sub-sonic rounds using Trail Boss

[hardcase]

I've read with interest some of the post using this powder. Hodgdon's receipts are somewhat lacking. I've been working on loads for my 300 Blackout using Trail Boss and Sierra's 125 gr HP bullets. Best I can get is 950 fps with 125 gr and 6.3 gr Trail Boss. 6.3 gr is what Hodgdon lists for a 115 gr bullet. My 300 Blackout is a Rem 700 bolt gun. 5.56 is a Stag Arms AR. .308 is a Rock River AR gun. As everyone knows, supplies of bullets and powder are not what they use to be. I'm new to the sub-sonic game.

It has now been 7 months since NTFA cashed my check. My dealer has agreed to meet with me and try out my cans. I'd like to also load a few .223 and .308 sub sonic rounds in the AM to take.

In addition to the .308s at 125 gr, I have 150 gr and 160 gr. I have 52 gr and 55 gr .224 bullets.

Any suggestions for using what I have with Trail Boss?

My local dealer has a 8 lb container of Little Gun but at $200.00, it is just to much powder for me.

[johndoe3]

For the 300 blackout, if you want 1050 fps:

6.3/950 = X/1050 solve for X
X= 6.9 gr of Trailboss for ~1050 fps

For my 308 subsonic for 175gr/178gr bullets: at ~1050 fps it is 10.8gr of Trailboss

10.8/175 = X/150 solve for X, the load using 150 grain bullets
X= 9.3 gr of Trailboss for 150gr bullet at ~1050 fps

The above calculation method will get you very close to your desired load, with slight variation in loads needed to account for barrel friction differences and barrel lengths (maybe off by 0.1-0.2 gr at most). Try it and let us know. I can't help you with Trailboss subsonic loads for 5.56/.223.

Or...did you mean using the 150gr and 160gr bullets in 300 Blackout instead of 308?

[hardcase]

For the 300 blackout, if you want 1050 fps:

6.3/950 = X/1050 solve for X
X= 6.9 gr of Trailboss for ~1050 fps

For my 308 subsonic for 175gr/178gr bullets: at ~1050 fps it is 10.8gr of Trailboss

10.8/175 = X/150 solve for X, the load using 150 grain bullets
X= 9.3 gr of Trailboss for 150gr bullet at ~1050 fps

The above calculation method will get you very close to your desired load, with slight variation in loads needed to account for barrel friction differences and barrel lengths (maybe off by 0.1-0.2 gr at most). Try it and let us know. I can't help you with Trailboss subsonic loads for 5.56/.223.

Or...did you mean using the 150gr and 160gr bullets in 300 Blackout instead of 308?

Thanks for the info. I'll print it out and save it. I wasn't planning, at least at this point, in using anything more than 125 gr bullets in my 300 Blackout. It is a new gun, bolt action, Remington SPS tactical (16" barrel). Since I'm not worrying about cycling with this bolt gun , I'll stay with smaller bullets if I can find them. I just hate the current supply crunch but that is another issue. I noticed some of my earlier rounds didn't have an adequate crimp. With a proper crimp, I was consistently in the 970-995 fps range today with 6.3 gr-125 gr- and 2.055 to 2.065 OAL.

My current plans, after a box or so of 300 Blackout, are to re-load .223, then maybe work on 308. I have an infrared chronograph set up in a barn beside my house and it is easy to check bullet speeds. My 5.56/223 is a gas piston AR type. My 308 is direct impingement. Getting the AR types to cycle with my can may have to wait a few more weeks (or months). I heard NTFA was shut down for 16 days recently over political haggling, adding to my wait time. Some say a can doesn't make any difference in cycling. Others say it does. The only reason I would load sub-sonic would be for using a suppressor. I'm 7 months plus (closer to eight) and counting for the stamps. Thankfully, my can dealer is a friend and doesn't mind occasionally going through a box or so of ammo with me.

[johndoe3]

A couple of strings below this one, Jer just developed a 5.56/223 load for a 55gr bullet, with 3.8gr of Trailboss and got 1005 fps. He was experimenting with a small amount of cotton stuffing.

