Yes I use an RCBS 3 way cutter and I even chamfered again with a vld tool to make sure that wasn't the issue. I trimmed all the brass to 2.005 and annealed it last night to see if that will solve the issue since the neck is narrow at the top measuring .291 at the rim but .2955 1/3 of the way down.
Cant fit a bullet down a fired case. Is this okay? HBN Causing Issues?
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How many rounds through this chamber?
Sounds like a case of carbon and or coating build-up in the neck area of your chamber. I've fought this a couple of times. If you have access to a bore scope it will be straight forward to confirm or dispel it as a factor.
Sounds like a case of carbon and or coating build-up in the neck area of your chamber. I've fought this a couple of times. If you have access to a bore scope it will be straight forward to confirm or dispel it as a factor.
dok7mm
Well-Known Member
Hope that fixes the problem. The only things I can think of are..... the reamer could different from the drawing ..........
or you have a carbon ring in the neck. If it's a carbon ring, the new trim length will only be a temporary fix, at best, as the ring can only increase in size. A borescope will let you know what's going on. From your posted measurements, that could be 2 thou, per side, reduction in neck diameter.
It has roughly 200 rounds through it but the first 50 was fire lapping and then cleaned with JB bore paste.
If you have any cases left that haven't been annealed it may work to chamber a sized case and see if the case comes out with a smaller mouth diameter than the remainder of the neck.
Personally, I think you have a good (careful) scrubbing session ahead of you.
Personally, I think you have a good (careful) scrubbing session ahead of you.
dok7mm
Well-Known Member
Yep, without a borescope, it's easy to miss the carbon buildup starting and it compounds over and over. It's a PITA to remove. I use half a thickness of a maroon pad with IOSSO or JB on a brush that's snug and ROTATE it in the carbon area, checking often with a borescope for progress. I also alternate with soaking time, BoreTech C4 on wet patches left in neck for a couple hours at a time, hopefully it will loosen some amount of the exterior carbon. Take a lunch!
dok7mm
Well-Known Member
Did you try seating a case into chamber, as suggested, to see if it reduced the neck, near the mouth? It may only get slightly smaller, as not being fired. It's easier to fix a problem, when you have some evidence as to where it is.
I just tried it and I cannot detect any difference whatsoever. After chambering an unfired sized round the measurement stays the same.
dougduey
Well-Known Member
You've got either a carbon ring buildup or a case neck that is too thick. Have you tried a different brand of brass to see if the same problem occurs?? It may be the Bertram brass. I had this issue with Lapua brand brass in my 338 Lapua. A switch to Nosler brass solved the issue. I also neck turned the Lapua brass and the problem went away. I had my smith check to see if I had a carbon ring first, and found out I did not. Good luck
dok7mm
Well-Known Member
If it is a carbon ring, this is not regular carbon fouling and the C4 will only have minimum effect. Take your time, it will take awhile.
You might try a 7mm bronze brush, rotating it slowly, passing from chamber, shoulder and into the neck/chamber end. You should feel resistance harden towards end of neck. Rotate by hand a couple minutes and carefully ease it out. You should see deformation of the new bronze 7mm brush and possibly some hard carbon in brush. That may show what & where. Good Luck
You might try a 7mm bronze brush, rotating it slowly, passing from chamber, shoulder and into the neck/chamber end. You should feel resistance harden towards end of neck. Rotate by hand a couple minutes and carefully ease it out. You should see deformation of the new bronze 7mm brush and possibly some hard carbon in brush. That may show what & where. Good Luck
There is one thing here though that makes me think that it may not be a carbon ring. Because I have had this problem from day one with the Hornady bullets and the hbn. I was shaving copper off of them from the very first bullet that I loaded and that is why I switched to the Bergers. This gun is near New as I only had it built about a month ago. And I also remember the Smith telling me that I had a .120 free bore and that does not match this reamer print. I am checking to see if I can find a carbon ring and get it removed and hopefully between that trimming the brass shorter and annealing it it will solve my problem. There is really no other brass manufacturer as of now other than Hornady which sucks but adg will hopefully have brass soon and then I will be able to try another brand.
Thank you to everyone for all of the help and the ideas and feel free to keep them coming. This is the first time I have ever ran into this problem out of 4 custom rifles that I have.
That's kind of where I'm at right now but wanted to get people with more experience to chime in with their opinions. I will just try to fix everything and hopefully I won't have any issues in the future.
