Bullet weights and choices for 10.5" AR

I shoot 73 ELD’s mostly from my 10.5” these days.

55grn BALL AMMO relies on impact velocity to fragment, but other bullets are happily able to expand and fragment at much lower velocities with much higher reliability.

What twist is your barrel?

Feed it what you want up to the 77’s. Not sure why you’d want to use 80’s/90’s in a 10.5”, but even the 90’s at 1700-2,000 should be at least marginally stable, so picking anything from the standard fare of 45-77 grains will treat you fine.

I shoot buttloads of 77SMK’s and 73 ELD’s from my pistols and SBR’s.

I am not convinced that any 55gr bullet is designed for a longer barrel. I understand that the OP is most likely referring to 55gr FMJ. However, there is a lot of gel testing where 55gr expanding bullets perform better (ie - expand, but don't shatter) out of shorter than 16" barrels. For instance, a 55gr SP will expand but also stay together better at lower velocities. Of course bonded .224" bullets are out there.

The Chopping Block did several tests with short barrels that I found interesting. Here are a couple, but there are more out there.

My 11.5" 223 spits out my 55gr loads in the 2700-2750 range where that same load gets about 2950-3K FPS from my 16"-18" barrels. Out to about 150 yds there is little difference in drift or drop. The velocity at 150 yds from the slower pistol would calculate out to about 2200 FPS. I would certainly think any 55gr bullet is still going to do what it was sent for at that speed. How far do you plan on shooting your pistol?

I'm running an 11.3" barrel and shoot a lot of Frontier ammo. It's what I have the most immediate access to at a fair price. I'm getting something around 2800 fps out of it and although I haven't shot anyone with it, it still makes a mess on freezer burns hunks of meat that I was going to throw out anyway. I think the threshold (just from what I've read) for 55gr fmj to do its job is 2500 fps.

I use the Winchester 64 grain Power Point load in all my defensive carbine and 10.5 " barrel lengths. What I keep the magazines full of at least. It expands well on pigs in a 10.5" to the 220 yard longest shot I've taken with it. I was for a while considering varmint bullets of 45 grains to 55 grains out of the 10" pistols, they do blow up or fragment but they do not quite meet the FBI standards or mine which is simply about a foot of gel penitration.

Balrog said:

I am considering a short barrel AR (10.5" barrel). Knowing that the usual 55g bullets are designed for longer barrels to achieve high velocity and fragmentation, I am wondering if there would be better choices for a short barrelled AR.

What bullet weights and choices are best for short barrelled ARs?

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Interesting question. First we need to look at the intended purpose. What is it that you want the AR to do and at what distance you want to do it at. If you want to plink within 100 yards a 7.5” with 55gr us fine. The 10.5” is very good for CQB but as a short barrel it lack the high speed so You can compensate by using 62gr GreenTips. For home defense the Hornady 75gr bthp are very good. Basically if you keep it under 300 yards you should be fine with 55gr practice ammo and under 100 for more serious stuff.

ETA: Anything that goes over 2400/2500 fps or higher is good to go.
Norma Tactical 223 55gr. They are advertised at 3240 fps and my 11.5 love it.

Gordon said:

I use the Winchester 64 grain Power Point load in all my defensive carbine and 10.5 " barrel lengths. What I keep the magazines full of at least. It expands well on pigs in a 10.5" to the 220 yard longest shot I've taken with it. I was for a while considering varmint bullets of 45 grains to 55 grains out of the 10" pistols, they do blow up or fragment but they do not quite meet the FBI standards or mine which is simply about a foot of gel penitration.

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I was wondering about the varmint bullets. I don't reload much anymore, although it looks like I'm gonna have to start doing 9mm. I prefer to spend my free time shooting rather than loading. Anyway, I was on Freedom Munitions site, and they sell 55gr VMax load for .40 a round. That seemed pretty good to me and the round always seemed to perform when I used it, but wasn't sure about it in a self defense load.

All I'm worried about is distances out to about 100 yards. I seriously doubt that I could get into a situation where I could justify shooting at anyone beyond that distance.

well here you go ! I believe a 10" barrel this will be the close in (less than 100 yard) performance of the round !


Here is the performance of a 16" barrel with a 64 grain bonded Defense round. Pretty close to the Winchester Ranger, Subtract about 250 FPS from the 2700 FPS velocity and it would be like a 10.5" barrel. Better penetration but still expands well.



You have to decide whether a 3" cavity starting at about 1 inch and going back up to 8"
OR a 1.5"- 2" cavity tapering back to 14" will be better for you. Either will certainly get an unarmored perps attention ! Either will kill up thru big dogs with the heavier killing deer ect. well.

And here is a 10" with real 55 grain personal protection ammo !

In our issued 10.5" guns (MK18) we used 77 grain MK262 mostly overseas, and 62 grain (M855 green tip) when the 77 wasn't available. 55 grain was the preferred stateside "training round" as it did less damage to steel targets than the M855. The 55 M193 was also the go-to in the Somalia era from both M16 rifles and the various carbines back then as it was thought to "yaw" better in soft, skinny targets and create more damage.

FL-NC said:

In our issued 10.5" guns (MK18) we used 77 grain MK262 mostly overseas, and 62 grain (M855 green tip) when the 77 wasn't available. 55 grain was the preferred stateside "training round" as it did less damage to steel targets than the M855. The 55 M193 was also the go-to in the Somalia era from both M16 rifles and the various carbines back then as it was thought to "yaw" better in soft, skinny targets and create more damage.

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I don't really know much , practically, about MK262 terminal effect, but I do suspect it is good even at 2300+- of the 10.5 barrel. It is however expensive in any similar format. I too used to load out M855 in my defensive carbines which is a 2500-2600 FPS load out of a 10-11" barrel ,maybe, as I was concerned about soft armor penetration . It does not kill game well tho, the M193 was better at that !
So I arrived at the 64 grain power point Ranger ammo as about optimum and have successfully killed a few pigs with it with a 10.5" barrel. In fact the newest Winchester Hog load is really a bonded (monolithic lead free, newest) version which is about optimum. They open to almost 1/2" and go deep, pretty sure that will do the trick for self defense. Maybe that 55 grain version of Speer's will be even better for pistol length AR use , I'm betting it's close to optimum for up to 200 yards.