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Thread: More work on .45ACP conversion.

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    Master Endmill Breaker Rhino_66's Avatar
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    Default More work on .45ACP conversion.

    Well, since the Gunco WV shoot is next weekend, I figured I'd better get some more work done. This project has been simmering slowly for over a year and a half, so the heat is now being turned up! This project began in fall of 2003. A lot of early discussion with HCPookie, Vis, Geodykt, Daewoo, Golovko, U.S.M.C.Man, and a few others, helped me develop my initial design. A lot of that time was spent calculating the clearances and cut dimensions. A lot more time was spent using Photoshop and MSPaint to move portions of photos around to get an idea of what problems would evolve and what to do about them. Here's where I'm at, right now.

    The gray paint makes it easier to see the areas that were machined. The raw machined surfaces wash out with the camera flash and are difficult to see.




    This is the basic machining done to the bolt carrier. The cuts were made before any welding because I wanted to make sure all the interferences were accounted for. The cocking handle has been removed, the clearance slot for the bolt lug is cut, the ejection clearance cut is made, and the firing pin access hole is drilled. Portions of the cuts will be filled with weld once the primary machine work is completed. The rotation channel will be welded up and a notch for the cocking handle will be cut.




    This shows the position of the bolt in the carrier. The bolt has been cut to the proper length. The triangular tab on the back of the carrier has been cut flush with the back surface. The bolt will eventually be welded into place.




    This is a close up of the cut bolt and carrier. I considered filling the 2 upper bolt grooves with weld and reshaping the bolt, but I think I'll just silver-solder the back end and leave all the welding at the front...




    This pic shows the clearance channel for the bolt lug. This is what allows the bolt to slide straight in before final welding. There are several large gaps that will be filled with weld and ground to shape before final assembly. This will allow for a more solid attachment, and prevent the possibility of cracking.

    The angled cut for ejection clearance can be clearly seen in this pic. It's tough to see in this picture, but this is the bolt that I opened up to fit the .45ACP cartridge. The extractor only required minor grinding with a dremel stone to get the groove to match the cup diameter.

    With the bolt in this position, the ejector lines up correctly with the slot in the bolt. The 7.62 ejector rail will work perfectly with the conversion.




    This pic shows the hammer engagement with the modified bolt and carrier. The striking face of the hammer is perfectly flat against the back of the carrier. Because I designed this for blowback operation, the bolt cannot be positioned in the forward position. For proper operation, the bolt must be shortened, moved closer to the back of the carrier, and rotated. The bolt is shortened 0.800". Because of the bolt being shortened, the hammer will not make contact. My design calls for moving the trunnion back the same distance that the bolt was shortened. This will position the back of the carrier in line with the hammer face in the same place that the original bolt stem was positioned. Hammer function is smooth and the carrier easily pushes it back down to engage the trigger and disconnector.





    I performed the alignment checks using a standard OOW receiver. This pic shows the carrier moved back exactly 0.800" from the postive stop of the trunnion. This lines the carrier up perfectly with the hammer. I will be using an IBE battle blank for the .45 receiver. The dimples in a standard receiver prevent the magazine from fitting into the receiver far enough. The thicker blank is a little easier to weld on, as well. By only shortening the receiver by 0.800", standard handguards can be used without modification.




    This pic shows the carrier seated against the positive stop of the trunnion. When the barrel is installed, the breech face will be right up against the face of the bolt. This gap between the carrier and trunnion is unavoidable, because of the position of the bolt. The barrel will take up most of the gap, but I will add a small piece of sheet steel to the top cover to keep debris out of the receiver. It will also look a little cleaner. This gap is present on the Bizon, too. The Bizon top cover is stamped to cover the gap.




