I've broken three Rock River Match hammers. All occurred at around the three thousand round mark --- Only the incidents occurred while using a 22 long rifle dedicated upper. Rock River replaced the trigger groups for free. But I later switched to a mil-spec hammer --- Though I have mothballed my two dedicated 22 uppers...due to the danger of OOB's occurring. The OOB's happened three times for me...though fortunately, no one was hurt. Appleseed has banned the use of 22 lr S&W M&P 15's in their competitions, some years ago, due to the danger of OOB's occurring. Though the dedicated 22 uppers I used were not Smith & Wesson.

I believe it was Clint Smith...of Thunder Ranch Training Academy, who insisted that anyone going to train at Gunsite...only use a mil-spec hammer in their AR's --- due to evidence of match grade hammers breaking during training. He also advised them to bring an extra mil spec hammer and other assorted AR parts.

I have never used a KAC hammer in any of my AR's...but I'll check into it --- Thanks

Interesting that you had three OOB events and broke three hammers at 3 thousand rounds... What other fictitious series of 3 have you had........

Interestingly enough, I have over 20,000 rounds on one of my RRA National Match triggers, and the only thing I have done to it is replace the hammer spring and disconnector spring, as I fell below the minimum 4.5lb trigger pull required for Service Rifle as my springs aged (tuned to be 4.5lbs when new). Another RRA Varmint has trigger has around 8,000 on it currently. One of my Geisseles NM 2 stage triggers is over 15,000 rounds over it, with no hiccups. I install a handful of these triggers every year still, if they were breaking for the high volume shooters who buy from/through me, I’d certainly have heard about it. Many of these guys are pumping out 3,000 rounds in a month or so.

:biggrin::biggrin::cool2::happy0001::D:hail:

You sound quite sure with yourself...like you've been reading tomorrow's newspapers.:action-smiley-099:

I would not stake my life on a non mil-spec AR hammer.

"Rock River Arms National Match Trigger - Failure and Repair"


In the vid...the hammer piece broke-off in the same exact place as my 3 other Rock River Match hammers.

I am very sure of myself and my judgement.

Can you comment to support your opinion of the “thin” design of the Geissele match hammer, compared to the thinner necked Mil-spec hammer with a greater head mass?

Have you ever actually seen these components side by side? Or ever?

I’m coming up on my 20yr anniversary with the AR this month. I bought a Spanish Mauser at a local gunshow in the fall of ‘99, which was mis-identified as a 7x57. After a week with it at home, I sought help from a local smith who had done some Garand work for my Service Rifle the year before, in hopes to identify the chambering - turned out to be a 308win, rebarreled with a Springfield Dual Groove. I began apprenticing under the smith shortly thereafter; an old school Mauser and Garandsmith who favored the 70 and turned his nose up at 700’s coming into his shop, and who abhorred AR’s. As a Garand builder for Service Rifle competitors at that time, he was seeing a lot of loyal customers turn toward AR’s, and he was too stubborn to welcome the new business, high customer demand and low labor demand as it was. I none-to-subtly suggested he let me take on the AR builds/rebuilds he didn’t want to keep old and draw new customers, and by March I’d swapped time for parts and built my own Service Rifle (to the tune of about $200). Bushmaster A2 clone with a Krieger barrel and their 2 Stage National Match trigger, nothing fancy, but compliant with NRAHP/CMP, and certainly shot smaller at 600yrds than I was capable.

Fast forward to today, I’ve built and rebuilt over 600 AR’s, uppers, and lowers, over 200 from the ground up. I’m much slower in the last ~8yrs than I was in the 2000’s, but I still crank out a dozen or so every year - I’m sitting on 8 uppers and complete rifles in queue at my bench right now.

Wait for it!!!!:D