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Thread: M1/M1a1 Tommy "how to"

  1. #1
    aka: SDK1968 dutigaf's Avatar
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    Default M1/M1a1 Tommy "how to"

    this was requested by a few people for more detail so here we go....


    this conversion is based off of the same set up as my 1928a1 conversion and will even let your semi lowers interchange between your uppers.

    the same conversion rules apply... and we'll get into those a bit later.

    It's DISCLAIMER TIME!

    you are risking a very expensive parts kit and if that bothers you........ then this build is not for you.

    im in no way responsible if you ruin a kit or cant get it to run! BUT with any conversion i do, its going to be simple not only in design, but in tooling and skill level too!

    this conversion is actually even easier than the 1928a1 because of the all 1 piece bolt. thats getting the cart in front of the horse a little bit, so lets get into the build.

    sdk
    say what you mean & mean what you say


  2. #2
    aka: SDK1968 dutigaf's Avatar
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    lets start by chatting about what we are working with here.

    Parts from the kit:

    m1a1 front stub and barrel
    m1a1 bolt, spring,buffer,recoil rod
    m1 lower (had trigger, selector, safety and cross bar part)
    m1 wood
    m1 rear site
    Phila Ord M1 partial rear section

    parts added for the conversion:

    hammer w/spring
    trigger w/spring
    discon w/spring
    trigger pins

    beginning notes:

    this was a VERY VERY early version of Phila Ord's rear section i used. it has no writing, engraving or marks of any type on it and the finish work is not near as nice as what Bob sells now.

    with that said, it was still dead on the money as far as length and shape and very easy to work with. :-*

    another note: the original parts of this build were in VERY rough shape. was fortunate to get a real good deal on this kit, but the trade off on good deals is that you get stuff that is not in as good of shape. it has pitting on the barrel, stub and even the lower.

    thats a small thing since this is the first of this set up and you wouldnt want to risk a super primo high dollar kit and find out later that this didnt work too well.... what? people doubt that i can make this work? dont they know better by now? :P

    the last note is that this will be a pistol build as im just not gonna fork over the money for the stamp right now with xmas coming up & my kids being spoiled rotten by me and the wife.

    also some certain individuals are wanting me to submit this one for a review to our lovely BATF... so it will be as a pistol this first go around.

    here is where you need to cut off the lug and then weld up both sets of holes for the rear stock to be "blocked".


    this eliminates any rear stock attachment with out breaking the "intent" part of the rules.

    enough "pre build talk" lets get started......
    say what you mean & mean what you say


  3. #3
    aka: SDK1968 dutigaf's Avatar
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    of course the first thing is to jig up and weld your sections together.

    we've covered how to do this with angle iron, flat bar, or a jig from Weasel or Terry or Trenches. ALL of these ways are well covered and we arent gonna spend much time on this part it was just too easy for any more details and in this particular build it was 1 weld to have the basic length of the receiver, then clean it up and work from there.



    the real work on this conversion is in a "usable" denial set up. we will spend a little time on this part.

    Denial work for this build:

    laying this project out in my head before starting told me that the denial "pins" from the 28a1 build would work, but if you put them in the same location they would be in a very thin part of the receiver due to its design on the outside verses the 28a1's super thick side wall. look at the pic below to see what i mean.

    28a1 denial location




    decided to include the denial for the bolt into the denial for block the lower/upper all at the same time.

    denial for bolt on m1


    this denial is one of several built into this design. heres how it works for the BOLT.

    the FA bolt wont go in this upper as a 1/4" thick x 1/2" wide x 2.25" long piece of steel is left in the way. i chose to mill out the front of the upper and set this in and then weld it in place in front from the magwell and then down the length of it and across into the notch where it rests.

    please notice that i put the bolt denial on the NON HANDLE SIDE of the receiver.



    if your working with a 80% that you have to mill out yourself you could just leave this in to start with and "mill around" this.

    now lets talk about the other denial work done here... we all know the "drill"

    the upper cant go on a FA lower
    the lower cant go on a FA UPPER
    the bolt cant go into battery in a FA
    the FA bolt cant go into battery in the SA
    say what you mean & mean what you say


  4. #4
    aka: SDK1968 dutigaf's Avatar
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    thats a lot of "cant do's"! this turns out to be easier than you would think on this build. heres why.


