.308 subsonic load

[UlicniTrkac]

Hello

I am doing some subsonic loads for my 308. Its 1 in 8 twist, and it should be stable with 220 grain lead bullet, that I made with 300 Blackout Lee mold.

I have read almost everywhere that Trail Boss is the powder I should use, but currently only IMR 4320 is available for me.

Any thoughts on starting load with this powder?

Thanks in advance

 

[Mike1234567]

Sorry to go OT but... where did you get a .308 Win with 1:8 rifling twist rate?

 

[UlicniTrkac]

custom made barrel, by a local gunsmith

 

[Swampman]

Sorry to be a party pooper, but it would be ill advised and possibly even dangerous to attempt loading subsonics with 4320. It's too slow burning and hard to ignite at low pressures. With cast bullets you probably wouldn't blow anything up, but you'll stick a lot of bullets in your barrel.

While Trail Boss seems to be the current "in" powder for subsonic reloading in larger capacity rifle cases, this is due to the fact that it's a very SAFE powder for this use, not for its accuracy or consistency.

I tried Trail Boss, but found that I got better accuracy and consistency with Red Dot.

Look around a bit and try to buy some fast burning, easily ignited and fairly bulky pistol or shotgun powder.
Any of them would be far better for your purposes than 4320.
Look around on Castboolits for load data, the Hodgdon website also has some subsonic data listed for non Trail Boss powders in .308.

Remember to start high and work your loads DOWN, not up.

BE VERY CAREFUL TO AVOID DOUBLE CHARGING A CASE, a double charge of pistol powder could very easily destroy your rifle and possibly you.

That's one of the reasons I like Red Dot, it's not as bulky as Trail Boss, but it does have enough volume to make a double charge stand out like a sore thumb under visual inspection.

Understand that there's nothing wrong with shooting that bullet with 4320, the problems arise when you try to load subs with it.

I have no doubt that you'll get great results with that bullet out of your rifle with the right powder and proper load development. My Remington 700 AAC SD with 1/10" twist does very well with them.

What diameter does your mold drop 'em at? When new, mine threw them at .3085, so I ended up honing the cavities out, one cavity to .311 for my .308 and the other to .313 for my SKS.

 

[au_prospector]

Hey this is cool, but I am wondering if it is even possible to be true subsonic and if so is it accurate and safe? Can you get a .308 to have a muzzle velocity of less than say 1000 fps and have it exit the barrel? What is the effective range of something like that? I could only guess the hold over would be quite high even at 100 yards.

Very interesting, please keep us posted on how your project progresses.

 

[ldlfh7]

Look around a bit and try to buy some fast burning, easily ignited and fairly bulky pistol or shotgun powder.

Could you use bullseye for a subsonic 308?

 

[Swampman]

Originally posted by ldlfh7

Could you use bullseye for a subsonic 308?

I haven't seen any reputable data posted and I haven't used it myself, so I'm not going to say "Yes".

But if I only had 4320 and Bullseye and I needed to load up some .308 subs, I'd definitely try the Bullseye.

The problem is that Bullseye is fairly dense and extremely "energetic". It would be very easy to double charge a case, and the results wouldn't be pretty.

Trail Boss, Red Dot and Clays are far better choices for loading subs because they take up more space in the case. This not only allows you to more easily detect a double charge, but gives better, more complete ignition and thus more consistent pressures and better accuracy.

For a good grounding in basic subsonic reloading, check out this link:

http://guns.connect.fi/gow/arcane1.html

The link is only to page one, there's a LOT more info available on the site. Please read it all before you try to start into loading subsonics.

As the saying goes: "A wise man learns from the mistakes of others, fools have to pee on the electric fence for themselves..."
A rifle blowing up in your face is likely to do far more damage than urinating on the average electric fence.

P. T. Kekkonen probably forgot more about loading subs than the whole bunch of us will ever know.

 

[Salmoneye]

+1 on Red Dot

Look up C E (Ed) Harris 'The Load', and work backwards from that...

 

[UlicniTrkac]

just to update a bit, I am still working on this load, it's a bit time consuming, trips to the range etc, but I am getting there, without TS. I am at 11,2 gn of a local shotgun powder, and close to 950 fps with 220-230 grain lead casted bullet. Silent as a mouse f**t
I had no problem with not fired round, even if a case isn't filled more than 7/12 of its volume.

 

[klausman]

+1 Swampman on the articles by P T Kekkonen There are 3 articles in the arkane series.

Also look at this http://www.gmdr.com/lever/pistolpowi.htm

My 45-70 is quieter than 22 cb caps with some Unique loads.

Unique was originally marketed as a reduced load rifle powder.

This is a fun project, but do be careful.

 

[rsrocket1]

My first subsonic loads were with the 200g Lee C309-200-R over 6g Red Dot in a 788 .308 rifle. The average MV was only 991 fps so I could have bumped the charge up a bit more and still stayed subsonic. There was no problem getting them out the barrel.

 

[TIMC]

I'm running trail boss with 220 grain bullets out of my savage hog hunter with a Thunderbeast 30P1 suppressor. 13.8 grains was the load I found for it but was still seeing velocity swings that were more than I liked. I drilled out the flash holes and used magnum primers to improve consistency and it improved it to satisfactory levels and very decent groups at 100 yards.