Barrel Venting Mod for Hudson M1A1?

Got to say i envy you guys who have these skills, i try things but never seem to be able to make them work, so i go to a reliable friend who know his stuff.

8ace wrote:

Thanks for that. It looks easier than fitting the modelgun type (although I'm sure it's not.)

It's definitely fiddly. There's a couple small undercuts, and getting it set at 30 degrees took some head scratching (no indexing head here). Ended up making some soft-jaws that hold it just right.

claymore wrote:

Got to say i envy you guys who have these skills, i try things but never seem to be able to make them work, so i go to a reliable friend who know his stuff.

Oh, I make plenty of mistakes, I just don't put those on the internet as much

I use one of these for quick and dirty angle measurements

https://www.globalsources.com/gsol/I/Laser-level/p/sm/1149985469.htm#1149985469

Although I got mine from ebay

I am very impressed to see what you skilled guys can do. Thank you for sharing your knowledge and experience here.

Got the extractor working sorta. Full auto jams after two or so rounds. I had to relieve some of the extractor to get to move easier and not chew up the carts and I might have gone a little too far. It was getting yanked out!

I'll play around with another one tomorrow.

Don't know why it's not locking back on empty, but I'll have to look into that tomorrow. Might be something on the mag is just bent, and not pushing that piece of the action up. Hopefully nothing broke without me noticing.

It ejects very well

nice to see the progress!!!
Keep up the nice work there.

Modelguns are very, very, very picky when it comes to spring pressures and minute adjustments. On the Hudson (or CAW) Thompson, if you have a lockback on empty issue, I'd check a couple of things first - one being the mag spring pressure. Another being the ride height of the mag in the receiver. Interestingly enough, both of these same things can also cause feed issues and may be part of the issue with your jamming on the auto setting.

Obviously, you would want to first make sure your trip lever on the mag is not damaged or the corresponding part in your receiver.

Best of luck and keep us posted!

ljerr2 wrote:

I'd check a couple of things first - one being the mag spring pressure.  Another being the ride height of the mag in the receiver.  Interestingly enough, both of these same things can also cause feed issues and may be part of the issue with your jamming on the auto setting.

I'll investigate those! Do you know about how high the mag should sit?

8ace wrote:

It ejects very well

Thanks, Ace! Very promising results, so far

For the mag height, I'd set it as high as you can. If you can insert the mag now and there is "play" in a vertical direction after it is locked in, then I'd adjust it until the play is gone.

Did some tuning yesterday. Semi auto is working better. Full Auto is jamming, but I think for regular model-gun reasons. I'll have to clean up and de-burr all of my carts to do a proper test.



I found out why the extractor was getting yanked out - it was actually because clearance is lower inside the receiver, so it was getting caught up on the back stroke as the round was getting ejected, and pushed out. I filed it down some, and worked the fit-up a little more for a smoother action. And I used some cold blue on it. Wish I had a hot-bluing set-up.



I think the lock-back issue was actually dirty carts, and not getting enough force to push the bolt back far enough.

Any tips for general tuning of the firing mechanism/springs for better auto function?

The other thing to consider is overall bolt weight. If the cap has to push back a significantly heavier bolt it will affect the cycling as the O-rings can only deal with so much pressure.

Just a thought.

8ace wrote:

The other thing to consider is overall bolt weight. If the cap has to push back a significantly heavier bolt it will affect the cycling as the O-rings can only deal with so much pressure.

Just a thought.

I'm definitely considering that. There seems to be enough force under ideal conditions, but dirty carts and dry o-rings definitely are cause for concern. Seems an ok place to leave things for now. I'm still trying to work out some way to get around that plugged barrel : / All the EDM drill shops in town turned me down. Too deep, I guess. I think they also just didn't want to take a weird job like that. Not sure it's worth trying to peck through. Extra reach carbide drills are so expensive. Maybe some way to bypass, though? I'm just thinking out loud, really.

Decided to make a new fire selector, and safety switch. Got the fire selector most of the way there today.









Just need to get the pin in there!

That is awesome! Did one of your levers break on you? I think the fire selector on the Hudson had a tendency to shear off with use.

Nice work!

Yeah, I was especially worried about the little nub that clips/indexes with the pivot plate on the other side. My safety snapped a while back, and I figured it was only a matter of time before the other one goes. Finally have the time to get around to it I think I can fit a real mag release as well with some file work and a little head-scratching. It will be nice to not have to worry about any of these parts breaking on me again!

ljerr2 wrote:

That is awesome!  Did one of your levers break on you?  I think the fire selector on the Hudson had a tendency to shear off with use.

Nice work!

A real mag catch will work, but it is a little wonky.

ljerr2 wrote:

A real mag catch will work, but it is a little wonky.

Yeah, I got it pivoting correctly after some work on the bottom of the catch lug. The shaft doesn't really play nice with the spring, though, so it'll either get sleeved, or use a different spring, or some combination of the two.

Realized I never shared these:



Finished off the new selectors for the Thompson.