    as you can see in the pix, for denials to be "hidden" as i think they should be, you have to work from the ridges and lips on the receiver.

    so the "notches" where the lower and upper meet are perfect to do this. we already said that we added the internal rail or diameter reducer to the upper, so why not just mirror that in the notch on the other side? thats exactly what ive done for keeping a FA lower from being attached.

    its the exact method we use for keeping a FA bolt carrier out of the Brens, DP's and so on.. fill in about an inch of the ridge on the upper with weld and then grind/machine it smooth... no more ridge!





    now why didnt we just put a full length denial like on the other side? BOLT WEIGHT AND STRENGTH. dont want to take any more off of that bolt than we have to. we'll get to the bolt in a minute. lets finish the upper.

    so now we have complete denial for a FA to be connected to this upper. internal ID is reduced by blocking rail/denial bar, and grooves are welded up to block a slide together of the upper and a FA lower.

    we also have to remove the back half of the outer ridge to be able to put the lower on for tear down, this will make more sense to you later, but you can see it in the pix.

    best yet its all invisible when the gun is assembled!
    say what you mean & mean what you say


  5. #5
    aka: SDK1968 dutigaf's Avatar
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    lets talk about the bolt work.

    first we used the floating pin bolt for this build cause it takes a ton of the work out of this conversion.

    so this instantly takes care of the floating pin requirement. we'll come back to the pin in just a bit. lets look at the lay out of the bolt and how this will work.

    this is what we start out with and the idea of where it needs worked on.



    first you know you have to eliminate the FA capability of the bolt. so we remove the FP and the "toggle" that operates it and weld up the toggle holes. this is no longer a FA bolt.

    next i welded up all the sear notches and extra spots on the bolt.



    now this is where you have to already know the idea of how you want the build to go. again based on the 28a design i did a couple years ago i knew that it would require a channel cut thru the bolt for the hammer to pass.

    the channel needed to be 3/16" x 2" long to have plenty of room, (the depth is "just enough to clear the hammer swing" and will vary for each person on their hammer location in the lower.) there is already a "starter" channel there from the toggle part and this is what i centered my slot off of.



    the thing that makes this so much easier than the 28a1 is its just the bolt! no extra pieces, nothing else to get in your way.

    after you cut your channel you will need to do the old extend the FP so that you can retain it.




    did this by adding 5/16" to the head of the pin and then putting the slot in it and hardening it with the Dan Diesel method on that end.

    then by taking a bit and making a starter spot in the bolt it got to where i could drill the retaining pin hole with a carbide bit. ad in your 1/16" pin and check your protrusion and retraction and you should be good to go here.



    now you have the hammer path and the FP done its about getting the bolt into the upper and functioning. time for the denial "relief" cut discussion. like the denial was at 1/4" x 2.25"..... made a matching cut out in the side of the bolt.

    [size=15pt]STOP!! [/size] please remember to put this on the correct side of the bolt!! the correct side would be the NON HANDLE SIDE!

    many reasons why i chose that side of the bolt. first your cutting out weight from the side and you get to make up some of that weight by filling in the bolt handle hole on that side.



    second reason is i didnt want the denials on the side with less metal intact.... the bolt handle side of the receiver. no use to maybe warp this thing when you didnt have to.

    third reason is your still using half of the bolt handle (which im about to explain) and it still has that weight on that side.

    lets stop here and show you how to do that part.



    in the pic is the complete bolt handle and what you should have after you cut it off. cut it off right behind the size change, and if you did your slot correct this is exactly the same spot that your slot will come to.

    this gives you a still stock bolt handle to work with from the outside but takes out the center section which is in your way.

    DONT THROW THE PART YOU CUT OFF AWAY!! your gonna re use that!

    now go cut the other bigger section off of the left over bolt handle... notice it still fits perfectly in the hole in the bolt on the side where you made your denial removal?

    so you take that part and put it back in the hole and weld it up! gives you even more of your weight back and re uses the old part all at one time.

    now after grinding down all the welds you added your bolt should go into battery with no trouble and your bolt handle should still operate the bolt just like it always did but without the center section in your way of the hammer swing.

    better welders will have better looking work than me... but hey im coming up with the ideas, so you guys can improve on it from there.

    one final thing before moving on to the lower stuff, since my section had NO bolt handle slot i placed mine to where it works the best for me. so instead of my handle removal notch being in the middle of the slot its at the rear. it doesnt have to be that way but it works out better for me that way and it still looks great.
    say what you mean & mean what you say


  6. #6
    aka: SDK1968 dutigaf's Avatar
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    now its time for the lower. other than having a few better pix there is really not a whole lot to explain here if you looked at the 28a1 set up.

    you strip out the lower and find your pin locations, taking care not to get too far into the mag release spring housing. as long as you dont get too far forward or too low you wont have any real trouble here.

