Suppressors on a bolt action SBR Question (now that the $200 tax is going away)

[Luke S]

I was thinking about a newer, lighter suppressor. I currently use a Rugged Radiant 762 (in long configuration) and a Polonium 30, both of which add about a pound to the rifle.

Now that the $200 SBR tax will be gone soon I was thinking of chopping a rifle barrel off to about 12 inches so I lose around 4oz and make everything more convenient to carry. Seems like it would be cheaper and a better overall deal then paying $800 or so for a suppressor that is only slightly shorter or lighter.

My question, if anyone has an idea, is how much louder this will be? I was planning on doing it with either my 308 and possibly with a 6.5 Creedmoor. If its going to be significantly louder then those rifles with a 16 inch barrel, I probably won't bother.

Plan B would be either a 14 inch barrel as a compromise, or a new 6mm ARC or 22 ARC. I don't make 600 yard shots so I can lose some velocity. But I don't know if I can get a .223 going fast enough out of an SBR to get me to 400 yards which would be nice.

Thoughts?

 

[HairyScandinavian]

I can't say with those cartridges but I had an 11.5" 5.56 that was just God awful suppressed nowhere near hearing safe. I replaced that with a 14.5" and it's so much better now. Seems like 12" is pretty short to get a good powder burn and I'd bet it's pretty nasty blast even with a Can.
55gr in the 11.5" gave me 2650 fps and 14.5" 2890. Didn't try anything heavier.

Edit: I can't remember if it was 10.5" or 11.5".

 

[Loper]

Good question OP. I’m following as I’m curious to hear what members have to say on this.

 

[Formidilosus]

I was thinking about a newer, lighter suppressor. I currently use a Rugged Radiant 762 (in long configuration) and a Polonium 30, both of which add about a pound to the rifle.

Those are large heavy cans.

My question, if anyone has an idea, is how much louder this will be? I was planning on doing it with either my 308 and possibly with a 6.5 Creedmoor. If its going to be significantly louder then those rifles with a 16 inch barrel, I probably won't bother.

Louder, on average around 2-4 dB from 16” to say 12”.

But I don't know if I can get a .223 going fast enough out of an SBR to get me to 400 yards which would be nice.

You absolutely can. 12.5” barrels have averaged 2,500+/- FPS MV with 77gr TMK’s. That gets 1,800fps impact to around 420 yards at 5k DA. I have used 55gr and 62gr Speer Gold Dots (Federal Fusion same/same) past 400 yards multiple times with good wound channels.

 

[Luke S]

Thanks Form. Sounds like a 12 inch 308 or 6.5CM would be borderline. I wouldn't want much louder than I already have.

Come to think of it we used a suppressed 6.5 Grendal pistol with a 1.5 inch barrel quite a bit. I'd say it was similar to the 308 with a suppressor and longer barrel as far as ear comfort. I imagine a bolt action with no port pop might be better? So an ARC caliber might be nice but I don't know about building a reliable one right now (limited time and budget to experiment).

I'm assuming those 223 velocities involve handloads, at least with the ammo I can get in Alaska. I do reload but for time reasons I'm trying not to need to. Of course I might consider it with the abundance of cheap practice ammo.

So 14 inch 308/6.5 CM with factory ammo...
Or 12 inch 223 and I need to start reloading...
Those are the easy ideas.

 

[Loper]

Come to think of it we used a suppressed 6.5 Grendal pistol with a 1.5 inch barrel quite a bit.

I’m not sure I’ve heard of AR pistols with barrels this short. Did you mean to say 11.5 inch barrel? Can you clarify this?

 

[M3Inline6]

I’m not sure I’ve heard of AR pistols with barrels this short. Did you mean to say 11.5 inch barrel? Can you clarify this?

That’s what I’m thinking as well. The shortest pistols I’ve seen were 6-8” barrels.

 

[Lwilliams]

I've got a 6.5 grendel barrel for a howa mini at the smith now getting chopped to 12" to make a little 300 yard and in gun. Ill respond back once it's finished. Should have it back this weekend. Ideally it will be a handy little suppressed rifle.

 

[M3Inline6]

I've got a 6.5 grendel barrel for a howa mini at the smith now getting chopped to 12" to make a little 300 yard and in gun. Ill respond back once it's finished. Should have it back this weekend. Ideally it will be a handy little suppressed rifle.

What supppressor do you plan to run on it? I have BANISH models for on my AR pistols, but I’m looking for a little something different for my .308.

 

[Luke S]

Sorry yes it's a 11.5 inch barrel.

 

[naked wombats]

Might be worth looking at some of the specialty pistol forums/load data to help get an idea on the various calibers performance, they have been running shorties for years in contenders and xp100's.

If I recall, 308 should give up less fps per inch than the smaller bores, but less recoil can be more manageable with short barrels.

 

[Lwilliams]

What supppressor do you plan to run on it? I have BANISH models for on my AR pistols, but I’m looking for a little something different for my .308.

Not sure on what suppressor ill run on this one. I've got over a dozen centerline suppressors of various manufacturers, I'll try several and find one that sounds the best to my ears and run with it.

 

[Tahoe1305]

Maybe I missed it. SBR tax is going away too….that just form4?

 

[Luke S]

I get that sound is complicated to measure but if someone understands this better let me know.

I looked up the 2024-2025 Silencer Summit to compare things.

• If Form is right, cutting a 308 based rifle to 12 inches adds around 2-4 decibels. According to the summit results, that would bring my suppressors from an average of around 140 db up to 144 which is theoretically equal to several 5 inch K cans tested. I'm skeptical it would be that bad with everyone bad mouthing every 5 inch K can I"m aware of. But, it might be bad enough I would not want to shoot without ear pro even hunting. So probably a no go.
• The numbers for a 223 shot through a Polonium 30 and Rugged Radiant 762 (long) are basically the same as from a 308. Does that pass that pass the smell test? I tried a 223 with my suppressor and it seemed less loud although there was still a pretty sharp crack. I was all set to look into a 223 SBR'd Tikka but if its just as loud as my 308 I'm not going SBR that way either.

Maybe I'm back to just getting a lighter silencer and calling it good. Anyone play with a Otter Creek Labs Hydrogen K? That would work with one rifle I have that already has a compatible pin and weld muzzle break. The pin and weld worked okay on a 308 RA. Problem was the gunsmith was super conservative with his measuring. He could have made it 1/2 to 3/4 inch shorter.

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[HairyScandinavian]

Anyone play with a Otter Creek Labs Hydrogen K? That would work with one rifle I have that already has a compatible pin and weld muzzle break.

Wife has their Polonium K on a 16" 6mm ARC and seems to perform pretty well for that application. We haven't shot it without hearing protection but plan to for hunting. Doesn't seem as loud as my B&T Ranger 6.5CM when shooting together.

 

[KyleR1985]

12” 6 arc gets you to right at 400 yards with factory 108 ammo - which is slow. Below is factory ammo results chart.

Handloading will get you there with the 87,90,95,103,and probably 108’s with an 1800fps threshold.

I’ve shot my 6ARC 12.5” with DD wolf hunter. It’s louder than my 16” 6 dasher but not obnoxiously so.

For this use case I’d do a 6ARC, dasher, or GT. Lots of information available on arc and dasher in short barrel/pistol