M40a1 build guide

I still get a kick out of the A1's. I still have the magazine from '95 that ran an article on Mike Lau's builds. It's falling apart from stashing it in my ruck to re-read the article a few dozen times over while out on post but its still on my bookshelf. Almost 15 years ago when I finally saved enough to send my gear down down to him the base rifles were going for $1750 then and it took right about 12 months door to door. It's a slick shooting, quality piece of kit though. And shortly there after, when forums were not much more than a single message board and you had to sift through to find your stuff was where I heard US Optics would be selling the MST's. Calling from overseas to CA means a late night but I was one of the first to get in line for the over two year wait for them to be released.

Next time I get into the safe I need to post up a pic or two to add to the eye candy.
 
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A couple gratuitous shots for the thread. TBA M40A1 and a US Optics MST100 (A1 version) at the range this morning. I tried to get a shot through the optic just for giggles, I think it turned out OK. That's a plate at 300yds.

Obviously the Harris and the stock pattern aren't spec but I still love shooting this rifle. Our range only goes out to 600yds for HP matches but it's still fun ringing the steel. My M24 was a solid shooter but it couldn't hold a match to this rig!
 
http://m.youtube.com/watch?v=MVPVtd2gkFs

Don't know if this has been posted in this thread already (I missed it if it was...) but here's an old USMC recruiting vid about scout/snipers. I saw this originally some years back when TBA partnered with some video company to do a sniper video thing. Anyhow, you get a few scenes at PWS at Quantico starting around 2:24. This was at the transition to the A1 and Unertl so you see some really early gear. Even a prototype Unertl and a Redfield being boresighted when the narrator says "a fixed 10x scope".
 
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I've been reading these twenty-odd pages, and I've tried to do some research on the web- I have yet to find a clear answer for my question... So: I know the recoil lug is tapered on both sides, but which sides are tapered? Also, what exactly do I have to do to the ADL box to get it to work with this build? Do I use the Remington follower and spring, or the M70's? Thanks for any help!
 
Recoil lug is tapered 2 degrees front to back. This causes the rifle to get tighter when fired (think wedge). The box is a BDL welded to the receiver and you use all Remington parts for the insides.

Also, use a stamped follower not cast as you need to modify that to fit 5 under the bolt.
 
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http://m.youtube.com/watch?v=MVPVtd2gkFs

Don't know if this has been posted in this thread already (I missed it if it was...) but here's an old USMC recruiting vid about scout/snipers. I saw this originally some years back when TBA partnered with some video company to do a sniper video thing. Anyhow, you get a few scenes at PWS at Quantico starting around 2:24. This was at the transition to the A1 and Unertl so you see some really early gear. Even a prototype Unertl and a Redfield being boresighted when the narrator says "a fixed 10x scope".

Look at the marksmanship portion of the video, at 14:43 into the video. Look carefully at the REDFIELD mount on that A1. NOT UNERTL. Just thought that was interesting
 
Nice picture.

This particular rifle has been discussed before. IIRC this is not a M40A1, but a M40 with a camo paint job. Take a close look at the barrel profile. Seems thinner than the M40A1. Its closer to the Remington Varmint profile (M40).

But the scope rings looks medium (M40A1, to clear the beefier barrel profile). The M40 used low rings.

I dont know... What do you guys think?
 
There sure enough were Redfield bases used on a select number of very early A1's. As I/we have seen in many instances, pic's, first hand etc., etc.....The A1 and Vietnam era M700 were all works in progress in the early stages of it's inception. My own personal feeling (so please dont eat my face off for voicing my opinion...lol) is that the word "Spec" when it comes to building these early rifles is really hard to define as they were all works in progress. Testing different scopes, bases, rings, barrels, etc. So you will see documentation, pic's and so on from time to time of early A1's in many configurations.
Hell, its not widely known but in the late seventies in the early stages of the A1's there were a number of M40A1's that were fielded to Force Recon with Weaver T10 scopes. So if your doing a build and happen to come across a T10 you wouldnt be off base with using this for your build.
It wasnt until after the inception of the Unertl base/ring combo that things became more of a "standard" for the RTE shop builds back then.
So try not to stress over the "Spec" mindset during your builds and think of it as more of a "standard" for whatever A1 timeframe build you decide to do.
This same mindset needs to be applied when we talk about other details of these builds as well. Have to remember. There have been many 2112's building these rifles over the years and I can tell you from speaking to several of them that you can line 5 M40A1 up all built by different 12's and there guaranteed will be minute differences in every rifle. Some maybe seen, some maybe not. Each build had certain requirement to meet but each was an extension of that particular 12's style of building, glassing, coating, stamping (when it comes to location of stamps on parts, etc), pencil engraving and so on. So try and keep this in mind.
Just a though of course......Alright, I've got my mouth piece in. Ready for the punches...lolol
 
