Mac 10

[sixduecebiscuit]

Hey everyone. I'm new to this site and I had a question that I was hoping to get an answer or feedback on. I just recently received approval for my first two NFA items. I purchased a Powder Springs M10 in .45 and also a SBS. The can for the mac went pending on January 29th so unfortunately I am still waiting on it. The guns were delivered to me on Thursday but I wasn't able to get to the range until Friday. I wanted to run the mac just to make sure it ran fine. My intentions were to run one box of 50 through it and then head out since I had prior engagements I had to make Friday night. I ended up running 250 through it instead, it was just too much fun. Ok so for the main question now. It fires from an open bolt. I loaded a magazine and got ready to fire it. I inserted the mag and then when I went to charge the bolt back it fired one round. I had the weapon pointed downrange of course but this still caught me completely off guard. After I ran the magazine through, I left it in the open bolt position and continued to run the other mags through until I was done. I'm just curious as to why it did this. Is this a flaw that I need to have checked out? Did this simply happen due to the fact that I loaded a mag in and then charged the bolt? I did not have my finger on the trigger when I charged it the first time. Out of the 250 that I ran through it, I had one fail to feed and then I had several times that it simply would not fire. I would engage the trigger for a mag dump and it would roll off maybe 8 and then stop. The bolt would still be open and I would just have to engage the trigger again and it would rock another 8 or so off and then same thing would happen. I'm curious as to what is going on but my main concern is why it fired that first round when I charged it. I would really like to get an answer as to why that happened since I see that as a major safety concern. Any help would be greatly appreciated.

 

[zignal_zero]

Congratulations!!!!! I'm pending since 11/14, any day now for me

First of all - u planned on running FIFTY rounds through it?!?! That funny

OK, like I said, BATFE hasn't approved mine yet, so my experience is limited BUT when u load an open bolt mg, u should charge the handle THEN insert the mag. The reason is it is easy to pull the bolt back far enough strip a round from the mag (and fire it) without pulling it back quite far enough for the bolt to engage the sear. I'd be willing to bet that is all that happened. The biggest safety slogan, with open bolt guns is: "control the bolt" cuz YES u can fire it without touching the trigger. Aslo, if u get a stoppage, drop the mag BEFORE monkeying with the bolt.

I love THR, but now that u got a MAC, u really need to get over to WWW.uzitalk.com there's a "MAC" section with more info than a human could possibly absorb

 

[dprice3844444]

prob was sitting on the edge of the sear.new mac or used mac?
http://www.cobray.com/ACC_34_MAG_CONVERTER-details.aspx mag converter to use standard grease gun mags.

gotta be careful with open bolt stuff.

only difference between mac mags and grease gun is mac cut 1/8 inch off the tab on the back.

 

[sixduecebiscuit]

Thanks for your responses. I was using a Cobray mag and and also a modified grease gun mag. The Cobray mag was the one being used when the single round went off. My first thought was that I did engage it by charging it with the mag in although I don't have too much experience with the open bolt stuff. Thanks again for the help though and I'll check out uzitalk for sure. Btw, I went pending on Oct 29 for the MG and SBS and they were approved end of March. Good luck with yours!

 

[Trebor]

With an open bolt subgun the correct procedure is ALWAYS to lock the bolt to the rear, and make sure it's locked, BEFORE you insert the magazine.

If you insert the mag, and then pull back the bolt, you can have an AD if the bolt slips while you are pulling it back or if the bolt does not fully lock back and "falls off" the sear when you let you. That sounds like what happened to you.

The big thing to remember is CONTROL THE BOLT.

Always pull the bolt back first, then load the magazine.

If you have a malfunction, always pull the bolt back first, and make sure it's secure, before you remove the mag. If the bolt is stuck on the mag and you pull the mag out, the bolt will fly forward and fire the round in the chamber or possibly grab the top round out of the mag and fire it.

Always, always, always, lock the bolt back securely before loading and before working on any malfunction.

 

[Prince Yamato]

This is interesting! I never knew this about open bolt guns... Stupid Hollywood does the exact reverse of what is talked about in these threads.

 

[Trebor]

This is interesting! I never knew this about open bolt guns... Stupid Hollywood does the exact reverse of what is talked about in these threads.

In defense of Hollywood, I don't know what the military procedure is for loading an open-bolt subgun. The procedure I described is the consensus among SMG owners/collectors as to the SAFEST loading procedure. That doesn't mean it was always done this way.

The simple fact is open bolt SMG's are more dangerous then a closed bolt weapon. The chance of an AD is higher if the bolt is somehow released as it will fly forward, strip a round out of the mag, and immediately fire that round (and possibly others).

In many open bolt guns it doesn't take much to jar the bolt off the sear and let it fly home. This would commonly happen if the gun was dropped, or sometimes if it even just was banged into something hard enough.

