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Thread: 1928a1 SA tommy build (requested)

  1. #1
    aka: SDK1968 dutigaf's Avatar
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    Default 1928a1 SA tommy build (requested)

    this thread will be for my Thompson 1928 semi auto build.

    im not interested in a submission or any of that type of stuff at this time. If this works and turns out nice and im 100% sure that it would get approved then we may go there.

    anyone who wants to attempt this needs to understand that your taking a chance on ruining a very expensive kit!!

    now heres where im at.

    after much kicking around with all of my buddy's about FCG's & striker's and so on... ive decided that yes a striker is doable & probably easier in the Tommy.

    so of course im NOT gonna do it that way. we are going hammer fired here.

    ive discussed several different groups.. AR,AK,FAL, CETME,870 and all the rest.

    this will get some frowns but im gonna go with the AR on this build. ive got several reasons for this and we'll get to them in just a bit.

    lets talk about the 922r end of this.

    there are no foreign parts here to worry about so its all about the blocking rail/pins and barrel length.. since im using the AR FCG there is no issue on the positive disconnect and all that jazz either.

    ive found some 16" barrels but i think they look like sh*t when you ad the compensator on it.. so my intentions are to take the 16" barrel and have it reworked a bit to where the compensator will be "back" on the barrel as far as possible.

    this will help in looking closer to the original.

    now lets get to the serious stuff.

    first i took and laid my AR FCG holes out by site on my lower just for a visual of "will this work".

    it actually looked doable and like i can get a FP hit just past straight up and down. this is good news. it also looks like my "in brain idea" of hammer travel and clearance will be okay to.

    good thing about this bolt is that there is already a path started for the hammer to swing thru.

    look at the front of the bolt. see that toggle area? we are gonna take that toggle out and mill out path right thru there....

    first thing you gotta do is take out the toggle piece (real technical aint i?). just shove the pin out and it will literally fly right out of there.

    this is where most of the guys are gonna bail out..... now is the time you have to decide if your gonna take a chance on ruining a bolt of one of the most popular guns in history. if not, then just watch and hope that i make mine come out.

    heres why: when you take out the toggle you will find that a Tommy FP has a hell of a spring on it. our first order will be to retain that FP in there, so im gonna drill a little hole thru the bolt and put a pin in there with a notch in the pin so that it will stay in place but still have full travel.

    lets talk about the FP for just a second:

    made a split in the FP for the retainer pin to go thru, then put a little touch of cap weld on the end and gave it a little "dome".

    yeah its blurry!!!
    heres a new pic to show you what im talking about...

    this gave just a small bit more FP to hit with the hammer and hardened it and quenched it in oil too!!

    back to the retaining pin:
    chose dead on top cause there was a little flat spot there for me to center punch and drill.

    yes of course i broke a bit doing this... very small hole!!

    now see the FP is retained?

    ok now the nerve racking part starts.... we are about to totally just cut up a tommy bolt!! im getting queasy just thinking about it. ;D
    say what you mean & mean what you say

  2. #2
    aka: SDK1968 dutigaf's Avatar
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    so we will start with the cocking handle...

    ive got some ideas in my head and have tinkered around with them before hand so im not just cutting in the dark.. but these are trial cuts so they will be "shy" of the mark and then tuned in as we go.

    now lets flip it over and make a prelim cut so that the hammer may have a chance to swing thru there.

    notice how this will take the current plug out of the bottom of the cocking handle? we will put a new plug in later after we get the distance firmed up.

    yes this is gonna shorten the throw of the spring a bit. we will deal with this later as the operation of this bolt is totally changing.

    in case you havent already noticed from the work im gonna do away with the Bliss lock set up in this gun.

    the hope is that the shortened spring travel and the addition of a hammer system will make up the difference for blow back operation. and if it doesnt we will adjust from there.

    this should be no problem with the additional spring for the hammer, the weight of the hammer and resistance of FCG.

    now back to the cocking handle.

    was going to pin the cocking handle to the bolt so that it could be removed to service the FP. After several pitiful attempts to drill thru the side of the bolt and handle ive decided that this was not my best idea and to use the space that was already open to me.

