I've read a lot of suppressor guys prefer 1 in 7 over the other twist rates......FWIW
I've read a lot of suppressor guys prefer 1 in 7 over the other twist rates......FWIW
Here's to pussy and gunpowder. One to live for, the other to die by.....Goddamn though, I do love the smell of 'em both !!!
A few years back I shot the hell out of some Adcom M855, about 4000 rounds through a Oly 16" A1, and Bushy M4gery A3. It was dirt cheap and gave me 450yds out of those rifles. Man I miss that stuff, I heard bad reports on other threads about said ammo but never had any problems even in the rain/snow. BTW it was made in the UAE. Now I just stick mostly to LC XM193, or XM855 ammo, some Winchester white box 55gr 5.56, and Hornady 55gr BTHP Tap for the S&WM&P 15t.
This thread is so good.... that it's getting sticky'd.
~Nemo me impune lacessit~
Last bit of Trivia on this topic. Anybody know why M855 and the SS109 bullet have green paint on it?
The answer is ............
The green paint on the tip is to let one know at a glance that it is the 62 gr. bullet. Usually only countries that used the 5.56 M193 ball round and then introduced the 62 gr. ammo use the green paint on the bullet. English Radway Green 62 gr. ammo didn't have green paint and as far as I know still doesn't.
Thanks for all the great info. Basically, if I am understanding correctley, M855 is a standard issue. SS109 is a penatrator.
ss109 is the bullet/projectile and XM855 is the loaded ammo itself with the ss109 bullet
Correct me if I am wrong but Isn't the rear sight on the M16A2 and M4A1 calibrated for the M193?
At distance you would be shooting high if you were using M855.
I have an A2 with a 1/9 barrel.. Should the sights still be calibrated for M193?
Not quite correct.
SS109 is a cartridge using the original M193 case with a 62 grain penetrator projectile and, crucially, a specially developed two stage propellant. It is NOT only the bullet.
The projectile, designed for penetration at long range , is significantly longer than the 55gr. It's not only heavier, but also less dense as it has a steel core which is lighter than lead (so it's longer for its weight). The round OAL was kept the same as the M193 for interoperability, leaving less case capacity available for the powder. Nevertheless, FN wanted to get the best muzzle velocity they could without excessive pressure. The two-stage propellant is designed to maintain high pressure behind the projectile after it leaves the chamber, and achieves a respectable muzzle velocity (I believe is a couple of hundred fps less than the M193 - Barnes gives 3250 for the M193, and wiki gives 3100 for the SS109) from a smaller powder volume. Given the higher BC from the longer projectile, it's a much better long range round than the M193.
The NATO STANAG (standardization agreement) for the 5.56 x 45 round was written around the SS109 - and mandates performance requirements such as velocities, chamber pressure, gas port pressures, penetration (steel helmet at 600m) and operation in a number of specified weapons (NATO nominated weapons), including the M16A2, and cartridge dimensions.
The M855 meets the STANAG specs - as do a number of European cartidges (the bigger NATO countries all manufacture their own ammo). The only 'real' SS109 is that made by FN. The STANAG does not define the SS109 - it defines NATO 5.56 x 45, which is based on the SS109. While it is correct that it does not require the same projectile as in the SS109, it does specify enough ballistics and penetration requirements to mean that a very similar projectile is required to meet the STANAG.
You can be confident that any cartridge made to meet the STANAG specs will perform very similarly to the M855 or SS109 - but the only cartridges that are accredited to meet the spec are those made for NATO military forces. A list of these, with their head-stamps, and NATO Nominated Weapons is available at http://www.dtic.mil/ndia/2009infantr...vArvidsson.pdf
Last edited by mfhall; 08-08-2013 at 11:23 PM.
That's double-base powder. Rockets are two-stage. Single base powders are composed of nitrocellulose, double-base powders are nitrocellulose and nitroglycerin. What your post is saying is they wanted a slower burn rate powder to not over pressure the case and to achieve the most speed possible given the 62 gr. bullet. Our M855 round is loaded as far as I know with WC844 which actually is a derivative of WC846. I use the WC844 surplus when I can find it, to load my 62 gr. SS109 type projectiles.
Last edited by Schuetzenman; 08-11-2013 at 01:46 PM.
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