View Full Version : Garand op rod damage
Hello all,
I read often that a hot load with the wrong pressure curve can bend or damage the op-rod on a Garand. I would like to know exactly where the op-rod bends when this happens. A picture of a bent op-rod would be great if someone has one. Also, is there a particular measurement or test to check for a slight bend if it's not visually apparent?
TIA
DaveL
honestly all the years ive heard this, i have never seen a bent op-rod. however there are many pictures out there of an M-1's heel being cracked!
Never seen any rifle damaged by the ammo alone. Never seen an M1 Rifle damaged by the ammo either. I'm of the opinion that the whole idea is an internet myth/fairy tale. Never heard this story until there was an internet. There is no documented or lab tested case of an M1 op rod being damaged by the ammo alone. All evidence is strictly anecdotal. The "I knew a guy on a range one time..." or "There was a guy one time..." posts. The very mention of it starts huge arguments on the assorted forums(never seen it here though). So does my having fired a box of Winchester 220 grain Silvertips(The original ST. A jacketed SP bullet with an Al cap over the exposed lead. Fabulous bullet.) out of my M1 with no fuss. Shot a ground hog with one long ago. Took the bottom of the head clean off and the second shot(the thing was still moving.) blew the entire off side into mush.
Considering that JC took a regular factory rifle, loaded ammo running from the regular Blue Pill of 75,000 PSI to 125,000 PSI before there was any damage(same rifle fired another 5,000 rounds of standard Ball ammo with no further damage too), the next story about it being "port pressure" isn't proven either. It follows that 75,000 PSI plus chamber pressure will also have higher "port pressure" too.
M1 op rods must be bent to work. It's how they go around the receiver from the barrel.
The end of the op rod(piston) and the gas tube itself can get worn to the point gasses blow around the op rod. There are gauges and actual measurements for that. Minimum diameter for the piston is .525". Max diameter for the gas tube is 0.532".
Op rods can bend between the tube and charging handle if pressures too high. Lead edge of cam slot can chip off. Rod can dismount if the rail lug is worn and undersized. These things can happen.
"...if pressures too high..." There's no laboratory documentation of any M1 Rifle being damaged by the ammo alone. Only second or third hand anecdotal evidence. And that did not appear, anywhere, until the Internet came along.
What is documented is JC himself testing the rifle with ammo he loaded that went up to 125,000 PSI. No damage to the op rod at all. At 125,000 PSI, the left locking lug cracked. The same rifle, with no repairs, fired another 5,000 rounds of service ammo with no further damage of any kind.
There's also the one about how using a heavier than 180 grain bullet will cause damage. John R. Clarke wrote a reloading for the M1 article in the March 1986 issue of American Rifleman magazine. Wherein there is load data for 190 and 200 grain bullets. Nice Matchkings too.
https://www.scribd.com/document/40852596/Reloading-for-the-M1-Rifle-J-Clarke
barretcreek
11-22-2017, 03:35
This site has some time-pressure curves and talks about the idea.
garandgear.com
Thanks for the responses guys.
barretcreek, that's a very interesting site. Definitely worth a look-see.
"...if pressures too high..." There's no laboratory documentation of any M1 Rifle being damaged by the ammo alone. Only second or third hand anecdotal evidence. And that did not appear, anywhere, until the Internet came along.
What is documented is JC himself testing the rifle with ammo he loaded that went up to 125,000 PSI. No damage to the op rod at all. At 125,000 PSI, the left locking lug cracked. The same rifle, with no repairs, fired another 5,000 rounds of service ammo with no further damage of any kind.
There's also the one about how using a heavier than 180 grain bullet will cause damage. John R. Clarke wrote a reloading for the M1 article in the March 1986 issue of American Rifleman magazine. Wherein there is load data for 190 and 200 grain bullets. Nice Matchkings too.
https://www.scribd.com/document/40852596/Reloading-for-the-M1-Rifle-J-Clarke
And yet op rods become damaged, chipped, bent, etc. "Ammo alone". What does that mean? That they weren't stepped on? The evidence is clear--some types of ammo deliver higher doses of energy into the system, such that in real-world conditions, the probability of increased wear and eventual damage is increased. Shoot 200gr bullets with slow powder at 80,000 PSI to your heart's content. I'll sell you some replacement op rods--at a premium, obviously.
