10.5” 5.56 SBR Ammo Recommendations

[TulsaMike]

Sorry bro, but you might want to go back and check this info. You lose or gain about 25fps per inch of barrel. A reduction of 5.5" is only about 137.5 ish fps reduction in velocity.
For your "heavy bullet" comment I'll use MK262 with it's 77gr SMK traveling at the advertised 2750fps from an 18" barrel as an example.

18" - 10.5" = 7.5" reduction in bbl length
7.5" x 25fps = 187.5fps reduction in velocity
2750fps - 187.5fps = 2562.5fps
MK262 out of a 10.5" SBR is traveling at around 2562.5fps using the advertised base velocity for MK262. It'll vary but put a chrono on it to see the actual. It certainly isn't going to be moving less or barely over than 2000fps out of a 10.5".

M193 55g is moving at 3250fps so out of the 10.5", it's leaving at approximately 3062.5fps or less because the advertised velocity is probably for a 20" barrel.

BTW, as long as you're running a tight twist, like 1-7 or less, >70gr projos work just dandy. 77gr from a MK18 or M4 is very accurate well past 500m.

Iim going to try and be a nice guy since I'm new here, but you're WAY off on ALL of your claims. Go buy a chronograph like I did and measure what your rifle ACTUALLY does, and you might be surprised how wrong the internet is. I admit I made a mistake in I meant to say the advertised velocity to a 10.5 is a 400 fps loss, not 16 to 10.5. A 75 grain bullet is also going to lose more speed going from 16 to 10.5 than a 55 gr will. The only difference comes when you have a powder designed around a short barrel, such as the TAP ammo specifically does. Most 5.56 ammo types are designed for 20 inch or longer, so the powder burn loss from 16-20 is decent, but not critical, where as going from 16 to 10.5 makes a significant difference not only in velocity, but energy. a 10.5 inch barrel is not achieving 3050+ fps with a 55 gr bullet. Not ever.

 

[GunSlingingPlatypus]

Shoot whatever you want and can afford. A 10.5" isn't used for long range competitions. Any 55 gr or 62 gr will work just fine out of it.

 

[JEVapa]

Iim going to try and be a nice guy since I'm new here, but you're WAY off on ALL of your claims. Go buy a chronograph like I did and measure what your rifle ACTUALLY does, and you might be surprised how wrong the internet is. I admit I made a mistake in I meant to say the advertised velocity to a 10.5 is a 400 fps loss, not 16 to 10.5. A 75 grain bullet is also going to lose more speed going from 16 to 10.5 than a 55 gr will. The only difference comes when you have a powder designed around a short barrel, such as the TAP ammo specifically does. Most 5.56 ammo types are designed for 20 inch or longer, so the powder burn loss from 16-20 is decent, but not critical, where as going from 16 to 10.5 makes a significant difference not only in velocity, but energy. a 10.5 inch barrel is not achieving 3050+ fps with a 55 gr bullet. Not ever.

You're good dude, thank you, but you don't have to be nice here. There's a generous population of D**k-Holes on this forum. If there's some d**k-holery going on, you go to the ignore list.

I did use the wrong number for the 55gr, but no problem. I'm going to the farm today with both guns and ammo and my chrono and see what I get.

 

[Jonny]

If you're not familiar with it, there was a very good barrel length/velocity test several years ago on ar15.com. Should help resolve any velocity questions.

Suppressed 5.56 SBR Velocity Tests--41 Factory Loads from 10.5", 11.5", 12.5" & 14.5" ALL DONE! - AR15.COM

Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.

www.ar15.com

 

[TulsaMike]

You're good dude, thank you, but you don't have to be nice here. There's a generous population of D**k-Holes on this forum. If there's some d**k-holery going on, you go to the ignore list.

I did use the wrong number for the 55gr, but no problem. I'm going to the farm today with both guns and ammo and my chrono and see what I get.

