My no-turn 22BR chamber is a .255 neck. With Lapua cases, the necks measure .2530 across the pressure ring of a flat based bullet. With those dimensions, a bullet is a nice slip fit in a fired neck.
Good shootin' -Al
With the later Lapua cases, you need to be pretty careful with a .254 neck. The early 'gold box' Lapua worked with a .253 neck and a .254 was a bit of insurance. Many of the 'no turn' 22BR reamers are spec'd on the early Lapua cases and haven't had the neck diameters changed to reflect changes.
In a .253 or .254 neck 22BR chamber, the Peterson and Norma 6BR cases are the safer play. Even in a .255 neck 22BR chamber, they will provide an extra bit of insurance with no accuracy loss.
Blue box Lapua 6BR, necked to .22 in a Redding 22BR Body Die, then f.l. sized in a Wilson 22BR bushing die. Bullet is a BIB 52 gr. flat base with a .2241 pressure ring. This lot is what I made the cases from for my .255 neck 22BR.
My other 22BR using 'gold box' Lapua cases (made the same way) results in the necks at .2515-.2518.
The main take away is to make sure there's adequate neck clearance. With 'no turn' stuff, it does leave the shooter at the mercy of the brass mfg. For example, there's one box of Lapua blue box 6BR here that has pretty significant neck thickness variations...close to .002 on 1/3 of them.For the no turn barrel for one of my 6BR's, brass gets checked and the culls go into a box that get neck turned for the 30BR's.
It's always better to check and know than to assume and hope.
Good shootin' -Al
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My 22BR reamer has a 0.255 neck and 0.130 freebore to shoot the 85-90gr bullets. I'm on my 4th barrel, Straight tack driver.
I stepped my Lapua blue box 6BR brass down in 2 steps. 258 bushing then a 249 bushing. I didnt loose a single piece of brass and Ive done 500 or so now..