MAC-10 approved yesterday, some questions

[lemonysword]

This was an eform 4, approved in 74 days. That was very cool.


First off my Mac was missing the safety which I knew in advance, I bought the 5 parts from practical solutions but when I went to install them today, the roll pin holes did not line up. I checked to make sure it was all assembled correctly but never got it to work.



Next I took the rear grip off, and after reinstalling the mag release is crazy tight, basically impossible to remove the mag. I tried it a few times and I’m not really sure what I’ve done wrong since there’s only one way it goes in.


Any thoughts fellas?

 

[timkel]

Practical Solutions parts are usually good to go. Can you assemble the safety assembly outside the lower. Might have to run a drill bit through to align the holes. It is tricky to assemble in the lower with the spring/ball and roll pin all in place.
Now as for the mag catch. What caliber is the lower? What is stopping the mag catch from releasing the mag? Try the catch without the plastic grip in place? Just thinking here.

 

[Manthony]

This was an eform 4, approved in 74 days. That was very cool.


First off my Mac was missing the safety which I knew in advance, I bought the 5 parts from practical solutions but when I went to install them today, the roll pin holes did not line up. I checked to make sure it was all assembled correctly but never got it to work.



Next I took the rear grip off, and after reinstalling the mag release is crazy tight, basically impossible to remove the mag. I tried it a few times and I’m not really sure what I’ve done wrong since there’s only one way it goes in.


Any thoughts fellas?

I have seen factory safety switches with the holes drilled out of alignment. It's best to return it for one that is in spec. As far as the mag release, before you install the grip assembly make sure the catch can move back and forth freely, then make sure the spring is straight and isn't bending over to one side when you install the grip.

 

[gww250]

There are at least three release springs on the market depending on source. The .75" long versions often bend and bind. Sam sells the correct .625" version that works the best.

 

[lemonysword]

Practical Solutions parts are usually good to go. Can you assemble the safety assembly outside the lower. Might have to run a drill bit through to align the holes. It is tricky to assemble in the lower with the spring/ball and roll pin all in place.
Now as for the mag catch. What caliber is the lower? What is stopping the mag catch from releasing the mag? Try the catch without the plastic grip in place? Just thinking here.

It's a 9mm. It seems as though the spring is too long/strong and it takes an unholy amount of strength to push the lever forward. I can release the mag, but i have to turn the gun upside down to get proper leverage on it and almost tear the skin off my thumbs. With grip and spring removed, the mag release lever moves freely. Of note, it was operating normally and mags were easy to remove before I took the grip off, which is why I am so confused. If the spring was too long, why was it not super tight beforehand? I just went and measured the spring and its .625" but has a little bend in it. I straightened it out but it didn't help.

As for the safety, outside of the gun the parts also wont line up, it seems as though the hole in the button itself is too low or, more likely, the hole in the slide is too high.

I have seen factory safety switches with the holes drilled out of alignment. It's best to return it for one that is in spec. As far as the mag release, before you install the grip assembly make sure the catch can move back and forth freely, then make sure the spring is straight and isn't bending over to one side when you install the grip.

I ordered the parts a few months ago while waiting for my stamp, so hopefully I can send them back. I need to order a sear trip anyways, I discovered that part was missing as well when I took apart the trigger group to try and install the safety. The previous owner was probably a pretty cool guy, full auto only with no safety.

 

[Poacher]

There are at least three release springs on the market depending on source. The .75" long versions often bend and bind. Sam sells the correct .625" version that works the best.

Yup, my early M10 had the same issue.
The shorter spring took care of that.

 

[DINK]

It's not too difficult to install the spring so it folds over and is inside the grip sideways (for the upper part of it). Your statements about the "unholy" amount of force needed to remove mags and the existence of a bend in the spring suggest this is the case. Try checking it again and re-installing it using utmost care to lower the plastic grip in place, keeping it perfectly parallel to the mag housing. If there's a bend in the spring when you pull it apart, try rotating the spring 180 degrees so the bend is in the other direction and re-install. If possible, clamp the receiver in a padded vise so the spring is pointed vertically as you are attempting to re-install the grip and you can use both hands to guide it down over the spring.

 

[lemonysword]

I was able to get it back together properly finally. There was a very slight kink in the spring, I had to force it over the end of a punch to straighten it out enough that it would stand straight on its own. Very carefully put it back together and now the mag release functions as normal. Crazy how a slight bend in the spring can make it exponentially more difficult to actuate the mag release