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Old 10-10-2006, 02:56 AM   #1
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Rifle-Grenade Mods

It seems there's a little confusion here about the modifications done to Garands for Grenade-launching.

According to all the reseacrh I've done on the Subject the only mods pertaining to Grenade-launching were;
1.) Lead-Dipping the heel of the receiver to anneal it and make it softer. This was a stop-gap measure.
2.) Developement of the M7 launcher and the Poppet-valve style Gas-Cylinder Lock-Screw. These two items completely solved the Grenade-launching problem and negated the need for any more receiver-dipping.
3.) Change of Ordnance-Grade Steel in receiver was done due to availibility factors and manufacturing factors only.
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Old 10-10-2006, 08:41 AM   #2
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If you are speaking about the receiver, I cannot find anything that contradicts or confirms the lead dipping of receivers.

The strangest part of this question is that no M1's were ever used in the field for Grenade Launching until the M7 was developed. Before adoption of the M7, the 03 was used for launching Rifle Grenades. Once the M7 was developed, no bolts should have touched the back of receivers because of the amount of gas that was vented. And one of the design features of the M7 is it would not fit on a rifle with a solid lock screw, so it could not have happened by accident.

The current thinking is that the lead dipped receivers are due to Grenade Launching, but nobody I know of has been able to confirm that from Government records. However it does sound logical.

There were several further modifications of parts. The Op Rod Spring was adopted (B14756 for current production in rifles to prevent the disconnection of the follower arm during recoil of rifle grenades. The long fork follower rod was also adopted, but I have no reference that it was strictly due to Grenade Launching.

The locks and lock screws also went through several changes, too many to mention here.
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Old 10-10-2006, 08:51 AM   #3
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Thanks for the info Bill. The info I got on Lead-dipping came from either Poyer or Duff, got it at home(I'm at work right now). didn't know about the op-rod spring change but it does make sense. I assumed the change from short to long fork was due to the fork jumping off the pins during recoil but , never considered grenade-launching.

This is the problem Bill, so much was lost that most of us depend on the older, more knowledgable collectors and delvers for our info.
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Old 10-10-2006, 04:06 PM   #4
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So the opt rod releaf cut has nothing to do with

Launching grenades as has been said repediatly? If thats the case then whats it for, to give them a nice place to break in half at?
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Old 10-11-2006, 01:53 AM   #5
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The op rod relief cut (don't know if it was strictly due to launching grenades) was to prevent breaking. Anytime you have a squared cut, it becomes a weak point. The relief cut allows the tube to flex at that joint and prevents breakage. If you look at other items, even in industry, you will see circular cuts in steel to prevent breakage.

Without the relief cut there is a greater chance of breakage, not due to it.
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Old 10-11-2006, 06:09 AM   #6
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War Dept Steel No. 3115 was first used. That was switched to War Dept Steel No. 3120, which was used to July, 1942. After that, No. 8260 Modified was used.
The M7 Grenade launcher was not standarized until Feb. 11, 1943, with production not slated to start until May, 1943. By Sept., 1943 only around 1500 had been produced.



THE M1 GARAND 1936-1957, Poyer & Reisch, pp. 26 & 27
U.S. INFANTRY WEAPONS OF WORLD WAR II, Canfield, p. 225
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Old 10-11-2006, 08:53 AM   #7
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Poyer is correct. During the month of Sept only 1500 were produced, all of them at Knapp Monarch.

The interesting thing is as follows:

Aug No production
July only 10 produced:

Here is one of those 10 prototypes produced by Springfield Armory, when production was turned over to Knapp Monarch. It is number 4 of the 10. Numbers 6 through 10 were manufactured with a front bracket to stabilize its locking ability. Happily #4 resides in my G/L collection.

The launcher has a different locking bracket and except for that bracket, is machined entirely out of a single piece of steel. The M7 was not just "adopted". It evolved over a period of time with Ordance setting up several requirements. The credit for the development of the M7 has always been given to Remington, who provided the T14. However the T14 had so many problems only a few of its characteristics were put into the M7. The M7 was a combination of Remington's T14 and improvements learned from several other launchers, including one design from Ft Benning (Infantry Board).



[img]http://www.billricca.com/gren_launch/prototype_right.jpg[/img]


A picture of one of the launchers from SA, 6 through 10, with the front stabilizing bracket.
[img]http://www.billricca.com/gren_launch/prototype_mounted_profile.jpg[/img]
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Old 10-11-2006, 06:56 PM   #8
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Does anyone know when they started lead dipping the heals? One of the reasons I posted earlier regarding the dates of the metal change, and the dates when grenade launchers were manufactured is the lag time. Over a year from when the Foundries switched to the 8620 steel till when the Grenade launchers would have started showing up.
If the authorization for lead dipping was prior to July, 1943, then the receivers were probably lead dipped for another reason.

