Cutting down .300 WM barrel length.
I have semi beat this topic up but here I go again please forgive me.
I have an Armalite AR-30 in .300 Win Mag. It has a 26" barrel that is threaded 5/8x18 pitch 1.5" in length for the factory muzzle break. I want to use this gun with my silencer which has a thread pitch of 5/8x24.
I have had 2 adapters built by a local gunsmith and neither worked. The first was built square as a stand alone mount. I ended up having a end cap "strike" you can see where the bullet rubbed against the exit hole but did not cause any real damage. The gunsmith then female threaded the adapter and male threaded it while the rifle was in the lathe. I got the same results with the strike in a different spot.
This leaves me with 2 options.
First is to find someone who has a better idea how to make an adapter that will work for this set up. One thing I have pretty much heard is that the wide 5/8x18 is hard to get the close tolerance needed for this kind of application. Second part I head is that it is hard to make things right without a shoulder on the barrel to set to. Are either of these true?
Here is a pic of the end of the barrel, the muzzle brake and a 5/8x24 adapter that has female 1/2x28 that works well with my AR's.
The next question is IF a suitable adapter can not be made how much performance loss can I expect by cutting off ~1.5" and having the barrel rethreaded. I would like to use this gun for long range (1000 yard) shooting.
Lastly if either of these can be done does anyone have suggestions of a quality gunsmith to do the work. I normally use Tornado Tech but it sounds like he is really backed up now.
I have an Armalite AR-30 in .300 Win Mag. It has a 26" barrel that is threaded 5/8x18 pitch 1.5" in length for the factory muzzle break. I want to use this gun with my silencer which has a thread pitch of 5/8x24.
I have had 2 adapters built by a local gunsmith and neither worked. The first was built square as a stand alone mount. I ended up having a end cap "strike" you can see where the bullet rubbed against the exit hole but did not cause any real damage. The gunsmith then female threaded the adapter and male threaded it while the rifle was in the lathe. I got the same results with the strike in a different spot.
This leaves me with 2 options.
First is to find someone who has a better idea how to make an adapter that will work for this set up. One thing I have pretty much heard is that the wide 5/8x18 is hard to get the close tolerance needed for this kind of application. Second part I head is that it is hard to make things right without a shoulder on the barrel to set to. Are either of these true?
Here is a pic of the end of the barrel, the muzzle brake and a 5/8x24 adapter that has female 1/2x28 that works well with my AR's.
The next question is IF a suitable adapter can not be made how much performance loss can I expect by cutting off ~1.5" and having the barrel rethreaded. I would like to use this gun for long range (1000 yard) shooting.
Lastly if either of these can be done does anyone have suggestions of a quality gunsmith to do the work. I normally use Tornado Tech but it sounds like he is really backed up now.
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Nwcid,
What's the major diameter of the barrel right behind the threaded section? Not that little step, the barrel diameter?
Best.0 -
Sure I had just put the brake back on an put it in the safe [:D]
The smallest part of the actual "untouched" barrel measured 0.687"0 -
Find a real gunsmith. If you ever have a strike, the threads are not concentric to the bore. Simply threading a barrel is easy.
LTS0 -
Nwcid,
Check your e-mail.
Best.0 -
Got the email and replied. Thanks again. 0 -
Contact TROS for the thread adapter.
It will be done correctly.
CP0 -
quote:Originally posted by cpermd
Contact TROS for the thread adapter.
It will be done correctly.
CP
TROS is the other adapter in the pic so I do know about them. I have not checked in a while but when I called them this spring they were not taking special orders.
I dont think the problem is with the adapter but how it works with this gun. This local gunsmith has done more then half of my threading on other guns along with an adapter for my 1911 with no problems.
Part of the problem with this gun is the lack of a shoulder to square it to. NN is researching it right now trying to find a way to make this work. Even cutting and rethreading the barrel will not work because the taper design does not leave enough of a shoulder.0 -
The adaptor needs to have class three internal and external threads so axial movement of the can is minimized. All threads need to be lathe cut and concentric both on adaptor and barrel. The the adaptor external thread should be cut to be a snug fit to the can's internal thread.
The barrel external thread probably isn't class three so the adaptors' internal thread needs to be cut to be a snug fit on the barrel.
A shoulder on the barrel will straighten any axial tilt between barrel and adaptor likewise, a shoulder on the adaptor will remove tilt between adaptor and can . Such a shoulder
can be created by spinning a threaded thick washer on the barrel and lathe facing the forward surface to be perpendicular to the bore.
However, if the threads are snug enough tilt will be minimized.
DAQ, 2203 Hwy AC, Goodson, Mo 65659 may still make all sorts of adaptors.0 -
Nwcid,
Happy New Year to you!
I am not sure what other solutions you might have came up with, but there is the option os sending the suppressor back to the mfg, and having them fit it with a thread larger than your barrel threads, along with two adaptors...1 in 5/8x18, and the other in 5/8x24.
Best0
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