Previously, courtesy of The Wound Channel we got our first looks at the stellar ballistics of the 7.62mm M80A1 EPR round, which proved to combine excellent fragmentation with good armor penetration and barrier blind characteristics, while being extremely consistent. Now, TFB has received ten M80A1 cartridges, so I decided to dissect one of them to take measurements of the new round and its 130gr EPR projectile.

To do that, first I broke the tension in the cannelure by using a press to seat the bullet more deeper in the case, then I mounted the round into a kinetic hammer and went to town against a hard rubber mallet until the bullet was dislodged. Then I measured the bullet’s components for weight using my powder scale:

The bullet measured 8.48 grams, or 130.87 grains.

The case with primer weighed 12.30 grams, or 189.82 grains. Large rifle primers typically weigh about 0.35 grams per, so we can estimate a case weight of 11.95 grams or 184.42 grains.

The powder in a stainless steel cup weighed 38.08 grams. The cup weighs 35.18 grams, so that gives us a powder charge of exactly 2.90 grams (44.75 grains).

Next I measured the bullet for size; the only picture that was very convenient to get was overall length, as for the others I would have needed three or four hands to measure and photograph at the same time.

There was a little corrosion on this round, which is why I chose to dissect it. You can see the black sealing tar used to waterproof this round, as well as other military cartridges. If practical, I like to use military rounds for personal defense for this reason.

The dimensions were:

Bullet overall length: 1.1865″

Nose length: 0.640″

Meplat diameter: 0.033″

Boattail diameter 1: 0.220″

Boattail diameter 2: 0.265″

Boattail length: 0.170″

I should also say that before I broke apart one round, I weighed all ten rounds that I received, and got an average cartridge weight of 23.72 grams (366.06 grains) for an M80A1 round.

Next, I tried to dissect the bullet. I say “tried”, because I did so without the benefit of a cutter or many of the other tools I would normally use for that job. So a vice and small hacksaw was it. I was able to cut the bullet along the cannelure, and once I had made some progress, I found that I was able to snap the bullet in half by hand!

You can see the different color of the copper slug against the gilding metal jacket in this photo.

I wasn’t able to dislodge the copper slug or the steel penetrator, but that didn’t stop me from getting some measurements:

Jacket thickness (at base of penetrator): 0.022″

Penetrator length: 0.731″

Copper slug length: 0.425″

Copper slug diameter: 0.261″

The jacket on M80A1 and M855A1 are not uniform in thickness all the way around; we can see the variations in this bullet section from wolfganggross:

Image source: AR15.com

Wolfgang gives a tested value of RHC 48-49 for the penetrator, which is nearly as hard as tool steel, and is a rating very typical of actual armor piercing steel penetrators (as opposed to mild steel cores). When I was working on cracking the bullet, several times my hacksaw skated off the penetrator without leaving a mark!

That’s all for now!

I am a nerd.