Subsonic .308 does and don’ts

[Sivispacemparabellum022]

Ok guys, I’m not new to the reloading scene but I am new to subsonic. The atf finally decided to approve me after more then 12 months. I’d like to start reloading for my .308 savage. I don’t even know where to start. I can’t find anything in my books, I’ve research some online, seems most that I saw were using trail boss and 175gr and heavier. Is trail boss the best? Can you use you IMR’s or Vargets for subs?

 

[Badfinger]

You’re entering a potentially dangerous area and one that you must be very careful in. FIRST, when working on reduced loads for subsonic ammunition you need to be aware of an issue where you reduce a load too much or using the wrong powder and the pressure builds down the barrel instead of in the chamber and can cause catastrophic damage to you and the weapon! There are reduced loads listed on Speer's and other website. It has been my experience that heavier bullets like 200 or 220 grain are easier to load subsonic. Trail Boss will get you subsonic, others like the attached won't and don't try to get there as warned above........

Click Here for an example

Here's a link to the Snipers Hide Subsonic reloading thread

 

[b6graham]

trail boss is the best. and do it without a can to start. i found myself in the 10-11gr range with 175s

just note that reducing a 'reduced load' is probably not a good idea

there is tons and tons of data on 308 trailboss loads available online and here in the reloading depot I'm sure

 

[Juggerxxx]

Definitely start high and work low. I used trailboss because there was a ton of good info on the net. It is very fluffy stuff and only 11.5gr of it filled the 308w case up to where the shoulder started. I used Barry’s 220gr plated bullets because they were cheap, in stock and it’s just a plinking round that is quiet as hell with a 25” barrel and suppressor.

 

[M_R_Woodard]

I use cheap 150 grain bullets for subsonic. They are more likely to stabilize than the longer heavier bullets. Hodgdon has trailboss data, just start high and work your way down.

 

[jet_lagged]

Hodgdon has data for Titegroup pistol powder.

Flat based bullets will be shorter for that weight of bullet. I use 180gn
flat base hunting bullets with an exposed rounded lead nose. The rounder nose is aerodynamic for subsonic.

 

[10ring1]

Do's and don't s .... Just don't. Drops like a rock. Might as well go BLK and don't look back

 

[karb]

Yeah, trailboss is the ticket. In Winchester brass, 10.6g, and a 190smk at 2.810. I can run it out to 300yds before losing elevation . About an 8"group at that distance. I have a 26" barrel 1/11.25 twist.

I hope you have a Chrono. You want to be just under 1125fps.....most will choose 1040fps, as did I......when colder, it still performs and is quiet enough.....

The heavy bullets were the ticket....for me.

 

[spife7980]

I use cheap 150 grain bullets for subsonic. They are more likely to stabilize than the longer heavier bullets *in typical 308s normal 10 & 12 twist rates*. Hodgdon has trailboss data, just start high and work your way down.

Just the one little edit for specificity


OP. trailboss is preferred because it is so light and fluffy it fills the case pretty full. If the powder didnt fill the case the small amount of normal powder used would leave most the case empty and with that much empty space it can lead to inconsistent ignition and burn rates.
With a small amount of normal powder it could be dispersed in an even line along the whole case length, it could be all clumped at the base to fire up immediately, it could all be up at the front and possibly miss some a lot of the primers energy, there just too much empty space to tell.
With trail boss being as slow and voluminous in that larger case you are packing it full enough so it has no choice but to burn evenly each time.

 

[ecm1997]

I have had good luck with 10.5 grains of trailboss with 180 grain soft tip bullets out of a 20" 1/10 twist barrel. In my opinion, subs are a lot more fun out of a bolt action instead of an ar.

 

[Sivispacemparabellum022]

Ok so I finally found trail boss powder. I also bought the new Hornady A-tip 230gr. Does anyone have any guidance for reloading 308 subs with trailboss and the 230’s and/or the 300blkout with trailboss and 230’s. And information would be beneficial! Thanks

 

[E-Tool]

I reloaded some with TB that worked out to 100yards, I bought some factory subs that keyholes right out of the muzzle.

 

[sid]

shoot your load into paper without suppressor first to make sure your bullet is stabilized. bafflestrikes sux

i use trailboss and 155 30-30 flatnose bullets from sierra

 

[LR308guy]

Just a added note about using Trail Boss, it does not like to be compressed ANY, you will get velocity variations and spikes in pressure, do not crush.

You might have a stabilization issue with the heavier 208-240 weights in a Savage 1-10 twist, shoot without the suppressor to make sure you are not keyholing and to eliminate baffle strikes in your brand new can. Standard rifle powders below the recommended start point in the reloading manuals is definitely not the right thing to do, you can and will get crazy burn rates, huge pressure spikes, and dangerous potential grenades.

hope this helps.