Mini or Full Size for my bolt? I cant decide

[Vmon]

Mini or Full size, I cannot decide. I am still debating which gun to build for my registered bolt. I do not want to cut the bolt down for the mini, just to find out that I would have been happier with a full size. I have fired a full size Uzi before but never fired the mini. I do not like the slow cyclic rate of a full size Uzi without the thicker buffer installed. Meanwhile, I also do not like the 1800+ rpm of a closed bolt mini, it's too much for me. I know some Mini's were made in an open bolt configuration which were supposed to have a slower rate of fire. So I would like to throw a few questions out there for anyone who has had experience with both; a full size and an open bolt mini.

Whats more fun to shoot?
What is a better investement?
What is more reliable?
What is the cyclic rate of an OPEN bolt Mini and how much less controlable is it than the full size?

I know its a lot of questions, but I really want to make the right choice so any feedback would be appreciated.

 

[RoverDave]

Mini's were made in open bolt and closed bolt. Most (if not all) of the registered Mini bolts are open bolts. If you have a registered receiver Mini (like a Vector), you can use either. An open bolt Mini runs about 1200 RPM, a closed bolt about 1800 RPM. Those rates can be adjusted to some degree if you modify buffers, springs and bolt weight.

The full size runs about 600 RPM but you can get it up to about 1000 RPM with a big buffer. At that speed you're close to open bolt mini speed. The full size will be easier to control due to size and weight, but I find my Mini easy to control. The Mini is hard to use in competition if you want to get singles, but for blasting it a hell of a lot of fun.

Reliability should be about the same. More accesories (.22 kits for example) are available for the full size. Investment tradeoff is anyone's guess. There are fewer Mini's around but more people seem to look for the full size. It's your guess what that's means in terms of future prices.

Personally, if you already have a full sized registered bolt, I wouldn't cut it down. Run it in full size for a while. If you don't like that, sell the whole thing and buy a Vector Mini.

 

[amphibian]

Roverdave offers some very good advice.
I agree that you should try the bolt in a full size for a while.
There was a guy that had a registered slotted bolt full size Uzi at the SMG match I go to and you could noticeably tell the ROF was faster due to the lighter weight of the slotted bolt.
I think a slotted registered MINI bolt would be approaching a pretty high ROF that sounds like you don't want.
If you do go the route of making it a MINI, I would recommend two things:
1. weld up the slot for increased weight
2. Mill the bolt so that it still has some small feet so that it will be reliable in stripping rounds off a fully loaded mag and still fit in a MINI with an UNmodified trunnion.

In regards to your questions:
Whats more fun to shoot?
That is like asking which car is more fun to drive. But for me its the MINI. I find my fullsize Uzi's kinda boring and very easy to shoot in 9mm. More fun in .45 but more expensive to feed also.

What is a better investement?
I think they are both good but I personally don't consider C3 to be an investment. I get what I want.

What is more reliable?
For me, they have been the same - both very reliable.

What is the cyclic rate of an OPEN bolt Mini and how much less controlable is it than the full size?
Roverdave already mentioned ROF's. I think with practice, you won't have any problems with the MINI.

I am now using my MINI for SMG competitions. I can singles out of my MINI most of the time with my custom weighted bolt.

 

[David Hineline]

I am

I am running a Open Bolt Mini SMG bolt in my Full Sized UZI. I like it a lot that way. faster rate of fire and less reciprocation mass. My Pact Timer is en route so no ROF data right now. The Open mini bolt with those sear legs sticking out front looks like a weak point to me, although I don't have enough time on this setup to see if they ever break.

 

[amphibian]

David,
I remember you posting about this before and I mentioned that if you put a MINI bolt in a full size Uzi, the cocking slot does not go back far enough to charge the bolt.

So I guess you had to either:
1. increase the length of the cocking slot
2. fabricate a special cocking lug for the topcover
3. charge the bolt by pushing it with your finger or something or taking the topcover off and charging the bolt
4. or ????

What did you end up doing?

I have a factory IMI closed bolt assembly for my MINI and have a MICRO on the way. I am considering milling out the MINI bolt for the MICRO's cocking lug since I can't locate a factory MICRO closed bolt assembly. This is actually what Vector is doing for the MICRO as they can't locate factory MICRO closed bolts either.
Since I have to change topcovers or remove the ratcheting pawl, I am considering making a longer cocking lug for the Closed bolt topcover.

BTW, I don't think you have anything to worry about with those feet. That bolt is pretty hard. It wore down the carbide mill used to bore a hole in one of my MINI bolts to make my "heavy" competition bolt. I highly doubt it could wear out.
Now I have seen a RR MICRO that had a bolt with feet in it that were VERY thin. I would say less than 1/16".

