Subsonic 300 win mag

[Wapitikid]

Trail boss powder was recommended to me using a Nosier 190 Accubond. 12 gr of TB shot perfectly. 1050 fps. My concern is i was cautioned by my gunsmith that too little powder could blowup the rifle. Then I saw on youtube to use dacron as a filler to prevent that problem. Hodgdon told me not to use a filler and they also said a bullet that is not spinning right and may damage the surpressor's baffles.

Your thoughts??

 

[Lynn Jr]

TrailBoss powder looks like a donut. It is round and has a hole through the middle of it.
It is a very voluminous powder and will fill the entire case before you see any lsigns of pressure.
The powders that detonate are the ones that don't fill the case.

I have no idea why subsonic loads would harm a suppressor.
Did Hodgdon say at subsonic velocity they see a lot of yaw?

 

[Wapitikid]

The 300 win mag brass was only about 15 % full. I guess they were talking about yaw. Filler use okay?

 

[Lynn Jr]

The 300 win mag brass was only about 15 % full. I guess they were talking about yaw. Filler use okay?

Something is wrong here!!!
You can only put 37 grains of TrailBoss into a 338 Lapua Ackley Improved case filled to the top of the neck. It will hold 113 grains of RE33 but only 37 grains of TrailBoss.
If your case is only 15% full your not using TrailBoss!!!!!!

 

[Wapitikid]

Something is wrong here!!!
You can only put 37 grains of TrailBoss into a 338 Lapua Ackley Improved case filled to the top of the neck. It will hold 113 grains of RE33 but only 37 grains of TrailBoss.
If your case is only 15% full your not using TrailBoss!!!!!!

It's a 300 Win Mag.

 

[spife7980]

Exactly. It should be way fuller than 15%.

Trail boss is so fluffy that you only get 1/2 a pound in a container than would normally have one pound plus plenty of left over space.

Fill a case up full of trailboss, pour it out and weigh it. See how much it can actually hold. I imagine 12 grains is actually way more than 15%

 

[Lynn Jr]

300 win mag case holds about 93 grains of water and a 338 Lapua Ackley Improved holds about 120 for comparison.
At 12 grains and with a bullet seated you should be over 50% full.
Regardless you don't need the fill but if you want to give it a try you can get it at Neco.
Most use the fill when using a powder like H4895 and subsonic because it doesn't fill the case very full. In that situation all the powder can sit close to the bullets base and cause a detonation.
To avoid that issue Hodgdon brought out TrailBoss.

 

[Huskydriver]

You need to use a heavier bullet for subs to take up case volume. When the case is not very full, the ignition of the powder becomes erradict and can cause pressure spikes. To help this issue pistol powders are used ie your trail boss. I bet if you switched to a 220 grain slug you would be about optimal in regards to case capacity. You will need to increase your trail boss load to compensate for the added weight more than likely.

I would strongly discourage using fillers.

I am surprised about the 12 grains of TB though that seems really low. I use 11.5 grains with a 220 grain slug in a 308 and it's about 75-80% full and is my go to subsonic load at 1050fps out of a 18 in tube.


You need to test your load at 25 and 100 yards to make sure the bullets are not yawing through the paper before you screw on your can. If the bullet is unstable, you will get a baffle strike and destroy your can.

I went ahead and attached a pic of a 308 with 11.5 grains since I'm loading these today anyway for reference?.

 

[Snuby642]

I am supprised hogden does not list cfeblk for this round, in thier online data.

 

[BuildItYourSelf]

I agree something isn't adding up.
12gr of trailboss fills a 308 to the neck.
Your case should be filled just fine to use trail boss.

Also I wouldn't load anything under a 220gr bullet in a sub 300wm. If you have a 1/10 twist you should be OK but in some cases you may not be. My 20" 1/10 308 does not group a 220smk very well. It does 175smk very well and no key hole at 200y. (this is why the next 308 sub "pistol" I'm doing is 1/8") so try it and see. Stay as heavy as you can in any sub gun. You will preform better with distance anyhow if it Flys good.
You have the case volume available, us it. A heavy bullet will also cause the powder to ignite and burn more consistently and also faster. Your accuracy will definitely increase.

If you are at 900fps+ there is a very little chance you will get a baffle strike unless you have very short barrel, low quality bullets loaded backwards, cast bullets, gas check (avoid those like the flu) or very very very inconsistent speeds (indicating a terrible load and you should rethink what your doing)


I would stay away from filler. This may sound crazy but look up a YouTube video by smarter every day that shows its true.
Unburnt ball powder or clumps of carbon will leave the barrel or suppressor before the bullet at supersonic speeds. Can you hear a single particle breaking the barrier? Not my deaf ears no. But dozens of them will create a noise that can be heard by the ears for a distinct greater then the rest of the shot noise. Does this decrease "hearing safe" levels? Not to an extent to worry. But it does happen and I can only imagine what a scoop of filler will do to exaggerated the effects of this. Plus you basically media blasting your baffles. No thanks.

Top your case off with trail boss and see how heavy that is. I typically fill the case to slight compression and work down untill no crack and speed is under 1050. And then go a step down. I had my 300blk crack this winter on a cold thick air day with loads that ran around 980fps +/- 20fps with a 180 Rainer plated bullet. (btw that bullet is very accurate and dirt cheap)

 

[Wapitikid]

Exactly. It should be way fuller than 15%.

Trail boss is so fluffy that you only get 1/2 a pound in a container than would normally have one pound plus plenty of left over space.

Fill a case up full of trailboss, pour it out and weigh it. See how much it can actually hold. I imagine 12 grains is actually way more than 15%

With the bullet seated and if I fill the case up to the bottom of the bullet, there is 19gr of TB. 12/19= 63%. Do you think that's a safe load?

 

[Lynn Jr]

YES

 

[BuildItYourSelf]

Absolutely.

 

[Wapitikid]

With the bullet seated and if I fill the case up to the bottom of the bullet, there is 19gr of TB. 12/19= 63%. Do you think that's a safe load?

Thanks all!

Thanks

 

[1clicktrick]

I never would have thought making a 300 win mag subsonic. Such a large case. You will truly create s dual purpose rifle for sure!! Be careful.