M1 Garand blow ups
- Thread starter Tulric
- Start date
I'vd seen a few, all were traced to the case not being propertly resized. (Too long between the shoulder and rim). Not allowing the bolt to lock up, then went off do to slam fires.
Now I carry a case gage (in 223, 308, & 06) when I'm running the line. If the suspected reloads dont fit the gages, the gun is pulled off the line until more ammo is found.
Now I carry a case gage (in 223, 308, & 06) when I'm running the line. If the suspected reloads dont fit the gages, the gun is pulled off the line until more ammo is found.
Dfariswheel
New member
Never actually saw one blow, but I've examined a few.
The "usual" reasons for a blown M1 are:
Over loaded ammo.
Someone just screws up and puts the wrong powder or too much powder in a case.
One I saw was one where the reloader just plain screwed up and dropped a charge of Bullseye pistol powder instead of IMR powder.
Slam fire.
This is where the rifle fires when the bolt closes, and before it's locked.
The most common reason for this is reloaded ammo in which the primer wasn't seated all the way.
The second cause of slam fire is a defective or worn rifle.
Blown M1's are not common, and in virtually every case it's because the owner screwed up in some way. Either with reloaded ammo, or by shooting a defective rifle.
The "usual" reasons for a blown M1 are:
Over loaded ammo.
Someone just screws up and puts the wrong powder or too much powder in a case.
One I saw was one where the reloader just plain screwed up and dropped a charge of Bullseye pistol powder instead of IMR powder.
Slam fire.
This is where the rifle fires when the bolt closes, and before it's locked.
The most common reason for this is reloaded ammo in which the primer wasn't seated all the way.
The second cause of slam fire is a defective or worn rifle.
Blown M1's are not common, and in virtually every case it's because the owner screwed up in some way. Either with reloaded ammo, or by shooting a defective rifle.
Another cause (I believe) is improperly resized brass in reloaded ammo. This can stop the bolt before the receiver bridge catches the tail of the firing pin during normal bolt lock-up. Even if the primer is properly seated, the free-floating firing pin could impact it hard enough to set it off, if the brass stops before it chambers.
This may be more important if you have a reproduction Garand, especially one with a tight "match" chamber.
This may be more important if you have a reproduction Garand, especially one with a tight "match" chamber.
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I had two out of battery slamfires in Garands, both with Federal primers. I had one in battery slamfire with Federal primers. One of the out of battery slamfires blew off the back of the receiver.
Since then I became very interested in the root cause of slamfires in these rifles.
I found that "common knowledge" was full of myth, legend, and misinformation.
The Garand/M1a has a free floating firing pin. You can verify that the firing pin is hitting the primer by just chambering a round. There will be a dimple on the primer.
The original round firing pin used in the Garand is a collector's item. I have never seen one, but I read that Orion 7 had them at $100.00 apiece. They sold out before I could get one. The Army lightened the Garand firing pin, and it must be obvious why: slamfires. They must have experienced slamfires with GI ammo and the heavier firing pin.
Ignoring mechanical malfunctions and debris on the bolt face, the primary cause of slamfires is overly sensitive primers. If that free floating firing pin hits a sensitive primer with sufficient energy, the primer will ignite. It is important to use the least sensitive primers you can find in these rifles.
Aggravating factors are overly long cases. In the pictures below, the bolt is at the location where the receiver bridge is starting to block the forward movement of the firing pin. These are two different Garand actions in very good condition. You can imagine, that if you have an overly long case, and a sensitive primer, just at this point the bolt is stopping and sizing the case to the chamber. While the bolt stops, the firing pin is free to go forward and hit the primer. If the primer is at the low end of the ignition threshold, the rifle will have an out of battery slamfire.
Avoiding slamfires is a process. The first step of which is full length resizing of cases, setting up the dies with a case gage, preferably using small base dies. The next is to use the least sensitive primers you can find, and seat them below the case head.
You never want a long case, a “fat case” or a primer above the case head. And you want to use the least sensitive primers you can find.
Below are other folks experiences with Garands and slamfires.
Since then I became very interested in the root cause of slamfires in these rifles.
I found that "common knowledge" was full of myth, legend, and misinformation.
The Garand/M1a has a free floating firing pin. You can verify that the firing pin is hitting the primer by just chambering a round. There will be a dimple on the primer.
The original round firing pin used in the Garand is a collector's item. I have never seen one, but I read that Orion 7 had them at $100.00 apiece. They sold out before I could get one. The Army lightened the Garand firing pin, and it must be obvious why: slamfires. They must have experienced slamfires with GI ammo and the heavier firing pin.
Ignoring mechanical malfunctions and debris on the bolt face, the primary cause of slamfires is overly sensitive primers. If that free floating firing pin hits a sensitive primer with sufficient energy, the primer will ignite. It is important to use the least sensitive primers you can find in these rifles.
