PDA

View Full Version : No-Neck Turn Chamber Measurement and Reamer Size



abintx
01-01-2008, 11:19 AM
Assume a case has a bullet seated in "Lapua" brass and the outside dimension measures .268 inches.

What size should the neck chamber measure to provide a "safe clearance" for a no-neck turn chamber ???

Should it measure .0015, .002, or .003 larger ???

What reamer size should be used ???

I ask this question because I've read somewhere that reamers tend to cut a chamber a tad larger than the reamer's actual size.

I'm looking for "no-neck turn standards" that can be applied to any caliber that uses "Lapua" brass.

Thanks for your response.

Happy New Year to all.

Edwin D
01-01-2008, 11:24 AM
Art,

I had to go to a .274 for a no neck turn chamber on my 6PPC.

.272 works great for me on my 6BR no neck turn chamber.

.276 works great for me on my 6 P.O. Ackley no neck turn chamber.

.272 works great for me on my 6BRX no neck turn chamber.

Happy New Year!

wnroscoe
01-01-2008, 11:28 AM
My 6XC has a .273" no turn neck but, a .272" no turn neck would have also worked. I know of several .272" 6BR's, they work and shoot fine.

abintx
01-01-2008, 11:43 AM
I appreciate your response. However, I'm not looking for the final chambering dimension. Perhaps I should restate my first question. I'm looking for the "safe incremental sizing difference" that led to the final dimension. Some number that can be applied to all no-neck turn chambers that use Lapua brass. Thanks.

hulk
01-01-2008, 12:01 PM
.268 with bullet seated = .270 on reamer print.

expiper
01-01-2008, 12:05 PM
Dave will help you with your decision.....I have found a reamer spec. of .003 larger than a loaded round to be "just rite".......I will let U do the math...Roger
PS ...you gotta measure what you have and are going to be shooting....and order the reamer to cut a chamber to suit.....((and hope the next lot of brass is the same or not thicker.!!!))

sundance
01-01-2008, 01:34 PM
Art,

I had to go to a .274 for a no neck turn chamber on my 6PPC.

.272 works great for me on my 6BR no neck turn chamber.

.276 works great for me on my 6 P.O. Ackley no neck turn chamber.

.272 works great for me on my 6BRX no neck turn chamber.

Happy New Year!


Have you found something peculiar with the 6PPC and 6 P.O. Ackley that require the extra clearance?

Edwin D
01-01-2008, 02:10 PM
Sundance,

yes.

Evidently the new batch of 220 Russian that I have is about .001-.002 thicker.

I had a .272 (no noeck turn) reamer, and some of the loaded rounds would not chamber, therefore had Dave alter to the .274.

No problems, AND evereything chambers.

The Ackley is shooting WW brass, and .276 insured NO PROBLEMS.

I am a simple guy, and I do NOT like problems.