I'm in a similar situation. i bought a Remington 742 chambered in 30-06 that had a flash suppressor on the end of the barrel. It looked like an actual Remington modification, because there was a flat spot on the flash suppressor indicating where the top of the rifle barrel was, and the front sight mount extended over that flat.I bought a Remington 700 LSS in a 300 RUM on this forum about a decade ago.
About 5 years ago, I decided to put a muzzle break on it. The gunsmith I found to do it did a great job. He fabricated the brake to look like it is part of the barrel. He also made me a thread protector that looks like there is not threaded piece on the end of the barrel.
Everything was great until I bought a suppressor. I bought my Rugged suppressor because it would handle the 300 RUM.
I tried the Rugged 5/8 x 24 muzzle break on there and it was too big. I thought he must have had to do it 1/2 x 28 because of the size of the barrel.
After buying a 1/2 x 28 device I determined it was too small! So I haven't measured it yet, but if I had to guess it is either 9/16 or some metric threads.
So where do I go from here? Find some kind of adapter or rebarrel the rifle?
I know, I don't post much on this forum. But I have read it for years and I am impressed with some of the knowledge here. I am not really looking to take the action and start over completely, but have considered replacing the pretty laminated stock with something a little more weather proof.
Thank you in advance for your comments.
Anyway, I wanted to put a muzzle brake on it and, like you, assumed it was the standard .308 5/8x24 thread. It wasn't. The threads were actually 9/16x18. I ended up buying an all-steel brake threaded in 1/2x28 (the 5.56 thread), drilling it out, and re-tapping it to fit using the tap set I will give you the link for. I had to use a 33/64 drill bit. Of course, it goes without saying that I had to make the hole bigger as well. You can't fit a 7.62 round through a 5.56 hole and expect a good result.
Anyway, here's some links to the stuff I used. If you have a thread protector, take it down to your local ACE hardware and verify the thread pitch before you go tapping anything.
Drill America Hand Taps. Hand Taps are the most versatile taps for hand use or for tapping under power. Hand threading tap is popular for use in general machine tapping or CNC tapping. This is also appropriate
Drill America 33/64 in. High Speed Steel Black and Gold Reduced Shank Twist Drill Bit with 3/8 in. Shank-KFDRSD3/8X33/64 - The Home Depot
Drill America KFD Killer Force Drill Bits are manufactured from premium grade M2 High-Speed Steel. Gold and black surface treated for use in stainless steel and other hard metal drilling. Killer Force
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