Home Forums Hunting & Shooting AR and Tactical Rifles AR-15 & 60 grn bullet loads

For those of you that have an AR-15 with 16" barrel....
What kind of speed (fps) can a person generally get with a 60 grn bullet load?
My barrel will have a 1 in 7 twist.

2900'ish...

Probably, but if you are loadin' em yourself, back it off to 2700 or so and your gun will run better and likely be more reliable, especially in hot weather.

I run 63's from my 18" to 2950 without even trying and feed/function is absolutely superb...

I do some perdiem work at a place where you literally walk around on 556 brass. Mostly mil units with M4's come there. Trust me. Hot ammo out of short barrels can cause issues, bolt-over base malfunctions, cracked bolts for starters.

You are right though, an 18in mid-length is a good bit more reliable. I believe a 16in is more reliable than an M4 length, but I don't have any data to prove it.

An AR is no different than any other gun (or machine) if you don't flog the hell out of it, it'll last longer.

The gas tube on the 16 and 14.5in is in the same place. If anything, the shorter barrel should give the better reliability because it allows the port pressure to bleed off faster. Port pressure on all the shorty's is just over 20kpsi which causes a bouncing effect of the bolt. The later style extractor springs helped to almost eliminate the issue with the extractor bouncing over the rim while the bolt comes back. Also, a lot of supposedly "mid lengths" still use an M4 length gas tube, which kinda defeats the purpose. Gas port pressure on a standard 16" is around 16kpsi IIRC.

M16's gas port pressure is 13kpsi, M4 gas port pressure is 26kpsi.

Well let's see, my notes show carbine gas at 26k, mid length at 17k and rifle at 13.5k. Assuming full blown 62,000psi loads.

A mid-length using a carbine gas tube? would be a carbine gas system in my book.

Chamber dimensions and gas port size would also alter readings.

I've run full blown hot loads in my Colt 16" carbines for a long time, given a gun built right, using the right extractor spring, a good extractor, at least an H buffer will run along time before falling apart. (BTW, I watched a great high speed video on bolt bounce and the buffer has more to do with it than anything in my opinion. Also don't use 9mm buffers, the solid core causes more bounce than loose weights.)

But yes going all out will speed wear and tear, part of the deal that I can accept.

Now for the 16" velocities, I've ran the 60gr V-max at an average of 2963fps with Benchmark. I have a new toy that I hope to use up the rest of these and am very interested in everyones loads.

Can't comment on the 60 grain loads as I don't recall mine anymore.

I can say I never shot mild loads, and with the gun setup correctly, at least with 20 inch tubes. But I never saw any gun abuse, never cracked a bolt etc and never used a weight on the carrier...

I mean't to say a 16in mid-length was supposed to be a more reliable setup than M4 length.

I run a 60 gr. V-Max @ 2900 fps. out of my 16" carbine, it consistantly shoots 3/4" @ 100 yds.