USGI Parts for WH Thompson

[Adg105200]

what was the reason to lower the mag catch on semi units?

Probably so they can sell $70-80 mags.

 

Andrew

[ron_brock]

what was the reason to lower the mag catch on semi units?

They didn't lower the mag catch, they reduced the height of the receiver to prevent full auto parts from easily fitting into the receiver. Doing so requires the hole to be moved.

 

Ron

[Paul in PA]

I run a 1928 Lower on my M-1, so I can have a removable butt stock. Allows me to take the butt stock off and lay the Thompson on a shelf in my safe. It works better than the A/O West Hurley removable butt stock kit.

[mohawk64]

I have some m1 parts for sale

[mnshooter]

This has been covered several times in the past, but one more can't hurt.

 

There is probably no need to replace your WH M1 lower, only the WH cast magazine catch -and even that might work once the problem is corrected. You might also have a cast sear, which should be replaced. TD has written excellent articles on all these parts.

Replacing the bolt with a GI M1 bolt assembly is also advisable, even if it isn't contributing to your mag problem.

 

The magazine seating problem (with the several unmodified WH M1's I have been able to examine) is:

 

The magazine well is too shallow, which keeps the magazines from seating properly, if they seat at all.

The 45 degree bevels need to be relieved slightly to give enough clearance for the mags to correctly lock in place.

This is an extremely simple machine job, and can even be done perfectly with files, if you're perfect with files.

 

If you look at the mag well on the WH M1, and a "real" GI M1, you will see that these angles taper to the outside of the receiver -almost to a knife edge. The WH isn't a knife edge, but a wider flat (was about .090" on mine before the fix), which shows roughly how much extra metal needs to be removed. Keep checking with several mags, until they fit, and stop there. No need to "fix it more than necessary". On mine, this left a little more metal than the Savage and AO, but it works fine.

Before the fix, I could only find a couple (out of several dozen) mags that would lock in place, and even those were a tight fit.

Afterwords, they all fit and functioned fine, even with the POS cast mag catch.

 

I have posted photos of the OEM WH, and a Savage M1 mag well, side by side, a couple of times, but can't seem to make photos post anymore. A search doesn't seem to bring up any of these past posts either.

 

This fix was all that was needed to make my WH M1 run as well as my Savage, with either the OEM or GI bolts.

FWIW, I tried the WH M1 lower (with the OEM cast mag catch) on the Savage; it worked perfectly.

 

Your WH M1 is one of the lowest WH production quantity -and of the very last transferable Thompson production.

Edited September 29, 2017 by mnshooter

[deerslayer]

Don't forget tight chamber on the west Hurley barrels. That's frequently another source of jamming.

[mohawk64]

The feed ramp on mine had an issue. Leading edge was sharp. Case mouths were catching. It was easy fix and I bet your problem is the same. Took me an HR to fix. I hate to see you wait 2 yes and pay big$$ for an HR fix.

[Petroleum 1]

Good info are there any threads or sites where this WH mod info is detailed?? I don't own a westie but I am still interested in the fixes and mods to make them dependable shooters.

[reconbob]

"Exremely simple machine job"? Really? Maybe for you. The minimum

for this would be a solid vertical milling machine and either vise jaws to hold

the receiver at 45 degrees - and these have to be custom made because the

cross section of the receiver is not square. So the bottom of the receiver seats

deeper in one jaw and the top part which is narrower sit less deep and its jaw

iis much shallower. Or you can use a 45 degree angle vise but one big enough

and sturdy enough to properly hold the receiver will not be found in most

machine shops. If you fo not hold the reveiver perfectly and it moves ever so

slightly the cutter could grab and either badly gouge it and maybe even jerk

it completely out if the vise. Now you've damaged your $15,000 WH and it

can't be repaired by welding since its leaded steel and now what. So lets

not mislead people.

You can't go wrong with files. They cut so slow and you are doing it by

hand so its easy to stsy out of trouble because you can keep checking -

something you can't do if the receiver is clamped in a milliing machine.

 

Bob

[mohawk64]

I have machining centers. Edms. Etc. Been doing tooling since 85. And...my westie feed problems were fixed with a file.

[buzz]

I would take a go at it with hand files.

 

But I would jury rig some sort of guide or jig to keep the cut uniform. Something to lay the file on so it maintained a uniform angle.

 

If the work was sloppy it would bother me a lot.

 

If you want to do something really good with your typical lame-o homeowner tools, you have to put a lot of energy and concentration into it.

 

If you observe people who do really nice work with their hands, you will see than they are taking their time and using a ton of concentration.

 

Or else they have so much practice at that particular task that it's second nature to them.

Edited October 1, 2017 by buzz

[shadycon]

And don't ask Bubba to barrow his dremil tool!