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Pearl M1a1 Thompson Question


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#1 AC556

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Posted 02 February 2006 - 07:06 PM

Customer has a very nice Pearl Thompson he wants to sell.
Can anyone tell me about a Pearl Thompson, good, bad about the same as a WH M1?
What is the current value of a M1A1 built on a Savage kit?

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#2 amafrank

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Posted 02 February 2006 - 09:01 PM

I talked with Marty Pearl at the SAR show and he said that he and Utah Conner built 38 M1A1's on their own cast machined receivers. I've seen and fired a couple of the guns and they are tops. Much better then the west hurley guns. Prices are all over on these though as most guys don't know what they are. I would say use the west hurley prices as a guide and stay about the same or a little higher.
Frank


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#3 amafrank

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Posted 04 February 2006 - 01:28 AM

I think that good castings are great when done well. You are right that Ruger uses them and lots of them. There are a lot of other parts cast and machined that you wouldn't expect which live quite well. In the Thompson receiver there isn't that much of a load so aluminum would almost be acceptable but not long lasting enough for the military.
I've seen a posty built from 6061T6 that has over 10K round through it and looks great. The 28's wouldn't like that though....
As for the Pearl tommies. They are all M1A1's and the castings were very well done from quality steel.
Thats it from here....
Frank

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#4 Ron Mills

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Posted 05 February 2006 - 12:13 AM

Phil: Please explain "investment castings". I'm a non-machine guy. I could guess all day long, but that's why we have a forum. Cast, forged, investments, OY!

Thanks,

Ron
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#5 amafrank

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Posted 05 February 2006 - 09:22 AM

Investment or "Lost wax" castings describe a specific method of casting which give extremely good finish and little waste. Investment refers to the plaster material which is poured around a wax or plastic version of whatever you are casting. Once the plaster is dry it is placed in a furnace where the wax or plaster is burned out of it. At that point the heat is turned up a bit and the molten steel (or whatever metal ) is poured in, the whole thing is cooled to solidification. Occasionally at this point the investment is dumped into water which boils all the plaster off the casting.......we do this in jewelry making anyway.
The use of injection molded wax or plastic forms allows easy mass production of very complex parts and the very fine grained plaster makes extremely fine surface detail possible as well as keeping distortion to a minimum. Unlike sand or some other casting methods the plaster is a strong medium which won't "move" when bumped, banged or due to the weight of the casting metal. This and the fact that there is little change in size due to heat makes near net shape castings that need very little finish work. The Pine Tree Castings division of Sturm Ruger makes almost all of the parts for their receiver and mechanics in this method. I think barrels are about the only metal part they don't cast.
Thats about it. Do a google search for " Lost wax casting" or "Investment casting" to get more detail.

Hope that helps
Frank


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#6 TNKen

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Posted 06 February 2006 - 02:39 PM

There is a guy locally that makes the Thunder 5 revolver. Much of it is investment casting. He also makes frames and other small parts for various manufacturers for 1911's, AR-15's, S&W, and a few others. I got to watch the process one day, neat stuff. If the casting doesn't turn out right, chunk it back in the mix and repour it next time.

Ken
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#7 Ron Mills

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Posted 06 February 2006 - 07:21 PM

Very fascinating, and innovative. Thanks, guys.
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#8 Mike Hammer

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Posted 06 February 2006 - 09:53 PM

This is the same method used to produce bronze and other metal sculptures, I did severeral of them in college many moons ago. As far as producing guns using this method, I find it hard to believe you can can produce exact tolerances which are so critical to gun manufacturing. But then again, look at all the hand produced guns that you will find in the middle east, it can be done.

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#9 Bisley45

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Posted 09 February 2006 - 11:09 AM

DING DING I belive we have a winner. I can't say thats' how everyone does it but the shop I work in gets a lot of those parts and we basicly dust them off. Light duty is for light duty, our shop uses the full size mills but tool wear is very low compared to cutting solid fordgings.

BB
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#10 Bob

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Posted 09 February 2006 - 11:34 AM

I'm not the brightest bulb in the shop and always wondered how they cut the feed ramp in the Thompson receiver. Last night I was looking at my old Nichols Miller and the lamp started to glow! Dang, that's how they do it.

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