SA M1A National Match Questions


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bpl
April 8, 2010, 10:10 PM
Are the investment cast recievers heat treated? If so, to what rockwell hardness? How does this compare to a cold hammer forged reciever? As an aside, are Fulton Armory M1As investment cast as well?

The SA comes in two flavors, it seems. Parkerized carbon steel barrel (NA9102) or stainless steel (NA9802). Is the NA9102 barrel chrome lined? If so, does this affect accuracy vs. the stainless steel barrel?

Are there any other differences between the two SA models?

Oh, has anyone ever heard of, seen or possibly even owned an M14 made by LRB Arms of Long Island. They advertise themselves as:
LRB ARMS MANUFACTURER OF THE ONLY AMERICAN MADE,
GENUINE HAMMER FORGED SEMI AUTO M14 RECEIVER
http://www.lrbarms.com/

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Birddog1911
April 8, 2010, 10:32 PM
LRB is probably the best receiver made today. They are indeed hammer forged. I've heard both good and bad about the Fultons; take them for what they are.

The investment cast receivers are only poor in the eyes of those who hold to the idea that they could somehow break them or wear them out. I have never heard of, and I don't believe anyone else has either, someone wearing one out or breaking it. If, perhaps, the rifles were still full auto, then maybe. I can almost guarantee you that you will not break one. As to the harness, I couldn't say for certain.

As far as either NM barrel, neither will be chrome lined. Chrome lining is actually a difficult process to do perfectly. The barrel has to be over-bored to allow for the thickness of the chrome. Chrome also doesn't like to disperse evenly, and is known to pool. This is why a chrome lined barrel, generally, will not be as accurate as a standard barrel, and therefore, not used in match rifles.

Z-Michigan
April 8, 2010, 10:38 PM
Are the investment cast recievers heat treated? If so, to what rockwell hardness? How does this compare to a cold hammer forged reciever? As an aside, are Fulton Armory M1As investment cast as well?

Springfield Armory Inc. uses 8620 steel for their receivers, a common choice when you want high surface hardness and lower through-hardness with high toughness. It's a good choice, and is also used for AR-15 bolt carriers and sometimes the bolts. They are heat treated, most definitely. The surface is around Rockwell C 50 ish if I remember correctly, internally it would be significantly less (C-50 is very hard, comparable to an inexpensive knife or a really hard ax). A drop forging is ideal but the SA cast receivers are known for being just fine. BTW no one makes cold hammer forged receivers - they would all be hot drop forged. Cold hammer forging is used for some barrels and very little else.

I don't know what Fulton uses. I believe that Smith Enterprise Inc. (SEI) makes forged receivers, and Entreprise Arms offers another cast receiver option. I would not buy anything SEI, personally, although for reasons unrelated to their quality.

The SA comes in two flavors, it seems. Parkerized carbon steel barrel (NA9102) or stainless steel (NA9802). Is the NA9102 barrel chrome lined? If so, does this affect accuracy vs. the stainless steel barrel?

The current barrels are not chrome lined. Accuracy will be very similar between the carbon steel and stainless barrels, though stainless may be a little better both initially and after a couple thousand rounds. Stainless is also potentially brittle in sub-zero temperatures, costs more, and is really shiny. For competition use I would prefer stainless, for most other uses I would personally choose the carbon steel.

Z-Michigan
April 8, 2010, 10:57 PM
The investment cast receivers are only poor in the eyes of those who hold to the idea that they could somehow break them or wear them out. I have never heard of, and I don't believe anyone else has either, someone wearing one out or breaking it

I have also not heard of anyone breaking or wearing out a SA cast receiver.

Using equal quality processes a drop forging is better, but hardly anyone will have an issue with the SA cast receiver. Maybe if you were firing proof loads day after day there might be a difference.

By analogy, FN-FAL receivers have been made, in FNH approved form, both as drop forgings and as investment castings (using 1970's era casting technology). They were made out of relatively basic 1060 carbon steel, which is fine but nothing at all special. The drop forged type I and II receivers were rated to last about 80,000 rounds, and the cast type III receivers only 40,000 rounds. Keep in mind that the FAL design puts more stress on the receiver and that the steel used is not as strong or tough as what the SA M1A receiver uses. I cannot give you any numbers for the M1A receiver life, but I can reasonably say (1) the drop forged receiver will probably last longer, and (2) either receiver, including the SA casting, will likely last far longer than the number of rounds you're going put through it.

