Fulton Armory

Slam Fires, Mags & SLEDs; Clint speaks out!

by Clint McKee

In my humble opinion, all self loading, gas operated, mag fed/clip fed rifles should be mag fed or clip fed, as appropriate. Sometimes, it's just so simple.

Why, you ask? Because they were designed to be fed that way!

Gas guns are self loading rifles. Thus, bolt velocities on opening & closing had to be determined. It takes a great deal more energy to strip a cartridge from a clip/mag than when they are hand fed. Try this at home, without live ammo of course. You will notice a significant increase in bolt velocity when letting the bolt "fly home" without a clip/mag, than when loading from same. If too fast, predetonation could occur. If too slow, the bolt may not close. So a balance is designed, in the best case. (The development of the box magazine Garand and then the M14 was delayed as stripping the top cartridge from a fully loaded magazine slowed the bolt too much! Not until John Garand's magazine design for the T31 was adopted, with its single lip arrangement, was the problem solved. --Walt Kuleck)

When we remove the clip/magazine, we change everything! After all, the rifle was designed to feed from a clip/magazine. Bolt velocity on opening & closing changes very significantly--more or less, depending on the rifle design discussed.

I really hate the "it's been that way for a bazillion years" argument. People play golf in thunderstorms all the time. Almost no one gets hurt. But, we've all heard about that cruel lightning strike, if we listen to the news. Is it rare? YES. That's why golfers keep playing in thunderstorms!

But it kills more people than you would think, each & every year.

The M1 Garand, M14/M1A, M1 Carbine & M16/AR15 all have a free floating firing pin. They all dent the primer on loading.

From left to right, an unfired primer, a dimpled primer, and a fired primer.

Indeed, the original Garand firing pin was redesigned to reduce slam fire by lightening the firing pin, even when fed as designed, by a clip. The M14 firing pin was blessed with that design wisdom. But then along came the M16 & it had a similiar problem, also when fed as designed, via magazine (see "Slam Fire, a parable"). It was fixed, again, by reducing the weight of the firing pin.

Use a magazine when loading a rifle designed for a magazine, or a clip when using a rifle designed for an en-bloc clip!

The advice of some experienced shooters when single loading without a clip/mag, calls for easing the op rod about half way or more forward before "lettin' her fly home". Good advice, as bolt velocity will closely replicate that found if loaded via a clip, in a Garand.

These opinions on how to load a Garand without a clip are sage advice. But they know a lot more than most, & most will screw up, & may get hit by lightning!

Further, get your hand out of the way when loading a live round. If any part of your hand is opposing the op rod, & it slam fires, forget about the neurosurgery/pianist career. Your hand will be opened up in the most ugly & horrible fashion possible.

Just my opinion.

--Clint McKee

PS: The story of the M16 firing pin, the .223's primer hardness, et.al., can be found in Stevens & Ezell's "The Black Rifle.". See Slam Fire, the M16 Story.

PS: Here's a true story from a rec.gunner who learned about slam fires the hard way!

"MAS-49/56 with load #06089702 shot 5 single rounds to test, first time to shoot reloads through the MAS49. Cases all looked OK. 2 round loads, rifle double fired, two more rounds, same result. Took rifle apart and dried excess lube from the bolt/carrier/firing pin, as I had liberally lubricated them, and reassembled rifle. loaded two more rounds. Fired normally and cycled action properly. Put three rounds in mag, first round fired as soon as the bolt slammed home, and the next two rounds fired as well. Then took crappy old Syrian ammo (50 rounds) and fired it all w/out mishap ('cept for Syrian hangfires). I chambered a Syrian round in the MAS-49 and then removed it and inspected the primer . There is indeed a small indentation in the primer (see graphic above; ed.); that seems to be enough to sometimes set off the reload primers, and not to bother the military primer. After this put the MAS-49/56 in the case!

"Observations afterwards:

I need to get the CCI hard military LR primers for the MAS-49. I need to doublecheck primer seating depth..."

"(Continued later...) Back on August 8th, I posted regarding my mishaps with inadvertant full auto fire with my handloads in a MAS49/56 rifle. Since that time I have ordered the CCI military hardness primers (5 thousand of them) and found a brick of them at a gunshow while waiting for them to arrive. The brick box of the primers was plain white, with the words '1000 M-34 Primer for 7.62 Cartridge' on the top, and the parent company, Blount, listed on the back. Nowhere does it say CCI. The individual boxes inside are labeled similarly, with the lot number on the front rather than the back. I loaded my Norma brass (50 rounds) and as test, some newly purchased Remington brass. Also, I had 10 rounds of ammo loaded with commercial Winchester primers checked for proper depth. This time I was in a hollow, in the hills of southern Ohio, away from people. The 10 rounds of commercially primed ammo acted as before, with 1 slam fire, and 3 double fires (never more than 2 rounds in the mag at a time). Needless to say, the rounds with the CCI milspec primers worked without a hitch. Over 70 rounds, with no slam fires, no malfunctions of any type."

--Paul Pelfrey

See, we told you so! --Clint & Walt

PPPS: Here's another true story, this from a c-r-ffl-lister:

One of my friends was a careless reloader. He did not set his dies for his M1A with the Wilson case headspace die and he seldom fully resized the brass. The problem magnified itself when a ctg. was loaded with excessive headspace and the bolt did not close all the way. The rifle was a Springfield M1A and it would allow the firing pin to fire the cartridge out of battery. This is a very dangerous condition and the resulting shot was spectacular. The round fired and the case was withdrawn from the chamber before the pressure curve was down to safe levels. The entire head of the cartridge was blown off, blowing his BOONIE HAT 35 feet in the air and destroying the 20 shot magazine. The club's rules do not allow shooters or spectators to be on the range without eye protection. This man's eyes were saved by the shooting glasses but he looked as if he had the chicken pox.

He had to have small pieces of brass removed from his face and he would probably won the LA. state championship if he would not have had this happen. Springfield Armory gave him a new receiver but could do nothing for the flinchitis he got from this incident.

I too, have seen disasterous results from careless shooting and reloading practices. Whenever I get a new M1-M1A-M14 in the shop, I put a primed case into the chamber and see how much the bolt may be opened and still fire the primer. If it is too much, the rifle should be sent to the factory for repairs.

Most people don't think about the rear of the receiver (receiver bridge, ed.) blocking the firing pin when the rifle is out of battery. We all should inspect and test our M1-M1A rifles for this defect.

--Doug Bowser

And yet another rec.gunner chimes in:


Well, after my first offhand match I found out how to make a Garand slam fire by single loading. I then read your articles and proceeded to buy a SLED for both myself and my wife. Well, we finally got a chance to go Mariotsville this weekend and guess what, no slamfires! I fired over 40 rounds through my Garand and didn't have a single one!

Again, kudos to you and Walt for the outstanding site and all of the educational material you put in it! Maybe we'll see about getting an M1A from you if we can find a good Springfield receiver at a reasonable price, as we don't make THAT much! HA!

Anyway, again THANKS!

--Brian Hall