I hope to start coming out with the shooting groups on here and having fun, but having only been in OK for 5 weeks, I don’t know where to shoot other than our LE range, which is only 50 yards. When I was in arizona, I had a private 1 mile range, a $20,000 reloading setup with 4 Dillon presses, 3 charge masters, and a lot of measuring equipment, benches, scales etc. 3 times a week I’d go out and play with different bullets, powders, casings, change oals and loads, crimp force, etc. I really got to see what rifle could do what, and see how they shot to the longest distance they could, as well as accuracy up close. I also spent a lot of time testing factory ammo out of each rifle, and was amazed that 3 10.5 inch guns with identical ammo could vary 100-150 fps, as well as standard deviation spreads between the rounds. Basically due to the abilities and resources I had, I went full nerd and just compiled tons of data out of boredom. I’m not trying to say that im better than anyone else when it comes to this stuff, but I can say with great confidence that much of what I discovered was significantly different than what the internet typically claimed, and way off from what manufacturers did. Some were making velocity claims based on 24-28 inch barrels, and in big bore, 32+ inch, which is insane and very deceiving since it’s rare anyone has a rifle configured that way.

Anyway, I don’t think anyone deserves to be talked down to, and I forget I’m not established here like I was back home with people who followed me or knew me, so I apologize for any attitude.

 

[JEVapa]

I hope to start coming out with the shooting groups on here and having fun, but having only been in OK for 5 weeks, I don’t know where to shoot other than our LE range, which is only 50 yards. When I was in arizona, I had a private 1 mile range, a $20,000 reloading setup with 4 Dillon presses, 3 charge masters, and a lot of measuring equipment, benches, scales etc. 3 times a week I’d go out and play with different bullets, powders, casings, change oals and loads, crimp force, etc. I really got to see what rifle could do what, and see how they shot to the longest distance they could, as well as accuracy up close. I also spent a lot of time testing factory ammo out of each rifle, and was amazed that 3 10.5 inch guns with identical ammo could vary 100-150 fps, as well as standard deviation spreads between the rounds. Basically due to the abilities and resources I had, I went full nerd and just compiled tons of data out of boredom. I’m not trying to say that im better than anyone else when it comes to this stuff, but I can say with great confidence that much of what I discovered was significantly different than what the internet typically claimed, and way off from what manufacturers did. Some were making velocity claims based on 24-28 inch barrels, and in big bore, 32+ inch, which is insane and very deceiving since it’s rare anyone has a rifle configured that way.

Anyway, I don’t think anyone deserves to be talked down to, and I forget I’m not established here like I was back home with people who followed me or knew me, so I apologize for any attitude.

So I think we are both correct and incorrect to which I can own. I should have known better than to apply a rule that works better for heavier/slow-er projos to small fast rounds and and shorter than 16". I also knew better as I've done this before on some stuff in a previous career but the 400fps in 5.5" pushed a button.

I went out on Monday and got the below data from 3 different guns: MK12 18" 1-8, Recce Rifle 16" 1-7, and a MK18 URG 10.3" 1-7. Two cartridges were MK262 77gr and M193 55gr (LC), with no mixed lots, and 5 round groups. (commercial)
No Atmospherics measured, but if someone's really concerned about it, they can go to the weather channel and look at Monday's data for Cement at 1400-1600.

BLUF: I'd take 77gr over 55gr for a 10.5", period. @18" MK262 is 2792fps, M193 is 3313fps; @16" MK262 is 22670fps, M193 is 2992fps; @10.3" MK262 is 2423fps, M193 is 2667fps. From 18" to 10.3", MK262 has a MV loss of 369fps and M193 has a MV loss of 646fps. 18" to 16" was 122fps and 321fps respectively. 16" to 10.3" was 247fps and 325fps respectively.
Both rounds were still smoking out of a 10.3" bbl. MK262 at 2423fps is certainly not barely over 2kfps and will wreck somebody's day all day every day. The M193 is over 2650 and out of a 10.5" bbl, would probably be closer to 2700fps.

No data on a 14.5", maybe later.
Additionally, MK262 from a 10.3" (2423fps) goes trans at ~660m; M193 (2667fps) goes trans at ~530-560m. MK262 has consistently more energy as well.

