Home Forums Hunting & Shooting AR and Tactical Rifles 5.56 barrel length and bullet performance

77gr TMK in gell, 10.5" and 20" barrels at point blank range:







Best video I could find of a 62-64gr bonded bullet, the 62gr Trophy Bonded Bear Claw:




Here's the 75gr Hornday:



69gr SMK:



40gr Mono bullet:



Mk262 77gr OTM, IMI style:


55gr GMX:




And How about some 55gr Sierra Blitz Kings lifting 16 pounds of gel off the table:

Knock it off dude - I thought I was on facebook there for a minute.

What gas do they use for a 12.5 inch? Carbine??

There are very few using 12.5”s. Mid-length 12.5” with a correct gas port, and suppressed has proven to work very well with A1.

SOCOM has chosen 11.5” over 10.5” for the future, with the 11.5”s being standard, not 14.5”.

It's not just about the weight of the bullet, but how it's made. When we switched to widespread use of SBRs we moved to the 75grain Gold Dot because it was what would reliably expand at lower velocities. The lighter bullets are made to be pushed fast and hold together at those speeds.

THIS

Blue,

Do you have any info comparing the GD's performance to a Hornady 75 BTHP or a Sierra 77 SMK or a TMK? Either in gel or some other test?

Thanks.

MM

75gr gold dot from 10.5" and 20" barrels in gel, and through a windshield into gel.

Thanks, AS.

That looks like pretty good performance............pretty significant difference in the violence of the impact of the gel block between the 20" barrel & the shorter version, even though the overall wound channel was that much different.

I'll have to go & try to dig up some gel test on the Hornady 75 & the SMK's for comparison.

MM

I already posted them above.


The 77gr Sierra TMK and 62gr bonded bear claws are pretty impressive as well.

Bottom line is , regardless of what the narrator in the video says, they would all be highly effective as home defense loads.

For environments where low penetration is desired, such as dense dwelling environments, check out the 55gr Sierra Blitz kings are pretty wicked as well.

If you want the best of both worlds, a mag a heavy bonded bullets coupled to a mag of the Blitz Kings, or something in that class.

Went back & looked at those...............good info & thanks for posting.

Yes, the TMK's are impressive as are the IMI 77's................for non-handloads, I shoot the IMI stuff quite a bit, both 55's & the 77's.

And I've loaded a lot of the 77 & 69 TMK's & both shoot well for me; I'm not splitting hairs for minor absolute differences in group size compared to SMK's, so I'm satisfied with both.

My only complaint with the TMK's is that when loaded to 2.250, the case neck is right at the ogive.......any deeper & you are into the ogive for sure. I usually use them in ASC mags which allow a little more length.

Here's a link & some pics from a MOLON post on SH that clearly shows what I just said.

BH Mk-262 TMK Info

MM

Somebody has the gel test results but I don't have them handy. I wasn't directly involved in the testing. But our selection accounted for things that might not matter to anyone else.... We had to have a round that would expand at 200 yards from whatever velocity it produced in an 11.5" barrel, would stabilize in a 1-9" barrel, and we could reliably source in very large quantities.

Pretty solid info on this site. Black column on left side opens up with variety of info.
AR15 Ammo Oracle

Beauty of AR platform is the variety forms it can be made into. Service rifle, CQB carbine, DCM target, DMR, hunting etc.
I shoot 16" 1:7 twist with Sierra 77OTM, and have no intention of using my carbine >200yrds. So my standard ammo is HFC.
Debate of light & fast vs heavy & slow is never going to end, regardless of application.
2 holes are better than 1.

funny thing about all of this, American Soldiers in Korea complained about 110 grain bullets at 2000 fps, and yet today we seem to be happy with short barreled results of 2200 with a 75 grain bullet. Given the 110 was a FMJ, OTOH the M1 carbine has not been used much as a deer rifle.

You’re comparing the ballistics of a 30 cal bullet with a BC of 0.178 against a 224 bullet with a BC of 0.395 Why?

Do you think external ballistics matters that much at 50-100 yards?

I think the terminal performance is much different, and most of that is based on bullet profile.

Fixed that for ya.

Jimmyp, if you're trying to form a conclusion about 5.56 based on a round nose 30 carbine FMJ bullet - just stop. They have very little in common and do not perform at all the same way. The type of bullet used makes a huge difference.