MAC M10 issues

[AK74U]

Regarding the 9mm upper and mag adapter:

-The bolt won't go forward because its hanging up on something and not picking up the cartridge and slamming it home into the chamber:
with the gun empty and an unloaded mag, check to see if it hangs up. take some pictures of what its hanging up on by looking through the ejection port.
1. It could be the mag and the bolt are hitting - as others have said a double wide bolt with a single feed mag - bolt is to fat to move across the mag feed lip gap. get the right mag for the bolt.
2. Mag height could be too high and catch or mag needs adjustment

Regarding the 45. If it feeds most of the time

I would suggest:
-Try a different, preferably new(ish) magazine or replace magazine springs. Grease gun mags are often WW2 vintage and vary in wear when you get them - but Keepshooting.com has new replacement springs some NOS mags still exist for sale.
The magazine spring has to be strong enough to lift a cartridge in the position by the time the relatively fast bolt is moving back home to chamber - if the mag springs are aorn - this can cause feeding issues.

-Try different factory ammunition, MACs should feed well with good factory ball ammo, but some ammo loads I've seen ESPECIALLY from recent new ammo give inconsistent results - high output (perhaps hurried) manufacture in especially in my 45 where the rate of fire slows and increases within the same box - meaning ammo is likely not loaded consistently precise. Some brands run less reliably than others as well. Lots of ammo is on the she shelf is good and It may be completely "safe" for use and run some guns, but not ideal for a machinegun reliability. Try some different brands.

- Clean lube the gun completely and inspect parts, It probably wouldn't hurt to change out a recoil spring on the bolt. check sear engagement and feel for friction points. I wouldn't tear it apart unnecessarily and swap parts unless something was amiss with a certain part.

-check extractor for wear - you can find replacement extractors for the old style bolts or find a newer bolt with the better extractor. (cases may not be clearing the gun and bolt closes on brass or jamming up the works)

Pictures of the jams would help find root cause.

Good luck.

I forgot that I accidentally bought a double feed 50rd 9mm mag by accident earlier this year. I will try that mag next time also. I will also take pics. The .45 I shot Freedom Munitions 230gr ball. The issue Im having is when I pull on the trigger and hold it, the gun cycles a few rounds and then the bolt stays back. When I release the trigger and pull again, it shoots again in bursts. I have some Federal 230gr ball I will run next time. I can bring another mag and test. I told my LGS to clean the gun Friday when I left. I haven't bought any extractors yet, but will snag some.

 

[A&S Conversions]

Watch out for Freedom Munitions ammo in an open bolt guns. The last I knew, they used two peice casings. The chambers tend to be generous in Mac style guns. The brass expands and splits at the inside step, which leaves a ring of brass in the chamber. The next round can't fully chamber and you'll get an out of battery with the next round. The stuff seems to work fine in closed bolt carbines and handguns. But not so well with open bolt.

Scott

 

[LawBob]

I forgot that I accidentally bought a double feed 50rd 9mm mag by accident earlier this year. I will try that mag next time also. I will also take pics. The .45 I shot Freedom Munitions 230gr ball. The issue Im having is when I pull on the trigger and hold it, the gun cycles a few rounds and then the bolt stays back. When I release the trigger and pull again, it shoots again in bursts. I have some Federal 230gr ball I will run next time. I can bring another mag and test. I told my LGS to clean the gun Friday when I left. I haven't bought any extractors yet, but will snag some.

Winchester white box
Blazer brass
Lawman

Try that

Ré 45 issue: earlier commenter suggested take the trip out and test. If it stays fa while trigger pulled, then replace the trip.

If not, it still bursts, your sear may be worn. Prob time for a new sear and trigger group then.

 

[LawBob]

Pics of that 50rd df please

 

[AK74U]

Will post pics later when I get off tonight.

 

[AK74U]

https://postimg.cc/gallery/N0SYbn8


The bolt and mag.

 

[BlackBelt]

For several years my M10/45 was shooting bursts like that. 2 to 5 or 6 shots per trigger pull. I replaced ALL fcg parts and tried different mags and ammo...all to no avail.

It was kind of depressing.

Finally, I was shooting it one day and one of the reinforcement tabs broke off. That was strange because I had checked everything inside that lower at least a hundred times or more.

So, I accepted my defeat, tore up my man-card and sent it to Sam at Practical Solutions.
After he got it he told me the receiver pin holes were not drilled correctly. He fixed it and did a beautiful refinish job on it.

Since I got it back it has worked flawlessly.
It would have never occured to me that the pin holes were not correctly drilled.

Not saying thats what is wrong with the OP's gun, but if all else fails I would send it to Sam.

