Best 5.56 ammunition for an SBR?

[WS6]

I have read the tacked page, and it covers the aspect of terminal ballistics completely, as well as the attributes of a good round from an SBR (barrier blind).

My question is as relates to the performance of the cartridge regarding internal ballistics.

I know the MK318 SOST was developed with the 10.3" barrel in mind. As such, it seems the powder has a rather quick burn rate, and a flash suppressant.

What other rounds produce minimal flash and have the most complete powder burn in 10.3-12.5" barrels, that are also barrier-blind in nature?

[C4IGrant]

The top choices would be (for me):

SPEER GD (55gr or 64)
Federal T1 or T3
TSX

All of these rounds are going to greatly extend the "lethality" of an SBR.



C4

[WS6]

The top choices would be (for me):

SPEER GD (55gr or 64)
Federal T1 or T3
TSX

All of these rounds are going to greatly extend the "lethality" of an SBR.



C4

I had originally pretty much settled on the 70gr TSX by SSA, but have read a lot on TOS about poor accuracy from them in SBR's, and Art from SSA even chimed in with this (not linked because of the rules?) People were saying they got 2-5MOA out of it from weapons that shot 1MOA normally, and pictures of same-day groups were posted indicating as much. I was VERY unimpressed. I don't want 1MOA accuracy, or rather, "require" it, but 4+ MOA is just crap.:

Originally Posted By 426ART:
suppressors will increase stability as well as accuracy as it channels the blast, we see this in testing all the time. The lose of accuracy in short barrels is a given because max pressure is reached around 1/3 the way down a 16' barrel. When you cut 4 to 8 inches from the barrel as the bullet leaves the bore pressures are higher up the down slope of the pressure curve. As the bullet leaves the bore (in shorter barrels) the pressure blows by the bullet throwing the base of the projectile, basicly it reacts on the bullet as if you had a damaged crown on the end of your barrel therefore lose of accuracy.

Suppressors also increases pressure into your gas port allowing you to use a lighter faster projectile that may short stroke your SBR without a suppressor..


Art - SSA

Personally, I find the above a bit odd considering the sub 1 MOA groups posted in threads where people couldn't get SSA's 70gr TSX (or any hand-loaded variation) to come even close. It did bad in SBR's, good in 16"+ barrels. Maybe the TSX is a poor design for an SBR. I wish I could link the thread. Some guy handloaded 62-70gr TSX's to all sorts of OAL's and charges and with different powders, and they did well from his longer barrel weapons, but they were all a big boat of fail from his Noveske, and Colt SBR's.

I am running a Surefire 556-212, btw, as well as a flash-hider, so my question about burn-rate is in regards to being nice to my blast-baffle, as well as wanting to reduce FRP/Flash.

I am looking for reliable, meaningful expansion out to about 200 yards. This is for the intent of it doubling as a hog gun.

With this, I want the most complete powder burn and least flash possible. I like the SOST round, but would prefer something with more expansion/less fragmentation.

[vicious_cb]

I had originally pretty much settled on the 70gr TSX by SSA, but have read a lot on TOS about poor accuracy from them in SBR's, and Art from SSA even chimed in with this (not linked because of the rules?) People were saying they got 2-5MOA out of it from weapons that shot 1MOA normally, and pictures of same-day groups were posted indicating as much. I was VERY unimpressed. I don't want 1MOA accuracy, or rather, "require" it, but 4+ MOA is just crap.:



I am running a Surefire 556-212, btw, as well as a flash-hider, so my question about burn-rate is in regards to being nice to my blast-baffle, as well as wanting to reduce FRP/Flash.

I am looking for reliable, meaningful expansion out to about 200 yards. This is for the intent of it doubling as a hog gun.

Heavier isnt necessarily better when it comes to expanding rounds. The 50gr TSX from Black Hills would be ideal or the other lighter TSX bullets would work as well.

[WS6]

Heavier isnt necessarily better when it comes to expanding rounds. The 50gr TSX from Black Hills would be ideal or the other lighter TSX bullets would work as well.

I have heard, and correct me if I am wrong, as I am new to the NFA world, that a lighter projectile is more likely to cause a baffle strike in a 1/7 twist weapon than a heavier one, provided that it isn't too long to have a GSTAB of 1.3 or greater.

From an SBR, the 70gr TSX will achieve optimal expansion to nearly 300 yards, the 50gr, only out to a bit past 100, based on MV, BC, and Barnes' specification for expansion/velocity threshold. Also, the 70gr tends to penetrate better on things like hogs.