MK12 18” BBL
MK262
AVG 2792 ES 33 S-D 16

2777
2809
2779
2787
2810

M193
AVG 3313 ES 64 S-D 24.9

3325
3351
3287
3305
3300

RECCE RIFLE 16” BBL
MK262
AVG 2670 ES 34 S-D 13.2

2666
2680
2672
2685
2651

M193
AVG 2992 ES 86 S-D 31.6

2947
2996
3006
2982
3033

MK18 URG 10.3” BBL
MK262
AVG 2423 ES 30 S-D 12.3

2428
2432
2418
2404
2434

M193
AVG 2667 ES 83 S-D 31.9

2612
2675
2678
2677
2695

 

[Grendelshooter]

Can’t go wrong with 75-77gn

 

[TulsaMike]

So I think we are both correct and incorrect to which I can own. I should have known better than to apply a rule that works better for heavier/slow-er projos to small fast rounds and and shorter than 16". I also knew better as I've done this before on some stuff in a previous career but the 400fps in 5.5" pushed a button.

I went out on Monday and got the below data from 3 different guns: MK12 18" 1-8, Recce Rifle 16" 1-7, and a MK18 URG 10.3" 1-7. Two cartridges were MK262 77gr and M193 55gr (LC), with no mixed lots, and 5 round groups. (commercial)
No Atmospherics measured, but if someone's really concerned about it, they can go to the weather channel and look at Monday's data for Cement at 1400-1600.

BLUF: I'd take 77gr over 55gr for a 10.5", period. @18" MK262 is 2792fps, M193 is 3313fps; @16" MK262 is 22670fps, M193 is 2992fps; @10.3" MK262 is 2423fps, M193 is 2667fps. From 18" to 10.3", MK262 has a MV loss of 369fps and M193 has a MV loss of 646fps. 18" to 16" was 122fps and 321fps respectively. 16" to 10.3" was 247fps and 325fps respectively.
Both rounds were still smoking out of a 10.3" bbl. MK262 at 2423fps is certainly not barely over 2kfps and will wreck somebody's day all day every day. The M193 is over 2650 and out of a 10.5" bbl, would probably be closer to 2700fps.

No data on a 14.5", maybe later.
Additionally, MK262 from a 10.3" (2423fps) goes trans at ~660m; M193 (2667fps) goes trans at ~530-560m. MK262 has consistently more energy as well.

MK12 18” BBL
MK262
AVG 2792 ES 33 S-D 16

2777
2809
2779
2787
2810

M193
AVG 3313 ES 64 S-D 24.9

3325
3351
3287
3305
3300

RECCE RIFLE 16” BBL
MK262
AVG 2670 ES 34 S-D 13.2

2666
2680
2672
2685
2651

M193
AVG 2992 ES 86 S-D 31.6

2947
2996
3006
2982
3033

MK18 URG 10.3” BBL
MK262
AVG 2423 ES 30 S-D 12.3

2428
2432
2418
2404
2434

M193
AVG 2667 ES 83 S-D 31.9

2612
2675
2678
2677
2695

Daniel defense barrels are very fast, but not all barrels are equal. I’ve seen a 150 fps swing with the same barrel length and different manufacturers. Regardless, good data, but I will still take velocity over weight. There is a lot more to the science behind it than just numbers. In a longer barrel, such as 14.5 and higher, I like heavier rounds. If you’ve used ballistic calculators and actually shoot long range, you also know the bc changes at lower velocities. Most people running a 10.5 or shorter don’t typically tend to shoot past 200 yards, but never the less, losing velocity loses a lot, and there are better rounds with a happy medium. Much of why my agency with 70 gr is because while not really optimal for any length, it works well on all lengths. Others went with 62-64 gr, which has been proven time and time again to be the best for short barrels, especially since most soft points in that range were developed for law enforcement. If you want a similar comparison, many are using 147 gr 9mm today because the fbi said it’s the best. Most testing was done in the Glock 17 for its abilities, and it’s silly to use that round in shorter 3 inch barrels that many carry for self defense due to the velocity loss. Weight alone doesn’t make it superior, and the rounds are designed to function within a certain velocity range to operate properly. In the end, enough hits from anything does the job, but more often than not, velocity is what kills, best so when properly matched to a weight that benefits it most.

