WS-MCR - Threading a SF Warcomp issue

DavenK

DavenK

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Good day nutters,

Posting here as I'm wondering if somebody else had the same problem as I do.

I recently acquired a 556 WS-MCR. It came with a A2 Flash hider, nothing fancy.
I have a SF Warcomp laying around on my 556 Ruger Ranch and decided to port it to the MCR.

It unthreaded fine from the Ranch. A2 also came off the MCR pretty easily.
As I'm trying to thread the Warcomp on the MCR, it won't go past 3/4 of a turn without brute force.

Now, I tried other different muzzle devices on the MCR and they all thread fine. Caliper reading is .495'' for the barrel threads. They look good, nothing out of place.
The Warcomp threads look good as well, not filled with carbon and else. It will also thread on all my other 1/2x28 barrels easily.

Next step is to chase the threads and/or use some lapping compound.


So... This situation ever happened to any of you ? If so, whats your input ?
My guess is the Warcomp is machined extremely precise and the MCR is too sloppy so they wont mate ...(?)
 
did you try the A2 on the ruger ranch? if that works, check the threads again and would recommend you do a clean in case some shavings/ debris may have gotten in between the threads, that would be my suggestion.
 
drago403 said:
did you try the A2 on the ruger ranch? if that works, check the threads again and would recommend you do a clean in case some shavings/ debris may have gotten in between the threads, that would be my suggestion.
Click to expand...

I should’ve mentioned it: Yes and it fits, same with thread protectors and different MB.
 
Thread class of SureFire WarComp device is a class 3

Mzl thread & other devices that fit are a sloppy/class 2-3 thread.

An adjustable die to chase the mzl thread would be the easiest...but not the most precise option.
 
DANS40X said:
Thread class of SureFire WarComp device is a class 3

Mzl thread & other devices that fit are a sloppy/class 2-3 thread.

An adjustable die to chase the mzl thread would be the easiest...but not the most precise option.
Click to expand...

Is there any other option you would recommend ?
Aside of: buying a new barrel or not using the Warcomp.
 
DavenK said:
Is there any other option you would recommend ?
Aside of: buying a new barrel or not using the Warcomp.
Click to expand...

With the appropriate measuring device(s) the muzzle thread could be mic'd & device threads mic'd.

Indicating & chasing the muzzle thread on a lathe or simply stoning the muzzle thread may be all that's needed.

As mentioned, chasing the thread w/ an adjustable die would accomplish the task IF you aren't concerned w/ alignment issues.
 
As everything screws on except the Warcomp I am thinking the threads on the Warcomp are the problem. Very possible it is not tapped deep enough. It it was tapped with a plug tap and a bottom tap wasn't used the bottom few threads may not be deep enough. First thing to do would be to run a tap down the hole before chucking the barrel in a lathe to recut the threads.
 
maynard said:
As everything screws on except the Warcomp I am thinking the threads on the Warcomp are the problem. Very possible it is not tapped deep enough. It it was tapped with a plug tap and a bottom tap wasn't used the bottom few threads may not be deep enough. First thing to do would be to run a tap down the hole before chucking the barrel in a lathe to recut the threads.
Click to expand...

But then the Warcomp also threads on anything else lol
 
do either of the threads look like the pictures below, with or without sharp peaks and valleys? the thread "class" was mentioned above. I would machine the MCR barrel before I would question surefire's quality control.


Diagram_of_thread_combinations_of_snug_fit.jpg
 
maynard said:
As everything screws on except the Warcomp I am thinking the threads on the Warcomp are the problem. Very possible it is not tapped deep enough. It it was tapped with a plug tap and a bottom tap wasn't used the bottom few threads may not be deep enough. First thing to do would be to run a tap down the hole before chucking the barrel in a lathe to recut the threads.
Click to expand...

The SureFire brake is QPQ'd/Salt Bath Nitrided & would destroy a tap in seconds if one attempted to chase the threads.
 
DavenK said:
Is there any other option you would recommend ?
Aside of: buying a new barrel or not using the Warcomp.
Click to expand...

You stick it in a lathe, pick up the thread with a threading tool, and cut the thread so it fits.
It's just a few minutes of fiddling around to pick up a thread properly.

Do some reading on the use of thread wires to check a thread's size. Three appropriately sized small drill bits will work, use a rubber eraser to stick the wires in to, to hold them while you measure across them.

Honestly, if the thread you already have, is properly aligned, I would go for the adjustable die. Put it on the thread with the die spread too wide, run it up and down as you adjust it smaller, measure as you go.

It's kind of a curse of things being made to tight tolerances. As long as both halves are made to match, no problem, but it's a pain in the arse to put a perfect 1 inch bar in to a perfect 1 inch hole. There has to be clearance between them, however miniscule.
 
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