That was the logic for my preference until I read of the accuracy issues people were having. my SBR is still a few months out, but I would like to start stocking up on some good ammo, and don't want to stock up on something "known to do poorly". Sure, my SBR may shoot horrible with something everyone else's likes, but it's a better place to start than with something that noone has any luck with.

[vicious_cb]

I have heard, and correct me if I am wrong, as I am new to the NFA world, that a lighter projectile is more likely to cause a baffle strike in a 1/7 twist weapon than a heavier one, provided that it isn't too long to have a GSTAB of 1.3 or greater.

From an SBR, the 70gr TSX will achieve optimal expansion to nearly 300 yards, the 50gr, only out to a bit past 100, based on MV, BC, and Barnes' specification for expansion/velocity threshold. Also, the 70gr tends to penetrate better on things like hogs.

That was the logic for my preference until I read of the accuracy issues people were having. my SBR is still a few months out, but I would like to start stocking up on some good ammo, and don't want to stock up on something "known to do poorly". Sure, my SBR may shoot horrible with something everyone else's likes, but it's a better place to start than with something that noone has any luck with.

If you're worried about stability the 70gr has one of the worst since its so long. Longer than a 77gr SMK.



From a purely shooting at 2-legged creatures from an SBR standpoint, the 50gr Black Hills load is ideal but trying to hunt hogs out to 300 yards with said SBR? I dont know about that. The 50gr TSX starts out faster, is more robust but has a higher velocity expansion threshold. The 70gr load starts out slower, has a lower expansion velocity threshold but doesnt do as well through barriers.

[C4IGrant]

I had originally pretty much settled on the 70gr TSX by SSA, but have read a lot on TOS about poor accuracy from them in SBR's, and Art from SSA even chimed in with this (not linked because of the rules?) People were saying they got 2-5MOA out of it from weapons that shot 1MOA normally, and pictures of same-day groups were posted indicating as much. I was VERY unimpressed. I don't want 1MOA accuracy, or rather, "require" it, but 4+ MOA is just crap.:



Personally, I find the above a bit odd considering the sub 1 MOA groups posted in threads where people couldn't get SSA's 70gr TSX (or any hand-loaded variation) to come even close. It did bad in SBR's, good in 16"+ barrels. Maybe the TSX is a poor design for an SBR. I wish I could link the thread. Some guy handloaded 62-70gr TSX's to all sorts of OAL's and charges and with different powders, and they did well from his longer barrel weapons, but they were all a big boat of fail from his Noveske, and Colt SBR's.

I am running a Surefire 556-212, btw, as well as a flash-hider, so my question about burn-rate is in regards to being nice to my blast-baffle, as well as wanting to reduce FRP/Flash.

I am looking for reliable, meaningful expansion out to about 200 yards. This is for the intent of it doubling as a hog gun.

With this, I want the most complete powder burn and least flash possible. I like the SOST round, but would prefer something with more expansion/less fragmentation.

That is interesting. I have a Noveske 10.5 (hammer forged) barrel that will shoot 1.5" groups (or better) with many different types of ammo.

I also have some brown tip (issued) ammo and I will have to shoot some for group to see if it is SSA's load or if what they are saying is accurate.


C4

[C4IGrant]

The 70gr load starts out lower but has a lower expansion velocity threshold but doesnt do as well through barriers.

I don't think any of the TSX loads do as well (through barriers) as the bonded bullets.




C4

[WS6]

From what I have read here and other places, the Gold Dot has a pretty low expansion velocity threshold. Does anyone have hard numbers from Dr. Roberts or Speer for the 64gr load?

[WS6]

If you're worried about stability the 70gr has one of the worst since its so long. Longer than a 77gr SMK.



From a purely shooting at 2-legged creatures from an SBR standpoint, the 50gr Black Hills load is ideal but trying to hunt hogs out to 300 yards with said SBR? I dont know about that. The 50gr TSX starts out faster, is more robust but has a higher velocity expansion threshold. The 70gr load starts out slower, has a lower expansion velocity threshold but doesnt do as well through barriers.

Both AAC, and another unaffiliated person told me to shoot 62gr or heavier through a 1/7 twist barrel with a suppressor.

As I understand it, based on the picture you posted, the 70gr TSX has a GSTAB of around 1.3. That is very near perfect, and what most manufacturers who make bullets and barrels try to shoot for. It is originally what M855 was slated to be fired through (M855 at @3100fps through a 1/9 barrel, as spec'ed through FN during the development of the Minimi, IIRC, is around 1.33GSTAB).

Has anyone else heard that one should avoid <62gr ammo in a 1/7 suppressed weapon?

Is this just because cheap 55gr may have a non-concentric core and could "wobble" if spun too fast?