Shoulder expansion after firing
- Thread starter perazzisc3
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I'd post this is the gunsmithing section, you'll get better answers. Do you have a concern though?
Are you talking shoulder length ie, shoulder bump or are you talking about diameter of the case body just below the shoulder? If you're talking about the latter, then really the more appropriate way to phrase the question is "How well do my dies fit my chamber?". The diameter at the shoulder is going to be a product of the sizing die dimensions, and each die can be a bit different. On my dies I see between 1-2 thou shoulder diameter reduction on one caliber, and perhaps 3-4 thou on another.
It just depends on what the smith cut. Some I've had .03-004, some go up a digit into the .01s for factory brass. Since you say it's a "tight" chamber I'm interested to know what 1) how you came to arrive at that, specs, smith said, random passerby at the firing line etc and 2) what your measurements were
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What's your frame of reference for expansion? Virgin brass? Factory ammo? Brass you've already resized yourself? How are you measuring the shoulder?
Sounds good to me. I've personally seen more, but 0.001-002 is perfect IMO. Less case stretch on initial firing, less likely to have case head separation down the road. Assuming you can resize your brass properly to get the right amount of shoulder bump and overall sizing for repeated firings then I'd say you have a perfect chamber.
.001-.002 in a semi? With a tight chamber and 10 - 15 rounds fired might the chamber be fouled enough to possibly cause cycling issues?
Well by default we go towards thinking of bolt actions but if you're worried about it that much run it until you have an issue and if you do then bump them back another 1-2 thousandths. I'm gonna assume its factory ammo since you didn't just set the shoulder where you wanted it to start with or you loaded all of your virgin brass at once but you can bump loaded ammo with a body die provided you're not shooting a compressed load and it has space to go.
The difference between a .223 shoulder and a 5.56 shoulder is 3 thousandths. That would lead me to believe that in an M-16 you would expect less than 3 thousandths of an inch of fouling between cleanings.
The other difference in .223/5.56 chambers is the throat. And yes you're shooting a 6.5, I am using the chamber specs for comparison.
The other difference in .223/5.56 chambers is the throat. And yes you're shooting a 6.5, I am using the chamber specs for comparison.
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