Question Subsonic Reloaders

[HenryTheAce]

First off I don’t reload. So I’m a complete novice.

I have a 10” 1:16tw barrel 450 bushmaster bolt action. Ammo I have is some Black Butterfly Maker Bullets 425gr subsonic buzzsaw. Originally I sighted it in suppressed (maybe shot 20-30rounds) no problem.. Fully cleaned barrel.. Just took it out on its second trip. Shot it suppressed again and it was on target 7-8 shots. Then all over the place. I mean some on target, some on target 8-10” off from POA, some not even on paper.

Went to check target and what I’m seeing is the bullet keyholing on some impacts.

Shot some full power factory Hornady FTX loads and it printed a good 3 shot group. Went back to the subs and all over the place.

Why would it shoot good the first 30-40 shots with subs then all the sudden be way off? Is 10” barrel at 1:16tw not enough length or not enough twist to stabilize them? I notice that the barrel gets extremely copper fouled. Can easily see heavy heavy streaks of copper with the naked eye. Is it possible that they only stabilize the first 10 or so shots out of a clean barrel then due to copper fouling become unstable the more shooting you do?

Did I just get lucky in not getting a baffle strike in the begging? Just chalk it up as a loss and not mess around with these subs anymore?

planned on using it for a 50-75yd deer gun with subs.

 

[Joeg26er]

Ladder load development and without suppressor

 

[Joeg26er]

Chrony. Get one and use it

 

[alamo5000]

If it's key holing this is a big deal. If I read your post right you have a 1:16 twist barrel? For me having no experience with your gun or caliber I would think it is definitely too slow of a twist rate to stabilize those bullets at those velocity ranges.

 

[HenryTheAce]

Chrony. Get one and use it

Had the chrono out today. Was averaging 963fps in a 10 shot group with a pretty large ES of 100 or so. I deleted shot 11 because it was 788fps

If it's key holing this is a big deal. If I read your post right you have a 1:16 twist barrel? For me having no experience with your gun or caliber I would think it is definitely too slow of a twist rate to stabilize those bullets at those velocity ranges.

Correct, 1:16 twist. I’m wondering the same, if it’s maybe the length of barrel not allowing enough “length” at that twist rate for the bullet to stabilize? On black butterfly website they claim 1” out to 100yds with the Ruger American Ranch (which is a 16” barrel)

I feel lucky to have not gotten a baffle strike

 

[HenryTheAce]

This keyholing was at 50yds by the way not 100yds. After I saw the target shown above I stopped shooting them and just shot supers. Weird though how they would keyhole after not doing so the first outing with it and the first couple shots of the day. Just coincidence and luck?

 

[alamo5000]

I think I have a better idea now (after a quick bit of reading). First off the barrel itself is really short for 1:16. You are getting just over half of a revolution at that barrel length.

The second problem is that's a 425 grain copper bullet which means it's substantially longer than any traditional bullets of the same weight class.

Longer bullets need more twist to make them work (generalization but for this conversation yes).

You are basically working from both directions. Only half of a revolution to start with and a much longer bullet.

Typically you want at least one full revolution to ensure stability. It's not a 100% or nothing proposal but one revolution is a guideline.

 

[HenryTheAce]

I think I have a better idea now (after a quick bit of reading). First off the barrel itself is really short for 1:16. You are getting just over half of a revolution at that barrel length.

The second problem is that's a 425 grain copper bullet which means it's substantially longer than any traditional bullets of the same weight class.

Longer bullets need more twist to make them work (generalization but for this conversation yes).

You are basically working from both directions. Only half of a revolution to start with and a much longer bullet.

Typically you want at least one full revolution to ensure stability. It's not a 100% or nothing proposal but one revolution is a guideline.

Gotchya Gotchya. Makes sense. Damn. That blows for me. Think it’ll stabilize full power loads at 250gr? Fired about 6-7 of Hornady’s 250gr FTX bullets and didn’t see any keyholing with them on target.

 

[alamo5000]

Gotchya Gotchya. Makes sense. Damn. That blows for me. Think it’ll stabilize full power loads at 250gr? Fired about 6-7 of Hornady’s 250gr FTX bullets and didn’t see any keyholing with them on target.

If you really have your heart set on this cartridge I would ask around about getting it barreled with a much faster twist rate.

At the velocities you are probably going to get I would think a 1:10 or something like that would open it up where you could shoot anything.

As it sits now that 1/2 of a revolution thing would scare me off of that gun.

 

[HenryTheAce]

If you really have your heart set on this cartridge I would ask around about getting it barreled with a much faster twist rate.

At the velocities you are probably going to get I would think a 1:10 or something like that would open it up where you could shoot anything.

As it sits now that 1/2 of a revolution thing would scare me off of that gun.

Yeah I’m gonna look around I think at some more options. It’s a big horn origin action so I guess different caliber options are out there. I have some other 450bm’s that I can hunt with here in MI, so not completely set on it.

Feel pretty lucky having blasted quite a few rounds through it all suppressed and not getting a baffle trike.

 

[alamo5000]

Yeah I’m gonna look around I think at some more options. It’s a big horn origin action so I guess different caliber options are out there. I have some other 450bm’s that I can hunt with here in MI, so not completely set on it.

Feel pretty lucky having blasted quite a few rounds through it all suppressed and not getting a baffle trike.

You are definitely lucky. I would not suppress that gun again until changes are made.

If you went through the hassle to get a suppressor for it then getting a new barrel wouldn't bother me a bit.

Fix it once then you can be comfortable with it forever.

 

[HenryTheAce]

You are definitely lucky. I would not suppress that gun again until changes are made.

If you went through the hassle to get a suppressor for it then getting a new barrel wouldn't bother me a bit.

Fix it once then you can be comfortable with it forever.

No doubt. Gonna contact some smiths to get started. Thanks for the help/info

 

[alamo5000]

No doubt. Gonna contact some smiths to get started. Thanks for the help/info

The better question to ask now is what twist rate for the barrel length you have in mind. I would think a 12" long 1:12 twist would be ok.

 

[alamo5000]

Think it’ll stabilize full power loads at 250gr? Fired about 6-7 of Hornady’s 250gr FTX bullets and didn’t see any keyholing with them on target.

There is one way to find out. Just don't shoot them with a suppressor.

 

[HenryTheAce]

The better question to ask now is what twist rate for the barrel length you have in mind. I would think a 12" long 1:12 twist would be ok.

That’s exactly what I was thinking if I go 450bm. Honestly might be a time to go with something else. Maybe 458socom or 300blk. Wanting to keep it as a little sub gun. Probably will stick with 450bm though.

There is one way to find out. Just don't shoot them with a suppressor.

I’ve put 6-7 rounds with the supers through suppressed and none of them keyholed on target.... then again the first outing and first couple shots shooting the subs they didn’t keyhole either. Very odd. Not wanting to put my suppressors anywhere near that thing now lol