How short can I go on a 308 bolt gun barrel to shoot only subsonic loads with a YHM Phantom stainless. Maybe permanently attached. 400 yards max range.
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how short for a 308 subsonic loads only
- Thread starter tmpohuski7
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Re: how short for a 308 subsonic loads only
If you are willing to perminently attach the suppressor and you don't care about the drop, then your only limiting factor is how long does a barrel has to be to stablize the 308 bullet. (You can count the lenght of the suppressor in the barrel legnth if it's perminently attached). I don't have a clue what that barrel legth is?. Another problem to consider is all the unburned power is going to reak havic on your suppressor.
If you want a short barrel rifle with the suppressor attached you might want to consider rebarreling to a 300 whisper or 300 blackout. These bullet usually stabalize in about 8".
If it was me I would go below 16", that way the can isn't married to the rifle.
Jeff
If you are willing to perminently attach the suppressor and you don't care about the drop, then your only limiting factor is how long does a barrel has to be to stablize the 308 bullet. (You can count the lenght of the suppressor in the barrel legnth if it's perminently attached). I don't have a clue what that barrel legth is?. Another problem to consider is all the unburned power is going to reak havic on your suppressor.
If you want a short barrel rifle with the suppressor attached you might want to consider rebarreling to a 300 whisper or 300 blackout. These bullet usually stabalize in about 8".
If it was me I would go below 16", that way the can isn't married to the rifle.
Jeff
Re: how short for a 308 subsonic loads only
If you went with the QD version of the YHM, you could go 14.5 and permanently attach the flash hider/ qd mount.
If you went with the QD version of the YHM, you could go 14.5 and permanently attach the flash hider/ qd mount.
Re: how short for a 308 subsonic loads only
If you are considering a dedicated subsonic platform, spend your money on a Whisper or Blackout. You will not be happy with subsonic .308 performance unless you go with an 8 twist or faster so you can shoot the heavier pills. Even then, subsonic .308 is not going to be nearly as consistent/accurate as the smaller-cased Whisper/Blackout round. Do not believe the internet claims of consistent half-moa performance out of Subsonic .308 handloads. I have had 3 different 16 inch .308's for subsonic use and have always gone back to the Whisper. My current subsonic platform is a 16 inch Remmy Douglas-barreled .300 Fireball and I absolutely love it. It is consistently sub-moa with everything from 155 Noslers to 220 SMK's.
If you are considering a dedicated subsonic platform, spend your money on a Whisper or Blackout. You will not be happy with subsonic .308 performance unless you go with an 8 twist or faster so you can shoot the heavier pills. Even then, subsonic .308 is not going to be nearly as consistent/accurate as the smaller-cased Whisper/Blackout round. Do not believe the internet claims of consistent half-moa performance out of Subsonic .308 handloads. I have had 3 different 16 inch .308's for subsonic use and have always gone back to the Whisper. My current subsonic platform is a 16 inch Remmy Douglas-barreled .300 Fireball and I absolutely love it. It is consistently sub-moa with everything from 155 Noslers to 220 SMK's.
Re: how short for a 308 subsonic loads only
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Scoop</div><div class="ubbcode-body">If you are considering a dedicated subsonic platform, spend your money on a Whisper or Blackout. You will not be happy with subsonic .308 performance unless you go with an 8 twist or faster so you can shoot the heavier pills. Even then, subsonic .308 is not going to be nearly as consistent/accurate as the smaller-cased Whisper/Blackout round. Do not believe the internet claims of consistent half-moa performance out of Subsonic .308 handloads. I have had 3 different 16 inch .308's for subsonic use and have always gone back to the Whisper. My current subsonic platform is a 16 inch Remmy Douglas-barreled .300 Fireball and I absolutely love it. It is consistently sub-moa with everything from 155 Noslers to 220 SMK's. </div></div>
Yeah, I'm gonna have to disagree with you on that. On every point of that actually. 308 or 300 Whisper/Blackout, you'll still need a 1/8 twist to run heavy subsonics. I just finished a Savage build with a 1/8 twist 16.25" barrel. I am able to consistently shoot it right around 1/2 MOA 5 shot groups. Multiple groups per target sheet and back to back groups. Not only is it just as consistent as any 300 Whisper/Blackout rifle, it is still capable of shooting supersonic rounds just as accurately.
