.300BO Keyholing With Different Sized Cans

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JRCmx
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.300BO Keyholing With Different Sized Cans

Post by JRCmx »

8.3" 1/7 barrel running subsonic 200 & 220gr bullets at 25 yrds
If I run the Sandman S she groups well and shoots straight.
Switch to the Sandman L, the group opens up and the projectile keyholes.
Tell me why.
Thanks
Last edited by JRCmx on Sat Sep 02, 2023 5:33 pm, edited 1 time in total.
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Capt. Link.
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Re: .300BO Keyholing With Different Sized Cans

Post by Capt. Link. »

If both of these suppressors perform without problem on other guns then the problem is the rifle. A minor misalignment of the mounting is the cause. Only a baffle strike or a near one will cause these issues.
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
JRCmx
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Re: .300BO Keyholing With Different Sized Cans

Post by JRCmx »

Some more data.
I have no issues with the can on my .308 or 5.56 rifles.
Ran an alignment through the BO with the can attached.
The rod was close to the 6 O'clock position at the endcap but no contact.
I took the muzzle device off and installed it on another BO pistol with similar results.
My assumption is the muzzle device in my pistol may not be in spec.
I'm going to install a different muzzle device and see if this changes anything.
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Capt. Link.
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Re: .300BO Keyholing With Different Sized Cans

Post by Capt. Link. »

JRCmx wrote: Fri Sep 01, 2023 12:15 pm Some more data.
I have no issues with the can on my .308 or 5.56 rifles.
Ran an alignment through the BO with the can attached.
The rod was close to the 6 O'clock position at the endcap but no contact.
I took the muzzle device off and installed it on another BO pistol with similar results.
My assumption is the muzzle device in my pistol may not be in spec.
I'm going to install a different muzzle device and see if this changes anything.
Alignment tool should be center not at six. A close graze is the same as a strike.
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
JRCmx
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Re: .300BO Keyholing With Different Sized Cans

Post by JRCmx »

Checked the .308 upper with the alignment rod with the same 6 o'clock results.

So I have similar results with 3 different uppers and 2 different muzzle devices.
This leads me to suspect that the suppressor body or the Keymo mount on the suppressor may not be concentric.
hangman
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Re: .300BO Keyholing With Different Sized Cans

Post by hangman »

Interesting - from what I understand, you seem to have no issues with keyholing when firing the .308?

If so, it sounds like you are right on mount concentricity, and the variance is highlighting a degree of additional instability in your 300 BLK. That could be related to twist rate or barrel length, as two likely culprits.

Also, a question for Capt. Link., have I just been lucky (since I'm not checking things with alignment rods)? Don't get me wrong, everything I have is currently "factory" made and threaded, but as I start manufacturing items, I'm guessing "everyone's" advice would be to always use an alignment rod?
Semper exaudiō,
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JRCmx
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Re: .300BO Keyholing With Different Sized Cans

Post by JRCmx »

hangman wrote: Sun Sep 10, 2023 1:03 am Interesting - from what I understand, you seem to have no issues with keyholing when firing the .308?

If so, it sounds like you are right on mount concentricity, and the variance is highlighting a degree of additional instability in your 300 BLK. That could be related to twist rate or barrel length, as two likely culprits.

Also, a question for Capt. Link., have I just been lucky (since I'm not checking things with alignment rods)? Don't get me wrong, everything I have is currently "factory" made and threaded, but as I start manufacturing items, I'm guessing "everyone's" advice would be to always use an alignment rod?
No issues with 300BO suppers either.
There may be just enough clearance to prevent a strike but enough distance to destabilize the projectile at subsonic speeds.

This looks like it maybe a cause, because I was watching some videos of subs exiting a suppressor. There are some waves that exit first and with the projectile that are faster than the projectile or close to supersonic.
Not having the projectile exiting at or close to the center of the suppressor may be knocking it off at one side.
JRCmx
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Re: .300BO Keyholing With Different Sized Cans

Post by JRCmx »

I got my Sandman S out of jail.
Ran the same tests and the rod is dead center out the endcap.
The L needs to be looked at. Either the lock/mount or the body are off center.
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