[HKSteve]

Hello. I’m a relatively new member here, I’m starting a small M1A collection, usually buy clean pre-ban M1As. I have a few heavy barrels (loaded) and a few GI standard barrels, collecting National Match rifles when I can find them. I’ve bedded two of them so far with the information on this forum, and Tony’s videos are a great resource obviously. I have a beautiful NM rifle pre-ban 05xxxx SN and it’s very clean, but the bolt is sticking closed when the trigger is installed. With no trigger it cycles fine; when I put slight pressure on the back of the firing pin, the op rod doesn’t rotate the bolt. It sticks closed. It’s almost like the ramp for the bearing on the op rod is behind. The other thing I notice is the bolt doesn’t rotate as far as the other ones do. Nothing looks worn. I’m wondering if the tolerances on the parts is just a little on the small side. They say USGI parts are interchangeable, I’m wondering if the op rod is a little off. It’s a HRT bolt and SA op rod. The corner of the firing pin was worn, rounded slightly where the small chamfer is. I thought that was the cause, the pin wasn’t being knocked out of the bolt enough, I replaced it with a good Fulton Arms pin, it didn’t help. Any ideas or comments would be appreciated. It’s a bedded rifle so I only want to have it apart one time. Thank you in advance

 

[KurtC]

How is the SA oprod marked? One line or two?

 

[migunshooter]

is this with the stock on or off. i had an M1 garand do this same thing and it was the stock. everything was fine until i dry fired it, then i could not open the action.

 

[MemphisMachinists]

I assume you mean the trigger group when you say the trigger. Easiest thing to change is the trigger group.

 

[MemphisMachinists]

Is this a new problem or was it like this when you got it. If it is a new problem what was changed (if anything)

 

[HKSteve]

So I’m assuming any trigger group will have some force on the pin correct? I will definitely change it out and see what happens. This is with the stock installed. I want to minimize the number of times I install and remove it since it is bedded. I’m very careful but each time it goes in slightly easier so I only want to remove it once more. I think it worked better without the stock, but that shouldn’t affect it you would think. Stranger things have happened. With the trigger installed maybe it is very slightly bending the receiver? Thanks for the help

 

[HKSteve]

I’m at work now so I can’t check the numbers on the op rod. I will tonight. Thanks

 

[HKSteve]

When I apply even a very light force on the back of the firing pin, it won’t rotate. With no force on the pin it rotates fine. So I’m assuming any trigger group will have a slight force there, but I agree I will change it out. I meant the trigger group, that’s correct. Thanks again for the help

 

[shooter86314]

Hey. I pulled my safe queen (vintage circa 1985, assembled from misc parts) from the safe and cycled my action, with trigger guard installed (with hammer forward) and without trigger guard (with slight pressure against firing pin). Corking forces were about the same for both configurations. A burr on the firing pin or bridge might could obstruct rotation; I previously removed burrs from both the bridge and and tail of the firing pin.
FWIW: OpRod number has two lines and the bolt is HRT.

 

[chief on one]

did you take the trigger apart, and put it back together ???

 

[highlandfarmer]

Sounds like something is hung up. With the hammer in forward position, there is a bit of resistance to cycle back the bolt. With the bolt in the locked position, there should not be a lot of resistance to cycle the action.

Are you sure there is not a goop of hard stuff stuck inside the action?

 

[anthonypd]

I’d remove the trigger group and send some pictures. You don’t have to take the action out of the stock if that’s a concern.

 

[nf1e]

If there is a problem with the safety bridge/firing pin fitment, you can point the muzzle to the sky and it may cycle properly. If when it's pointed to the ground and doesn't cycle, this would indicate the problem is with the firing pin bevel and safety bridge interaction. Try a USGI firing pin and see if that helps. Some after market pins have sharp edges.
Take your trigger group apart and re-assemble just to be sure it's not something like the trigger guard caming lug on the wrong side of the hammer.

 

[MemphisMachinists]

Reassembled with the trigger guard cocking bar on the wrong side of the trigger?