    sometimes you just have to look at something a little longer to get a fresh idea. this is what happened here;

    edit note: once the build was finished i found out that you didnt have to remove the handle knob from the actuator.... its got just enough room for take down.
    decided that since the Bliss lock channel was already there why not just put some "ears" onto the charging handle? this would keep it from going back wards, leave it easy to remove for cleaning and even help with adding some weight to the bolt. a win-win situation!!

    so welded some "lumps/ears" on to it and thats what you see in the picture.

    at the same time also welded up the lower part of the slots for the Bliss lock set up to ad some more weight back in and give the bolt some extra strength since we did quite a bit of cutting on the bolt.
    say what you mean & mean what you say

  3. #3
    aka: SDK1968 dutigaf's Avatar
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    lets get this bolt finished up, as you can see ive milled out a path in the bottom of the bolt for the hammer to swing thru.

    it took several slow going attempts with lots of test fits to get the path to what looked like it would work with the AR hammer i had laying around.

    you will need to come back on the bottom of the bolt right past where the factory groove is and stop there for your bulk cut out, then fine tune it in for your hammer from there. its a pretty good guess that everyone who tries this will be a few K's different.

    you will also need to take a little out of the front of the bolt where the pin is at so that the hammer can get all the way up in there.. just had to square out my corners a bit is all.

    after getting this far had to go back and mill out a little more in the charging handle area so that the hammer could swing thru without dragging. you may as well expect to do this a couple of times, as i wanted to leave as much of everything as possible.... take a little out is good, but trying to put it back sucks!!!

    once you get this far be sure and check that pin for hang ups and easy travel, you dont want to have to come back to this again later.

    yes i heat treated this as best as a garage builder can... used the Pirate method of heat it up and then quench it oil.
    say what you mean & mean what you say

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    aka: SDK1968 dutigaf's Avatar
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    now we get to the part that actually went way better than id hoped.

    lots of info for this...... as before building this the FCG was always the big question mark on this build.. so far this has fit way better than planned.

    again if you have ANY issues with cutting or milling on a very expensive kit then this build is not for you!

    lets get busy:

    first strip out the lower

    next step was to see if the AR parts would set in there... they do almost perfectly width wise.... now how about the height? hmmm this will be close, but im betting about $650 worth of parts kit that it will work.

    after stripping out the lower and doing a drop in of the trigger to see about its location and getting a place that i thought could work..

    used my trusty little AR FCG template to lay out where my holes would be..

    checked it, checked it again..... said oh Pelosi and checked it again.

    looks like it will be fine on the trigger end, but will hit the front housing with the hammer!! did some measuring and it seems like it will be ok even if i get into the mag release spring housing.

    so with my trusty template in place i drilled the holes.

    now the trouble starts!!

    the trigger holes are fine and the trigger drops right in and thru and out the bottom. the factory trigger is very wide and the little AR just falls right thru with no place to catch the trigger return spring. after looking at it for a few minutes decided to put the trigger return spring "up" on the little shelf in the front of the housing.... it was long enough and all i had to do was dremel a little groove for the spring arms to ride in.

    now that-that was solved i squeezed the trigger. nope no movement at all. yep it fit but it was dead against the bottom and couldnt toggle.

    lucky enough there is enough room in the bottom to just mill out some of what you need and then grind off a small angle on the bottom of the trigger to have the 2 work together and give you what you need.

    so the trigger is squared away and has a nice feel to it.

    oh last thing on the trigger: you will have to cut off about 1/8" from the bottom so that it doesnt drag on the trigger guard.. just bevel the edges and it looks fine.

    now lets move on to the hammer... it would appear that when drilling the hammer hole that my jig moved and let the hole get a little higher on the right hand side.. about 1/16"!! this bummed me out but it will still work and you have to look very close to notice. im only even telling you guys this so that you will double check your jig before drilling on thru to the other side. this could have also been drill bit deflection?? i should have turned it over and marked it off and drilled it from the other side...... but that was then and hindsight is always 20/20.

    as a remedy for this welded the hole up and ground it smooth then re drilled it and BINGO!! looks great now and is in the perfect spot..

    you can fix most small mistakes if your willing to put in the effort

    yes the inside lower will need milled out, but go slow here and dont get crazy and go too far into your spring housing for the mag release! you will break thru but this is no big deal, all you have to do is put the release back in before the hammer is installed and it will pass right by and then its out of the way with no trouble.

