- Thread starter Judd
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Re: Pressure on AR???
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Beef</div><div class="ubbcode-body">Primer flattening doesn't always mean much, but it is something to get you looking. I find with mine heavy ejector marks and the extractor tweaking the rim are pretty clear indications. </div></div>
What he said^^^^
primer flattening is really very deceiving, and some flattening is a good sign.
The ejector marks will show up as brightly shining scrape marks on your brass, this is telling you you are at/near max. Go no further in powder charges.
If you're REALLY into high pressure territory, then you will get the actual IMPRINT of the bolt face engraved into the brass. The brass will flow into the ejector hole on the bolt. The headstamp and primer may even be "smeared." Do not fire any more of this ammo.
I have found that many AR's, even though marked 5.56 on the barrel, are not truly chambered 5.56 and show pressure signs much earlier than the true 5.56 guns. I bought a Christensen reamer and ran it through all my AR's. Only my Colt was a true 5.56--all the elcheapo AR's were not, even though they are marked as such. They are now, thanks to the reamer. More info on this at michiguns.com.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Beef</div><div class="ubbcode-body">Primer flattening doesn't always mean much, but it is something to get you looking. I find with mine heavy ejector marks and the extractor tweaking the rim are pretty clear indications. </div></div>
What he said^^^^
primer flattening is really very deceiving, and some flattening is a good sign.
The ejector marks will show up as brightly shining scrape marks on your brass, this is telling you you are at/near max. Go no further in powder charges.
If you're REALLY into high pressure territory, then you will get the actual IMPRINT of the bolt face engraved into the brass. The brass will flow into the ejector hole on the bolt. The headstamp and primer may even be "smeared." Do not fire any more of this ammo.
I have found that many AR's, even though marked 5.56 on the barrel, are not truly chambered 5.56 and show pressure signs much earlier than the true 5.56 guns. I bought a Christensen reamer and ran it through all my AR's. Only my Colt was a true 5.56--all the elcheapo AR's were not, even though they are marked as such. They are now, thanks to the reamer. More info on this at michiguns.com.
Re: Pressure on AR???
On can also mic the case head. Measure before firing just above the extractor groove where the case head is solid. Measure after firing. Expansion of this part of the case is not a good thing. Recommendations as to the limit vary from .0005" to .001". Just remember that if the solid part is expanding, it's doing so because of lots of pressure.
On can also mic the case head. Measure before firing just above the extractor groove where the case head is solid. Measure after firing. Expansion of this part of the case is not a good thing. Recommendations as to the limit vary from .0005" to .001". Just remember that if the solid part is expanding, it's doing so because of lots of pressure.
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