BM59 (Garand) Receiver Re-Build Suggestions
I found this while going through listings and couldn't control myself. It looked to be a good project, now I'm looking for suggestions on how to proceed. National Ordnance BM59 receiver (built from Garand receiver), which of course, is considered a "re-weld" but I;ve heard from lots of people that re-welds aren't really a big concern. Here's what I bought:
http://www.gunbroker.com/auction/ViewItem.asp?Item=8293625
Questions are:
1. The necessary crack repair, thinking about braze instead of weld. I'd like to avoid re-heat treating the receiver if I could. I didn't feel localized repair in a limited, non-critical area would really justify complete heat treat.
2. The hole under the site plate, much to worry about?
3. The tolerances are probably pretty loose right now, thinking about methods to tighten things up.
Suggestions appreciated.
To err is human, to moo is bovine.
http://www.gunbroker.com/auction/ViewItem.asp?Item=8293625
Questions are:
1. The necessary crack repair, thinking about braze instead of weld. I'd like to avoid re-heat treating the receiver if I could. I didn't feel localized repair in a limited, non-critical area would really justify complete heat treat.
2. The hole under the site plate, much to worry about?
3. The tolerances are probably pretty loose right now, thinking about methods to tighten things up.
Suggestions appreciated.
To err is human, to moo is bovine.
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Wow Boeboe, I think you may be opening a big can of worms with that receiver. The first thing I'd do is run the receiver on an M1 receiver gauge (this detects reductions in the distance between the locking lug engagement surfaces) this is often called a receiver "stretch gauge". After that, run it on the thread timing gauge to check the barrel shoulder location relative to the receiver threads- that way you can determine if barrel draw will be within normal ranges. For the last check I'd run the receiver on a bolt lug location gauge- too much wear here and the bolt face distance will be all wrong and you'll hammer away at the rear of the receiverand possibly the bridge. All of these gauges are expensive (I don't even have them) so you'll be visiting a gun smith.
If the receiver is within tolerances you can start taking a look at the other issues. The clip latch pin area is not a very high stress area so I would feel that you could repair the crack yourself without much worry. There do appear to be far too many holes in the receiver to suit my tastes. The large cut out portion under the clip release is a big chunk and I'd be nervous. I am more interested in what appears to be a hole in the receiver area under the rear sight cover. The clip latch cut out is for the new bolt hold open latch, but there is no reason for a hole to be under the sight cover. This "heel" area is supposed to be the strongest part of the receiver and there should never be an opening present. I'd consider this area weakend and consider rewelding the hole closed.
One of your problems is that heat treated 8620 ordanace steel, used in most M1 rifles, does not weld very well to begin with and the typical high nickel alloy weld/fill material is not favored for use with 8620. Alloy differences, heat elongation, carbon migration, shrinkage, cracking at the weld edges...lots of possible problems. This does not even include problems that may already be present in the rewelded reciever right now. Even if the receiver was rewelded using a fixture, receiver wall and bridge warpage is nearly impossible to eliminate due to metal expansion caused by welding heat and localized shrikage during cooling. This is why you need to gauge the receiver first thing as deminsional errors are present in nearly every case.
Boeboe, I've been collecting M1's for over 25 years- they are my number 1 firearms interest- and I have passed over every reweld I've come across. I just don't believe that there are any good rewelds and National Ordnance had, in my opinion, one of the WORST reputations for quality control of any service rifle rebuilder: Carbines, Springfields, Garands...they all had problems and will continue to have problems. I wish you good luck on your project...you seem to have a lot of things going on. What is happening with that AR type pistol?
Mark T. Christian0 -
Mark,
I was sure hoping you'd take the time to give me your impression and opinion, it is much appreciated and held in very high regard. I'm not even sure if there's a gunsmith in our area with the proper gauges. The receiver hasn't been sent to me yet, and the seller is, of course, offering a return policy, I will need to make up my mind within a short time. I know a few guys around who are Garand fans, but I'll have to look/ask around here and see if there is a smith locally with the proper gauges.
You asking about my AR project prompted me to explain, I do have a bit different way of looking at the servicability of things. Some 31 years ago I was an apprentice machinist, operating and setting up mills and lathes. In 1976 I got into Nondestructive Testing (NDT) as an occupation, but kept a Southbend lathe in my garage to do work from time to time. My carreer in Quality also lead me into doing Machine Parts Inspection when things were slow in NDT. But honestly, NDT has been what I've specialized in for 20 years now.
My wife has put aside $500.00 to buy me a little Homier Mini-Mill, which I want to have before starting for the AR project. Waiting for a Homier show while I'm in town, as I travel a lot. I've got an eye open for another lathe, and I have something most shops don't have already. A bunch of magnetic particle (magnaflux), penetrant (zyglo), and ultrasonic test equipment, and the necessary skills to use them.
So my initial approach may be a bit different, as may my method of proving out the safety of a firearm project. That is, firearm projects like removing excess weight from an AR receiver, or looking at the servicability of this used BM59 receiver. One of the things I have done is monitor experimental aircraft components using NDT, looking for crack initiation and growth. With that in mind, the first thing I'm going to do to this receiver is some very sensitive NDT. If there are any areas where fatigue cracks have started, I will find them. If there are not any areas showing fatigue, I will be inclined to ask myself, why doesn't this show any signs of failure?
My background in aerospace lets me know critical safety items are most often given a 200% margin of error from a design standpoint, even with much consideration given to weight reduction. In the case of this receiver, I have to ask myself, is there really a need for a Garand receiver to be that strong in the first place? The reason why there is a hole in the area under the sight cover, now that is interesting. Maybe when I look at it, I will find out why. I can't see much reason for it, my only thinking is, this particular area is where the bolt slides back in a groove, how thick was this area in the first place? It doesn't look to be too thick on my BM59. Could it be it was shot so much it just wore through? Or perhaps it was just too thin to start with. What is going on there? I don't know.
On the other hand, I wonder, just because there is a hole there, does that make it unsafe? This is a rather thin area in the receiver anyway. If strength was a factor, it probably would have been designed to be thicker. Rather than weld it, maybe I would be better off drilling the ragged edges out, burring it, and then monitoring it over the course of a couple of thousand rounds of ammo to see if it grew.
Anyway, that's kinda how I look at it, just my background. But I will be looking around to see if any local smiths have the necessary gauges.
But I tell you what, Mark, if you ever have a need for some NDT work, let me know. I'll give you a couple or three hours worth for free.
To err is human, to moo is bovine.0
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