Gunsmithing Subsonic/Supersonic Rifle Build

[Agent007]

Hello all,

I'm starting a bolt action rifle build and am held up on what cartridge to go with. I have two purposes with this build. 1.) Target shooting out to 1,000 yards (perhaps some competition in the future) and 2.) As a side business, I go around to vineyards, farms, etc. and help with pest control of nothing bigger than a turkey. As with that, sometimes the owners don't want to hear gunshots (including the supersonic crack of a suppressed shot) hence the subsonic need as they are okay with that. At first, the obvious choice and still a strong contender is the 308 winchester.

However, out of curiosity, I wanted to see what other choices there were and maybe have a little bit of fun and go with an unorthodox cartridge.

One of 3 other calibers that seems to fit my bill is the 7mm-08. There are high b.c bullets in the 150-168 grain range and also heavier bullets of 190 grains for possible subsonic loads.

I've always been interested in the 6.5 grendel and want to see if this caliber can fit my bill. I would use flatline 123's and for subsonic the heavier 154 grain from hornady.

Lastly, the 6mmx45 got my attention. Shooting the flatline 88 grains and heavier 115 for subsonic.

I'm asking the members of this site whom are much smarter than I am for tips and advice. Does anyone have experience with these calibers? Especially when it comes to the subsonic load data of them? Are any of these calibers worth pursuing or should I just stick with the 308? Thanks in advance.

Alex

 

[Snuby642]

I wish you luck.

Can't haul much corn and feeders in a sports car.

I have 300blk, 308, 6.5 grendel etc. . You are asking too much for one gun to do well.

Money better spent on two guns and two very different scopes as well.

If you play your cards right they may share one suppressor.

Ihmo.

 

[Mordamer]

I think you should build an awesome 1,000 yard gun with a good cartridge like 6 Creed or 6.5 Creed or one of the other great options.

Then you should go buy a Ruger American Ranch in 300 blackout for shooting pests subsonic. These guns cost about $400 and are perfect for what you want to do.

No reason to use the same gun for both tasks.

 

[ah1356]

I have an 18-in, 10TW .308 barrel from Criterion that I can mount to a Bighorn TL3 with a Savage nut. My primary purpose for this barrel was fun quiet subsonic loads. Second was an easily maneuverable suppressed option for hunting. A distant third was "What the hell - let's see if I can get hits at 1K."

It is very quiet with 220gr subsonic loads, extremely accurate to about 600 yards with supersonic loads, I did get a deer with it, and I have made hits at 1,000, so mission accomplished. But to be clear it is no match for my 6.5x47 in any way other than subsonic suppressed fire, which I have never bothered to try with the 6.5x47.

You can do it all with one gun - if you have reasonable expectations for what it will and won't do well.

 

[2muchcowbell]

Hello all,

I'm starting a bolt action rifle build and am held up on what cartridge to go with. I have two purposes with this build. 1.) Target shooting out to 1,000 yards (perhaps some competition in the future) and 2.) As a side business, I go around to vineyards, farms, etc. and help with pest control of nothing bigger than a turkey. As with that, sometimes the owners don't want to hear gunshots (including the supersonic crack of a suppressed shot) hence the subsonic need as they are okay with that. At first, the obvious choice and still a strong contender is the 308 winchester.

However, out of curiosity, I wanted to see what other choices there were and maybe have a little bit of fun and go with an unorthodox cartridge.

One of 3 other calibers that seems to fit my bill is the 7mm-08. There are high b.c bullets in the 150-168 grain range and also heavier bullets of 190 grains for possible subsonic loads.

I've always been interested in the 6.5 grendel and want to see if this caliber can fit my bill. I would use flatline 123's and for subsonic the heavier 154 grain from hornady.

Lastly, the 6mmx45 got my attention. Shooting the flatline 88 grains and heavier 115 for subsonic.

I'm asking the members of this site whom are much smarter than I am for tips and advice. Does anyone have experience with these calibers? Especially when it comes to the subsonic load data of them? Are any of these calibers worth pursuing or should I just stick with the 308? Thanks in advance.

Alex

I honestly don't think you can go wrong with .308. There's already a market for terminally effective subsonic bullets in that caliber, so it'll be easy to make it work. 7mm is a fantastic caliber for external and terminal ballistics - in the supersonic range. It's always been a bit of a redheaded stepchild in the American market, and particularly for expanding subsonic bullets.

I'd be interested to see a 7mm subsonic build, but the *easiest* way is to simply go .308. Or, as suggested above, go with two different guns.

 

[2muchcowbell]

I honestly don't think you can go wrong with .308. There's already a market for terminally effective subsonic bullets in that caliber, so it'll be easy to make it work. 7mm is a fantastic caliber for external and terminal ballistics - in the supersonic range. It's always been a bit of a redheaded stepchild in the American market, and particularly for expanding subsonic bullets.