    This is one modification that early on I realized was necessary after deciding to weld the bolt in the carrier. The firing pin retaining pin cannot be removed once installed, unless a clearance hole is drilled. Once the bolt location is determined, the clearance hole was marked and then milled. I used 1/8" carbide end mills for this step. I started with a ball end mill to make the hole in the underside of the carrier. Then I switched to a standard end mill to punch through the top of the carrier. The rounded surface inside the recoil spring tube prevents drilling through the material. The sharp corners of the mill bit easily cut into the curved surface and allowed the holes to line up without breaking a drill or screwing up the hole.



    My next steps will be to fill in the carrier slots with weld, attach the cocking handle, and then permanently attach the bolt. After that is completed, I can work on the receiver and barrel. After that, I can work on the magwell and think about test firing. WHEW!!!!
    Last edited by Rhino_66; 12-13-2005 at 10:40 PM.
    The most damning evidence is the truth.

    That which does not kill you, really really really hurts...



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    Master Endmill Breaker Rhino_66's Avatar
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    Thanks for the compliments, . I'm just a hack machinist. I have worked in various industries and my dad taught me more than enough to get by with the mill and lathe. There is still a LOT I need to learn, but I can muddle through for now...

    I'm going to use M3 "Greasegun" mags for this. The Thompson stick mags have a couple issues that make their use a little difficult. The issues could be dealt with, but the M3 mags don't require any modification and are excellent feeding mags. They look like a Sten mag on steroids.

    For a magwell, I'm using one of the magazine conversion kits for the MAC-10. There is a kit that has a magwell and catch that replaces the original one on the MAC. I'm just going to trim the height to get the feed lips lined up with the barrel and weld it to the receiver. There's a similar kit for the M11/9.

    Winn hooked me up with some RPK barrel blocks, awhile back. Those will fit the .45 barrel easily. I have an RPK lower handguard for it. I'm thinking about having Z-Recto do a Polish laminated stock, pistol grip, and upper handguard to match it.

    I'm going to sandblast all the parts and parkerize the whole thing. After that it's going to get GunKote, but I'm torn between satin black or the GunMetal blue.

    There's a lot of work being done on pistol caliber conversions lately. Vis, jungp, jpglee1 (if he can get those welds cleaned up... ) and a few others have some irons in the fire. When I get this finished, I will put together a scrapbook of what went into my conversion. There are a few issues to deal with, but I think I have most of them ironed out.

    I'm considering dropping the original recoil spring assembly and making a new one that uses 1911 recoil springs. That would allow me to tune the action by using different "weight" springs. 1911 springs range from 6 to 24+ pounds, so tuning the recoil should be feasible.

    I won't get any more work done on it for a couple of weeks, but I am bringing the parts with me to the shoot.
    The most damning evidence is the truth.

    That which does not kill you, really really really hurts...



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    Gunco Regular pupwag's Avatar
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    Excellent.Thompson barrel?Good job thats a fair amount of meat to chew off the carrier.Thanks for the very enlightening post.
    It's only metal, it's not magic.

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    RIP Sangrun Hunter's Avatar
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    Great work Ryan!

    Cannot wait to see those parts in person. I bet you have been anxious to complete this, but you have taken your time on this to do it right and the next project will go faster from what you learned.

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    Happy Camper hcpookie's Avatar
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    Looks good! I wondered if you were going to put the firing pin hole into the carrier.

    Question, since you milled off the rear spur, what are the chances of an out-of-battery discharge?

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    Master Endmill Breaker Rhino_66's Avatar
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    Quote Originally Posted by hcpookie
    Looks good! I wondered if you were going to put the firing pin hole into the carrier.
    Thanks! I had to put it there. With my luck I would have broken the firing pin on the first shot...

    Quote Originally Posted by hcpookie
    Question, since you milled off the rear spur, what are the chances of an out-of-battery discharge?
    Only slightly more than the Bizon. The Bizon doesn't have the spur. Of course the Bizon does have the auto-sear to prevent hammer fall until the bolt is all the way forward...



    I have to remove the spur. If it's left on, the hammer can't hit the firing pin.