Now considering the OP asked specifically about 308 subsonics, I would stick with 16" barrels and most certainly go with a 1 in 8 twist. I've run 220 SMK's out of my Savage, and have 2 boxes of 240 SMK's waiting for load development.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Scoop</div><div class="ubbcode-body">If you are considering a dedicated subsonic platform, spend your money on a Whisper or Blackout. You will not be happy with subsonic .308 performance unless you go with an 8 twist or faster so you can shoot the heavier pills. Even then, subsonic .308 is not going to be nearly as consistent/accurate as the smaller-cased Whisper/Blackout round. Do not believe the internet claims of consistent half-moa performance out of Subsonic .308 handloads. I have had 3 different 16 inch .308's for subsonic use and have always gone back to the Whisper. My current subsonic platform is a 16 inch Remmy Douglas-barreled .300 Fireball and I absolutely love it. It is consistently sub-moa with everything from 155 Noslers to 220 SMK's. </div></div>
Yeah, I'm gonna have to disagree with you on that. On every point of that actually. 308 or 300 Whisper/Blackout, you'll still need a 1/8 twist to run heavy subsonics. I just finished a Savage build with a 1/8 twist 16.25" barrel. I am able to consistently shoot it right around 1/2 MOA 5 shot groups. Multiple groups per target sheet and back to back groups. Not only is it just as consistent as any 300 Whisper/Blackout rifle, it is still capable of shooting supersonic rounds just as accurately.
Now considering the OP asked specifically about 308 subsonics, I would stick with 16" barrels and most certainly go with a 1 in 8 twist. I've run 220 SMK's out of my Savage, and have 2 boxes of 240 SMK's waiting for load development.
Re: how short for a 308 subsonic loads only
I shoot a 308 with an 18inch barrel, ten twist.
It does pretty well with subs; not great, but good enough. Usually wind up with 1.5 inch or so at 100.Sometimes better or worse, but that is a pretty good average. Load tweaking could improve maybe, but I just havent put the time into it.
Shoots supersonic very well.
43.2 grains of varget and 175 smk will get me a little under 2600 fps on this rifle and 2640ish on my longer barrel 308 (22 inch). Havent shot the 18incher past 600, but it does well out to there.
Pretty happy with the compromise, but if I were only shooting subs, I dont see why 16 inch wouldnt be better. I have been wanting to do a whisper or blackout though...
I shoot a 308 with an 18inch barrel, ten twist.
It does pretty well with subs; not great, but good enough. Usually wind up with 1.5 inch or so at 100.Sometimes better or worse, but that is a pretty good average. Load tweaking could improve maybe, but I just havent put the time into it.
Shoots supersonic very well.
43.2 grains of varget and 175 smk will get me a little under 2600 fps on this rifle and 2640ish on my longer barrel 308 (22 inch). Havent shot the 18incher past 600, but it does well out to there.
Pretty happy with the compromise, but if I were only shooting subs, I dont see why 16 inch wouldnt be better. I have been wanting to do a whisper or blackout though...
Re: how short for a 308 subsonic loads only
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Qld4390</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Scoop</div><div class="ubbcode-body">If you are considering a dedicated subsonic platform, spend your money on a Whisper or Blackout. You will not be happy with subsonic .308 performance unless you go with an 8 twist or faster so you can shoot the heavier pills. Even then, subsonic .308 is not going to be nearly as consistent/accurate as the smaller-cased Whisper/Blackout round. Do not believe the internet claims of consistent half-moa performance out of Subsonic .308 handloads. I have had 3 different 16 inch .308's for subsonic use and have always gone back to the Whisper. My current subsonic platform is a 16 inch Remmy Douglas-barreled .300 Fireball and I absolutely love it. It is consistently sub-moa with everything from 155 Noslers to 220 SMK's. </div></div>
Yeah, I'm gonna have to disagree with you on that. On every point of that actually. 308 or 300 Whisper/Blackout, you'll still need a 1/8 twist to run heavy subsonics. I just finished a Savage build with a 1/8 twist 16.25" barrel. I am able to consistently shoot it right around 1/2 MOA 5 shot groups. Multiple groups per target sheet and back to back groups. Not only is it just as consistent as any 300 Whisper/Blackout rifle, it is still capable of shooting supersonic rounds just as accurately.
