BWE 22 bolt modification

[CKxx]

Hello,

Does anyone have any photos, measurements, weights, or other details or data on how Richard used to modify the UZI 22 conversion bolts to add weight? I understand some of the aluminum bolt is milled away and steel is added, but I'm interested to know how much steel (weight) was added, as well as dimensions of said plate. I'm contemplating modifying a kit I have here in a similar fashion.

Thank you.

This is the only photo I can find:

SAR UZI 22 ARTICLE

 

[Garrett]

That’s a fairly comprehensive article. I hadn’t read it before.

One comment, the article notes the original Subgun Ord kits had a firing rate of 875-900 RPM, and the BWE slowfire conversion reduces them to around 600 rpm.

Maybe the Vector kits were different, but I get anywhere from 844 rpm to 1094 rpm, depending on ammo. And I had the BWE slowfire conversion done on mine. I had not clocked it prior to sending it off, so I can’t say how much of a reduction the conversion provided.

Not that I’m complaining. I like this ROF in a .22 Uzi.

 

[SecondAmend]

Not my bolt; a photo from a source not remembered:

 

[CKxx]

Ah, very interesting. Thank you. There are 4 attachment points instead of 3, as pictured above.

If anyone is willing to remove the weight for measure, that would be great. (I don't know how well it's affixed, or if removal is possible.)

 

[K2]

Hi All,

With both weights in the Vector/Group kit running a 100 coil spring, mine runs at 740 RPM with the latest CCI Mini Mags.

Richard's first slow fire bolt ran as low as 675 RPM. I was not able to get my gun running reliably below 725 RPM.

The second weight goes in a cut-out in the bolt. It is captured between the bolt and bolt carrier. Group/Vector cut out some steel in the bolt. IMHO, Joe had it right by deleting that cut-out.

As usual, YMMV,

K2

 

[Garrett]

I get 10.72 oz on my Vector bolt.

Although it should be simple, I’m not keen to take apart my bolt. However, I can apply some math.

The steel insert is 6”x.75”x.125”. Using .283 lb/in^3 for a mass density of steel, I get .159 lb or 2.54 oz. for the added weight.

Using .055 lb/in^3 for a mass density of aluminum I get .055 lb or 0.88 oz for the mass of aluminum removed.

This gives a total added mass of .104 lb or 1.66 oz.

So an unmodified bolt should weigh around 9.1 oz. Can anyone verify the weight of an unmodified Vector bolt?

 

[ktk120]

my unmodified vector is showing 8.545 oz

 

[SecondAmend]

To assemble the heavy/slow fire Uzi .22 conversion bolt I have, I fastened several pinewood derby car underbody weight tungsten plates in the recesses on the sides of the bolt. Pretty low cost; and no machining, but some drilling and some tapping involved. I don't have the firing pin/extractor block or the sear plate installed on the bolt now, but IIRC, when installed the total weight was ~10.8 oz. I haven't shot it in five or six years, and didn't have a ROF meter at the time.