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chris in va
May 14, 2011, 01:52 PM
I was wondering when this would happen.

Loaded about 800 so far for my Garand with no issues, but yesterday I had a double tap. I may switch to a harder primer than CCI LR, although I suspect the primer was a bit higher than it should have been.

I have to say, this thing ripped off that second round darn fast. I almost didn't realize what happened until I saw two cases go flying. You really don't expect all that mass to move that quick.

Howard31
May 14, 2011, 01:59 PM
You got one too many trigger jobs done.sounds like a worn trigger or sear. Take the sear out and you can go full auto
A slam fire is when you close the bolt and a round fires. Big difference because the bolt is not always closed all the way.

hps1
May 14, 2011, 02:13 PM
How is your trigger? Sounds like your rifle may have just doubled, rather than a slam-fire. If trigger has been lightened, the disconnect may not have sufficient engagement to prevent rifle doubling. If your trigger breaks below 4.5# I would have it checked out.

As for slamfires, soft primers can be responsible, as you suggest. The CCI #34 & #41 military primers have a hard cup to duplicate GI ammo, most of which is loaded with a hard primer. Handloaders must be aware of other factors that can result in slam fires, as well.

http://www.cci-ammunition.com/products/primers/primers.aspx?id=30

A slamfire in either the M1 or M14 can have disastrous results if it occurs before the bolt is in battery. Lack of care in following careful reloading practices or a bit of debris on bolt face, or perhaps a broken firing pin, combined with a soft primer can all contribute to a slamfire.

While the following concerns an M1, hopefully it will illustrate what can happen should a rifle slamfire while not in battery. I have personal knowledge of several other such events that I did not actually witness. One was an M14 using military issue ammo in which the shooter received some serious injuries, so the hard primer is not absolute insurance against a slamfire.

A friend who is a very experienced highpower competitor and reloader wrecked his match grade M1 Garand using the same handloads he had used for years when the rifle slam fired out of battery. Bent his op-rod, blew extractor/ejector out of bolt and rounded the receiver locking lug recess about 1/8" showing the bolt lug (thankfully) had barely entered the recess but was not fully in battery at the time the slamfire occurred. He received a cut on the forehead and had somewhat of a problem with his trigger control for a while thereafter. Fortunately, the rifle, and his shooting ability have since been restored.

Upon examination of the remaining lot of ammo, we found that the rounds did not have sufficient headspace (clearance) in his snug, match chamber. He had loaded this batch of ammo using the same (full length) die setting as always. Remember, all previous lots had measured OK. The problem stemmed from the fact that this particular lot of brass had been fired at least 8 times and had work hardened. His dies had been set to give proper headspace with once fired brass and he failed to check headspace on this lot after loading. The harder brass springs back more than softer brass after sizing which resulted in oversized (for his chamber)rounds.

Other than a dirty chamber, a broken firing pin or a pin that is no longer free floating for whatever reason, IMHO, ammo is probably the number one cause of slam fires in the Garand & M14. Anything that can cause the round to "stop short" of full chambering can result in the firing pin hitting the primer with sufficient force to set it off. If this occurs before the bolt is in battery, it can be disastrous!

First, make it a practice to run your thumb over the primer as each round is removed from the press to be sure that the primer is fully seated.

Secondly, each cartridge must be sized sufficiently to fit your rifle's chamber giving proper headspace clearance. I would not load for any "gas gun" without using a cartridge case headspace gauge. Best practice is to run each case through the case gauge at the time the loaded round comes off the press after determining the actual headspace required for your rifle; remember, all rifle chambers are not created equally. At the very least, spot check every few rounds in a given lot of reloads (for this to be acceptable, one must keep all brass in lots that have been fired the same number of times).

Hopefully, this information may help someone else avoid this pitfall.

Regards,
hps

AK103K
May 14, 2011, 03:00 PM
If the recovered brass looked normal, it probably wasnt a slam fire. If the gun was going off before lock up, even if real close, the case necks would most likely show it.

I had a DCM M1 slam fire on me during a match. Luckily, it was during the slow fire string and the rifle wasnt in my shoulder. When it cut loose, it blew the bolt rearward hard enough to blow the back of the receiver off at the serial number. The stock was cracked, and had a big chunk missing. The op rod handle tore my palm open requiring stitches. Even with ear plugs in, it was LOUD.

The gun had doubled a couple of times during the rapid fire strings, and I was thinking it must have been me until I saw the recovered brass later. A couple of pieces did have the case necks blown out somewhat, which led me to believe the gun was firing out of battery before it cut loose. If I had been able to recover my brass after each string, on seeing that, I probably wouldnt have shot the gun anymore that day.

These days, I no longer single load a Garand unless I use a SLED. Im also very careful with my reloading for these type guns, and check both the cases closely and the primer depths.

bamaranger
May 14, 2011, 03:21 PM
I'm bad about riding the trigger when i shoot a garand or
M1A from the bench. The rifle actually bump fires from the shoulder.


when shooting from bags, on the bench I now single load, and lower the bolt carefully

chris in va
May 14, 2011, 03:50 PM
Possible it was a bump fire, now that I think about it. Shooting on a bench tucked into my shoulder, possible that recoil touched off another one. The trigger doesn't feel light at all and I've certainly done nothing to alter it since buying it at the CMP last May.