Now considering the OP asked specifically about 308 subsonics, I would stick with 16" barrels and most certainly go with a 1 in 8 twist. I've run 220 SMK's out of my Savage, and have 2 boxes of 240 SMK's waiting for load development. </div></div>
Glad to hear that you are having good luck out of your .308 with sub loads. What's your recipe? What does your first shot from a cold bore do compared to the rest? I ask because every .308 I have loaded subsonic ammo for has shot well after that first cold bore shot, but that first shot would be anywhere from 3 to 6 inches lower than the others. Get that first one gone and they shot well (~1 moa) after that. I wanted to be able to hunt with the stuff and not being able to count on where that first shot would go was a deal breaker for me. For whatever reason, I have never had that problem with any subsonic loads in any of my several Whispers. Go figure.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Qld4390</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Scoop</div><div class="ubbcode-body">If you are considering a dedicated subsonic platform, spend your money on a Whisper or Blackout. You will not be happy with subsonic .308 performance unless you go with an 8 twist or faster so you can shoot the heavier pills. Even then, subsonic .308 is not going to be nearly as consistent/accurate as the smaller-cased Whisper/Blackout round. Do not believe the internet claims of consistent half-moa performance out of Subsonic .308 handloads. I have had 3 different 16 inch .308's for subsonic use and have always gone back to the Whisper. My current subsonic platform is a 16 inch Remmy Douglas-barreled .300 Fireball and I absolutely love it. It is consistently sub-moa with everything from 155 Noslers to 220 SMK's. </div></div>
Yeah, I'm gonna have to disagree with you on that. On every point of that actually. 308 or 300 Whisper/Blackout, you'll still need a 1/8 twist to run heavy subsonics. I just finished a Savage build with a 1/8 twist 16.25" barrel. I am able to consistently shoot it right around 1/2 MOA 5 shot groups. Multiple groups per target sheet and back to back groups. Not only is it just as consistent as any 300 Whisper/Blackout rifle, it is still capable of shooting supersonic rounds just as accurately.
Now considering the OP asked specifically about 308 subsonics, I would stick with 16" barrels and most certainly go with a 1 in 8 twist. I've run 220 SMK's out of my Savage, and have 2 boxes of 240 SMK's waiting for load development. </div></div>
Glad to hear that you are having good luck out of your .308 with sub loads. What's your recipe? What does your first shot from a cold bore do compared to the rest? I ask because every .308 I have loaded subsonic ammo for has shot well after that first cold bore shot, but that first shot would be anywhere from 3 to 6 inches lower than the others. Get that first one gone and they shot well (~1 moa) after that. I wanted to be able to hunt with the stuff and not being able to count on where that first shot would go was a deal breaker for me. For whatever reason, I have never had that problem with any subsonic loads in any of my several Whispers. Go figure.
Re: how short for a 308 subsonic loads only
My 10" SBR 8 twist in 300 whisper shoots great and is super handy, should have done this years ago.
My 10" SBR 8 twist in 300 whisper shoots great and is super handy, should have done this years ago.
Re: how short for a 308 subsonic loads only
Right now, I'm using Sierra 220 SMK, backed up with 11.7 grains of Trailboss, with Lapua brass and CCI BR2 primers. I have them chronographed at about 1030 fps. At first, I had the same problem as you. The first round out of my cold, clean barrel was always about 2 inches low. I found that on a cold, but fouled barrel, I had no discernible drop, or POI shift.
On your Whisper barrels, do you shoot out of a fouled barrel, or a clean barrel? Also, out of curiosity, is it a semi auto (AR15) type, or a bolt action setup?
Right now, I'm using Sierra 220 SMK, backed up with 11.7 grains of Trailboss, with Lapua brass and CCI BR2 primers. I have them chronographed at about 1030 fps. At first, I had the same problem as you. The first round out of my cold, clean barrel was always about 2 inches low. I found that on a cold, but fouled barrel, I had no discernible drop, or POI shift.
On your Whisper barrels, do you shoot out of a fouled barrel, or a clean barrel? Also, out of curiosity, is it a semi auto (AR15) type, or a bolt action setup?
