300BLK Bolt Gun Project - Looking for Barrel Advice

[overmatch]

Hi all, I'm looking to put together a 300BLK bolt gun and will be running a Sig SRD762 Ti Direct Thread suppressor on it.

• Shooting will be primarily subs, but I'd like the ability to run supers if I ever wanted to.
• Barrel can be between 8-8.5" and I'm really looking for advice on twist rate.
• Suppressor will be direct threaded on with Sig taper, and won't ever be removed. Can is 9.3" long ( ͡° ل͜ ͡°)

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Looking at how Q does 1:5 for their 8" barrel on the Mini Fix and some of the latest literature supporting faster twists, I am leaning towards 1:5, but want to be wary of having bullets come apart in the can, especially if I run supers. Can someone smarter than me please explain:

• What causes bullets to "come apart"
• What types of bullets are more at risk for this, and
• Ultimately if I can run a 8" 1:5 barrel without having to worry about this.

 

[spife7980]

Being spun faster than they can hold themselves together.

Thin varmint bullet are at higher risk as they are disgnes to come apart easier. Or poor quality bullets with nonuniform jackets that don’t get pulled in equally.

I see no reason to go 5, 7 twist will be more than adequate for subs and supers.

Range gain? Bot sure what you mean. Being a subsonic the velocity is capped regardless of barrel length so you won’t gain any advantage there. Supersonics, a half inch won’t make a lick of difference.

 

[wvfarrier]

1:7 twist is what you are looking for. A 1:5 is way too fast.

 

[overmatch]

1:7 twist is what you are looking for. A 1:5 is way too fast.

Interesting. Do you know how / why Q seems to have it work well with their 8" 300Blk bolt gun? Not meaning to refute your statement since I have no clue, just trying to understand factors that may impact it. Appreciate you chiming in

 

[overmatch]

Being spun faster than they can hold themselves together.

Thin varmint bullet are at higher risk as they are disgnes to come apart easier. Or poor quality bullets with nonuniform jackets that don’t get pulled in equally.

I see no reason to go 5, 7 twist will be more than adequate for subs and supers.

Range gain? Bot sure what you mean. Being a subsonic the velocity is capped regardless of barrel length so you won’t gain any advantage there. Supersonics, a half inch won’t make a lick of difference.

Appreciate the responses! Thank you.

 

[wvfarrier]

Interesting. Do you know how / why Q seems to have it work well with their 8" 300Blk bolt gun? Not meaning to refute your statement since I have no clue, just trying to understand factors that may impact it. Appreciate you chiming in

Beats me but I tried a 1:5 in my Rem 700 spun up by wolf pack armory and it wrecked projectiles. I tried several different types and none faired very well. The only thing what worked for me was FMJs. I had a Barnes 130 speer tnt actually come apart in the barrel. Grsnted I was using a 16" barrel not a shorty

 

[overmatch]

Beats me but I tried a 1:5 in my Rem 700 spun up by wolf pack armory and it wrecked projectiles. I tried several different types and none faired very well. The only thing what worked for me was FMJs. I had a Barnes 130 speer tnt actually come apart in the barrel. Grsnted I was using a 16" barrel not a shorty

Gotcha. Appreciate your data given you've actually tried this yourself. Unless I can find someone with a 8-9" barrel at 1:5 telling me there's gains to be had and no safety issue, looks like 1:7 it is.

 

[WillHugh]

Interesting. Do you know how / why Q seems to have it work well with their 8" 300Blk bolt gun? Not meaning to refute your statement since I have no clue, just trying to understand factors that may impact it. Appreciate you chiming in

I think there was some testing done that showed the 5 twist had marginally better terminal performance then the slower twist barrels. You'll significantly limit what bullets you can shoot through it though. For subs you'll have to stick with jacketed (no plated, and cast/powdercoat is probably questionable), and for supers you'll probably want to solids, like the TAC-TX.

That Sig can is one of the quietest blackout supressors ever made. They're also collectible for clones, and possibly not repairable, so I'd avoid blowing it up

 

[overmatch]

I think there was some testing done that showed the 5 twist had marginally better terminal performance then the slower twist barrels. You'll significantly limit what bullets you can shoot through it though. For subs you'll have to stick with jacketed (no plated, and cast/powdercoat is probably questionable), and for supers you'll probably want to solids, like the TAC-TX.

That Sig can is one of the quietest blackout supressors ever made. They're also collectible for clones, and possibly not repairable, so I'd avoid blowing it up

Thanks, sounds like 1:7 is the no-brainer then. My buddy recently found out the hard way that the cans are still full repairable by Sig. I actually picked mine up for a LVAW build, but pivoted to this after the guy making the rails went AWOL. The SRD762 Ti direct thread is up there (and maybe a little quieter) than my Full Nelson. Appreciate your help.

 

[WillHugh]

Thanks, sounds like 1:7 is the no-brainer then. My buddy recently found out the hard way that the cans are still full repairable by Sig. I actually picked mine up for a LVAW build, but pivoted to this after the guy making the rails went AWOL. The SRD762 Ti direct thread is up there (and maybe a little quieter) than my Full Nelson. Appreciate your help.

No problem. I have the same can on an LVAW build (got one of the rails from the batch last year). The 5 twist MCX drives me nuts though on ammo selection, so figured I'd pass the info along.

Good luck on your build.

 

[overmatch]

No problem. I have the same can on an LVAW build (got one of the rails from the batch last year). The 5 twist MCX drives me nuts though on ammo selection, so figured I'd pass the info along.

Good luck on your build.

You have no idea how much I appreciate it. Because I bought the action without a barrel, I'm having a barrel spun up for it, so I'd feel even dumber picking the wrong twist given I had the option to choose.