I have been busy and out of the loop for a bit, but I am going to take a few to comment on this one. I was in a STA platoon at 1mardiv in the 90s. While at my unit and in the school house I saw many M40A1 rifles, all of them that I can remember from first hand account were outfitted with bottom screw Lugged Unertl bases, EXCEPT MINE! Mine had a PIC rail (manufacture unknown) with GGG rings. At the school house SGT. Parisi took notice to this and wanted to know why. I had no clue or answer, I was a pig and a boot that wasnt interested in why at the time. I was more worried about it becoming a KIMS game question or bear crawling to find a pole. Later I learned that some school houses and MUESOC units weapons varied in order to gather end user feedback. I never was asked about the weapons system or asked to give feed back. After returning from Mogidishu. I went to a non deployable unit. I later returned to a V unit and was the STA platoon Sgt. I was responsible for the platoon. We had no LT. so it was me that carried the burdons of accountability. Anyhow, it was there I took notice to the weapons configurations. I started to study them in detail, look for variations etc. Very few variations at that point. The stocks, varied as to length of pull, paint jobs, custom cheek peices and camo patterns. NONE of the barrel crowns were like the A3 and later style that you see builders calling "USMC SPEC" they were a square cut maybe 10-15 deg if any, but not a 45 deg taper. This was noticed at every cleaning, because we q tipped them clean. The words "USMC SPEC" could be debated on every rifle, as the true spec rifles would have to be a usmc issued serial number. Lets face it, unless you got your hands on a USMC issued receiver or made one and roll stamped that serial number on it, it will never be a spec rifle. I have seen it published that the M40A1 had a Weaver 10x on it, with a lugged Unertl base. Then we saw the movie with the Redfield base. So I guess it all depends on what rifle version you want to build. Yes the majority of these rifles were Unertl bases and Unertl 10x scopes, but as we all know, the rifles varied depending on the era and mission. HOWEVER, I never saw a rifle with a 45 degree taper on the muzzle crown until the USMC went to the M40A3 system. After that I saw PMO with an old A1 that had been rebarrelled with a schnieder barrel and had that crown, but that was after the fleet was already using M40A3s in OIF.
 
For the guys who didn't seem to realize the M40A1 originally had Redfield scopes and bases, here is a brief evolution of early M40A1s I pieced together....

M40A1
_______________________________
Funding approved Feb. 1976
Funding in place by Fall 1976

M40A1 production "well underway" early 1977
Formal CMC adoption letter 29 June 1977 ("incremental fielding")
Phase in of 120 rifles for fiscal year 1977
By Nov. 1977, 113 in FMF, 20 in MTU

1977
REDFIELD SCOPE, REDFIELD BASE

UNERTL SCOPE (transitional knobs) 21 Mar. 1980
UNERTL SCOPE (final production knobs) 13 Jan. 1982
fully converted to Unertl scopes by Fall 1983

REDFIELD BASE WELDED < Apr. 1981

UNERTL BASE developed ~1980-1981
fully converted to Unertl bases, including reserves, by early 1984

-------------------------------
Possible combinations, and rough dates:

Redfield scope; Redfield base (unwelded) 1977 - 1981?
Redfield scope; Redfield base (welded) ?< Apr.1981 - Fall 1983
Unertl scope; Redfield base (unwelded) Mar.1980 - 1981?
Unertl scope; Redfield base (welded) ?< Apr.1981 - early 1984
Unertl scope; Unertl base 1981+
------------------------------------------------

Then there were the top screw rings (never welded that I have seen) versus the "2nd generation" bottom screw rings, and the 40X bases vs. the supplemental round-cornered 700-SA bases. All kinds of possible combinations good to go on a smear stock.

As for crowns, I know the crown TWOMANATTACK (great post, btw 2man) is refering to. It shows up in most of the period photos which show the crown, basically just a flat recess with a surrounding lip.