    IF YOU DO? this is how this build can get very expensive very fast!! YIIIIIKKKKKESSS!!

    be careful here and measure it several times and check it before you start taking any out. you can keep taking it out, but it sucks to try and put it back in on this old metal.

    ive had literally HUNDREDS of people ask me: "why dont you just post the numbers for location?"

    here is the same answer they all get.... because NO 2 of these have been the same and they have all had a couple of K's difference in the internal dims on them. ive been a part of building more of these conversions than im ever gonna say at the various build partys and get togethers we have and again: THEY ARE ALWAYS SLIGHTLY DIFFERENT

    can i give you a ball park number to start out in? sure. from the front go back about .685 and start looking there for your hammer pin placement.

    notice i said ABOUT. your results will vary but you get the idea and its just standard AR spacing from there.

    here are some more pix of the set up that may be better than the 28a1 pix




    in setting up your hammer, dont get it too short right off the bat. just like everything else you can keep going shorter but once your too short your wasting money.

    my pic shows you a good general area to start with for fitting the hammer.

    test your set up before you go any farther! put the mag release spring set up back in and make sure your stuff clears in that pocket.

    does the hammer drag on the spring housing?
    does the trigger hit the grip screw in the bottom?
    did you measure both sides and get the holes in line? (nope ive never got a set perfectly straight yet)

    got all this working good? GREAT :-*

    as a foot note: i used the tommy trigger, cut it off and welded back to the bottom of my ar trigger so it would look more "correct"... (and the fact that the AR trigger laying around had the bottom cut off of it for another project a while back)

    now lets see if we can get the factory lower stuff back in there to give you a safety and the proper look.

    here are some pix of the mods to the crossbar and retaining plate set up.





    as you can see your trying to match the angle on the top side of the bar to your hammer profile and clearance to lock in..

    on the lower side your trying for clearance of the front part of the discon. the rear of the cross bars and retainer plate needs nothing.

    once you have this its time for the touchy part.

    the selector is now about to become your safety. a lot of work goes into this little part.



    to have any chance of getting this in there you will have to "notch" the back of the trigger assembly out as you see.

    go careful here cause where you put your trigger will decide if you need more or less than i did. GO SLOW! trim a little, test fit, trim a little more, test fit.

    thats really how you do this one. remember what your after here...

    in the one position you want the trigger to be able to fire easy and when you flip it over you want the trigger to not move.

    that just means that one side of this will be smaller than the other. check out the pix for the idea of what you want.





    got it? if so then its time for putting it all together and test fitting it all up.

    here's a last look at it all squeezed in there....


    say what you mean & mean what you say


  7. #7
    aka: SDK1968 dutigaf's Avatar
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    things to check at this point.

    did you get enough clearance on all your denials so that the parts will slide together? this is a good time to check before you go any farther.

    did you get enough clearance on your hammer into bolt? check it before you put it together! set the bolt on the completed lower and hold it down with your hand. can you slide it back and forth on the lower with not trouble?

    if so, slide it to the forward position and hold it with your hand, pull the trigger... did it drag ? hit the pin? knock it out of your hand? these are what your looking for before you stick it all together. if it does any of that stuff then it will only be worse when you put it together so get your clearance down now.

    so lets say that you got that down or made the adjustments that you needed.

    so its about getting it to work together now. you still have the matter of the recoil rod, spring buffer and holder to deal with so lets knock that out of the way.

    1st your gonna need to shorten that spring by 2" and work from there. why 2"? because you took 2" out of the bolt for the hammer slot and you made need to drop another coil or 2 to avoid spring bind. (you can trim it to fit yours from there)

    2nd your gonna need to take 1" off of the spring guide rod to start with and this is a tough piece of steel in mine.