Surely not

 

[RAMMAC]

When I apply even a very light force on the back of the firing pin, it won’t rotate. With no force on the pin it rotates fine. So I’m assuming any trigger group will have a slight force there, but I agree I will change it out. I meant the trigger group, that’s correct. Thanks again for the help

That's how the rifle is designed. If you put pressure on the back of the firing pin you prevent it from moving backward and clearing the safety bridge.

No, the trigger group will not prevent the firing pin from retracting if the safety bridge is cut properly and has no deformities. My guess is that either the angled cut on the bridge/firing pin contact area isn't cut properly, or it has been worn from use, and it may have a burr on it.

 

[Cranky182]

1. When you install the trigger group and then try to cycle it, is the Safety in the ON position?
2. Is your hammer installed correctly?
3. Is the Oprod guide rod installed correctly?
4. Is the Oprod dragging on the stock when the trigg assy is installed?
5. Is there any bedding material “overflow” in the trigg assy or in the receiver?
6. Is the oprod tab completely in its groove?

Please share pics so that we can see what is going on as then we will be able to get you back on track

 

[HKSteve]

Thank you guys for all of the good comments, I appreciate them. I plan to work on this tonight after work. The firing pin was from FA, it was GI. The extractor spring tip shot across the shop, and I got on my knees until I found it. Good times there. The trigger is TRW, very clean, never been apart. What concerns me is that if I hold the back of the firing pin forward, and forgive me for repeating this, the bolt wont cycle. One person said this is by design. When I look into the receiver, I see the trigger (hammer I assume) forward against the bolt. Since the hammer hits the firing pin, its making contact. So isnt that the root of the problem? Any trigger will be in contact with the FP after its shot, correct? So shouldn't the bolt rotate with pressure on the firing pin? Theres that angled notch in the receiver, looks fine, doesnt appear to be worn. But the old firing pin hasd a slight worn corner where the chamfer was. I figured thats the issue, its probably not making contact where the tip should be, but that seemed to make it a bit worse. This being said, if I ground the corner of the firing pin with a small rsdius (where the chamfer is) that would seem to fix it, but there must be a reson why thats not done. I will send pictures later after work, thanks again.

 

[HKSteve]

I will try the gravity effect tonight, as you suggest. The safety is off, hammer I assume is correct (how could it not be and still be installed?), Oprod is installed, how could that not be correctly installed if its in the slot?, oprod not contacting the stock, no bedding overflow, yes Oprod in the groove fully. Incidentally, I have rmeoved eight M1A oprods, this one is by far the most difficult. You get the square aligned with the releif and its VERY difficult to rotate the oprod out of the slot. Like I said, the previous FP had a small radius worn over the chamfer. I hope its not a worn receiver slot. I have a TIG welder and a small mill, so if its weldable steel which it seems to be, I can TIG weld the groove and re-machine it. Heat treatment would be the concern. Thank you again.

 

[deuceguy]

Change the firing pin before you do anything. If the firing pin is forward while the bolt is in battery, the bolt should not retract unless it’s rotated.

 

[nf1e]

Thank you guys for all of the good comments, I appreciate them. I plan to work on this tonight after work. The firing pin was from FA, it was GI. The extractor spring tip shot across the shop, and I got on my knees until I found it. Good times there. The trigger is TRW, very clean, never been apart. What concerns me is that if I hold the back of the firing pin forward, and forgive me for repeating this, the bolt wont cycle. One person said this is by design. When I look into the receiver, I see the trigger (hammer I assume) forward against the bolt. Since the hammer hits the firing pin, its making contact. So isnt that the root of the problem? Any trigger will be in contact with the FP after its shot, correct? So shouldn't the bolt rotate with pressure on the firing pin? Theres that angled notch in the receiver, looks fine, doesnt appear to be worn. But the old firing pin hasd a slight worn corner where the chamfer was. I figured thats the issue, its probably not making contact where the tip should be, but that seemed to make it a bit worse. This being said, if I ground the corner of the firing pin with a small rsdius (where the chamfer is) that would seem to fix it, but there must be a reson why thats not done. I will send pictures later after work, thanks again.

As deuceguy suggested change the firing pin first.
The design of the safety bridge is not to prevent the bolts rotation and should retract even with thumb pressure on the tail. If it does not, there is either a firing pin or bridge problem. Do the simplest operations first.