# Another subsonic thread



## Wado (May 15, 2011)

This is aimed mainly at .308 Winchester subs so here goes. Primer flash holes, do you drill them out and if so what size drill? I saw a video where they drilled them to 9/64". I hate to say it but the actor in the video was asking for a sore finger the way he did it but he made it without a hitch. Second, lubing the bullets. I don't do it for 300 Blackout, same bullets same velocities so what's the input on that? I don't drill out my 300 brass but maybe the larger volume of the .308 brass requires it to get consistent ignition. I'm not sure I want a magazine full of bullets wiped with Crisco either, talk about a bunch of dirt magnets. Something dry maybe like Moly Lube. I was getting ready to make a few .308 subs for testing so any help would be appreciated. For some idiotic reason I had the threads on my barrel removed and a target crown cut when we put my 308 together so it's back in the lathe to be threaded again, more dinero. Any other bumps in the road?


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## horned frog (Nov 9, 2008)

I have never drilled flash holes. My 300 BLK handi-rifle has 1:7 twist and my 300 BLK AR-15 has 1:8 twist. Both stabilize 220 grain bullets.

My 308 Ruget Gunsite Scout has 1:10 twist and likes 150 gr subsonics. Ballistic Silvertips designed for reloading 30-30 work especially well.

I use a purple sharpie permanent marker to color the primer of the subsonic loads for easy identification. The subsonic 308 will not cycle in a semi-auto.


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## Bird (May 10, 2005)

I don't drill out the flash holes. I do use a flash hole deburring tool to help clean the inside of the flash hole. You'd be surprised how much metal burr is inside from when the primer hole is punched originally. I use a magnum primer and Trailboss powder. I've posted my 308 sub recipe on here before but I'll try to post it tomorrow after I wake up (I'm on nights). 220 grain Sierra pro hunter round nose bullets and 13.7 grains of Trailboss, 1040 fps average per my chrono.


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## muney pit (Mar 24, 2014)

Never drill primer holes execpt on my match loads. Never even heard of lubeing. WLR primers,220 rn & trailboss.


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## Ready.Fire.Aim (Sep 22, 2009)

I use 15g Trail boss powder and Hornady 180 gn round nose bullets. COAL is 2.65"

FN Patrol Bolt, integrally suppressed. 

I don't clean flash holes.


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## Wado (May 15, 2011)

Thanks for all the input. I de-burr the flash holes but have never re-drilled them. I finally found a can of Trail Boss down here to load some.


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## Bird (May 10, 2005)

Ready.Fire.Aim said:


> I use 15g Trail boss powder and Hornady 180 gn round nose bullets. COAL is 2.65"
> 
> FN Patrol Bolt, integrally suppressed.
> 
> I don't clean flash holes.


From my limited experience, sub sonic loads for integrally suppressed guns take a little more powder than if shot through a gun with a removable can. A buddy loaded up some 308 subs for his Rem700 integrally suppressed that were a quiet as I've ever heard. When I shot them through my bolt gun with screw on can they all went super and had bullet crack. Note the powder charge difference from RFA's load to mine and I'm using a heavier bullet.


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## Chase4556 (Aug 26, 2008)

Shot some of my 308 subs today. 

150gr speer btsp, over 10gr of Trailboss. Can't remember the COL off hand. WLR primers. 

Issue I was having was my velocity being all over the place. 1-200 fps spreads.... is this normal, will drilling the primer holes help?


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## Bird (May 10, 2005)

Chase, what was your muzzle velocity max? Without anything else, I'd suggest seating the bullet deeper and/or using magnum primers. Generally when I've had that problem I've added more powder or seated the bullet a little deeper. Since you're shooting subs, which restricts your velocity, adding powder might not be the answer. If you're close to super sonic then seat the bullet deeper. Both affect case pressure. Trailboss is a pretty fast powder so complete and even ignition is important for consistent velocities, which is why I use a magnum primer.


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## Wado (May 15, 2011)

Well, I searched the forum and read the posts on sub sonic 308 from a while back and loaded some 220 grain round nose with 13.8 grains of Trail Boss. The twist is I drilled the flash holes to 1/8", dry lubed the bullets and used Bench Rest primers. My rifle is a 98 Mauser with a Remington factory barrel 1 turn in 12 inches that is 18 1/2 inches from the bolt face to the muzzle, kind of short but it was made for a suppressor originally. The poop was it came off of a rifle from the prison in Beeville. I had the threads parted off and and threaded for my Mauser action and recut the chamber. Made it a bit short. Prettttyyyyy sure it went super and the bullet made it through all three of my telephone books but landed in the trap so I was close, but no cigar. I reckon I will load some down and get a chrono and order some 180 grain bullets if it doesn't stabilize.


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## Wado (May 15, 2011)

Pictures from today's science project.


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## Wado (May 15, 2011)

I STOLE THIS QUOTE FROM ANOTHER FORUM.

One word of caution, but I had read that 20" is as long as you want for shooting sub sonic 308 (barrel length). What I read was after 20", the drag of the bullet in the barrel caused inconsistent velocities. The load I had above was 1050 fps in a 20" barrel. The longer barrel may be why the folks above are quoting heavier powder loads.

Maybe that's why they smeared Crisco on their bullets in the video I watched.


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## Bird (May 10, 2005)

1:12 twist might be a little slow for stabilizing 220's. My Savage is 1:10 twist with 20" barrel.


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## muney pit (Mar 24, 2014)

Wado said:


> I STOLE THIS QUOTE FROM ANOTHER FORUM.
> 
> One word of caution, but I had read that 20" is as long as you want for shooting sub sonic 308 (barrel length). What I read was after 20", the drag of the bullet in the barrel caused inconsistent velocities. The load I had above was 1050 fps in a 20" barrel. The longer barrel may be why the folks above are quoting heavier powder loads.
> 
> Maybe that's why they smeared Crisco on their bullets in the video I watched.


Never have a problem with my 24" 5r or a buddies 26" TRG. If you work them down i dont see there being a problem. Never see speratic fps change either. Also never heard of this lubing subs untill here either.


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## Wado (May 15, 2011)

I guess when everybody started getting suppressors there was a lot of experimentation going on. It's a little different trying to slow bullets down than getting max velocity with lower pressure. New to me I must admit. My quest has always been accurate loads and haven't paid too much attention to speed. This practice sometimes limits you because some bullets and firearms like speed.


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