Author: Tina Garcia

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Will a Semi-Auto Safety Slide Function in your Full-Auto MAC Machine Gun?

Here is a common problem we get from customers:  “My MAC Machine Gun will only run with irregular burst fire regardless of the position of the selector lever.”  Often times when our customers have this problem, prior to coming to us for help they will throw parts at the problem such as a new bolt, new springs, new extractor, and the list will sometimes go on and on.  Then after researching the issue further the customer will discover that the Safety Slide is what is causing the problem.  The cheapest and most prevalent source for a new safety slide is an aluminum safety slide designed for the Semi-Auto MACs.  See picture below:

So this brings us to the title question.  Will a Semi-Auto Safety Slide function in your Full-Auto MAC Machine Gun?  This a good question and the short answer is yes but not for long.  OK, so that’s not a good enough answer.  Here’s the long answer and explanation.  

The original style safety slide was made of cast aluminum.  Now-a-days, most of the safety slides on the market are also cast aluminum.  Aluminum is a soft metal and when under heavy stress it will wear out pretty quickly.  In the case of an aluminum safety slide, when in use, it is constantly being compressed by the sear which keeps the sear from dropping too far and thus allowing the machine gun to shoot full auto without the trip getting in the way of the disconnector.  However, with each round, that steel sear wears away at the aluminum safety slide and after a certain point, the safety slide is worn away too far and the resulting malfunction is irregular burst fire. 

Sometimes the customer will purchase a safety slide designed for a semi-auto MAC because these are the cheapest and easiest to come by.  This option will work in the short run.  Go back to the picture listed above; look at the semi-auto safety slide furthest to the right.  See where the arrow is pointing to the worn area?  The semi-auto safety slide comes new with that cut out area.   So, not only is the area that holds the trip in place cut away when it’s new, but it’s also aluminum so it’s soft and will wear quickly. 

Now look at that same area on the full-auto safety slide just to the left.  As you can see, it’s not cut out in any way.  This allows for more material to hold the sear from dropping and thus allowing for full-auto fire.  This part will last much longer than the semi-auto safety because it will take more time for the sear to wear away at the aluminum.  This is what we call an actual repair, not just a temporary fix.

Lastly, look at the two safeties on the left.  These are designed and manufactured by us, Practical Solutions, as an improvement to the original design.  Not only do our safety slides have even more surface area to stop the sear travel than the original, but they are also made of steel.  Steel on steel will last much much longer than steel on aluminum. 

If you are having issues like these with your MAC, you can buy one of our safety slides or if you have questions, please call us at:  410-404-0320 or email us at:  sales@macmachineguns.com

Happy Shooting!

Key words:  MAC Mac-10, M10, M10/9, M10/45, Cobray®, Ingram, Military Armament Corp., Jersey Arms Works, JAWS, Hatton Industries, Marshall Arms, MPA, Masterpiece Arms, M11, MAC-11, M11/9, M11A1, M11-380, Machine Gun, SMG, Repair, Practical Solutions, SWD, RPB, Lage, Uzi, Grease gun, Zytel

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M11 Kit Update

We have fitted a few M11s with kits and they run just as reliably as the M10s.  We will begin working our way through the list as soon as we have our magazine perfected.

Magazines:  We have approximately 200 magazine bodies back from the laser welder and we are working the bugs out.  The 20 and 30 round mags work great.  The high cap mags, however, continue to be a bit of a problem. We tested several 40 round mags (in the white) with our local beta testers and it was thumbs up all the way. We then parkerized them and in an effort to save time and reduce costs, we replaced our follower with a Black Dog Machine follower. Before test firing the new follower, we sent them out to beta test volunteers.  As soon as we had those practice mags in the mail, we discovered that the Black Dog Machine followers (through no fault of their own) were too small for our spring. The parkerizing also made the inside so rough that the follower would not slide correctly. Our high cap mag that (in the white) would hold 42 rounds were now only allowing 17-20 rounds if you smashed the last rounds into the mag.  So, we have modified the followers so that they work with our springs in our mags and sent them out to our volunteers.  To avoid the rough interior wall caused by parkerizing, we have set up for bluing the mags to keep a smooth polished finish on the inside. We will be test firing the latest mags this week and are waiting for reports from our volunteers.

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Comparison of Magazines

We are currently bending the magazine bodies so that they can be sent out to the laser welder.  Below is a picture of the unfinished 12″ mag bodies w/ an H&K 270 20 round mag in the middle for comparison.

M11 Kits:  All of the programming for the parts is completed and we are currently machining the first run of 10 kits.  We expect to send these kits out to be coated late next week.

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Another Magazine Update

We have located a company that will do the laser welding we need for the back of the magazine bodies.  Shipping today, is enough sheet metal to fabricate 200 magazines.  We anticipate receiving the materials next week, however we are preparing for vacation (13th-19th) and will probably not start bending up the sheet metal until we get back – Christmas week.  After we have them bent, the laser welder speculates a turn around time of 3 weeks.  When we have the completed mags inhouse, we will have them beta tested and begin sending them out to those that have already purchased one of our .22 kits.

M11 Kit:  We have cut up the material and it is piled everywhere.  We are in the process of programming the rest of the pieces that make up the kit.  We anticiapte that we’ll have some kits ready to be sent out for coating by the end of the month.

We are also working on the hardware for side cocking uppers for the M10 and M11 .22 kits.  This hardware will also retro fit any side cocking M10 or M11 upper.  The difference between ours and other manufacturers is that ours is spring loaded and the charging handle will always return to the front of the upper on it’s own.

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Magazine Update

The picture below shows the results of our dry run for our new tooling.  As you can see, we’re displaying 30 and 40 round mags sandwiched between the H&K 20 round mag we are currently selling with our kits and a typical Sten mag.  We have not yet testfired these mags but intend to do so in the near future.  Our first step was to make sure we could fabricate what we wanted in the way of mag pieces.  There are some quirks in the tooling that make reproduction difficult at best and we are working that out now.  Next, we will begin beta-testing.  We apologize for the delay.  We have undergone a few setbacks, design changes, and delays; but we are pushing forward as fast as we can.

M11 Kit update:  Because we made a slight design change early in the summer, we resubmitted our M11 Kit to ATF for approval (because they instructed us to do so if we made even the slightest design change.)  We have finally received a positive response from ATF and are free to move forward with production of the kit.  We will be working on them over the next couple of months and will get them out as soon as we can.