I'd be interested to see a 7mm subsonic build, but the *easiest* way is to simply go .308. Or, as suggested above, go with two different guns.

Or. OR. You could use an interchangeable-bolt-face action like a Bighorn Arms Origin/TL3 to have both a 6.5/7mm precision rifle AND a separate .223 bolt face/.300 BLK barrel, then change the barrel/bolt face out as necessary.

 

[Agent007]

I figured 308 or two separate rifles would be the best way to go. However, I came across a guy claiming to have built a 6.5 grendel subsonic load by using imr8208 and the heaviest 6.5's he could find. I forgot what the accuracy was, but I think around 2-3 moa at 100m. My brain says 308, but my heart and curiosity say to play around with the 7mm and slower powders. I just haven't found much data on subsonic 7mm(probably for a reason). But any reason to have to buy more rifles I'll take, peer pressure is a heck of a thing Ill tell the wife

 

[Praeger]

Agree with @Snuby642 and @Mordamer. 300BLK suppressed and any of the other cartridges for a 1K gun. The 300BLK is a much more efficient subsonic cartridge, far less empty volume than a subsonic 308. I built a 300BLK on a Tikka action and it runs very quiet on Red Dot and 220 grain cast lead epoxy coated bullets from a 16" barrel. Subsonic loads won't group like supersonic, so keep your expectations in check but slow, heavy bullet on steel will put a smile on my face every time.

 

[Snuby642]

If you have a 1/7 twist 300blk 16 inch barrel 220gr will group 1 moa.

Forget the factory stuff.
12.5gr cfeblk, 220 hornady interlock.
1015fps on a cold day, will not crack in 100 degrees.

 

[Easy_E]

Hello all,
Lastly, the 6mmx45 got my attention. Shooting the flatline 88 grains and heavier 115 for subsonic.
Alex

Similar to the 6mm ARC factory brass and ammo

 

[Shootin Stuff]

308 for shooting turkeys?!?!

What you are looking for is a switch barrel rifle and something built off a 223 bolt face is exactly what you need.

.223 ackley improved with 75-90 grain projectiles is no joke and will get you to 1,000yards on steel easily.

If you need something that hits harder than subsonic .223 (more weight) then get a 300 blackout barrel spun up with wrench flats on the muzzle and swap barrels out in the field in under a minute.

Same stock/chassis, scope, action, bolt, mags etc.
Just switch barrels depending on what you’re doing, but make damn sure you don’t accidentally chamber and fire a 300blk in the 223 barrel.

 

[Yondering]

Hello all,

I'm starting a bolt action rifle build and am held up on what cartridge to go with. I have two purposes with this build. 1.) Target shooting out to 1,000 yards (perhaps some competition in the future) and 2.) As a side business, I go around to vineyards, farms, etc. and help with pest control of nothing bigger than a turkey. As with that, sometimes the owners don't want to hear gunshots (including the supersonic crack of a suppressed shot) hence the subsonic need as they are okay with that. At first, the obvious choice and still a strong contender is the 308 winchester.

However, out of curiosity, I wanted to see what other choices there were and maybe have a little bit of fun and go with an unorthodox cartridge.

One of 3 other calibers that seems to fit my bill is the 7mm-08. There are high b.c bullets in the 150-168 grain range and also heavier bullets of 190 grains for possible subsonic loads.

I've always been interested in the 6.5 grendel and want to see if this caliber can fit my bill. I would use flatline 123's and for subsonic the heavier 154 grain from hornady.

Lastly, the 6mmx45 got my attention. Shooting the flatline 88 grains and heavier 115 for subsonic.

I'm asking the members of this site whom are much smarter than I am for tips and advice. Does anyone have experience with these calibers? Especially when it comes to the subsonic load data of them? Are any of these calibers worth pursuing or should I just stick with the 308? Thanks in advance.

Alex

Alex - it's important to understand that there is practically zero crossover between good 1,000 yard cartridges and good subsonic cartridges (and yes I'm talking about handloading your own, not just factory ammo). You can find some that can do both, sorta, like the 308, but none are really good at both simultaneously. For long range you want high b.c. and decent velocity, which means at least moderate case capacity for the bore size. For subsonic you really want small case capacity for the bore size. I base this on many years of loading subsonic ammo for suppressed shooting.