 

[AK74U]

For several years my M10/45 was shooting bursts like that. 2 to 5 or 6 shots per trigger pull. I replaced ALL fcg parts and tried different mags and ammo...all to no avail.

It was kind of depressing.

Finally, I was shooting it one day and one of the reinforcement tabs broke off. That was strange because I had checked everything inside that lower at least a hundred times or more.

So, I accepted my defeat, tore up my man-card and sent it to Sam at Practical Solutions.
After he got it he told me the receiver pin holes were not drilled correctly. He fixed it and did a beautiful refinish job on it.

Since I got it back it has worked flawlessly.
It would have never occured to me that the pin holes were not correctly drilled.

Not saying thats what is wrong with the OP's gun, but if all else fails I would send it to Sam.

The guy I bought it from sent it to Sam before I purchased it. I spoke to Sam personally and he told me he checked the gun out and fired it with one of his side charging uppers.

 

[smec_289]

mine did the same thing, only would pull short bursts. replaced the trip, same thing. custom ground the trip, no problems after that.

 

[cherenkov]

I forgot that I accidentally bought a double feed 50rd 9mm mag by accident earlier this year. I will try that mag next time also. I will also take pics. The .45 I shot Freedom Munitions 230gr ball. The issue Im having is when I pull on the trigger and hold it, the gun cycles a few rounds and then the bolt stays back. When I release the trigger and pull again, it shoots again in bursts. I have some Federal 230gr ball I will run next time. I can bring another mag and test. I told my LGS to clean the gun Friday when I left. I haven't bought any extractors yet, but will snag some.

The note that it holds the bolt back on its own and then resets when trigger is released again is a clue about that there is some interaction with the fire control group that isn't correct. The disconnector is grabbing it like its semi auto when it catches the bolt like that which could be a few possibilities. It is hard to evaluate without looking at the entire gun observing it and examining it first hand so note this is a blind-interpretation and there can be several possible causes but suggest trying some simple things.

A few things I would suggest -

If your not up for replacing parts, take it to a MG gunsmith that is familiar with MACs.

If you are competent in parts replacement and disassembly of the MAC fire control group.

As others have said you can take out the trip and see what happens - Its a full auto only at that point.

I'd Consider disassemble, examine springs, possibly replace some springs & retainer spring and pay careful attention to proper re-assembly with the retainer.
I'm wondering if the retainer spring or trigger torsion spring are not behaving the way it should - perhaps its bent, worn or improperly re-assembled. This video https://youtu.be/2P2Tn4DLX9k?t=60 seems decent on the assembly disassembly. This is a low cost effort except time, so might be worth trying.

You can replace many of the parts with new if need be - they are still around (good thing about MACS)

Good news is FTF has a reasonable price on the entire fire control group that you could replace every part if you needed to. https://www.ftfindustries.com/product/ET-SPM10FCG-F.html

There could be other considerations with wear and tear on contacting surfaces between bolt, upper etc. but I'd try the lower group and trip (as others stated).

Still focus on getting good mags with good mag-geometry for the 9mm as well to eliminate other problems- Focus on one problem at a time.

Be safe. god luck.

 

[AK74U]

Went to the LGS yesterday. I tried the double feed 9mm mag with the 9mm upper. It doesn't strip a round from the mag, but the bolt went forward when trigger was pulled. Im going to try buying another 9mm mag adapter and see if that's the problem. Here is the internals pic.

https://postimg.cc/ZBYmMGqR

 

[cherenkov]

Went to the LGS yesterday. I tried the double feed 9mm mag with the 9mm upper. It doesn't strip a round from the mag, but the bolt went forward when trigger was pulled. Im going to try buying another 9mm mag adapter and see if that's the problem. Here is the internals pic.

https://postimg.cc/ZBYmMGqR

To confirm - You are saying that
1) the fully inserted mag with ammo in it would not pick up a round. AND
2) With the mag in it, the bolt goes forward but does not strip a round off into the chamber.

That sounds like the magazine is sitting too low for the bolt to engage. Assuming correct bolt and mag combo.

Do the over-insertion tabs on the side of the 9mm mag make intimate contact with the bottom of the mag-well grip or are they a bit distant? it not close? As if the mag isn't seated all the way up?

I wonder if the magazine catch is a mag catch for using 45 un-modified grease gun mags and latches the 9mm mags so they are seated too low.

 

[AK74U]

To confirm - You are saying that
1) the fully inserted mag with ammo in it would not pick up a round. AND
2) With the mag in it, the bolt goes forward but does not strip a round off into the chamber.

That sounds like the magazine is sitting too low for the bolt to engage. Assuming correct bolt and mag combo.