    now install your hammer and make sure it all functions. if you used a good template or laid it out with the right math it should work just fine and the front of the unit will act as a hammer stop to boot.

    now what to do with all those holes?

    well it just so happens that if you wanna keep the original look, you can!!

    it takes a LOT of grinding and .......grinding lol but you can put everything right back where it was at.

    does it work the same? NO

    heres what ive got, you may choose to do yours differently.

    the safety lever is now just a dummy.. unaltered but unused and still locks into either position

    the fire selector is now your safety lever and uses the standard "rolling block" effect to work, just look at the pix.

    it took a lot of careful grinding and you just had to have in mind a picture of an AK safety bar on the inside as you are going to cut a "hump" out in it so that it will clear for install and function.

    lots of dremel work to get this to work..... but if it had broken i was just going to weld a new piece back on it to the inside and use it anyway. if this one ever breaks that will still be what i do.

    now about the double pin bar with the flat spring...

    same deal the rear is untouched and needs nothing done, the front however does go thru the hammer and trigger area and has to be ground from both side and the top. your damn near taking all of this dude out..... all your really after here is for it to still be in 1 piece so that it gives you your mag release stop on the other side.

    see ive ground this baby from all directions to get it to clear the hammer and let it disconnect if needed and let the trigger bar work underneath it.

    speaking of disconnector.... this did take a little adjustment.

    its a common problem on these "short" subguns that when you cut enough off of the bolt/hammer area to get it to slide over that then it just barely has enough left touching to reset the hammer and not enough to go all the way down to the disconnector if the trigger hasnt released....

    in short description, it doesnt disconnect!! this will not pass and is not acceptable. its also not very hard to fix. this AR group is pretty easy to work with and if you move the bolt back across the action and slowly see what the problem is here...

    mine was that it came up about 1/16" short of hitting the disconnector with the trigger held in the fired position. worked perfect on trigger release. but the speed of the bolt almost always means you cant let go fast enough for this to happen. you dont want a run away on this build and to get your self in trouble or injured... so you gotta make sure this part works!!!!!

    in the motion i see that the angle of the disconnector is fine just the distance cant really be covered with this small movement of the hammer.

    your taking a risk on ruining your disconnector here, they dont cost that much.. many people can just make a new one if they have mills and such...... you should know this by now: DONT HAVE A MILL OR LATHE!

    so picked up the trusty welder and put just a small bead on the end of the disconnector to extend it out and then filed it to shape.

    test it, then adjust.... did this several times till i was happy that everytime i held the trigger it would grab the disconnector and when i let go it had just enough drag to make it hit the usual fire position.

    heated this back up a bit and oil quenched it and will move on. this part may unsettle some of the builders, but ive seen it on a few builds before and figured the part was cheap enough to risk it and then if im not happy later i can have Pirate make me one to the proper shape.

    its good to have friends!!

    now lets move on.......

    these are pretty blurry pix, but this is what you get from a guy with shaky hands and no help.

    now its done and you just need to adjust your hammer for the bolt path..

    im pretty proud of this part as the only thing that is different from the outside is the 1 pin that you see and after i blue all of this it will be a tough see anyway.

    did you notice that the other pin is hidden behind the spring and lever?? cool eh???

    yeah im stoked at this point!! can you believe that we are only half way done with this build??
    say what you mean & mean what you say

  5. #5
    aka: SDK1968 dutigaf's Avatar
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    now we move to the uppper area....

    this is going to be a reweld build so we will have to use a denial set up as we mentioned in the first post.

    gonna use a double pin set up just like a very well known company does on their builds... if its accepted for them it shouldnt be a problem for me.

    will be using 3/8" rod, will spot holes and drill them and then cut a length of rod drive it in and weld into place.

    ok you see the holes.. now you see the pins in them..

    i try to never show any of my welding until after the grinding....

    of course you need to mill out the part of the bolt to go with this.

    now this is where i remind you that i do NOT have a mill or access to one im doing all this work with a grinder and a Rotozip!! so it looks like it was done with a grinder and a Rotozip not a mill or a lathe.

    obviously the yellow area is where i removed for the pins to have plenty of clearance.

