300 Whisper Upper + Gemtech HVT suppressor = Problem
 

Ok guys, I bought a 300 Whisper upper and a Gemtech HVT suppressor but I have a compatibility problem. After taking off the flash suppressor I cannot tell what the thread pitch is. I thought it was going to be 1/2 x 28 but the threads are finer. Doing research online it appears it can be either a 1/2 x 32 or 1/2 x 36. Does any one know a good way to figure out which? The other problem is that my suppressor is 5/8 x 24, I intended to get an adapter but I have read some posts that state adapters and suppressors are a bad idea because they can compromise the precise alignment and lead to baffle strikes. Any advice on this? Does anyone know where I could even get this type of adapter? Is it better to simple get another barrel with a 5/8 x 24 threading? Thanks.

check with TROS when you figure out your threads. they make good adapters and you would be fine with one of them.

can't you just measure how many threads are in the 1/2" or am i way off with that one?

I had to use an adapter on my 6.8 with the 7.62sd. worked great. I was worried also about how it would line up, but if you get one from a quality manu, it'll work fine. I used rock set on mine to make sure it didn't budge.

2 ways to do this. measure 1/2" of threads and count the threads. or line up a ruler and your threads take a picture and then post said picture so we can tell you.

or measure the diameter of the barrel and if its over 5/8" then have it re threaded to 5/8x24 tpi

It's 1/2x36, here's the link to my thread about the same issue and sharky47 made my adaptor and has more of them;

http://www.quarterbore.net/forums/showthread.php?t=2381

Enjoy

Edit: That's the thread pitch on the M1S barrels.

This is the best solution. You might have a problem if your barrel is right at 16" as you would shorten the barrel when you cut off the old threads to have new threads turned.

threads
 

If it's a M1S upper it's 1/2-36 , I just made my own.

What is the length of the threaded section (5/8" x 24) at the end of the barrel required to fit the Gemtech suppressor?

http://www.suppressormounts.com/Model1_sales_300W.php

I made these for myself originally, but made them available online shortly after.