Converting a mini from full size

[MrM4]

First of all, I’m a 07/02.

Looking at doing a conversion of a mini carbine to a postie, years ago guys cut down full size receivers to make minis. More interested in can I chop a bolt and the top cover and mod a grip frame to make it all work with alittle welding ? Can it be done or do I “need” some original mini parts.
Thanks!

 

[slimshady]

Grip frame is the same on a full size and a mini. You can cut a section out of the topcover and weld it back together, but they are available. Bolt again requires a section cut out and rewelded. Also have to mill in the "feet" which usually requires modding the receiver to fit, making it an RR instead of a registered bolt. Or you could go with a closed bolt setup, if you don't mind the MG42-like rate of fire...

 

[Jones]

It can be done but having a few mini parts sure makes the project go faster, and with better results.
Go with a mini bolt. If you try to shorten a full-size bolt, you end up opening up the front of the ejection port because most of the excess length is in the front.
Mini top cover 'cause the relief for the ejection port is shifted slightly and won't line up. The sliding cover for the cocking knob slot needs to be shorter with a reduced width on the back end.
Mini repair section for he same reason; ejection port location is different.

This drwg is worth it's weight in gold when you I start laying out the pieces prior to welding.

https://ibb.co/YfX0rk2

 

[MrM4]

Excellent, thanks!

 

[rentprop1]

yeah just buy a mini top cover for $ 90 save yourself the hassle of trying to chop and weld one back together, you can chop a bolt and leave the front completely open its ugly but it works, feet are not necessary if you wanna be a cowboy

 

[NewHobby]

Start here. He sells top covers and lots of mini parts.
Reach out to him https://www.gunbroker.com/All/search?Sort=13&IncludeSellers=1666103&PageSize=30

 

[Jones]

Ditto to NewHobby's post. The guy was super helpful and he's the one I got the dime-as-spacer trick from. He also let me in on shortening and trimming the slot cover.

 

[trilogymac]

yeah just buy a mini top cover for $ 90 save yourself the hassle of trying to chop and weld one back together, you can chop a bolt and leave the front completely open its ugly but it works, feet are not necessary if you wanna be a cowboy

Ive thought about this bolt mod (open port) a lot in the past. I believe Dave mentioned once, that an engineer in Israel was doing it this way at one time. I even thought about taking a full size SMG open bolt, chopping it in this fashion and doing the mill work to turn it into a closed bolt. Its doable. No welding required! Im surprised you don't see more Registered full size bolts converted to mini/micro in this way.

My registered Micro bolt is a B&G made from a semi pistol bolt. Honestly, I think I would have preferred an open port converted full size. That way the welding of the feed lip could never be an issue.

I also think a skilled guy could chop a full size SMG bolt (open port) and leave feet on it if you really wanted an open bolt.
Lots of ways to skin that cat.

 

[CKxx]

Centerfire has some mini kits for sale right now.

 

[trilogymac]

Centerfire has some mini kits for sale right now.

Out of stock.

 

[slimshady]

Out of stock.

Yeah, took about 20 minutes I think.