 

[JEVapa]

Daniel defense barrels are very fast, but not all barrels are equal. I’ve seen a 150 fps swing with the same barrel length and different manufacturers. Regardless, good data, but I will still take velocity over weight. There is a lot more to the science behind it than just numbers. In a longer barrel, such as 14.5 and higher, I like heavier rounds. If you’ve used ballistic calculators and actually shoot long range, you also know the bc changes at lower velocities. Most people running a 10.5 or shorter don’t typically tend to shoot past 200 yards, but never the less, losing velocity loses a lot, and there are better rounds with a happy medium. Much of why my agency with 70 gr is because while not really optimal for any length, it works well on all lengths. Others went with 62-64 gr, which has been proven time and time again to be the best for short barrels, especially since most soft points in that range were developed for law enforcement. If you want a similar comparison, many are using 147 gr 9mm today because the fbi said it’s the best. Most testing was done in the Glock 17 for its abilities, and it’s silly to use that round in shorter 3 inch barrels that many carry for self defense due to the velocity loss. Weight alone doesn’t make it superior, and the rounds are designed to function within a certain velocity range to operate properly. In the end, enough hits from anything does the job, but more often than not, velocity is what kills, best so when properly matched to a weight that benefits it most.

None of these are DD barrels. Douglas, Wilson Combat, and LMT. I'll stick with the 77gr in all my house/truck guns.

 

[Norman]

Daniel defense barrels are very fast, but not all barrels are equal. I’ve seen a 150 fps swing with the same barrel length and different manufacturers. Regardless, good data, but I will still take velocity over weight. There is a lot more to the science behind it than just numbers. In a longer barrel, such as 14.5 and higher, I like heavier rounds. If you’ve used ballistic calculators and actually shoot long range, you also know the bc changes at lower velocities. Most people running a 10.5 or shorter don’t typically tend to shoot past 200 yards, but never the less, losing velocity loses a lot, and there are better rounds with a happy medium. Much of why my agency with 70 gr is because while not really optimal for any length, it works well on all lengths. Others went with 62-64 gr, which has been proven time and time again to be the best for short barrels, especially since most soft points in that range were developed for law enforcement. If you want a similar comparison, many are using 147 gr 9mm today because the fbi said it’s the best. Most testing was done in the Glock 17 for its abilities, and it’s silly to use that round in shorter 3 inch barrels that many carry for self defense due to the velocity loss. Weight alone doesn’t make it superior, and the rounds are designed to function within a certain velocity range to operate properly. In the end, enough hits from anything does the job, but more often than not, velocity is what kills, best so when properly matched to a weight that benefits it most.

Not to be that guy, but I disagree with most of your opinions on ammo.
First, if the 62 grain FBI loads you were talking about were the Federal FBIT3, those are a 62 grain Trophy Bonded Bear Claw. Those were not designed for ‘fleshy targets’. They are literally one of the best, if not the best barrier blind round made. They’re bonded, and have some of the best penetration in the 223/556 load.

Second, speed doesn’t kill. Tissue disruption kills. A Ford Taurus going 75 MPH will mess you up more/faster than any AR/AK/SKS round will. It disrupts more tissue. IF speed is your primary concern, MK262 is running about 100-150 FPS slower than the FBIT3 62 grain load out of an 11.5” barrel. MK262 is arguably the best SD round when barrier blind rounds aren’t needed, including in the 11.5” barrel. The only exception to this is around 200 yards plus when velocity hit about 2100 FPS and fragmentation stops.

Lastly, stay WELL away from varmint bullets, especially in the 40-55 grain range. They explode on impact, and they do not penetrate NEAR enough for consistent incapacitation. Remember, ballistics gel =/= flesh. It’s merely a standardized metric for penetration and tissue disruption. They throw an awesome cavity for a few inches of gel and stop. That lack of penetration potentially means lack of reaching organs. This is made worse by higher velocities.

There’s plenty of documentation about theses rounds, including Doctor GKR if you want to look further into them.