The dangers of open bolt guns were recognized by various militaries over time. The Germans had to add a "safety notch" where the bolt is essentially locked in place after numerous AD's with the MP 38.

The designer of the UZI added the grip safety in an effort to reduce the chance of an AD.

The danger of open bolt guns is magnified by the fact that SMG's are relatively rare in private hands and most people who shoot an open bolt gun for the first time don't understand the proper procedures or completely understand how they function.

 

[mattmann]

I have no idea but I am so jealous of your guns. How about some pics??

Sent from my DROID RAZR

 

[SharpsDressedMan]

30 rounds in 1.5 seconds, as I recall.............

 

[smkummer]

If you don't already have the book "Machine Gun Buyers guide" spend $15 and read it. Almost all open bolt guns are loaded safely by cocking the bolt then inserting the mag.. Also remember that most open bolt guns are NOT safely carried with the bolt closed on a loaded magazine. One exception is the UZI with its ratcheting cocking handle and grip safety. Agree with the above to find a Mac forum and discuss what happened, your sear or bolt notch may be worn. Or as always a good oil-n-clean may be the issue. Never be afraid of pulling the bolt back with authority to cock it. It is important that you understand your weapon before letting others try it. And when you do, instruct them on the open bolt operation and if a stoppage occurs, to safely hand the weapon to you to clear. Always start a new shooter with 3 or 4 rounds only in the mag. first. When they show that they can control the gun, then allow more. It is probably best with a Mac to run a can or fake can with new shooters. A Lage upper will be your next purchase, it almost makes 2 guns out of one. I R/O the subgun matches at Knob Creek and the Lage upper allows these guns to compete very well. Always drop the mag. when clearing a stoppage. And lastly, have fun, be safe and share your fun with others. (Let them buy there own ammo)

 

[JT-AR-MG42]

+1 for cocking the bolt completely when a stoppage occurs or before inserting a mag when just generally shooting.

Remember the cocking knob on your Mac does work as a bolt lock when the bolt is forward though.
By rotating it 90 degrees either direction, it effectively locks the bolt from the 'dropped gun' discharge.

Better than trusting the safety on a cocked gun, as parts would have to break for the bolt to retract when locked forward.

Being new to the gun, I would sure get some 'dry fire' practice cocking it over a full loaded mag with dummies at home before doing it with live mags in the field.

The mac makes a good first gun. They do shoot pretty fast though.
I load 185 jacketed SWCs with 4 grains of Bullseye or lead 200 SWCs with as light as 3.3 grs Bullseye.

The latter load in particular - will not even begin to function a standard 1911 - really slows the gun down for other beginning and younger shooters.
Lighter weight bullet makes the gun more controllable for them as well.

Feeding of the SWCs in my gun are 100%

My 02, JT

 

[hentown]

Got a hole in the ceiling of my bedroom from just such an event. MAC 10 had belonged to my father, who sold it to the local sheriff's dept a few months before my father died. Sheriff let me play with it awhile (16-yrs-ago), and I had been cleaning it in my bedroom.

Not having fired the MAC for many years prior to this event, I had forgotten that it fired from an open bolt. Sitting in the bedroom, I was going to see if it "cycled o.k." Big mistake. Fortunately, had the suppressor installed at the time and had the muzzle pointed up and away from me, windows, etc. Bullet bounced off a rafter and I recovered it from the attic later.

I wouldn't buy a MAC now, but did occasionally enjoy shooting my father's. Actually, after the f.a. novelty wore off, which didn't take long, I just preferred shooting more precise firearms.

 

[sixduecebiscuit]

Here is the 870 and the MAC. Thanks again for all the input. I just got done giving it a good oil and clean and we are headed back to the range in about an hour. Hopefully this will solve some of the problems. I will definitely be cocking the bolt before inserting any mags this time. I will also look into picking up a copy of the buyers guide. I like your suggestion of 3 or 4 rounds to start for new shooters. I had only shot a MAC with a can before this one and this is quite a bit of difference when shooting one without. Hopefully I only have a couple more months before the can is approved. I'm also going to run a couple of different loads through it this time to see how that affects it. I know a lot of people don't really care for these guns but I just never get tired of shooting them. In time that might change but it's still a blast. As a civilian buying MG's it can get a bit expensive when you start looking at other options. Thanks again for all the input though and I'll keep ya updated on how the session today goes.

 

[SharpsDressedMan]

A fixed wooden stock and barrel entension (a heavy, ventilated tubing set up designed to add weight and length) made my MAC10 .45 a lot more controllable. The wood buttstock just temporarily replaces the foldng wire one, and the barrel entension serves when you don't want to keep wearing out or dirtying up your suppressor.