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tappedandtagged
17 May 2014, 15:32
My SWR/SilencerCo Specwar 556 came in so I started playing with sub sonic loads, just for fun. With a can of IMR Trail Boss in hand and a box of Hornady 55 grain flat base soft points I started messing around. NOTE: Please verify your barrel can stabilize sub sonic bullets before you put a can on it and shoot to avoid a baffle strike.

The data that IMR put out for sub sonic 223 is meant for a 24 inch barrel. I scoured the interwebs for information on what that would translate to for a 16" barrel with no luck, so I'm hoping this will help someone somewhere.

IMR shows that 4 grains of Trail Boss under a 55 grain FMJ will push that bullet at 1, 074 FPS.

Here's my data:

Gun: Windham Weaponry MPC with 16 inch barrel and 1:9 twist
Brass: Federal Once Fired
Primer: Tula Standard Small Rifle
Powder: IMR Trail Boss (duh)
Chrono: Pro Chrono Pal at 10 feet
Elevation: 350 feet above sea level
Temp: 78 degrees
Humidity: 46%

I was short on time so I was only able to take one shot of each loading.

I started with 4.0 grains and got 776 FPS

I bumped it up to 4.2 and it jumped to 937 FPS

4.3 grains was 1034 FPS

4.5 grains was 1084 FPS, which is as fast as I want it going. In all reality, I'll probably stick with 4.3 grains.

I did shoot the 4.2 grain loading into a Midway USA master catalog (actually, two stacked back to back). The FB soft point 55 grain projectile mushroomed greatly, separated from the jacket and the main lead core was found around page 957 of 1059. The catalog was split all the way through and through, but no fragments penetrated. I guess the stress from being struck just split the pages along the path the bullet would have continued had it not lost energy.

I'll add pictures later. I have to be at work in a bit so off I go. Hope this helps someone.

ArsonMachine
18 September 2014, 09:55
Thats actually pretty good. Everyone I know that has tried subs in a 223 rifle had either serious issues or they couldn't get them to actually go sub sonic. BTW how was the accuracy with the subs? Would be interesting to try this with some of the heavier 223 bullets out there. Wish I had the time to reload more.

Former11B
18 October 2014, 22:53
I've played around with .223 subs in my suppressed bolt action rifle. I've actually found Titegroup has a better tone and is way less dirty. Trail Boss is filthy even with 4-4.5gr.

I was using 3.1gr of Titegroup with a 55gr bullet and I think 4.2gr of Trail Boss. Both sounded like the hammer dropping and not much else. Accuracy was minute of man at 100 yards...probably 6" groupings.

Sak007
21 October 2014, 16:44
Just got back from trying out some 55gr with 4 gr of TrailBoss on my 7in barrel and a 7.62 Saker . It didn't cycle but sounded great , I'm gonna work the load up to see if I can get it to cycle .

http://tinypic.com/r/jtapeu/8]View My Video

Former11B
21 October 2014, 18:27
I hate to say it but the rounds will be going supersonic long before you get an AR to cycle with Trail Boss unless you do some serious gas regulating and swapping out springs/buffers/carriers etc.

Save the reloading supplies and stick with 4 grains and manual cycling. It's even more fun when you get a bolt action .223. Something unnatural about hand cycling an AR every round that I didnt like so I rarely shoot subs through my suppressed gas guns.

Sak007
22 October 2014, 15:26
It would definitely be nicer with a side charger then the regular charging handle .