However, when I did my build in 1991 I called Quantico with several questions, one of which was about the crown. I was told then, "Fifty-thousandths deep, two hundred-thousandths from the edge of the bore, and forty-five degrees out, leaving a one-sixteenth to one-eighth inch lip."

I've come to learn that crowns varied. That's just how it was. But based on my conversation with the MTU in 1991 (Gunny Cook, if I remember correctly), I wouldn't be surprised if there weren't at least some crowns being cut that way at that point in time. (And likely incorrect on my build representing the 1982-1983 period, come to think of it)
 
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I agree. So many variations in the early years of the A1. Continuous TE in its evolution.
I remember having a discussion with another class mate in SSBS (1-93 Stone Bay) (STA 1/2) when cleaning rifles one day as to why we had different variations in the crown. At the time no one seemed to be able to answer, to include our cadre'. As I later learned upon talking with 12's , it was up to the individual builder as to what crown was cut.
This is a great thread. So much information and knowledge for those deciding to build.

I agree...Great post TWOMANATTACK!
 
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I looked thru this thread looking for some examples of the paint jobs used on the originals but only saw one about 10 pages back.
Does anybody have some good original pictures to post of the camo work done after the rifles were deployed?
If you can wait till early spring time and want your stock painted, i can help you with that. Just send it out and we can paint it. It will look EXACTLY like an 8541 painted it. No charge as long as we have creative freedom
 
If you can wait till early spring time and want your stock painted, i can help you with that. Just send it out and we can paint it. It will look EXACTLY like an 8541 painted it. No charge as long as we have creative freedom

Thanks for the kind offer but I think I will pass.
You would hopefully paint it up with the same care and expertise that your issue weapon will receive but in the back of my head it just seems like I would be opening myself up to a real "unique" paint scheme.
It could end up like anything, a giant painted pecker seems the most likely.
 
Hey, new to the site. In the process of building one of these things, just took it out today to check bbl/cham. Worked like it was supposed to... went bang and no bad things happened. Has anyone spoke with USO lately concerning another run of MST 100 scopes? I called them a 2-3 months back and they were taking names for those interested.
 
Hey, new to the site. In the process of building one of these things, just took it out today to check bbl/cham. Worked like it was supposed to... went bang and no bad things happened. Has anyone spoke with USO lately concerning another run of MST 100 scopes? I called them a 2-3 months back and they were taking names for those interested.

They just sold a few before christmas. $2850 will probably be a while before you see more from them
 
Twoman...is that open to any return stock. Mine is fairly new and clean looking like the ones that were in my armory, kept in cases. My parts are going to george in a few months, i just like the sound of that generous offer S/F. Jeff
 
I will paint anyones USMC SPEC rifle or stock as needed free of charge as long as I dont hear any bitching at the end. If its winter time and the veg is green, your paint job will be green. If its dry out and the surroundings are brown or tan, you get a brown or tan paint job. Camoflauge is continuous....TUFL i am happy to paint your stock if you need me to, but I wont be able to get to it until early spring time.
Twoman...is that open to any return stock. Mine is fairly new and clean looking like the ones that were in my armory, kept in cases. My parts are going to george in a few months, i just like the sound of that generous offer S/F. Jeff
 
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Hey, thanks latinaincovina. Guess I got forgotten or they fibbed because it was well before x-mas. You got one of these or getting one? Thinking of a Bushnell Elite Tac while I'm waiting, have to build a mount though. Also have a SS 10x42-16x, might be fun... still have to build that mount though.
 
I've got one that I haven't seen on here yet. Looks like an M40A3 in a M40A1 Stock. Any thoughts? I just had a build finished in this exact configuration by Leo Conring. Thanks to D_TROS for the service pic. Leo was a 2112 Armorer.

