Jump to content

M1A1 firing pin protrusion spec?


Recommended Posts

There is a gauge for checking that.

https://www.apexgunparts.com/thompson-firing-pin-protrusion-gauge-without-hole-nos.html

 

The low and high measurements are engraved upon it.
With M1A1 bolts getting to be hard to find and expensive I am wondering how long before someone offers a service to fit a replacement into the bolt face?

Richard

Link to comment
Share on other sites

Richard+ thanks for the info, I ordered a gauge from Apex just to have really. .044 & .050" I got off a picture of another gauge.

 

Replacing the firing pin is easy if you have the right tools; I'm just hoping the bolt will fit in my lathe chuck & make it real easy if needed.

NMCA

Edited by newmexicocoonass
Link to comment
Share on other sites

So let me make sure I am understanding this correctly-you are worried about changing out the firing pin on your M1A1 bolt as you have had only one failure to fire? I'm wanting to make sure I am reading this correctly before I make anymore comments referring to things......not to be too rude but you do know how much .0045 is right? Its 1 1/2 pieces of notebook paper, not enough to cause you to have consistant failures. How dry is the gun? They need to be lubricated. Hows your recoil spring? Thats really the heart of the beast as well as the magazine. You might want to check a few other things before worrying about the hard part. Also as stated-might want to try different ammuntion as that can change how the gun functions. One last detail-make sure its tight to your shoulder and you aren't flenching forward when you pull the trigger as that can cause issues too....not that I've seen any of these when helping diagnose gun issues. 7-10 times its one of the afore mentioned things and not the firing pin, espically on an M1A1 bolt

Link to comment
Share on other sites

That's kinda funny, Ron. Fiocchi 230 ball is what prompted my post. I had FTFires with it that were driving me crazy. Before launching my diagnostic plan, I tried a friends S&B ammo and It ran well so I bought a case. Virtually flawless, problem solved. The Fiocchi 45 ran well in my other 45 cal guns and I use a lot of their 9MM in my subguns. It's good, clean ammo but their 45 will not run my '28 Savage worth a damn.

Link to comment
Share on other sites

Bob,

 

I feel S&B runs amazing in Tommies. Its my favorite! One year I got a decent deal on a case of Fiocchi. It was ok, but I felt not as hot and reliable as the S&B. Ive not done a side by side comparison, but would love to put some data to this theory, of course burn rate and other variables play into the equation more than just velocity.

 

Id certainly try other ammo in known good mags before condemning GI parts. Not to say theres not a chance (I think of Recon Bobs off center Actuator I think it was he that ran into that one and posted).

 

Ron

Link to comment
Share on other sites

Is the M1A1 spec the same as for the m1 (.044-.050")? Mine comes in at .0395".

 

Thanks NMCA

I normally shoot reloads, but tried a box of Fiocchi 230 off the shelf & had a FTF. Did anybody (GU) read the original post? I was asking for specs, not comments and opinions.

 

As indicated, Bob from PhilOrd was kind enough to email me back with the correct specs for the M1A1 firing pin (.040-.002"); as .044-.050" are for the 28/M1 hammer-actuated firing pins.

 

Sounds like Fiocchi is not a good choice for my Tommy. Thanks all.

 

NMCA

Edited by newmexicocoonass
Link to comment
Share on other sites

Why yes I read the original post and then the following posts as well. Since you clearly know more than any of us here, and instantly jump to the conclusion that your bolt is bad, and want to cut it up to fix a non existant problem, by all means I'll refrain from offering advice on how to diagnose issues with a Thompson. That also being said-you may kindly kiss the lower opposite of my front. Forgive me for trying to help when someone knows all the answers, sure am glad we have more and more like this in the Thompson community.

  • Upvote 2
Link to comment
Share on other sites

Last time out with the M1A1 (which was my first time out with it too) I had a couple of FTF with Fiochhi .45 ammo.
It was quite old (least the boxes looked that way).
I was using it because I ran out of my mixed WW2 surplus 45 (Reising ate it all) that I had purchased back when it was coming out of Russia in plain thin cardboard boxes!
I have a bunch of Yugo / Serb surplus 45 I need to try in the Thompson.
TOO BE HONEST, those FTF's made me stop and think about my M1A1 bolt and its machined in firing pin.
Being a "parts seller" I always think about what spares I have for my guns and what I parts I should have put away for myself and am now sold out of!
I should have retained a complete M1 bolt when we had them.
Now I will attribute the FTF's to the ammo.

OH, one thing that Fiochhi 45 DID DO was blow a bowling pin in half lengthwise, that made me laugh!
My 9MM SMG's just push those pins around.

Richard

BTW, my M1A1 is the gun pictured at the top of the page in the Thompson parts category on the APEX web site.

Edited by APEXgunparts
Link to comment
Share on other sites

I'm a gunsmith, so I always think about those things too. And, my bolt was made in 1943. Worth having the specs, parts do wear out. That was my point of this post.

 

It is not difficult to press in a new firing pin if you have the right tools. I've wanted a Thompson since I was probably 10 years old - finally got one, and I want it to run a good long time.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...