Jason_G
April 8, 2010, 11:00 PM
If you're concern is the quality of the steel of the receiver, the SAI receiver is just fine. Forged receivers are more expensive and troublesome to produce, and therefore might give some folks a higher pride of ownership, but the cast receiver ought to outlast you, even with pretty intensive shooting. I've yet to see any evidence to the contrary.

Jason

madcratebuilder
April 9, 2010, 05:32 AM
IMHO the investment cast receiver is more than adequate for a semi auto only M14. I have a 1980 and a 1989 made SA and I'm not seeing any wear that I'm concerned about. Both have been 100% reliable with only the extractors being replaced early on. One rifle is all SA and the other is all GI.

There are a lot of these rifles out their, if there was a problem it would be well known by now.

SlamFire1
April 9, 2010, 12:04 PM
There was a long debate on forged receivers on this thread. In the end, the main critic of cast receivers did additional research and concluded that the sources of the negative information he heard were unsupportable.
http://www.thehighroad.org/showthread.php?t=20673&highlight=forged+receivers

The years when the M1a ruled the Across the Course firing line is over. It faded quickly starting about 1994. Around 1995 about half the service rifles on the firing line were M1a, by 1998 you might see one every twenty fire points.

During the period, 70’s through 90’s, if you were a civilian and wanted to shoot service rifle you either had a State Association M14 or you bought a Springfield Armory rifle.

The only common failure mechanism to GI receivers and aftermarket was cracking in the sidewalls. The bolt rebounds off the back of the receiver heel and the sides, given enough impacts, a receiver would crack along the sidewalls behind and underneath the rear sight.

In 1996, USMC shooter Julie Watson was working on winning NRA Highpower week, after having won CMP Service Rifle Week at Camp Perry when her M14 receiver cracked, and her M14 started flinging shots at 600 yards. :mad:

Springfield Armory added material to the sidewalls of their receivers making them more resistance to impact cracking and a bit stiffer. GI receivers, and close copies of GI receivers, and that includes the LRB receivers, have a thinner sidewall.

I purchased a M1a which for the first owner the receiver cracked. Springfield Armory replaced the receiver for free. I have a shooting bud whose SA receiver developed a crack above the bolt release, SA replaced that for free. The second rifle was on its sixth barrel, which is about $15,000 in ammo shot through it, so I think the customer service from SA is excellent.

I have examined LRB receivers, they are very well made. LRB receivers are made from 8620 steel which was the steel used by the military.

8620 is a decent steel, but I have asked SA and Lou why they did not make their receivers from a higher grade of steel, such as 4140. Basically it is because of the people who think “mil spec” is perfect and the negative comments they would get from such fanatics.

Incidentally the Chinese made their receivers from a 5100 series steel. Mil Spec fanatics foam at the mouth about this, but if you look up the use of 5100 steel in Machinery Handbook, that steel is used in much tougher appications than 8620.

Springfield Armory receiver showing thick sidewall

http://img.photobucket.com/albums/v479/SlamFire/M1a%20and%20Garand%20Receiver%20Pictures/ReducedDSCN6762SAM1areceiverrightsi.jpg
LRB double lugged receiver.

http://img.photobucket.com/albums/v479/SlamFire/M1a%20and%20Garand%20Receiver%20Pictures/ReducedNicesideview.jpg

http://img.photobucket.com/albums/v479/SlamFire/M1a%20and%20Garand%20Receiver%20Pictures/ReducedRailReceiverrightside.jpg

Z-Michigan
April 9, 2010, 01:05 PM
Great post and photos Slamfire.

Incidentally the Chinese made their receivers from a 5100 series steel. Mil Spec fanatics foam at the mouth about this, but if you look up the use of 5100 steel in Machinery Handbook, that steel is used in much tougher appications than 8620.

They also made 1911s out of 5100 series steel. Terrific stuff. Once hardened it is basically unmachineable with conventional (steel) cutters and tough even with carbide cutters. It would be a superior steel for most firearm uses, but my understanding is that it's not much used in the west (1) because of machining difficulty even before it's been hardened, and (2) it's simply stronger and tougher than most firearm uses require.

Z-Michigan
April 11, 2010, 12:02 AM
Here's a little more steel info:

http://www.fulton-armory.com/8620.htm

madcratebuilder
April 11, 2010, 07:41 AM
Excellent post SlamFire1, I think you covered the subject very well.

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