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My build
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Just thought I'd share another M40A1 configuration.......Tickle
 
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NONE of the barrel crowns were like the A3 and later style that you see builders calling "USMC SPEC" they were a square cut maybe 10-15 deg if any, but not a 45 deg taper. ...snip....
HOWEVER, I never saw a rifle with a 45 degree taper on the muzzle crown until the USMC went to the M40A3 system. After that I saw PMO with an old A1 that had been rebarrelled with a schnieder barrel and had that crown, but that was after the fleet was already using M40A3s in OIF.
I know what you mean on the crowns differing. I was in STA 2/2 95-96 and STA 3/6 98-01 and while I'm working off my memory that fades daily, as I recall the crowns differed by the barrel make. That could have been hearsay though and dependent on who it was building at the time they got in whatever particular barrel batch, but I remember seeing different crowns based on whether they were a HS Precision, Hart, or whatever barrel across the 90s. When we started getting the Schneider barrels on a new batch of M40A1s (new build C and G series receivers) in 3/6, that's when we got what is now known as the "standard" for A1s.
 
Redman, I agree with you that I saw two different crowns through out the 90's as well. Although, I have to say. The barrel crowns has nothing to do with the maker of any particular barrel.
PWS now nor RTE from the past received barrels pre cut or crowned. They receive all of their barrels as barrel blanks and they cut, crown, chamber and thread all of their barrels in house at the shop prior to coating and assembly.
Im not sure about you, but I know that when I was in STA and even to this day, once a rifle is assembled, or even looking at a blank prior to assembly, I can't/couldn't tell you who made the barrel or blank without asking someone (2112) where it had come from.
Also, at the time. I really didnt have an interest in who the particular maker was. It wasnt until after I EAS'd and looked onto building one did I really start to pay attention. I saw little differences in things between rifles (ie...different pattern stocks,early short shroud vs. later longer shroud, different crowning, SIMRAD caps, and even slightly different fitting/cut shape of bottom metal) but really didn't give it a second thought then.
 
They listed the barrel make in our gun books, that's how we knew what was what on them. I think it was an old grunts tale on the crown difference being dependent on the barrel make though, but it is what I remember as our own reasoning.

Hmm... I don't remember differences on the bottom metal, but I don't think I ever paid that close of attention to that either. Bolt shrouds, scope mounts and stocks certainly though.
 
"They listed the barrel make in our gun books, that's how we knew what was what on them. I think it was an old grunts tale on the crown difference being dependent on the barrel make though, but it is what I remember as our own reasoning.

Hmm... I don't remember differences on the bottom metal, but I don't think I ever paid that close of attention to that either. Bolt shrouds, scope mounts and stocks certainly though."


Just to add to the above statement. .. Regardless of the barrel manufacture, the crown was determined by the 2112 who cut it. Again I never saw the A3 style crwon until after A3s were being used by the fleet. Just like the Unertl bases, the bottom metal was hand fit. The modification was done by hand, so they varied a bit from rifle to rifle.
 
only A1s I ever saw with schnieders and 45 deg crowns were on PMO M40A1s that were hanging around after the fleet was using A3s. There were a handfull of A1s still floating around after A3s were being widely used. My company had side bold release receivers on the first A3s we received.
 
And to reiterate what I stated above....I know for a fact as I was issued one. I had a A1 in 1992 that had the angle cut barrel crown. This was an actual topic of discussion during class one day in my SSBC at SB. So they were out there. Maybe not many, I dont know. But as we have seen, there have been many minor variations to the standard regarding many aspects of the A1.
 
Sorry, cant get anymore pictures of the crowns for a while. Measurements ... I will contact the builder and see what the specs are on that cut. Looks to be VERY SIMPLE. The owner of GA Precision had some pictures of take off barrels in the RTE shop at Quantico. They showed the same recess crown as my rifles. If you are tight with him you could have him email them to you
 
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Hi all, got mine done this week... still naked though. Going to target it this weekend and see how she does. If I'm happy I'll rip it all down and engrave what needs engraving and send it to the finisher then start with the prelim. handloads. Don't have an MST yet so I'll have to make due with an SS I had but it's been good so it'll do. What kind of loads are seeming to work best in these? I used to shoot 168 Sierra Matchkings over 41.5-42 Gr. H-4895 in Mil. cases w/ CCI-200 LRP when I was shooting M-14's. Was a pretty standard load back then but was very consistent and accurate at 500 and still seems to be. I was going to stuff some 175 Sierras and see how they do too but wanted to stay with H-4895 due to other loading needs plus I have a dumptruck load of the stuff.
 
Im looking at starting my m40a1 build already have the correct g prefix clip slotted action, the correct trigger, and can get a hold of a barrel and lug. Im wondering if anyone knows where I can get the rest of the parts at would prefer take off parts.