    Since I don't have an auto sear, there could be an out of battery discharge. But there would have to be a catostrophic failure of the trigger hook for that to happen. A double hook G2 trigger group will provide an extra level of redundency (also gives me 3 U.S. parts). If the hammer breaks, I'll just have to ride it out. The only way to ensure there would be no OOB, would be to install an auto... I mean safety sear. Kind of like what is on the Romak 3. Somehow, I don't think the Feds would accept that as a reasonable excuse.

    That brings up another topic, the parts count...

    These will be the U.S. made parts.

    1. Trigger
    2. Hammer
    3. Disconnector
    4. Receiver
    5. Barrel
    6. Magazine body
    7. Magazine follower
    8. Magazine floor plate
    9. Muzzle device (if I make one...)

    The bolt carrier and bolt have been substantially modified. Modified to the point that they will not function in the original firearm in their current state. The scuttlebutt is that if enough modification is done, imported parts magically become U.S. made parts. If so, I get 1 additional part for the bolt (bolt and carrier get welded into a single unit).
    The most damning evidence is the truth.

    That which does not kill you, really really really hurts...



    Gunco Member #21

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    Happy Camper hcpookie's Avatar
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    Quote Originally Posted by Cephus
    I DON'T KNOW FOR SURE POOKIE BUT IT LOOKS LIKE THE CARRIER WILL STOP THAT ,
    TAKE A LOOK AT THE 5TH PIC DOWN AND YOU CAN SEE THAT IT WOULD HIT THE BOTTOM OF THE CARRIER IF IT WASN'T CLOSED .
    IT KIND REMINDS ME OF ONE OF THE OLD FALLING BLOCK .22'S IF IT'S NOT ALL THE WAY UP IN PLACE THE HAMMER WON'T HIT IT.

    I COULD BE ALL WRONG BUT THAT'S WHAT I SEE THERE.
    MAN I WISH I COULD HAVE BOTH OF YOU GUYS HERE FOR THE SHOOT
    SEEING HOW I CAN'T SHOOT MUCH I'D LIKE TO PICK YOUR BRAINS
    ALITTLE .
    Ah you're right! OK that looks better now in my mind. I know this has been discussed before but safety always lurks in the back of my pea-brain mind.

    Yeah I wish I could come too but I'm just not going to be able to do anything with this work project I'm on. With any luck it will finish up on or around May 15... BUT I'm hopeful that it could be even sooner. I want to have my Spring back.

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    Happy Camper hcpookie's Avatar
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    Quote Originally Posted by Rhino_66
    That brings up another topic, the parts count...

    These will be the U.S. made parts.

    1. Trigger
    2. Hammer
    3. Disconnector
    4. Receiver
    5. Barrel
    6. Magazine body
    7. Magazine follower
    8. Magazine floor plate
    9. Muzzle device (if I make one...)

    The bolt carrier and bolt have been substantially modified. Modified to the point that they will not function in the original firearm in their current state. The scuttlebutt is that if enough modification is done, imported parts magically become U.S. made parts. If so, I get 1 additional part for the bolt (bolt and carrier get welded into a single unit).
    You know that's one of the great things about these conversions - you have so many US parts that you almost don't need additional US parts. I was doing the math on the Bizon and I think I'll have no problem with US parts, and will be able to use the original trigger group. That magazine really helps out.

    What kind of muzzle device you looking at? I'm thinking that I can make that Dragunov-style flash hider with relative ease on the lathe & mill. I need to get one more cutter but everything else should be relatively easy to fab. Speaking of which, has anyone considered using a BFA as a starting piece for a muzzle device? It's already threaded & everything... if one put threads on the outside, presto there's an adapter. If you welded a pipe to it, presto there's a new muzzle device...

  9. #9
    Vis
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    Gunco Regular Vis's Avatar
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    Rhino_66
    AK-47 user and abuser since 1980.
    http://strzelecka.net

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    Gunco Regular Francisco Pizarro's Avatar
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    wow! I can't wait to see pics.

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