    3rd your gonna need to make a spring stop in whats left of that spring channel.

    for my spring stop i used the piece of guide rod that i cut off and drilled a hole in the channel as far forward as i could get it and went thru from the top side down into the bottom section a bit. before you ask why i went from the top of the bolt for this just think about it for a second.............. yep gravity is your friend in this and no drag.

    DONT WELD THIS IN! you will need to be able to take this out any time you want to get to your FP thats why its removable.


    (look close at this pic, on top you can see what im talking about.)

    i left a very small hole all the way thru my bolt so that if i wanted this back out to get to my FP all i had to do was stick a small pin in there and shove it out. works very nice, and since the pin is the same size as the hole there is no way the spring can go around it.


    this also means that you need to add a bigger buffer in there to take up that space that you can no longer travel.

    here is the cut off rod, spring, buffer, and extra buffer:

    here is a pic of it all in there together:


    a poly buffer would be nice and maybe i'll make one later. im just a poor boy on a garage budget so naturally im using the same type of heavy duty 3/4" hose that has over 2,500 rounds on it in the 28a1 tommy.

    the length of this buffer is determined by your bolt travel.



    this is my maximum bolt travel with the bolt hitting the guide rod. naturally i want to stop it a few K's before this while still giving as much recoil as possible and dampening it all at the same time.

    this part it purely experimental with every build. oh theres plenty of "super math genius" types out there who can tell you what it "should" be.. but i just go with what works.

    added 1/4" for compression of the rubber to the distance of the bolt at fully open and put it together and hand cycled it.

    no matter how hard i tried to slam the bolt back it didnt bottom out, so this is a good starting point. YES YOU CAN ALWAYS MAKE IT SHORTER and adjust it down to the minimum as you go.

    edit note changed method on 12/29/09
    last minute late change made in the guide rod set up as i just thought it could be better.

    by using a sleeve in the front of the guide rod passage way.... it was a piece of 3/8 brake tubing that i reached down in my pin hole from the top and tacked into place.

    this makes a spring support sleeve and still allows the full length guide rod to slide thru.

    it also eliminates the need for the extra buffer in the back.

    ive still got a 1/4" rubber buffer in there as i just didnt like the sound of it hitting the metal faced buffer from the factory.

    it has better bolt closing force now and the guide rod is all the way thru so there can be no spring bind.

    sdk


    that brings you up to hand cycling and feeding of shells.

    first i took some dummys and put them into my mag and hand cycled them thru to make sure the spring was strong enough to force them in with the shorter stroke. it works good by hand and ejects with no trouble.

    since this worked it was time for a live test and the 10 second video was posted a while back... here it is again.



    that says the basics of feed, fire, eject & cycle are all working just fine.

    im guessing video imbedding is not good here?
    say what you mean & mean what you say


  8. #8
    aka: SDK1968 dutigaf's Avatar
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    that only leaves the final finishing

    after sandblasting it became pretty clear right away that the metal on this kit was just too rough for bluing and making it look decent. it was full of pits on all the hardware and the lower and the barrel and front stub.

    while it will function perfectly this build will always look "aged & worn" so it will have to get a different finish and im going with KG GUNKOTE on this one. it wont cover like the ALUMA HYDE II but it will hold up pretty good.

    like wise the wood on this kit was in very rough shape and since im no wood worker, just went over it with some sand paper to knock the splinters off and then cleaned it real good and hit it with some "olde english dark". Then after that dried, gave it a nice coat of furniture polish. YES IM SERIOUS.

    this is a pistol build and the stock is not attached and it cant be as the holes for the attachment have been removed and welded up.... but you can lay it there for the purpose of the picture!





    this is after the sling has been added and the lugs completely removed....



    much like im not a machinist, im not a woodworker either.

    im a garage builder thru and thru. my builds are designed and set up for a regular builder with just regular tools and skills and above all else : to be FUNCTIONAL... not wall hangers!


    as usual the proof is in the pudding so here's the full video test.

    my nephew Robbie giving it a try:




    hope you decide to try this build & thanks for looking!

    sdk1968
    say what you mean & mean what you say


  9. #9
    aka: SDK1968 dutigaf's Avatar
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    videos are fixed and working.

    ask away, but look closely before you ask.

    its all there. :-)
    say what you mean & mean what you say


  10. #10
    NoWorkCamp4Me railbuggy's Avatar
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    Well done Sir;Thanks for the post.
    SOON-We already lost the war. You are the resistance.

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