I am the armorer for American Legion Post 4 in Billings Mt. and am having a problem with several of the rifle op rod jumping off the bolt.

Using blank ammo is it possible for the op rod and or bolt tab to have excessive wear?

I understand using M2 Ball ammo can wear these parts, but the current blank ammo is VERY anemic and inconsistent.

Does anyone have the correct minimum and maximum dimensions for the bolt, and the op rod cut that it rides in as well as the tab of the op rod so that I can mic them out and find the REAL problem.

I do know that CMP has a program for VSO rifles that have bent or worn op rods , they will exchange them for $40.00 or so.

Thanks to all!

Randy

Randy it sounds like you are on the right track. Look at the tab on the op rod that rides in the track of the receiver for wear and then also check the lump in the op rod that the bolt lug engages to check for excessive wear or broken corners. I've had a couple of Garand's that experienced the same problem and after having the op rods rebuilt the problems were solved. If CMP does indeed have a replacement program that sounds like it might be money well spent to test on at least one of the problem rifles. Another option would be just try giving the CMP armorers a phone call to discuss the issue. Might try the following numbers from their website.
CMP Anniston AL (256) 835-8455
CMP Port Clinton OH (419) 635-2141
This site does give the dimensions for the op rod tab and shows what the bolt lug / op rod lump should look like. M1 Garand Part Inspection

Great link!!! Even has measurement for me to compare and find the REAL problem instead of just changing parts until it works.

Thank You!

Randy

I maintain all the M1s for Amvets post 106 that I'm a member of and it's not uncommon for these older guns to need the Op-Rod rebuilt.
I currently have one out for rebuild now. There aren't many places that do that kind of work and do it well but I can assure you that the link I'm providing is one of the places that does a very good job rebuilding Op-Rods. Total cost will depend of how much work is required and of the 4 rods I've sent in the price was 90-120 dollars.


Columbus Machine Works, Inc. - Custom Machining - Machine Shop Services

P.S. all the rods I've gotten back have worked perfectly.

Was the re-build price 90-120 for all 4 or each?

Have you ever had to replace a bolt due to excess wear? Seems like the op rod is the usual culprit.

Also, how often are you changing out Op Rod springs? I don't think these have ever been changed. Most measure 19.5-20 inches which is supposed to be in spec.

Last...are you finding that the new (6 star crimp CBC) blank ammo to be very inconsistent?

3 years ago I replaced all of the blank firing adapters with the new style and am getting better results but not 100%.

It doesn't always cycle the bolt all the way for a complete cycle... therefore short stroking the rifle....

Lately we seem to have a number of live casings badly gouged in the box. Making them garbage.

Thanks for your help!!

Randy

The price per each, these M1s are DOD guns and we can't use the CMP for replacement parts. The DOD has and will replace a complete rifles but not parts and it takes forever.
If you can get a new op-rod from the CMP for 40 bucks you might be better off, but if your getting a used one you may be in the same place as the old one.
We're still using the 5 star blanks which work well enough with only a few failures.
I replaced all the blank adapters 2 years ago with the newer style "POPs"
adapters and they are a huge improvement over the older ones and much safer. So far I haven't gotten any short cycles but I service the rifles at no more then 250 rounds because blanks are really dirty.
Complete take down and cleaning at 250.
When I first started taking care of these rifles they had not been thoroughly cleaned in 1000s of rounds and were failing.
The first one I did was so filled with carbon you couldn't see the rifling, it looked like a smooth bore.
I do this at no cost for the Honor Guard but I do require good record keeping...

Sorry missed one question, never had to replace a bolt, op-rod has always been the problem and have not had to replace a spring.

What are you finding on worn bolts and the replacement of Op Rod springs?

Do you remove the Blank Firing Adapter and run a brush and rod down the barrel and gas cylinder as well. I have been stripping all old lube and regreasing about every 250 like you are, but haven't run a rod down the barrel for awhile.
How about gas cylinders? I found a crack in one and replaced it.

Randy

Randy, another thought on your short cycling issue. You may need to measure the bore diameter of the gas cylinder and then the piston on the op rod. If the gas cylinder bore is worn/oversized or the piston is undersized or both, you will wind up with short strokes. I've never used blanks so I'm not sure if those are your issue.
+1 also on Columbus Machine Works.

Will check orifice diameter, any one know the min./max diameters for the gas cylinder and barrel?

Will also mic out the piston end of the rod for wear as well.