I guess this is why they teach holding the trigger back after firing...

dahermit
May 14, 2011, 04:57 PM
Had the same problem. Worn part.

jrothWA
May 14, 2011, 07:31 PM
and the firing pin tang is not catching on the rear receiver bridge. Its slipping past and causing the slamfire.

The replacement of the trigger and hammer will complete the repair.

Jeff F
May 14, 2011, 09:10 PM
That was not a slam fire. Either it doubled or you accidentally bump fired it. I would shoot it some more and see if it does it again. If it was just a bump fire its no big deal. If its doubling you need to get it fixed. Do a safety check on it.

Slamfire
May 15, 2011, 10:20 AM
That was not a slam fire. Either it doubled or you accidentally bump fired it. I would shoot it some more and see if it does it again. If it was just a bump fire its no big deal. If its doubling you need to get it fixed. Do a safety check on it.

Why not a slamfire? It could have been. The Garand has a free floating firing pin and guns with free floating firing pins slamfire in battery and out of battery. Slamfires are rare, because overly sensitive primers are rare, but reports of slamfires in Garands have been in the literature for decades.

Having had two out of battery slamfires with Federals with trigger groups that are still working today, slamfires don't have to be mechanical in nature. Sometimes that heavy free floating firing pin and a overly sensitive primer is all that it takes.

I will totally agree that milking the trigger or bump firing due to a loose hold on the bench will give the appearance of a firing pin initiated slamfire. However mechanical issues don't correct themselves. If the sear surfaces are worn such that the hammer "follows" the bolt, it will happen a lot. Sometimes every ten rounds.

Back in the day when M1a's ruled the firing line you would see and hear doubling. Someone's trigger job was allowing the hammer to follow the bolt. This is dangerous as all get out as the rifle could fire out of battery. Even so the shooter always wanted the alibi and we did not want to disappoint, after all it could have been a milking the trigger problem. One hundred percent of the time the rifle would double on the next ten round rapid fire and we would have that rifle removed from the firing line.

Tight cases that require the gun to crunch fit them to the chamber increase the risk of an out of battery or in battery slamfire. While that bolt is crunching the case to the chamber, the lugs are not engaged or fully engaged yet that firing pin is absolutely tapping the heck out of that primer. You absolutely want no delays to bolt closure in a Garand/M1a.

I highly recommend small base dies and I recommend, regardless of die type, you want to use a cartridge headspace gage and size the cases to gage minimum.

http://img.photobucket.com/albums/v479/SlamFire/Reloading/35Whelenheadspacegage.jpg

You also want to use the least sensitive primers you can find. Since my out of battery slamfires were with Fed 210M’s, the most sensitive primer on the market, and most reported Garand slamfires were with Federals, I am not using Federals in my gas guns. I am using CCI #34’s. I have heard that some Russian primers are mil spec. That is what you want to use.

Wayne Faatz got a slamfire in a Garand with Federal primers, and his American Rifleman article was included with every Springfield Armory M1a I purchased. Wayne was able to show that high primers will slamfire. So I ream the primer pockets of all my gas gun ammunition to ensure that all primers are below the case head. I hand prime with a Lee Priming tool and visually verify the primer is below the case head.

This is a good read as the mechanisms are similiar

http://www.zediker.com/downloads/14_loading.pdf

hps1
May 15, 2011, 01:39 PM
Tight cases that require the gun to crunch fit them to the chamber increase the risk of an out of battery or in battery slamfire. While that bolt is crunching the case to the chamber, the lugs are not engaged or fully engaged yet that firing pin is absolutely tapping the heck out of that primer. You absolutely want no delays to bolt closure in a Garand/M1a.

you want to use a cartridge headspace gage and size the cases to gage minimum.


Very good advice!

Even if your trigger group is functioning properly the firing pin on the garand/M14 rifles will peck the primer every time the bolt slams home on a round. If you doubt this, next time you load your garand on the range, eject the loaded round you just chambered and look at the primer. You will see a slight dent in the primer, even with a new firing pin and no wear on your receiver bridge. The firing pin simply catches up with the round being chambered before the receiver bridge blocks the firing pin.

Regards,
hps

Regards,
hps

Tim R
May 15, 2011, 02:07 PM
+1 on Slamfire's reply. sounds to me like you were milking the trigger which is the most commom reason for a double.

RampantAndroid
May 17, 2011, 07:32 PM
A friend who is a very experienced highpower competitor and reloader wrecked his match grade M1 Garand using the same handloads he had used for years when the rifle slam fired out of battery. Bent his op-rod, blew extractor/ejector out of bolt and rounded the receiver locking lug recess about 1/8" showing the bolt lug (thankfully) had barely entered the recess but was not fully in battery at the time the slamfire occurred.

This sounds like the piece of paper that comes with every M1A sold by SA right now...

The M1A will tap the primer, sure...just make sure the primer is seated well :)