    im a GARAGE BUILDER: not home machine shop

    Mike, Pirate and the boys are PRO's! they have tools and skills that i do not. their builds will show it.

    oh and they take way better pictures than me too....... : :

    now lets do some weld up of the upper sections and insert the bolt to test out the line up.

    how did the upper get lined up? since im a poor boy with no fancy set ups, i do it the old way: angle iron clamped on all sides along with using a digital mic to set the distances and tack it together in between the angles edges then work my way around. then lots of test fitting and some grinding of my "non-Pirate" welds.

    ok after some fine grinding on the welds on the inside it will now all fit in and operate by "finger power".. this is a all important test to me. if it wont work by finger then its not fitting right and i'll go no further.

    lets look just a bit closer at the upper mods.

    the bolt had the path cut out for the hammer and the denial pins & we added some weight and strength back in by welding up half of the Bliss lock slot. we left the other half open for the charging handle mod.

    the charging handle was modified earlier & we did away with the Bliss lock set up by adding some weld on the side to make a permanent knob in place of the Bliss lock. this gave us a way to cock the bolt without the handle coming separate from the bolt.

    originally i thought that the handle on the charging handle needed cut off and drilled and tapped for cleaning so i went that way. but after getting here it turns out that it didnt have to be that way after all... but it does make it a lot easier to take down and reassemble this way.

    now its about that recoil spring. since we shortened the charging handle pathway the spring will have to be shortened to match. again im one of those people who will take off a little at a time and work my way to where we want to be. in the end it was 2" of spring that had to come out to keep it from being spring bound in there.

    at Pirates recommendation ive added a buffer... yes its a piece of 5/8" heavy fuel hose thats 1" long. this gives just a shade of buffing right before the spring guide rod can hit the pin inside of the charging handle pathway.

    this is easy to replace or change as needed and lasts a long time.
    say what you mean & mean what you say

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    aka: SDK1968 dutigaf's Avatar
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    now we install the ejector and put it all together for some dry cycling.

    on the put together:

    did have to make a few adjustments here.. to get the bolt and upper to go on the lower, the rail that slides onto the lower had to be removed from the back to half-way forward on the upper. this allowed you to pull the bolt back and while holding it in place... take the lower and slide it into place. its way easier than it sounds. this let you still keep the rest of the lip to hold it down and the detent pin in the rear to keep it from sliding.

    if for some reason after testing it out that this doesnt seem solid enough i will just tap that detent hole and use a hardened screw to hold it back and down instead. its still very strong and tight in this set up and im just not thinking its gonna be a problem.

    ok cycled the bolt and dry fired it about a hundred times all seems to be working fine. of course a live test will be the real teller.

    and thats coming up!!

    lets move on to the barrel now.

    im not gonna do a SBR on this as its a home build and im not interested in going thru all that Pelosi. (thats my opinion and im allowed to have one)

    so ive got a 16" barrel which also looks like crap! im going to cut this 16" barrel down to 13.15" and then ad the Cutts compensator to it that way im legal but still as short as possible.

    ive seen this done and it doesnt look nearly as "out of place" as that 16.5" barrel with the 3" compensator making it near 20" long.... it just doesnt compare with the original that way.

    my original measured 13.5" with the compensator and mine will measure 16.25" so its just 2.75" longer not bad at all for being legal.

    first we need to measure everything several times and mark right where we want this thing to mount at.

    next we cut up a brand new barrel

    now we see how we're gonna mount that compensator..
    say what you mean & mean what you say

  7. #7
    aka: SDK1968 dutigaf's Avatar
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    see im just at 16 & 3/16"!! just enough to have no legal worries and as short as possible with no SBR.

    how will we get it to stay in place?

    the original is threaded and pinned as we mentioned. well after cutting the end off the barrel, now we dont have the threaded part.

    well why not just thread the end thats left? because its still smaller than the threaded area of the original end.

    so looks like welding a small bushing on and then threading it, or pinning thru them both.

    im not wanting to weld on this new barrel so im going to try and re thread the end of this barrel and get enough " raise" in my threads to catch the threads in the compensator. and yes im going to change the threads on both to something i have instead of that crazy thread from the factory.

