M193 + 1/7 twist SBR = baffle-strike?

[WS6]

I have been told by several people (one that works for AAC, answered the phone when I called), that 55gr ammunition from my 1/7 12.5" barrel is more likely to cause a baffle-strike than something 62gr and up. Is this the general consensus?

[Cameron]

I've never had one, or even seen one, with multiple 10.5" 1in7" barrels from LMT or Noveske, or a BCM 11.5" 1in7". Using Gemtech M4-02 or a Surfire Mini, and M193 or even commercial .223 55gr FMJ, for thousands of rounds.

Now I've probably jinxed myself, and will have a baffle strike tomorrow....

Cameron

[WS6]

I've never had one, or even seen one, with multiple 10.5" 1in7" barrels from LMT or Noveske, or a BCM 11.5" 1in7". Using Gemtech M4-02 or a Surfire Mini, and M193 or even commercial .223 55gr FMJ, for thousands of rounds.

Now I've probably jinxed myself, and will have a baffle strike tomorrow....

Cameron

IGMAN
PPU
PMC
Federal

Which M193 should I get? Looking for clean/accurate.

[Iraqgunz]

I have close to 10k through my AAC M4 2000 and most of it was 55gr. and 62gr. No baffle strikes yet.

[tctlrld]

I have been told by several people (one that works for AAC, answered the phone when I called), that 55gr ammunition from my 1/7 12.5" barrel is more likely to cause a baffle-strike than something 62gr and up. Is this the general consensus?

Sounds completely counter intuitive. I would worry more about longer (70gr TSX or 75-77gr BTHPs) than I would with 55gr. Granted 12.5" won't have the velocity of a 20" barrel, but those M193 were designed to be shot out of a 1/12 barrel originally.

[lunchbox]

Sounds completely counter intuitive. I would worry more about longer (70gr TSX or 75-77gr BTHPs) than I would with 55gr. Granted 12.5" won't have the velocity of a 20" barrel, but those M193 were designed to be shot out of a 1/12 barrel originally.I was wondering about that. The lower than 60gr bullets not recomended for 1/7twist, maybe its along the "if theres smoke theres fire" thought. That if 1/7 twist caused 55gr bullet wobble, 1/7 with supp. is more likely to baffle strike. Maybe is thought process.

[jjw]

I have close to 10k through my AAC M4 2000 and most of it was 55gr. and 62gr. No baffle strikes yet.

what he said. way past any normal mnumbers. i cant believe the people in this business who THINK they know whats so


jjw

[Failure2Stop]

That sounds odd to me.
I'd really like rsilvers to comment on this.

[WS6]

That sounds odd to me.
I'd really like rsilvers to comment on this.

+1

It came of a phone-call to AAC, which is why I lent some weight to considering it very heavily. Obviously I am not trying to say this is AAC's official line on the subject, just that the guy who answered the phone told me such.

[rsilvers]

I don't see how that would be true. 55 grain is fine for 1/7 twist.

[WS6]

I don't see how that would be true. 55 grain is fine for 1/7 twist.

Good. I just ordered a couple thousand rounds of it. Thanks for weighing in!

If I may continue along this line of thought...50gr Barnes TSX 5.56...okay, too?

[rsilvers]

1/7 twist can shoot anything from 40-80 grains.

1/8 - up to about 77 grains, depending on bullet length.

1/9 can shoot up to 69 grain or so on longer barrels.

1/12 is pretty much 55 grain and less.

[WS6]

1/7 twist can shoot anything from 40-80 grains.

1/9 can shoot up to 69 grain or so on longer barrels but not necessarily on short barrels. 1/12 is pretty much 55 grain and less.

Thanks! I know I have shot 40gr VMAX from a 1/7 twist and it did fine, I just didn't know if the lighter projectiles had more fleet yaw than safe near the muzzle before settling down with the higher twist rates, and how that translated to safe use of a suppressor, if it existed.

[Hydguy]

Thanks! I know I have shot 40gr VMAX from a 1/7 twist and it did fine, I just didn't know if the lighter projectiles had more fleet yaw than safe near the muzzle before settling down with the higher twist rates, and how that translated to safe use of a suppressor, if it existed.

google SS109/M855 development. It will give you some good insight on the development of the projectile and how the 1/7 twist came to be the standard.

[WS6]

google SS109/M855 development. It will give you some good insight on the development of the projectile and how the 1/7 twist came to be the standard.

The ss109 was paired with the 1/9 twist rate when originally developed for the FN MINIMI. The tracer round burn distance was altered. 1/7 became necessary to accommadate the longer m856 round.

[Chase45]

If its grouping well down range and nothing looks odd I would not worry about using 55 grain bullets.

I use 55grain handloads pretty much exclusivly in my 12.5 with aac m4-2000.

several thousand rounds of a mix of handloads, m193, and wolf. no baffle strike with my 1/7 12.5

[Asmodeus097]

2,000 suppressed rounds through LWRC M6A2 10.5" with Federal XM193 here. Zero baffle strikes on Surefire MINI and FA68K.