It's also important to know that bullet selection is absolutely critical for subsonic loads, much more so than high velocity bullets. Something like the heavy 7mm bullets you mention? Forget it, if you want to safely take out small game; penetration of subsonic rifle bullets can be measured in yards, not inches, with the rare exception of bullets designed for the application. Seriously, something like the common 220gr 300 Blk loading will shoot through several horses at once. You're a lot safer to use something like a high velocity 40gr 223, regardless what the non-gun landowners think. If you have to use subsonics and need to use a centerfire rifle, you really need a bullet with a massive hollow point and thin construction, or keep weight very light. A cartridge shooting pistol bullets can work well though, like a 35 Remington using 9mm or 357 hollow points, or for that matter a suppressed 9mm or 38 Spl single shot or bolt gun (you'd have to build that from a 22 TCM like I did).

IMO the better alternative if you have to use subsonics is a 22 LR with good ammo like CCI subsonic HP or subsonic segmented HP; it's quieter and the bullets are actually designed for that speed. And just pick a separate rifle in an appropriate cartridge for long range.

None of the switch barrel stuff is really worthwhile IMO, because of the need for optic rezeroing (and sometimes different optics altogether). By the time you handle that, you might as well just have two rifles.

 

[Shootin Stuff]

^^^^ He doesn’t NEED the energy of 220gn projectiles for shooting pests in vineyards, subsonic 223 is plenty for small rodents/varmints, he could even cast his own round nose lead....

If in future he decides he needs more subsonic punch (somethinng bigger than turkeys), then a 300blk barrel will deliver that, whilst still remaining 100% functionality with his current rifle setup and ancillaries.

Hornady, Lehigh and several others make projectiles designed for reliable subsonic expansion so there are options that wont “shoot through several horses at once”, have you got any proof of such an event occuring?

POI shift between shouldered barrels is measureable and repeatable, once it has been established and confirmed swapping barrels is a non issue.

As stated already, a fast twist 223 AI shooting heavies will get him to 1,000yards and can easily be down loaded to subsonic rodent slaying level.

If I didn’t already own a 300blk I would be strongly tempted to get another spun up as a switch barrel for one of my 223 bolt guns just for the fun of it, hell I might even still do it anyway.

 

[Yondering]

^^^^ He doesn’t NEED the energy of 220gn projectiles for shooting pests in vineyards, subsonic 223 is plenty for small rodents/varmints, he could even cast his own round nose lead....

If in future he decides he needs more subsonic punch (somethinng bigger than turkeys), then a 300blk barrel will deliver that, whilst still remaining 100% functionality with his current rifle setup and ancillaries.

Hornady, Lehigh and several others make projectiles designed for reliable subsonic expansion so there are options that wont “shoot through several horses at once”, have you got any proof of such an event occuring?

POI shift between shouldered barrels is measureable and repeatable, once it has been established and confirmed swapping barrels is a non issue.

As stated already, a fast twist 223 AI shooting heavies will get him to 1,000yards and can easily be down loaded to subsonic rodent slaying level.

If I didn’t already own a 300blk I would be strongly tempted to get another spun up as a switch barrel for one of my 223 bolt guns just for the fun of it, hell I might even still do it anyway.

 

[High H2o]

Just started with subsonic .blk. having fun with it, but was curious about supersonic accuracy? I know it wont go 1k, but 6? 8? just curious to see what the more experienced have experienced with the round...

Thanks!

 

[Snuby642]

I was thinking of deer and hogs for pests. If smaller pests are the problem why not use 22 lr in standard velocity with a can.

I shoot a tweaked 10/22 with cci sv and pretty much movie quiet with a sparrow for a can. A shaw barrel gets me sub moa with the cci's.

Shooting a game animal with rf is illegal in Texas but may vary for depredation tags for the Turkeys?

 

[Yondering]

Just started with subsonic .blk. having fun with it, but was curious about supersonic accuracy? I know it wont go 1k, but 6? 8? just curious to see what the more experienced have experienced with the round...

Thanks!

For relatively short range (i.e. inside 300 yards) the 300 Blk can produce pretty good accuracy. For longer distance though it's really not a great choice; it just doesn't have to ballistics to do well at long range. While the best ammo choices can technically reach out to about 600 yards before dropping into the trans-sonic region, you're dealing with a lot of drop and wind drift by that point so it's more challenging to hit with than the faster cartridges. It can be fun to plink with at extended distances though, just for the challenge of it!

There are exceptions of course, I've seen a couple decent targets from a 300 Blk fan shooting at 1,000 yards just to prove he could, but for all practical purposes it's one of the poorest options for long distance in the AR15 platform. With that said, it can do anything the 7.62x39 can do, but better because of better bullets and the AR15's capability for much better accuracy than the AK.

Hope that helps.

 

[sirhrmechanic]

I think you should build an awesome 1,000 yard gun with a good cartridge like 6 Creed or 6.5 Creed or one of the other great options.

Then you should go buy a Ruger American Ranch in 300 blackout for shooting pests subsonic. These guns cost about $400 and are perfect for what you want to do.

No reason to use the same gun for both tasks.

^^^. This!