    then will pin thru the factory hole on top of that for extra safety and proper looks.

    now lets sit back and look a bit at the over all package before a test fire.

    so now you see it in the rough version and im gonna test fire it with live rounds before putting any type of finish on it, prefer it this way in case i have to make any adjustments...which is always possible.

    test firing:

    first went back over and cleaned it all and as you can see some of it got blasted already... this will have to be done again as im going to oil it up and run a few rounds thru it.

    im also gonna go back at this point and try to get some better pictures for any that werent very good.

    started out with the 20rnd stick mag. did the usual 1 round in the clip.. all went well. 2 rounds in... all went well. 4 rounds in... all still well. good ejection, good feed and cycling seems fine.

    at this point i opened up on it and emptied 10 rounds in my next clip. still no issues.

    now go to the drum and loaded 10rnds. give it 9 clicks on the wind up and this is where you remember the only downfall of a drum on a Tommy when your by yourself...

    if you dont have great hands, its a pain in the A$$ to put the drum on with out a bolt hold open set up, which original tommy's didnt have.

    my stick mags all have last round hold open gates, but that doesnt help you after you take the mag out.

    lucky for me ive shot quite a bit of FA Thompson and can hold the bolt back in the hand thats holding the gun and load the drum and work the release with my other hand... its still not something you would want to do under a high stress environment but it can be done.

    so here we go, run 1, run 2, run 4 run the rest...... still relatively short runs of 20 but at this point im not looking for the endurance test. just testing function and fit. so far we have a winner!!

    gonna go tear it back down now and inspect the brass for primer hit & depth and gun fro wear or drag marks.

    here is a primer hit shot from the very first few rounds

    it all looks pretty good to me so now im gonna get ready to put the finish coat on gun and try to get it all to match.

    im not gonna go into a lot of detail here as the wood is just gonna get cleaned and tung oiled... its dark anyway and im just gonna gloss it up a hair... may switch to the "gangsta front grip" later.

    on the metal ive mentioned im going to try to match up using my typical cold blue tutorial that is on the site already, so all the parts are headed to the sand blaster and will add more pix when its finished and hope to add a video shoot soon.

    there you have it!! a FUNCTIONAL SEMI AUTO THOMPSON!!!! and they said it wasnt doable...

    ok with the first video you will see the trigger stick on the disconnector once!! just had a burr on it....

    next is the short drum test

    had a huge storm coming in and jsut wanted to get these up real quick ... longer vids later.

    say what you mean & mean what you say

  8. #8
    aka: SDK1968 dutigaf's Avatar
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    here is a quick update and new short wobbly video.... ;D

    Abby my 7yr old decided she could shoot the last run of the day in the tommy..

    she made sure she kept the gun in the picture.

    made a few improvements in the cycle as i thought it was too slow...and as you can see it gained a good bit of speed. it now has 325 rnds thru it.

    as of 1/26/2010 this tommy now has over 4600 rnds thru it and is a fan favorite everywhere i go!!

    there have been at least 35 built this way that are up and running that i know about (have helped tuning on several of them) and im sure there are others who just dont want their names out there. if you ever want a reliable semi auto tommy this is a great way to get one!

    did this design & tutorial a while back, but lots of people have asked for the full tutorial so after talking to GUNCO about it.. here it is.

    is it exactly the same as the M1/M1a1?
    NO the receivers/bolts are different so the upper part of the tutorial is not the same.

    do the lowers convert exactly the same? YES!

    why dont i post numbers for the build locations of cuts and so on?

    after doing many of these, the first thing you learn is that no 2 are made exactly alike and they are all a couple of K's different.

    YES thats just enough of a difference that you cant just throw a number out there that will work for all of them. just not enough room.

    so instead im showing you how to do it and how to look for the perfect spot in YOUR build.

    say what you mean & mean what you say

  9. #9
    Gunco Member andyman's Avatar
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    That's really something! I might have to try it on my dummy gun.....

  10. #10
    aka: SDK1968 dutigaf's Avatar
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    its a very very reliable build and we will be doing 3 more at the Deep South Build Party in Alabama on June 4-6th next month.

    im pretty sure they will be m1's and m1a1s but the same practices go into them.

    thanks for looking!

    say what you mean & mean what you say

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