[119er]

First off, I won't post the SAAMI drawing because of the copyright at the bottom of the page so I will link to it if anyone wants to see it.

http://www.saami.org/PubResources/CC_Drawings/Rifle/30-06%20Springfield.pdf

I have an M1 Garand with a Criterion match barrel installed. The gunsmith that built the rifle said that he reamed a "tight chamber". I am in the process of sizing the brass for this rifle and noticed that the disassembled bolt would just close with no resistance at 2.037" via Hornady headspace comparator. SAAMI minimum chamber spec is 2.048" The bore in the gauge bushing measures .370" for a datum that is .375", so I don't believe it is on oversized bushing reading from further down the shoulder.

The brass is used only in this rifle and I set the die to size to 2.035" or .002" under the headspace clearance I noted. This was achieved before making contact with the shell holder using a Redding NM resizing die. The last time I loaded for this rifle I followed the directions and adjusted to cam over. Luckily for me that die sizes down pretty far!

I suppose my question is, does this matter or is this typical for match rifles?

[Hummer70]

Sorry but I don't follow you on "the bore on the gage bushing"??????

If you have a micrometer measure the diameter of a fired cartridge case .200 up from rim marked as ".200b" on the SAAMI drawing. Though the drawing calls for .4698 -.008 I believe you will find all new unfired 30.06 measures .465 at this point.

Note: the chamber dimension is .4708 +.002".

If your fired case is not SMALLER than .4698 it was not fired in a "TIGHT" chamber. I suspect you have a close headspace only and a big fat chamber which will give you fired cases in the .471" range. I have seen Garands give birth to cases in the .475" range ! ! ! !

The FL size dies for 30.06 I have seen measure .466-.469 on the base dimension.

I run tight chambers on 30.06 bolt guns and I have three reamers. One cuts a .467 base dimension, next one cuts .469 base dimension and the other one a .471 base dimension.

Chambers in the .467-.469 can give phenominal case life if the right size FL dies are used.
Case in point I use my .466 size die to FL size cases fired in .467" chamber and basically there is no dimensional change as fired cases go from .465 to .467 and spring about to .466 after firing thus when the FL die gets through the base of the case is .001 smaller than chamber and basically has not moved.

I have one 30.06 LC Match case I have loaded 157 times in a .467 chamber. On my guns with .469 chamber I size them with either .468 or .469 FL dies. I have a fourth set of FL dies and the biggest sizes at .470 which I use for cases fired in factory chambers.

Sorry to be the bearer of bad news but I don't think you are going to get that many reloads from your rifle unless you size the brass to .469 range.

This may only work for slow fire matches and single loading as you pretty well have to size 30.06 ammo down to around .466 at the base in order to get the reloaded ammo into the Garand clips. Thus for max case life you are going to need to segregate your brass between single loading and semi auto loading.

[higgite]

FWIW, my Hornady headspace comparators for .223 and .308 (sorry, don't have .30-06) both read .010-.011" short of SAAMI specs when measuring no go gauges for those calibers. The Hornady tool is a comparator, not an actual headspace measuring device. That could account for your rifle's "short" headspace measurement.

[119er]

Thanks for the reply Hummer70 but I am talking about the headspace dimension as measured from the case head to the datum point on the shoulder. The dimensions you mentioned are of the diameter of the case. Basically my chamber is shorter in overall length than the minimum shown in the drawing. As I resize brass for this rifle, it is not being squeezed very much at all on the body. Fired cases for this rifle do not grow very much at all.

[119er]

I think I just confirmed your answer higgite. I pulled some brass that I neck size only for a 1903A3 and they measure 2.035" as well. Basically it is a tool of reference to give repeatability rather than an exact measurement. I have a Redding instant indicator on the way. I'll see if I can compare the two and see which is more accurate.

[steve4102]

The Hornady Comparator is designed to "Compare" your fired brass to your sized brass. It is not designed to "compare" to SAAMI specs. It is a universal comaparator that will work with dozens of different cartridges to be compared at the reloading bench only, not to a manual or SAAMI spec sheet.

[243winxb]

As said, tool is to compare fired to sized. I have read some gas guns open the action early. This lets the brass stretch, resulting in a false reading. Turn off the gas to measure fired brass.