# M855 vs M193 @ 22" barrel @ TWC



## AquaHull (Jun 10, 2012)

I'm getting 3200 ish with my Horn 55 FMJBT loads


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## Smitty901 (Nov 16, 2012)

That test is worthless at that short a range. The Green tip 5.56 62 gr was designed for a 16 inch 1 in 7 the M193 round was designed for a 20 inch 1 in 12.
He needs to repeat that with a 16 inch 1 in 7. Put some pretty good holes through steel with the M855


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## AquaHull (Jun 10, 2012)

Ar you saying the M855 was going too fast and that's the reason for coming apart?


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## Smitty901 (Nov 16, 2012)

AquaHull said:


> Ar you saying the M855 was going too fast and that's the reason for coming apart?


 The rounds behaves different when fired out of a 1 in 12 or 1 in 14 twist. The 22 inch may have been either it was not a 1 in 7. More to it than speed how the round acts in flight is important.
I agree the M855 is not an AP round. The reason it was designed was to penetrate better at longer ranges with the 1 in 7 16 inch barrel and that it did.


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## Arklatex (May 24, 2014)

For a 16" 1 in 9 is there any issues using the 62 gr? Or is it better to stick with the 55 gr? Range is under 300 meters.


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## AquaHull (Jun 10, 2012)

IMO the 1 in 9 was designed for the 62 gr SS109,the 1 in 7 was designed for the longer tracer M856.
*disclaimer- my opinion has been formed by my keyboard commando status. I do a lot of loading,shooting and backyard testing though.


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## LunaticFringeInc (Nov 20, 2012)

Arklatex said:


> For a 16" 1 in 9 is there any issues using the 62 gr? Or is it better to stick with the 55 gr? Range is under 300 meters.


My 1-9 barrel twist has no problem what so ever stabilizing bullets from about 53gr SP to 69gr SMK's. I have has some issues with some of the 60 something gr Barnes Tripple Shocks and extremely high BC bullet profiles in the neighborhood of 62 plus grs.


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## PaulS (Mar 11, 2013)

The twist necessary to stabilize a projectile is dependent on the temperature, pressure and relative humidity. At colder temps, higher pressures and lower humidity it takes a faster twist to stabilize the same bullet that would be stabile when fired at high temperatures, low pressures and high humidity levels. What works under one set of conditions at some elevation may not work at coldertemps at lower elevations. If you want to have a good set of guidelines run the Miller stabilization calculator and check it out. You need to have at least a 1.5 stabilization rate under the conditions of use to be assured of a stabile flight. If you want to use it for hunting the go for at least a 2.0 for light game and for medium game go for at least 2.5 ratios.


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## Smitty901 (Nov 16, 2012)

What became the M855 the ss109 was first intend for the 249 SAW. It's use was expanded to the M4. For those that never had the chance the 249 SAW Squad automatic weapon, replaced the M60 at squad level. a full auto only 5.56. max rate of 800 rounds pre minute 100 rpm all day long. 700-800 meters belt fed. works well and could also use AR15 mags but was known to damage them. 20 round mag did not last long in one. It was intend to be a suppression weapon and works well.
Just made little sense to have the SAW carrying one round and the rest another. The SAW has a 1 in 7 twist. Is was my last assigned Automatic weapon .


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