Aggravating factors are overly long cases. In the pictures below, the bolt is at the location where the receiver bridge is starting to block the forward movement of the firing pin. These are two different Garand actions in very good condition. You can imagine, that if you have an overly long case, and a sensitive primer, just at this point the bolt is stopping and sizing the case to the chamber. While the bolt stops, the firing pin is free to go forward and hit the primer. If the primer is at the low end of the ignition threshold, the rifle will have an out of battery slamfire.
Avoiding slamfires is a process. The first step of which is full length resizing of cases, setting up the dies with a case gage, preferably using small base dies. The next is to use the least sensitive primers you can find, and seat them below the case head.
You never want a long case, a “fat case” or a primer above the case head. And you want to use the least sensitive primers you can find.
Below are other folks experiences with Garands and slamfires.
No Sir:
When I talk about Case Gage here, I'm talking about the Wilson, Dillon, etc case gage that measures the case from shoulder to base. Used to set up your sizing die to make sure it sizes the case to specs.
What happens when a gas guns goes off, the gas pushes the bullet down the barrel, when the gas hits the gas port, or hole, it excapes pushing the operating rod back, starting the process of ejecting the empty case. The op rod/gas pistol, or straight gas blow back (depending on rifle) starts the bolt's extractor pulling on the rim WHILE the gas is still pushing on the inside of the shoulder, thus stretching the case, which needs to be brought back to specs during resizing.
If not, the case, from shoulder to rim, is too long, causing: FTF, FTE and in worse cases slam fires.
Two wilson gages are shown in this photo, the 223 & 308, the '06 is one I made. Notice on the wilson gage there is a slot on the top of the gage, Any case sticking out beyond the base is too long in head space, any case that sticks below the grove indicates short head cases. Also the gage lenth tells you if the case needs trimed.
RCBS makes a digital gage, its pricy but tells you how much out of specs. With the Wilson/Dillon you need a caliper to tell you how much.
They are simple to use, simple stick the fired case into the gage, determine if its flush, if not, adjust your sizing die until it is. Don't think SB dios will solve the problem, they size the diameter, you still have to adjust for lenght.
Most range officers I know, carry such gages to check suspected reloaded ammo and will have it removed from the line for safety reasons.
They are about 20 bucks, cheap insurance, or if you have a lathe, chamber reamer and old barrel you can make them yourself.
When I talk about Case Gage here, I'm talking about the Wilson, Dillon, etc case gage that measures the case from shoulder to base. Used to set up your sizing die to make sure it sizes the case to specs.
What happens when a gas guns goes off, the gas pushes the bullet down the barrel, when the gas hits the gas port, or hole, it excapes pushing the operating rod back, starting the process of ejecting the empty case. The op rod/gas pistol, or straight gas blow back (depending on rifle) starts the bolt's extractor pulling on the rim WHILE the gas is still pushing on the inside of the shoulder, thus stretching the case, which needs to be brought back to specs during resizing.
If not, the case, from shoulder to rim, is too long, causing: FTF, FTE and in worse cases slam fires.
Two wilson gages are shown in this photo, the 223 & 308, the '06 is one I made. Notice on the wilson gage there is a slot on the top of the gage, Any case sticking out beyond the base is too long in head space, any case that sticks below the grove indicates short head cases. Also the gage lenth tells you if the case needs trimed.
RCBS makes a digital gage, its pricy but tells you how much out of specs. With the Wilson/Dillon you need a caliper to tell you how much.
They are simple to use, simple stick the fired case into the gage, determine if its flush, if not, adjust your sizing die until it is. Don't think SB dios will solve the problem, they size the diameter, you still have to adjust for lenght.
Most range officers I know, carry such gages to check suspected reloaded ammo and will have it removed from the line for safety reasons.
They are about 20 bucks, cheap insurance, or if you have a lathe, chamber reamer and old barrel you can make them yourself.
I use a Wilson type case gage. The Wilson is cut “fat” between the shoulder and the head, it measures length only. This does allow you to drop a fired case into the gage.
For gas guns, I size to gage minimum.
Before I got case gages, I followed the usual advice supplied with dies, which was to adjust the sizing die to the shell holder and add a quarter turn. After I got gages and was able to measure what was going on, I found this advice to be totally bogus.
A small base die sizes the case closer to factory dimensions than a standard die. RCBS told me that their small base dies size the case head .002” more than their standard die.
You can also over size cases with a SBD, unless you use a case gage to set up the die.
Folks have expressed sizing problems with SBD’s. The typical problems they express are extremely hard sizing, or stuck cases. This is because they are using a spray on lube, or some other inadequate lubricant. I use RCBS water soluble lube (because I wash my cases after sizing in soapy water) or Imperial sizing wax. These are very slippery lubricants. They do not make Small Base sizing effortless, but they really do reduce the effort.
Still, if you have a ballooned chambered rifle, squeezing the case back down is going to be a lot of work!
Just this week I purchased a 308 small base X-Die from RCBS. I don’t know if they make one in 30-06. I hope to have the small base sizing I want, and no trimming!