Randy

Springs all seem to be holding up fine, the steel in the bolt is much harder then the op-rod which will wear first.
When I service one of the rifle it's a complete take down and cleaning.
Yes I remove the blank adapter and clean the bore, if you get to much carbon build up in the bore it will clog the gas port and cause it to malfunction.
The gas cylinder should be cleaned but thoroughly dried after, oil and fire don't go well together it makes a gooey mess. A swab of acetone will dry out any oil left over.

Am doing a complete take down of all rifles on the service call....I used to use a drill bit on my M1A to clean carbon out of my gas port and the threaded gas plug. Any idea what drill size is correct for the barrel port of the M1?

Do you disassemble the trigger group and bolt as well? I haven't been doing that as I don't have a bolt take down tool.

Randy

I don't take down the trigger assembly or bolt, just use a spray cleaner for that unless something is broken which hasn't happened.

growr - my apologies for a significant thread drift. There is so much expertise here on SWF, so I thought I’d ask: I have a CMP barreled receiver, complete, but the stock was lost in a move (Army) many years ago. Do any of you Gents know or recommend a place to get a nice stock installed for it? Shooter grade stock would be fine, and I understand the metal for the stock will be pricey too. Thanks!

Check eBay and Gunbroker sometimes you can find a stock set complete with all metal hardware already on it........is your barreled action all one mfg. ie. all Springfield, Winchester, HRA, International Harvester? Do you have the trigger group and op rod?

If you are wanting to keep it all SA for example, finding a stock with SA markings is not very hard, the others get a bit more challenging.

Others on the forum may be able to have one ready for you to buy.

Randy

Another question for the armorers of M1 Garand at the posts.....

Do you own your own go-no go gauges, micrometer/caliper, gas cylinder tools, bolt disassembly tool, etc or does the post own them.? I don't own any of those other than a caliper.....would it be out of line to ask the club to invest in a set for themselves? Maybe even the Kunhausen manual as well?



Randy



PS. What drill size is needed to clean the port in the barrel and gas cylinder?

I would just get those tools on a need basis.

I personally own most of them and have bought them over several years as needed.
As far as the headspace gauges I just use a field gauge for general use.
Blanks are pretty low pressure so headspace usually isn't a problem.

here's a excerpt on the drill size you need for the port.


The next item to inspect is the gas port. The gas port is a hole drilled in the barrel as shown above. Its function is too allow gas to flow into the gas cylinder; facilitating the cycling of the rifle. The dimension of this hole is important and should be checked prior to use. If the hole is plugged with carbon fouling, insufficient gas flow will cause short stroking of the rifle. If the hole is too large, excessive pressures can develop causing damage to the op-rod or receiver heel.

An easy way to inspect the gas port is to purchase two numbered drill bits from your local hardware store. You want to purchase a #47 and a #46 drill bits. These will become our GO and NO-GO gages respectively.

The #47 drill bit should fit into the gas port. If the gas port is plugged with fouling gently spin the drill bit with your fingers as you clean the port. DO NOT USE A POWER TOOL. After the port is clean, take the #46 drill bit and using the smooth end (not the drill end) verify that the drill bit will not fit into the gas port.

The post called me yesterday and said one of the M1s was malfunctioning
so I'll head in tomorrow and pick it up.
I asked what it was or wasn't doing and as usual the answer was it's just not working so I'll figure it out when I get it.

Great info. ......will get the drill bits today.

Randy

Another tool I would recommend is a 9/16 x 36tpi thread chaser.
The threads on the muzzle are bad about getting roasted when using a blank firing device do to the flash back.
I check the threads during every cleaning and if the need chasing If I do that and coat with a high temperature grease to help prevent thread erosion.

Where are you finding this item? I can find 9/16 x 24 but not 36 TPI

Randy

Randy, I know nothing about this company, but a Google search came up with Victor Machinery Exchange. The link brings you to the special pitch taps page that covers 9/16 taps. They show a 9/16 x 36 TPI tap for $16.80. Hope that helps you out.

Jim

Jim, they DO show a thread chaser/die in that pitch....will order tomorrow.
Thanks so much!!

Randy

Very handy tool to have, when I first started servicing the posts M1s they still had the older style blank adapters and some of the threads were so bad they were blowing the adapters off the rifles which was very dangerous.
I talked them into the newer style adapters, chased all the threads and so far they are working just fine.

Had the same problem with the VFW rifles and then changed BFA's ...still had one that would launch the BFA and gas cylinder down range....a clean up of the threads would have gone a long way on that one.

Thanks So Much for your tips and willingness to help out!!

Randy

You more then welcome Randy, it's been my pleasure keeping the M1s running for the honor guard.
I figure that the families and the veterans that get the final salute are well worth any effort I make.