Chamber case neck

[blvedere]

Recently purchased a 30 cal 308 McGowen barrel on line. I have been having trouble making it shoot the way I want, 600 yards. Had a chamber cast made and found that the chamber neck was 0.348" and my loaded round is 0.333". Other than over working my brass do you, as I do, think this is effecting my load development. I have my own answers just want some other feedback. My turned case necks are 0.012 Thanks

[Robinhood]

Seems loose to me. If I remember correctly SAAMI is like .344 and almost every match reamer is less. A lot could depend on how the cast was removed though. Is there any reason you turn your necks down so much without specifying a tight neck on a reamer?

[blvedere]

Was told it was a PTG match reamer. Other shooters here use that reamer and all turn there necks. I had no reason to question what the neck size would be, 20/20 hindsight, All my other Lapua benchrest brass, 6BR & 30BR, are turned to 0.012.

[Robinhood]

http://i72.photobucket.com/albums/i174/softcock/308jpg.jpg
Are your benchrest reamers tight throat?

[Robinhood]

I have heard of a PTG match having .3435(Bisley) mostly .342 when the buyer recieved it. The one match is around .339 if I can recall correctly. Normally the Palma is used and Dave adds freebore for the heavier bullets.

[blvedere]

Thanks for the print, it looks like my case neck is about 0.006" o'size. It appears that I should not have turned the necks. If I had left them alone they had a wall thickness of 0.014/0.015. Guess if I want to use this barrel I will have to find some heaver wall brass. Do you have any suggestions? Thanks again.

[Robinhood]

Well brother, I think your chamber is Over Sized regardless.

[Robinhood]

Lapua and the great quality LC brass is all in the .015 range. Norma and Nosler too.

[FW Conch]

I have a 358 Win, A&B barrel that is worse. I only size 3/4 way down the neck, and leave a "false shoulder". It shoots less than MOA, and I have no need to do any better with that one.

[yobuck]

I have a 358 Win, A&B barrel that is worse. I only size 3/4 way down the neck, and leave a "false shoulder". It shoots less than MOA, and I have no need to do any better with that one.

Or a custom sizing die?

[blvedere]

I see where that would work, but I think it would shorten the life of your brass having to resize 0.006", or what ever number it worked out to be, to bring your brass to correct bullet size.