Just some thoughts.
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Old 10-11-2006, 07:37 PM   #9
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I have a 5 digit 68XXX that is lead dipped and have seen a 68XXX just 13 numbers away that was not dipped. I have seen receivers as late as 2.5M with the heel dipped and personally own a 1.7M with a lead dipped heel, as well as a 6 digit 992XXX and a 1.3M and a 1.4M all with lead dipped heels. My Winchester 144XXX also has a lead dipped heel that was dipped at such an angle to include the bottoms of the rear receiver legs. I cannot find my source, but I have read that lead dipping of receiver heels was also done a the maintenance and repair depot level. If this is the case, then there will be no specific range of serial numbers that were lead dipped, thus explaining the two 68XXX receivers, one dipped and the other one not.
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Old 10-12-2006, 02:49 AM   #10
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JAS, I agree that it was spotty which leads me to believe it was done at Depot-Level or below. I have a six-digit, 9805xx that is dipped and a 2.3mil that isn't.
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Old 10-12-2006, 12:16 PM   #11
 
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My launcher is as follows
H.S.M. CO.
M7 LAUNCHER
FOR M1 RIFLE
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Old 10-12-2006, 06:03 PM   #12
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Hawley Smith Machine Company, which is still in business today. I met one of the production managers in 1976 and he went into great detail, educating me about several aspects of the production.

Hawley Smith was a pretty late contractor, circa Jan-Mar 45.

I see you are from Maine. There was an M7 contractor in Maine. It was Fay & Scott. They were in business a while back, do not know about today.

The name, at some point in time, changed to Fay Scott Manufacturing.
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Old 10-13-2006, 05:21 PM   #13
 
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Lead dipping was more common than not on early rifles

It's very difficult to find early receivers that haven't been annealed. Many people who are trying to restore a '40 or '41 rifle, if they have a good barrel and good wood, have a heck of a time finding an appropriate receiver that hasn't been annealed.

I think that people that are doing primary source research: Bill Ricca and Ed Clancy for examples will eventually be able to find documents that answer some of these date questions about annealling.
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Old 10-13-2006, 08:15 PM   #14
 
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I can't remember where I read it, but the article said lead dipping was used because the receiver is basically case hardened to a depth of 10 to 15 thousandths. The back of some recievers will become hard and even brittle if not annealed as they may be only 30 thousandths thick and end up hard through.
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Old 10-14-2006, 08:57 AM   #15
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Here is what I can tell you from observation and 35 years of tool & die experience.
M1 receivers are case hardened. When a tool steel is hardened througout, you generally have to make a compromise. You can heat treat and draw it to it's highest hardness which gives excellent wear resistance, but leaves the part somwhat brittle and unable to stand much shock without cracking or breaking. Or you can draw the part back and sacrifice wear resistance to gain shock and stress resistance. The M1 receiver requires both. You need high wear resistance so the bolt locking lugs do not wear and cause the headspace to open up, and you need a very hard surface in the op-rod track where the op-rod tab slides back and forth. However, if the bolt locking lugs were that hard all the way through, they would be prone to cracking and possibly shearing away under the 50,000 psi stress of firing a .30-06 cartridge. With case hardening, you first heat treat the receiver through to a very tough shock resisting hardness, and then by adding additional carbon the the skin of the part in a secondary heat treating process you harden the surface to a very hard wear resisting state, while keeping the interior tough for shock resistance. You get the best of both worlds, hardness and toughness, in the same steel part.
The hardened skin, or case as it is called, is .010 to .020 deep on the M1 receiver. You can measure the thickness in the receiver heel using a proper sized gauge ball and micrometers. Early receivers are noticeably thinner than later ones. As you get into the late two million and early three million receivers, you will notice that the receiver heel is also not as rounded, especially at the edges, which also adds material thickness to the heel. Weight was always a concern in the design of the M1. John Garand never did achieve the 9 pound limit that ordinance originally specified. Contouring the heel on the early receivers to more closely match the interior dimensions helped to keep the weight down. This also made some early receivers as little as .055 to .060 thick in the heel. If the case hardening depth approached the maximum allowable depth 0f .020 both from the top and bottom, you could be left with as little as .015 core of tough material to hold things together.
It is my opinion that a slightly thicker heel with less rounded corners, along with tighter heat treating controls, eliminated the need for lead dip annealing to prevent cracked receiver heels.
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Old 10-14-2006, 07:28 PM   #16
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Just to add to the discussion;
A couple of friends of mine were over today and we were discussing this subject. One of them said he thought the newer receivers were wider too. Sure enough, when we measured the outside width of a 5 digit receiver and a 5.8M receiver, the late receiver was .055 wider outside while the internal dimensions are the same. This has the effect of adding .0225 thickness to each of the side walls of the receiver heel in this critical area.
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Old 10-15-2006, 06:42 AM   #17
 
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JAS, thanks for the input. That's the most logical, understandable explanation of heat treating and Garand I've seen.

The depot level dipping theory gets more plausible as time goes on. I've several 6 digit SA's and a WRA 1.2 that weren't dipped but an SA 1.9 that is.
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