Do the over-insertion tabs on the side of the 9mm mag make intimate contact with the bottom of the mag-well grip or are they a bit distant? it not close? As if the mag isn't seated all the way up?

I wonder if the magazine catch is a mag catch for using 45 un-modified grease gun mags and latches the 9mm mags so they are seated too low.

Correct. Goes forward, but no bang. Ammo stays in the mag. I hear the click when the mag locks into the grip.

 

[cherenkov]

Correct. Goes forward, but no bang. Ammo stays in the mag. I hear the click when the mag locks into the grip.

Seems like the mag catch is engaging the mag notch so that it sits too low. There are mag catches made for different mag engagements, some for modified grease gun mags (original Powder Springs set-up) or un-modified grease gun mags and 9mm. Depending on the mag you have, the rear spine on the notch will engage at a differnt height. It is hard to tell without looking at it to tell what you have - If your 45 mags don't look modified maybe you have a catch designed for unmodified grease gun mags. You can swap out the catch for a 9mm as a chance that might take care of it - see below link. It could be just stacking of tolerances equals your gun might need the notch on the mag spline different location - depending on your mag you might be able to notch the back of the magazine spline with a notch lower than the current one on the mag - measure how much heught you need to go up to engage a catridge - USE DUMMY rounds to look.and check

https://macmachineguns.com/?product=m109-mag-release-2

 

[AK74U]

Seems like the mag catch is engaging the mag notch so that it sits too low. There are mag catches made for different mag engagements, some for modified grease gun mags (original Powder Springs set-up) or un-modified grease gun mags and 9mm. Depending on the mag you have, the rear spine on the notch will engage at a differnt height. It is hard to tell without looking at it to tell what you have - If your 45 mags don't look modified maybe you have a catch designed for unmodified grease gun mags. You can swap out the catch for a 9mm as a chance that might take care of it - see below link. It could be just stacking of tolerances equals your gun might need the notch on the mag spline different location - depending on your mag you might be able to notch the back of the magazine spline with a notch lower than the current one on the mag - measure how much heught you need to go up to engage a catridge - USE DUMMY rounds to look.and check

https://macmachineguns.com/?product=m109-mag-release-2

I bought a Lage thumb release grip. Maybe I should try that too? I dont know which mags are modified vs non-modified for the grease gun mags.

 

[KickStand]

I bought a Lage thumb release grip. Maybe I should try that too? I dont know which mags are modified vs non-modified for the grease gun mags.

That’ll work with BOTH factory or modified grease gun mags.

Post a video of the gun. It’ll help everyone with finding the problem(s).

 

[AK74U]

That’ll work with BOTH factory or modified grease gun mags.

Post a video of the gun. It’ll help everyone with finding the problem(s).

I have video of me shooting it. But no video of the internals. I will post the video.

 

[AK74U]

Video is too big for me to upload to the third party site.

 

[LawBob]

Video is too big for me to upload to the third party site.

Your initial issue was the bolt not going forward w the SF mags.
Using df mags, the bolt goes forward but doesn’t strip a bullet

I’d say you’re sf bolt isn’t stripping the cartridge from your DF mag bc the bolt area is sliding by the cartridge.

Modified gg mags will have a noticeable
zipped area on The back, and both sides on the over-insertion tabs.

If those are the 45 mags that work, then you mag catch is holding your SF 9m mags too high.

If you are using unmodified gg mags (no dremmel looking zips), that mag catch sits the 9mm mags too low.

The Lage thumb grip adapter - does it come w a two stage adapter? Even so, it’s not a 9mm mag catch

You need a 9mm mag catch. It’s different.

The magwell adapter isn’t your issue. It just takes up space inside the magwell. Certainly it can be adjusted wrong, but that’s not the issue you’ve outlined

 

[AK74U]

Your initial issue was the bolt not going forward w the SF mags.
Using df mags, the bolt goes forward but doesn’t strip a bullet

I’d say you’re sf bolt isn’t stripping the cartridge from your DF mag bc the bolt area is sliding by the cartridge.

Modified gg mags will have a noticeable
zipped area on The back, and both sides on the over-insertion tabs.

If those are the 45 mags that work, then you mag catch is holding your SF 9m mags too high.

If you are using unmodified gg mags (no dremmel looking zips), that mag catch sits the 9mm mags too low.

The Lage thumb grip adapter - does it come w a two stage adapter? Even so, it’s not a 9mm mag catch

You need a 9mm mag catch. It’s different.

The magwell adapter isn’t your issue. It just takes up space inside the magwell. Certainly it can be adjusted wrong, but that’s not the issue you’ve outlined

That's correct. In the video of me shooting you can see the GG mag. I dont know what a zipped area is sorry. I dont have the exact mag as I leave it in the LGS safe with everything else.