 

[Vmon]

Mini or full size

Well after listening to all of your opinions (thanks guys!) I decided to go with the Mini/Micro combination. Rex at Vector is going to cut my bolt down in a way so it will work in my pistol, as well as in my mini (I hope that B&G metal is as strong as Uzi metal for the sake of the sear feet). Rex is going to install a special cocking lug on the mini's top cover so it can chamber the micro bolt. He is also going to modify one of my 2 pistol lowers to select fire, so I have a SA lower left to switch the pistol back to SA while the bolt is not installed. I may even have a special lug made for the top cover on my full size Model A and go for the trifecta! My pistol does not have a stock, and both my full size and mini are registered as SBRs, so interchanging the bolt between all three guns will be perfectly legal as long as I install the SA lowers back on them when removing the registered bolt.

My only questiona are: Do the SA receivers/trunions on any of the three Uzi's have to be modified to properly accept the front feet of a mini/micro bolt? If, so does the rifle become an illegal machine gun when the bolt is not installed? If the gun does become an illegal machinegun, what can I do to prevent having to modify the receiver but to keep the gun functioning properly?

 

[Vmon]

Closed Bolt for Micro

Amphibian, why would you want to put a closed bolt in your Micro? The ROF must be insane! Wouldn't the micro be easier to control and be more reliable with an open bolt?

 

[davidl]

why can't vector build a weld on the bolt face, mill out a feed lip,then heat treat. like the old days.

 

[amphibian]

Re: Mini or full size

Rex is going to install a special cocking lug on the mini's top cover so it can chamber the micro bolt.

Vmon, I'm curious. Did you tell Rex my idea of making a special cocking lug or did he already do one?

I hope that B&G metal is as strong as Uzi metal for the sake of the sear feet

TMK, B&G never made any bolts. They registered factory IMI and Group bolts.

My only questiona are: Do the SA receivers/trunions on any of the three Uzi's have to be modified to properly accept the front feet of a mini/micro bolt? If, so does the rifle become an illegal machine gun when the bolt is not installed? If the gun does become an illegal machinegun, what can I do to prevent having to modify the receiver but to keep the gun functioning properly?

This is a long answer. I'll contact you off the boards with my number so you can call me if you want more details but here goes.

1.For the full size: no trunnion mods but then you can weld up that slot for extra weight for the MINI and MICRO application.

2. For the MINI: the trunnion would have to be relieved for a FACTORY IMI bolt but you should be able to make the feet more narrow and less tall than a factory IMI bolt and it will work.

3. For the MICRO/Pistol: I've seen a RR Uzi pistol at a Gun show that had very thin and small feet on the bolt. The seller also had a couple Uzi Pistols there. He let me take them both apart and compare the trunnions. The RR Uzi Pistols trunnion and the standard Uzi Pistol trunnions looked the same.
This distance between the receiver and trunnion is very small and the feet have to be very thin - too thin for my tastes.
But evidentally, someone figured that it was worth the effort to do this mod for that particular RR Uzi pistol. I would be concerned with them breaking.

Note that a factory MINI's receiver is shaped to accept the feet of the open bolt. The full size Uzi's are not shaped for this. In the case of the Vector MINI's which are cut downs from Full size Uzi's, Vector had to cut the receivers to allow the feet to poke through. On some of the Very early Vector MINI's, Vector just left the holes there and you wouldn't see them unless you looked down in the receiver or you removed the handguards to see them. Later Vector MINI's they welded over the holes.

So I'm guessing that if you had a registered bolt that had the feet for a MINI w/ an unmodified trunnion, it still may end up being kinda long and contacting the full size Uzi receiver.

But if you had the tiny feet like I've seen on that RR Uzi pistol then it make work on all three but then I'd be afraid of the feet breaking.

Amphibian, why would you want to put a closed bolt in your Micro? The ROF must be insane! Wouldn't the micro be easier to control and be more reliable with an open bolt?

I'm getting the MICRO since I want to have the entire Uzi family in FA.
I want to have my Uzi's in all the configurations that IMI actually sold/made. I'm almost there. I have the full size. I have the MINI in both open and closed bolt. TMK, the MICRO was only offered in CLOSED bolt so I want CLOSED bolt for collecting reasons mainly. (I'm sure it will see some occasional use)

Actually my RR Uzi Pistol is pretty unusual as it's receiver has been modified to accept the MINI bolt, as well as having cuts in the bottom of the receiver to use the CLOSED bolt method as used in the FIREPOWER publications book as seen in this pic below:
It came to me in Open bolt configuration though. So I plan on having my MICRO setup in 3 variations:
Open bolt,
FACTORY IMI Closed bolt
and the "FIREPOWER Publications" Closed bolt configuration which looks more reliable than the Factory one as long as the parts hold up.