more neck dimension questions

[tcr1146]

As you saw from a previous thread, I have only ever fl sized or neck sized using RCBS dies or Redding dies. I recently bought a 22-250 A.I. which came with loaded rounds, resized brass, unsized brass, bullets, and Redding deluxe dies. The seller did not load for center fire, his brother did it all. Therefore, he had very little knowledge about what his brother did. Anyway, all the brass was Lapua and again, I have no way of knowing how many rounds fired. The rifle was an older 700 bdl trued, bedded and floated by Mark Penrod with a stainless Kreiger barrel. When I started checking out the brass, the fired i.d. dimension of the brass was .2195- .2205. This shocked me as I could not insert a bullet in order to find the lands the old fashioned way! Furthermore, about 100 brass that had been sized had an I.D. of .2195-.220. However, I then did a much larger sample and found the unsized brass fell into two lot sizes! The one stated above and the other one of .2235-.2245. There did not seem to be any in between! Does this make sense? I am having trouble understanding the lot that measured .2195-.2205? When I checked a lot of brass out of my 40 xb 22-250, the i.d. of the fired unsized brass was very consistent and .226-.227. I just have to assume the chamber is bigger in the xb! Anyway, can anyway explain my dimensions in the A.I. Thanks, Tom

 

[wapiti25]

it sounds like you will need to turn the necks on the brass that has a thicker neck. You need to find/measure the neck dia on that chamber.

 

[Keith Glasscock]

Please do yourself a favor and cast the chamber. When bullets won't enter fired brass, bad things can happen.

I've forgotten your intent for the rifle, but .003" neck clearance won't hurt you a bit.

 

['Freak]

Howdy, Tom – Of the two different size lots, it figgers that those AI necks where you’re getting the smaller ID ranging from .2195” to .2205” were resized after they were last fired.

It also figgers that those AI necks where you’re getting a larger ID ranging from .2235” to .2245” have not been resized since their last firing. If after firing along with a bit of spring back, the neck ID is left the same or even less than a bullet’s diameter, then without reducing neck wall thickness via turning, those necks left with wall’s that are too thick are going to be too fat for the AI chamber’s neck ID, assuming accurate measurement.

And, if measuring by the same method you’re getting between .226” to .227” for fired case neck ID’s from your 40XB then yes, apparently the 40XB chamber neck ID is somewhere betwixt .0015” and .0035” larger than the neck diameter of your AI’s chamber.

All said above depends somewhat to entirely on how and what you’ve been using to measure those inside diameters. Pin gauges in increments of .0005” would be great. Small-hole gauges then read using a micrometer can be made to work well enough. But, trying to measure any sort of a smallish inside diameter using a caliper by its lonesome is nothing other than wasted effort. Even though narrow, the flats of the caliper blades simply can’t conform to or at the major diameter within the curvature of the inside walls.