If I were you, I would try about 3.9gr of Trailboss and no stuffing for the 52gr and 55gr bullets you have. You might have to adjust it a little bit, but it would likely be very close to 1050 fps. I'm not convinced that one needs any stuffing, so your development would answer that question of whether the stuffing helps at all.

[hardcase]

A couple of strings below this one, Jer just developed a 5.56/223 load for a 55gr bullet, with 3.8gr of Trailboss and got 1005 fps. He was experimenting with a small amount of cotton stuffing.

If I were you, I would try about 3.9gr of Trailboss and no stuffing for the 52gr and 55gr bullets you have. You might have to adjust it a little bit, but it would likely be very close to 1050 fps. I'm not convinced that one needs any stuffing, so your development would answer that question of whether the stuffing helps at all.

Will do. I tumbled 150 pieces or so of LC 5.56 brass last night and am swaging the primer pockets today. Then it's size, trim, re-clean, etc. I'll post what I find out in a few days.

[jmorris]

I run 10g of trailboss behind cast and coated 170g bullets, the run just a tad over 1100fps.

One thing I would suggest would be to go try ALL of the "new" loads out BEFORE you try them with your new cans. To trash them before you can even posess them would suck.

[paper9]

300 BLK, 16 inch bolt.
Trial Boss 4.5 Grains
Primers; Federal 205, WSR, Rem 7.5
OAL 2.045
Hornady 110 GR SP #3010
V average 958, more than 100 rounds measured with a Magneto Speed Chronograph.

Trail Boss 5.0 Grains
Primer Rem 7.5
OAL 2.045
Hornady 110 GR SP #3010
V average 1100, about 20 - 30 rounds measured with a Magneto Speed Chronograph.

Trail Boss 5.4 Grains
Primer Rem 7.5
OAL 2.045
Hornady 110 GR SP #3010
V average 1167, about 20 - 30 rounds measured with a Magneto Speed Chronograph.

Trail Boss 4.6 Grains
Primer WSR
OAL 2.045
Hornady 110 GR SP #3010
V average 1014, about 20 - 30 rounds measured with a Magneto Speed Chronograph.

Trail Boss 4.5 Grains
Primer Rem 7.5
OAL 2.21
Hornady 125 GR Sierra HP #2121
V average 967, about 20 - 30 rounds measured with a Magneto Speed Chronograph.

Trail Boss leaves smelly wet film in the blast chamber of the can.
I know of no way to make it cycle a semi-auto.
WSR and Federal 205 primers increase velocity 20 - 30 fps.

[hardcase]

I run 10g of trailboss behind cast and coated 170g bullets, the run just a tad over 1100fps.

One thing I would suggest would be to go try ALL of the "new" loads out BEFORE you try them with your new cans. To trash them before you can even posess them would suck.

Other than having a to small can for a bigger bullet or the threads not being in align what would I need to be avoid to mess up a suppressor? Not my first choice but only ones I could get in a reasonable time frame were YHM.

[jmorris]

All you need to do is shoot some rounds to make sure the bullet makes round holes. If the bullet keyholes at the target you would risk a baffle strike that could damage the can.

This problem exists with slow heavy bullets in barrels that do not have the correct twist rate to make the bullet stable.

The reason I said ANY is because you can go to the other extream with say Speer varmit bullets, that were designed for 1:14 twist barrels and they come apart ( at "normal" speeds) in the faster twist rate barrels that are common in AR's and will also F--k s--t up.

It is fast and easy to check, also free, so it sould be done.

[hardcase]

All you need to do is shoot some rounds to make sure the bullet makes round holes. If the bullet keyholes at the target you would risk a baffle strike that could damage the can.

This problem exists with slow heavy bullets in barrels that do not have the correct twist rate to make the bullet stable.

The reason I said ANY is because you can go to the other extream with say Speer varmit bullets, that were designed for 1:14 twist barrels and they come apart ( at "normal" speeds) in the faster twist rate barrels that are common in AR's and will also F--k s--t up.

It is fast and easy to check, also free, so it sould be done.

Thanks. As involved as it is to get a suppressor, the last thing I want to do is mess one of them up. I'll check this first thing with any new bullets/gun combination, if I get my stamps before I pass on .