaky, then swab your chamber with a patch wrapped around a brush soaked with non chlorinated brake clean. This will eliminate any lube in the chamber or on the case and give more grip.
You nailed it on the head earlier talking about the .200 line.
The Alpha brass that I have measured is .4675-.4680 measured with a micrometer. Lapua brass is more like .4685-.4690.
That being said the Lapua brass expands less to go from .4685 to .4715 than the Alpha going from .4675 to .4715. It may only be a thou different from one to the other but that difference coupled with a harder head equals less expansion. Less expansion equals less grip on the chamber walls, which equals more bolt thrust.
Rick’s experience with the Dasher shows this a little more. A standard Dasher has a .200 line of .4707, so it is smaller than the BR variants at .4714 or more.
Also to note case lube left on the case can also cause similar issues, and or exaggerate current issues. So you can also try another test and use non chlorinated brake clean and wipe off a couple of cases so they feel squeaky, then swab your chamber with a patch wrapped around a brush soaked with non chlorinated brake clean. This will eliminate any lube in the chamber or on the case and give more grip.
urbanrifleman
Site $$ Sponsor
Lapua brass starts out at .4685"ish.
My 6br Ackley and 22br Ackley reamers are all the same. They are based on the original Alex Wheeler spec. The reamer spec is .4715" at .200.
I don't think that's the problem.
People forget there are tolerances in these reamers. I was told that by JGS. Thinking they can hold a couple ten thousandths might be a bit ambitious.
The Harrels #3 sizes the base to .4695".
The Wilson sizes to .4705" .
Both are perfectly acceptable with the .4715 reamer spec.
I have gotten used brass from others that were larger than .4715 at the base. Definitely shooting in fat chambers. Worked fine after resizing in a Harrels #3.
My 6br Ackley and 22br Ackley reamers are all the same. They are based on the original Alex Wheeler spec. The reamer spec is .4715" at .200.
I don't think that's the problem.
People forget there are tolerances in these reamers. I was told that by JGS. Thinking they can hold a couple ten thousandths might be a bit ambitious.
The Harrels #3 sizes the base to .4695".
The Wilson sizes to .4705" .
Both are perfectly acceptable with the .4715 reamer spec.
I have gotten used brass from others that were larger than .4715 at the base. Definitely shooting in fat chambers. Worked fine after resizing in a Harrels #3.
Last edited:
NC/Br Shooter
Silver $$ Contributor
I don't have any problems using Alpha bra brass.
Been using it , 2 1/2 years that's 6 boxes of 100. Wilson dies,
Been using it , 2 1/2 years that's 6 boxes of 100. Wilson dies,
Appreciate the insights and advice. I'll try your idea on the brake clean and see if that helps mitigate any of the bolt thrust.
If I understand correctly, the folks over at Alpha have indicated their brass isn't designed for a chamber cut to .4715 at .200. apparently their reamer is designed to cut .4712 at .200. Currently using a Whidden sizing die, but will certainly look at others. Just not sure that is a solution for the bolt thrust issue with my chamber?
urbanrifleman
Site $$ Sponsor
That is basically the same thing. Some of my prints say .4714". I have asked Manson and JGS and basically .0002" is less than the tolerance of the manufacturing process.
I don't think that is your problem.
Appreciate your thoughts. Any suspicions as to what my problem might be?
urbanrifleman
Site $$ Sponsor
Is your chamber shiny?
Are you suggesting I hone the chamber to help the case grab onto the chamber walls?
urbanrifleman
Site $$ Sponsor
It shouldn't be shiny. Not polished.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.