Threading Remington 300 Win Mag Factory Barrel

[jareese]

You could also buy a custom sized clamp on brake from Witt machine! I have one that's great

Yes, they work well. The biggest issue I see with the clamp on brakes, especially the Witt Machine, is people not getting proper measurements of the barrel diameter at the correct lengths. Then they come on forums and FB and complain that the brakes suck, yadda yadda..

 

[Roughrice]

The simple answer is yes, your gunsmith can thread your muzzle for brake/suppressor. If your barrel is not thick enough for 5/8X24, you just screw on an adapter to get up to 5/8X24. I have several rifles that have 1/2X28 threads and I use a Silencer Central adapter.

I've done this on 2 different rifles with 24" factory sporter barrels in 284 Win and 30-06.
Both failed in accuracy after putting the adapter and suppressor.
POI was all over the place unless I loaded way down.
I contribute this to the extreme barrel whip (harmonics)with the weight hanging on the end of a long sporter barrel.

 

[Hoss50]

Shorter barrels often have to be threaded 1/2×28. I have several threaded that way and have brakes and suppressors mounted on them.

If you have enough 5/8×24 is better so you have the extra meat. Either will work though.

 

[arch408]

I was able to obtain a .338 RUM factory barrel that someone had threaded for a muzzle brake. It was machined off center and the bullets were striking the brake. I didn't think that there would not be enough of a shoulder if I installed a 5/8x24 brake. I also didn't like the thickness of the barrel if I would have installed a 1/2-24 brake. So I faced off the threads and and machined the muzzle to install a 9/16-32 muzzle brake. I felt that it was a compromise between a sufficient shoulder for the brake and maximizing muzzle thickness. I made a brake with four ports on the sides and three on top. The rifle also has a light synthetic stock and recoil was brutal before I installed the muzzle brake.

 

[FEENIX]

You could also buy a custom sized clamp on brake from Witt machine! I have one that's great

Unless I misconstrued the OP, he wants to thread the muzzle with 5//8-24" so he can use a muzzle brake or suppressor that has a 5/8-24" thread. A Witt Machine clamp on MB will prevent him from using a suppressor.

 

[WA Coyote]

I had a Kimber Montana in .300 WSM chopped to 17" and threaded 1/2x28. Ran an adapter and suppressor on it without any issues.

Just got back from shooting a 19" Kimber Montana in 7 WSM with the very same adapter and suppressor. It shot like a champ (162s at 2950).

I've heard of issues with .30s threaded 1/2x28, but never actually seen it.

 

[Panhandlin Pat]

Measure your OD at the muzzle and consult with a competent and reputable gunsmith. A competent and reputable gunsmith can create a thicker shoulder adapter even if the barrel is too thin for a 5/8-24" thread.

Either do this or thread it 1/2". For reference, a friend of mine has 2 factory weatherby 300 magnums, with factory breaks. Both RMEF banquet rifles (a vanguard and last years 307). Both are threaded 1/2x28. If weatherby sees it fit to thread a 300 weatherby to 1/2 your 300 win mag should be fine. Also know of at least one 300 RUM factory threaded to 1/2x28 for a break.

How about Henry threading their 45-70 to 5/8x24? Not much meat there either. I followed suit when I rebuilt a 450 Marlin, it wears 5/8 thread to accommodate a dead air primal. After consulting a couple machinists and local smiths they told me to go with 5/8, but to make sure the break or can is tight as a strike would likely result in the threaded portion of the barrel shearing off and ending up down range.

 

[VinceMule]

Panhandle, you may want to consider using JB weld to epoxy that brake on the barrel. Threads do wear over time. Threads cut to a class 3 fit on the brake helps tremendously, and you have to be sure to keep a good grease on the threads.