[url]https://www.scribd.com/document/40852596/Reloading-for-the-M1-Rifle-J-Clarke[/url
Thank you for this link! Sincerely. bruce.
Pete Davis
12-05-2017, 06:58
There's always the adjustable gas plug option.
I have hunted with an M1 using Remington CoreLokt 150's. Still goin'.
PD
Lead edge of cam slot can chip off.
I've seen a few OP rods with a chip off the bottom of the cam. These chips are miniscule and have no effect on functioning in my experience. I have never seen a bent rod or even a photo of one.
I've seen a few OP rods with a chip off the bottom of the cam. These chips are miniscule and have no effect on functioning in my experience. I have never seen a bent rod or even a photo of one.
I'm sitting on one that has more than a miniscule chip on it. Columbus Machine must see enough of them to quote a price for repair. The "effect on functioning" is in how you look at it. By reducing the bearing surface, an increase in wear occurs on the surrounding contact area. Does it matter? My answer is that if they would have wanted them that way they would have made them that way in the first place.
I'm sitting on one that has more than a miniscule chip on it. Columbus Machine must see enough of them to quote a price for repair. The "effect on functioning" is in how you look at it. By reducing the bearing surface, an increase in wear occurs on the surrounding contact area. Does it matter? My answer is that if they would have wanted them that way they would have made them that way in the first place.
My usual disclaimer: What a person does with his/her own property is their own business.
M1s are vintage rifles most of which have seen a lot of use, sometimes very hard use. At the very least any M1 that has been through a rebuild has a minimum of 10,000 rounds through it and probably a lot more. They are not indestructible and using ammunition in them that will work but is out of spec isn't a good idea, especially with a worn or weak op rod spring; just mho.
That I have not seen something doesn't mean it doesn't happen. I had the op rod on an M1 jump the race while firing Remington .30-06 FMJ ammunition in it. The result - bent op rod that I sent off to a fellow named Schuff, I believe, who had a cottage business repairing op rods that were, among other things, bent out of spec. I later learned that Remington advised against the use of this ammunition in M1s. I baby my MilSurps. There will never be any more of them. I look on myself as a caretaker for these fine old weapons. Feeding them the ammunition in the spec they were specifically designed for is the least I can do.
psteinmayer
12-08-2017, 08:07
Amen to that!
By the way, Tim Schufflin of Schuff's Parkerizing is a great guy and an amazing gunsmith who specialises in M1s and their variants only. You could do a lot worse!
I don't know about the internet rumors, but the most authoritative and thoroughly researched book by Hackely, Wodin & Scranton, "History of U.S. Military Small Arms Ammunition" Volume 3 page 112 notes that some late lots of .30 Ball M2 being loaded for use in machine guns for South Vietnam under the Military Assistance program were loaded using WC-52 ball powder which had failed the M1 rifle gas port pressure test and was restricted for use in machine guns, linked 4 ball 1 tracer. Some of the remained in U.S inventory and in 1987 the CMP program requested that the ball ammo be repacked in 8 round clips.
"Unfortunately it was not realized that this ammunition was loaded with restricted propellant that caused higher than normal gas port pressures in M1 rifles and which, after prolonged use, could distort the operating rod. Most if not all of the repack operation seems to have taken place as Red River Army Depot during 1988-1994, and was identified by the depot's RR prefix repack lot numbers."
Use at your own risk, I guess, but I won't shoot it in my Garands, but will happily use in M1903s.
danco101
12-24-2017, 10:19
I have seen one early uncut op rod come apart and the back end swing past the shooters head. I believe that's why they put the relief cut on them.
I just came back from the Advanced Maintenance Course at CMP.
They told us op rod damage was common with the wrong ammo. But they said the damage was usually cumulative over time, not a catastrophic failure from firing 1 or 2 rounds.
The op rod can bend (over time) and the machining of surfaces on the op rod can be damaged. Different parts of the linkage can be bent, too.
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