I have Redding, RCBS small base dies. You can buy them individually or with a seating die.
Life is a risk, reloading is a risk, but once you understand what to do for these rifles, shooting them is very low risk. I shoot mine regularly, just this weekend shot some reloads over the chronograph to determine velocities. The last I shot my match Garand in a Highpower match was Mar 09. It was a 100 yard reduced match. Posted are my two best targets. The other two targets: let's not talk about them. :barf: Since this thread is about Garand blowups, I will not go into powder selections and recommended velocities.
For gas guns, I size to gage minimum.
Before I got case gages, I followed the usual advice supplied with dies, which was to adjust the sizing die to the shell holder and add a quarter turn. After I got gages and was able to measure what was going on, I found this advice to be totally bogus.
A small base die sizes the case closer to factory dimensions than a standard die. RCBS told me that their small base dies size the case head .002” more than their standard die.
You can also over size cases with a SBD, unless you use a case gage to set up the die.
Folks have expressed sizing problems with SBD’s. The typical problems they express are extremely hard sizing, or stuck cases. This is because they are using a spray on lube, or some other inadequate lubricant. I use RCBS water soluble lube (because I wash my cases after sizing in soapy water) or Imperial sizing wax. These are very slippery lubricants. They do not make Small Base sizing effortless, but they really do reduce the effort.
Still, if you have a ballooned chambered rifle, squeezing the case back down is going to be a lot of work!
Just this week I purchased a 308 small base X-Die from RCBS. I don’t know if they make one in 30-06. I hope to have the small base sizing I want, and no trimming!
I have Redding, RCBS small base dies. You can buy them individually or with a seating die.
Life is a risk, reloading is a risk, but once you understand what to do for these rifles, shooting them is very low risk. I shoot mine regularly, just this weekend shot some reloads over the chronograph to determine velocities. The last I shot my match Garand in a Highpower match was Mar 09. It was a 100 yard reduced match. Posted are my two best targets. The other two targets: let's not talk about them. :barf: Since this thread is about Garand blowups, I will not go into powder selections and recommended velocities.
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May I suggest locating...
Kuhnhausen's book on the M1 / M14 &M1A series of rifles.
The explanation of the "Slam fire" is excellent.
there are two area of concern to deal with:
1: improper ammo, including "High" primer, where the primer are seat, with the impact surface above the face of the case head.
Here here best course is to swage the primer pocket to correct dimension and also remove remeants of teh crimp if using MIL_SPEC brass.
Small based dies rework the bras to minimum size as almost being a new case, but it cost you is fewer reloads. BUT if you are loading between two different rifle. then you may want to consider the SB dies.
I have used both commercial resizer and competition dies, the way I set the die, is to strip the bolt, then size a case long, place in chamber and attempt to close the bolt, if not closing then 1/8th turn the die down, resize until the bolt closes with no axial motion, one more 1/8th turn to just give me some perceive axial play.
This give max reloads per case. I've had no problems since doing HP in 1983.
Second, due to wear the rifel maybe at fault. Look at the M1 rifle stripped of teh bolt. under the rear edge of the reciever, is across-bar, with an "radial" slot about the 7 -8 o'clock position. The purpose is it allow the lower firing pin tang to slide along the inside face as the bolt rotates to closed position, this prevents the Fp from impacting the primer while the bolt is unsupported. The FP tang maybe worn or the slot has widen. ALso the nose of the hammer,
strikes the bolt forcing it closed before the FP is hit, this maybe worn.
Locate a gunsmith that was service trained, he can check out your M1.
Kuhnhausen's book on the M1 / M14 &M1A series of rifles.
The explanation of the "Slam fire" is excellent.
there are two area of concern to deal with:
1: improper ammo, including "High" primer, where the primer are seat, with the impact surface above the face of the case head.
Here here best course is to swage the primer pocket to correct dimension and also remove remeants of teh crimp if using MIL_SPEC brass.
Small based dies rework the bras to minimum size as almost being a new case, but it cost you is fewer reloads. BUT if you are loading between two different rifle. then you may want to consider the SB dies.
I have used both commercial resizer and competition dies, the way I set the die, is to strip the bolt, then size a case long, place in chamber and attempt to close the bolt, if not closing then 1/8th turn the die down, resize until the bolt closes with no axial motion, one more 1/8th turn to just give me some perceive axial play.
This give max reloads per case. I've had no problems since doing HP in 1983.
Second, due to wear the rifel maybe at fault. Look at the M1 rifle stripped of teh bolt. under the rear edge of the reciever, is across-bar, with an "radial" slot about the 7 -8 o'clock position. The purpose is it allow the lower firing pin tang to slide along the inside face as the bolt rotates to closed position, this prevents the Fp from impacting the primer while the bolt is unsupported. The FP tang maybe worn or the slot has widen. ALso the nose of the hammer,
strikes the bolt forcing it closed before the FP is hit, this maybe worn.
Locate a gunsmith that was service trained, he can check out your M1.