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jpatrick_09 01-21-2010 02:09 AM

IBM M1 Carbine help
Hello, I have an IBM M1 carbine and the receiver is loose and moves left to right quite a bit. When I disassembled the rifle the trigger group also was loose and moved side to side. The trigger housing pin seems to slide in and out quite easily, im not sure if this is correct. I put the barrel and receiver back into the stock installed the hand guard, and installed the re-coil plate. The receiver still moved back and forth. When i purchased the rifle it came with an M2 stock and hand-guard. I would like to know if anyone has any suggestions on where to begin rectifying this problem. Could the retaining pin be incorrect? Could the trigger group housing be wallowed out? Is there a particular hand-guard and stock that need to go with the rifle to fix it? Any help would be appreciated.

Highpower 01-21-2010 03:49 AM

Have a read through this:

jpatrick_09 01-21-2010 04:54 AM

Thank you for the information,
Regarding Page 2 paragraph 4 regarding the front band and the recoil plate being correct. Do you know if there are different types of recoil plates? For example does an IBM receiver need to be fitted with an IBM recoil plate? The reason I ask is because it seems that the recoil plate I currently have allows a bit of play. Could this be my problem?
Again Thank you for your help

Highpower 01-21-2010 01:37 PM

There were 3 different 'versions' of recoil plates over the years IIRC. Slightly different design angles to help improve the fit between the recoil plate and the receiver. A good tight fit here is essential to a carbines accuracy. It isn't absolutely necessary to have an IBM recoil plate mated to an IBM receiver. However by the time IBM started producing rifles they were built using the final version (tightest fit) of the recoil plate, and would be most correct (historically) for your rifle.

The recoil plate should be a snug fit to the receiver (out of the stock) and should require moderated thumb pressure to get the bottom of the plate to touch the receiver. Ideally, the lower tab should wedge itself into the receiver and hold the recoil plate in place. If the tab touches the receiver under it's own weight - it's too loose. If it does, the above .pdf describes a method of working the recoil plate for a tighter fit.

Your other option would be to try to obtain a number of recoil plates and trial fit each one to find a better fit. Be aware that any unmarked recoil plates are either of the earlier types, or a cast aftermarket part and should be avoided. (The cast ones.)

CA357 01-21-2010 02:45 PM

Here's a link to Sarco. I use these guys a lot. They don't gouge you and they sell good stuff. Hope it helps.

Sarco, Inc., Firearms, Firearms Parts and Accessories

jpatrick_09 01-21-2010 05:21 PM

Thanks for the information guys. Yeah the recoil plate I currently have is unmarked so I'm pretty sure it's not correct for the rifle. It is also extremley loose and takes no effort to join it with the receiver. I'm going to attempt to use the brass hammer method. Not to worried about hurting the recoil plate since it is currently not serving it's purpose. Do you have any advice concerning the loose trigger housing? The retaining pin seems to slide in and out with no effort. In fact it will fall out if the trigger housing is held on it's side.

Highpower 01-22-2010 05:08 PM

The fit of the retaining pin itself is not important other than it should be readily removable for maintenance. For reference, the std diameter of the retaining pin body should be .179" (-.001").

If the trigger housing is loose on the receiver and moves around, that is another story.

The fit of the trigger housing to the receiver is determined by the lugs at the front and the rear of the trigger housing itself. The rear lugs can be worked for a better fit to the receiver by judicious use of a .100" bar, a swaging punch, and a diamond hone. Not a job for the average do-it-yourself-er.

Receivers have been destroyed by people attempting to squeeze the rear receiver legs in a vice in an effort to tighten the fit. That only results in the legs snapping off due to the hard brittle steel of the receiver after it has been heat treated.


jpatrick_09 01-22-2010 10:14 PM

Again thank you for the information. I was able to replace the retaining pin and that made a world of difference. The trigger housing does not move independently of the reciever now. I am going to gauge the old pin to see how far off it is from the specs you have provided. Now it's on to the re-coil plate. I was able to get in touch with my previous boss who owns an airplane maintaience shop, and he said i could use his tools to try to modify the fit of the plate....the only problem is trying to get a rifle into his shop on the airport. :) thank you. I plan on firing it this weekend weather permitting.

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