Sig Sauer 77gr OTM: An Accidental Review

I accidentally the whole thing…

Let me explain the use of that ‘ancient’ internet trope.

On this particular trip to the range I did not intend to evaluate Sig’s 77gr OTM 223 Remington ammunition… yet.

There were a number of other tasks already on the plate and isolating that one and testing the ammunition was going to be a later task. But I did bring it out to get some pictures in the sunshine and if the fates aligned on other items I would shoot some to group and zero.

Then the shooting started… and during a particularly vigorous live fire drill in the afternoon I started grabbing magazines… magazines that had been loaded with my supply of shiny 77gr OTM

Several magazines later, a pair of 20rd and a pair of 30rd on the end, I had a smile on my face and a nice hot SCAR 16. My eye caught the tail end of a case though and I was momentarily puzzled. It wasn’t a Federal headstamp, like the 55gr I was shooting had…

After a few Holmesian deductions the inescapable conclusion was I had just estactically burned through my pile of 77gr OTM. Oh well. No crying over fresh fired brass. I did enjoy it.

I had wanted to save some for “social” use. The kind that should someone become lethally anti-social and begin the murders, kidnappings, or rapes I could hit that share button and demonstrate just how effective 77gr is at stopping such abhorrent activities. A real SJW activity, more commonly referenced as the rights of self preservation.

What happened on the range?

I was having a good time and started grabbing ammo from the closest magazines.

Performance wise: Sustained fire groups shrank by about 50% in my SCAR firing supported. 55gr XM193 punches the target I want but the 77gr went unerringly where I told it to go. This accuracy increase is consistent with SOCOM’s evaluation on Mk262, a 77gr OTM round.

REFactor Tactical has some excellent accuracy diagnostic targets

Shooting at the REFactor Tactical GTG Baseline I went A-G across the target. I was shooting rapid fire/sustained rate and the rest of target was already dirty with other shots and zeroing other guns. [This is an excellent consistency drill target, review on a set to come]

The A-G circles were clean though and 50 meters was fun to pop shots.


Tore out the A raggedly with 30 rounds. Reload.


Tore out the B with a couple fliers. Reload


C tore up with several shots just outside. One punched the D. Whatever, I’m having fun. Reload.

20 rounder this time and I can get low and steady on the bench. My friend is beside me playing single shot and controlled pair talking guns with me and his new 14.5″ AR with LPVO firing center mass.

Fire. Tear out the D. Tight group. I felt I had zoned in on my cadence. (I had also just switched to the 77gr)

Reload. Fire. Reload. Fire. Reload. Fire. D through G had some seriously impressive groups looking through my ACOG. 20, 20, 30, 30 in nice notably tighter patterns from the A-C shooting.

I need to bench this ammo through a precision set up in the future but the accuracy in rapid is encouraging to see.

Why Sig 77gr?

This is a factory match load. It’s well made. Well regulated for discrepancies and variance and flies very accurately. Bullets will be consistently made, powder consistently measured, and brass inspected on loaded to a higher standard.

For true match purposes I’m certain a handload could do best but I’m not looking for a Precision Rifle Series load… yet. I’m looking for an effective social/duty round.

So on top of the increased accuracy, consistent performance, and extra attention given to the load at the factory I require something that gives excellent terminal performance.

“Ballistics tests found that the round [Mk262 77gr OTM] caused “consistent initial yaw in soft tissue” between 3 and 4 in at ranges from 15 feet to 300 meters. Apparently it is superior to the standard M855 round when fired from an M4 or M16 rifle, increasing accuracy from 3–5 minutes of angle to 2 minute of angle. It possesses superior stopping power, and can allow for engagements to be extended to up to 700 meters when fired from an 18-inch barrel. It appears that this round can drastically improve the performance of any AR-15 weapon chambered to .223/5.56 mm. Superior accuracy, wounding capacity, stopping power and range have made this the preferred round of many special forces operators, and highly desirable as a replacement for the older, Belgian-designed 5.56×45mm SS109/M855 NATO round. In one engagement, a two-man special forces team reported 75 kills with 77 rounds.[121][122] The Mk 262 has a higher ballistic coefficient than the M855 of (G1)0.362 / (G7)0.181, meaning it loses less velocity at long-range.[109]” – Synapsis on the Mk262

The 77gr round is better at the job across the board. Mk262 Mod 1 is a militarized variant on a .223 Remington match round from Black Hills Ammunition. They swapped to 5.56x45mm brass and optimized the powder for low flash and increased chamber heat in a higher rate of fire military application. The round, originally designed for bolt action slow fire, was toughened for running in semi-auto and automatic fire.

Sig Sauer’s variant on the 77gr OTM has been developed where higher rate of fire semi-automatic use is the norm. Their round feeds and cycles flawlessly and the performance on the target is precisely what I wanted to see. The lead core rounds are superior to the M855 when it comes to terminal ballistics and overpenetration concerns. Superior wounding capability and improved range just further opened the envelope of what the rifle I put it through can do.

In short, its title says “Elite Match” however it is an even more ideal self defense and home defense candidate. The 77gr OTM boosts accuracy, tissue disruptive properties, and avoids many of the limitations and potential hazards of the partial steel core M885/SS109.

At $24.95/box or less (bulk) it’s right in the range of reasonable defensive ammo.

Keith Finch
Keith is the former Editor-in-Chief of GAT Marketing Agency, Inc. He got told there was a mountain of other things that needed doing, so he does those now and writes here when he can. A USMC Infantry Veteran and Small Arms and Artillery Technician, Keith covers the evolving training and technology from across the shooting industry. Teaching since 2009, he covers local concealed carry courses, intermediate and advanced rifle courses, handgun, red dot handgun, bullpups, AKs, and home defense courses for civilians, military client requests, and law enforcement client requests.