Bullet Rechambering Test - OAL

Discussion in 'M, C, L and S Series' started by Syntax360, Jun 2, 2006.

  1. Syntax360

    Syntax360 Moderator

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    Inspired by a thread on another forum, I decided to take a new round of my carry ammunition and chamber it multiple times to observe the effects on the OAL of the round.

    I used a recently recalibrated Mitutoyo digital caliper.

    The weapon tested was a relatively new Steyr M9A1 with probably just a hair under 1000 rounds through it. The barrel was replaced by Steyr a few months ago and probably has about 300 rounds through it.

    The ammo tested was new Winchester Ranger 127gr. +P+. I measured quite a few new rounds and found the OAL varied roughly .05mm.

    So, on to the testing.

    Each time, I took an empty magazine and loaded the round. I inserted the magazine and used the slide release button to chamber the round. When I began, the OAL of the test round measured 28.27mm. After being rechambered 20 times, the OAL measured 28.22mm. Rechambering the round did indeed make a small difference of .05mm. The bullet was also notably scratched.

    I will probably perform this test again in the next day or two on a few more rounds, and I will post the results.

    So now comes my question to more knowledgable members: is this .05mm difference in length going to make any difference in the chamber pressures? I would certainly assume not, as that is the exact length the different bullets varied in the pack.

    Thanks guys!