Re: how short for a 308 subsonic loads only
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Qld4390</div><div class="ubbcode-body">Right now, I'm using Sierra 220 SMK, backed up with 11.7 grains of Trailboss, with Lapua brass and CCI BR2 primers. I have them chronographed at about 1030 fps. At first, I had the same problem as you. The first round out of my cold, clean barrel was always about 2 inches low. I found that on a cold, but fouled barrel, I had no discernible drop, or POI shift.
On your Whisper barrels, do you shoot out of a fouled barrel, or a clean barrel? Also, out of curiosity, is it a semi auto (AR15) type, or a bolt action setup? </div></div>
I tried every way possible to get rid of that first shot inconsistency (clean barrel, lubed barrel, fouled barrel, tipping the muzzle up before the shot so that the propellant was nearest to the primer, magnum primers, drilled-out primer holes, everything!) and was never able to shake it. Of the three 16 inch guns, one was factory Savage, one factory Remmy and one custom Remmy with a PacNor barrel. Went back through my notebooks and found that I had tried it in two other full-custom builds (GAP Remmy w/20 inch Bartlein tube and a GAP 20 inch AR10 with a Rock tube - both 11.25 twists) with the same first shot variance.
To date I have had 8 different Whispers/Fireballs (.300 Whisper TC Contender by SSK, Two different factory Olympic .300 FB AR's, two different Noveske 10.5 inch Registered SBR AR's, a PacNor-barreled CZ527 bolt gun, a 7-twist Douglas-barreled HOWA bolt gun and presently an 8-twist Douglas-barreled Remmy 700 bolt gun) and not one of them has exhibited the first-shot-low phenomenon. Go figure! I have shot them clean, dirty, and in between with no real difference. A very dirty barrel shoots lower than a clean barrel, but all the shots (including the first from a cold bore) are together.
My guess is that it has something to do with the case size vs powder fill. Obviously the Whisper-size cases are filled to a higher percentage than the bigger .308 cases. Just a guess. What I have observed is not a guess though. What consistently has happened in my subsonic .308's has not happened in my Whispers/Fireballs.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Qld4390</div><div class="ubbcode-body">Right now, I'm using Sierra 220 SMK, backed up with 11.7 grains of Trailboss, with Lapua brass and CCI BR2 primers. I have them chronographed at about 1030 fps. At first, I had the same problem as you. The first round out of my cold, clean barrel was always about 2 inches low. I found that on a cold, but fouled barrel, I had no discernible drop, or POI shift.
On your Whisper barrels, do you shoot out of a fouled barrel, or a clean barrel? Also, out of curiosity, is it a semi auto (AR15) type, or a bolt action setup? </div></div>
I tried every way possible to get rid of that first shot inconsistency (clean barrel, lubed barrel, fouled barrel, tipping the muzzle up before the shot so that the propellant was nearest to the primer, magnum primers, drilled-out primer holes, everything!) and was never able to shake it. Of the three 16 inch guns, one was factory Savage, one factory Remmy and one custom Remmy with a PacNor barrel. Went back through my notebooks and found that I had tried it in two other full-custom builds (GAP Remmy w/20 inch Bartlein tube and a GAP 20 inch AR10 with a Rock tube - both 11.25 twists) with the same first shot variance.
To date I have had 8 different Whispers/Fireballs (.300 Whisper TC Contender by SSK, Two different factory Olympic .300 FB AR's, two different Noveske 10.5 inch Registered SBR AR's, a PacNor-barreled CZ527 bolt gun, a 7-twist Douglas-barreled HOWA bolt gun and presently an 8-twist Douglas-barreled Remmy 700 bolt gun) and not one of them has exhibited the first-shot-low phenomenon. Go figure! I have shot them clean, dirty, and in between with no real difference. A very dirty barrel shoots lower than a clean barrel, but all the shots (including the first from a cold bore) are together.
My guess is that it has something to do with the case size vs powder fill. Obviously the Whisper-size cases are filled to a higher percentage than the bigger .308 cases. Just a guess. What I have observed is not a guess though. What consistently has happened in my subsonic .308's has not happened in my Whispers/Fireballs.
Re: how short for a 308 subsonic loads only
You don't need much barrel at sub-sonic speeds. So if you want to go the SBR route, just in front of the stock.
You don't need much barrel at sub-sonic speeds. So if you want to go the SBR route, just in front of the stock.
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