22LR Conversion Kit Tuning Procedures.

BWE Firearms

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The following is a joint work in progress between K2 and myself. I hope it helps.

This is an attempt to help get more Uzi F/A 22 conversion kits running. The sequence of adjustments is important. About 70% of the guns can benefit from tuning. Think finesse as opposed to brute force when tuning! Any operation that uses live ammo shall only be performed without a barrel in the gun.

Step 1: 22 conversion bolt - Verify that the steel sear surface is not loose in the bolt. Repair as necessary. Examine the sear surface of the bolt for a raised burr on the bottom surface. Remove the burr if it is present. Examine the 22 extractor. It should be tight on the firing pin/breach face insert. This may be tightened by removing the extractor and gently tapping (with a small hammer) the legs of the extractor together. This can be done several times before the extractor cracks & fails. Before reinstalling the extractor break all the edges that project ahead of the bolt face. Be careful around the hook of the extractor. The edges just need to be broken enough so the so they are not sharp.

Step 2: Bolt friction in the receiver. - Remove the 9mm barrel, bolt, and recoil spring. Drop the 22 bolt into the receiver w/o the top cover or recoil spring. With the fire select on F/A, pull and hold the trigger with one hand while cycling the bolt with the other hand. There should be no binding felt at all while moving the bolt. Remedy any binding or interference. Frequently the muzzle end of the ejection port cut on the receiver hangs on the bolt. Do not file or grind your receiver. Carefully bending of the receiver to the desired shape should be performed.

Step 3: Top Cover – Top cover/bolt fit is important in a 22 conversion kit. A sloppy top cover can keep the extractor from working correctly. Adjust the top cover for a minimum bolt/top cover clearance. Do not test this with ammo or a magazine in the gun! Verify that there is no binding by installing the 22 bolt & top cover without the recoil spring. Set the fire select to F/A and pull the trigger. Tip the muzzle down and up. The bolt must slide freely all the way forward and back w/o binding.

Step4: Extractor Height – Apply layout dye to the extractor grooves in the 22 barrel. Install the 22 barrel, 22 bolt, recoil spring, and top cover. Cycle the bolt and read the wear marks in the extractor groove on the barrel. Shim the firing pin/bolt face insert (if required) to center the extractor in the barrel extractor groove. The shim pack (if required) is normally between .005” and .012”.

Step 5: Feed Ramp - If after adjusting your extractor height the bolt hits the surface between the feed ramp and the chamber you will need to have this area clearanced just enough so the bolt clears. The top and bottom edges of the feed ramp should be radiused and the sharp edge of the chamber should be slightly chamfered and polished so it doesn't shave the bullet as it is feeding into the chamber.

Step 6: 9mm Ejector – With the bolt, barrel and top cover removed, insert a 22 magazine with several rounds in it. Verify that the 9mm ejector doesn't strike the rim of the 22 cartridge in the magazine. If it does, trim the nose of the 9mm ejector back until the rim just clears. Keep the 9mm ejector face perpendicular to the bore axis.

Step 7: Recoil Spring – A dedicated 22 recoil spring is often necessary. Verify that the guide rod in the spring is straight. This can be done in a lathe or remove the rod from the recoil assembly and roll it on a flat surface. Most kits will benefit from a reduced spring coil count also. Coil count is not a really good way to measure spring force but it is a start. 100 active coils is a good starting point. For BWE Slow-fire kits, it is easy to verify the spring force. Set the spring “buffer” on a table with the spring vertical and set the bolt in place on the spring. The end of the guide rod should be even with the front of the bolt. If it sticks out, you may have cut too many coils from the spring. If it doesn't come flush, carefully cut coils until the guide rod is flush with the end of the BWE Slow-fire bolt. This is only a guide. Some guns need more or less spring to run. (Hot ammo, M-22, Dynapoint & CCI etc., are easy to get running. Federal bulk can take some careful tuning.)

Step 8: Magazine Height – Install the 22 bolt w/o recoil spring. Remove the spring and follower from your 22 magazine. Insert the magazine into the gun. With the magazine pulled down onto the mag catch, verify that the 22 extractor and “stripper” (the portion of the bolt that strips the round from the magazine) clears the feed lips on the magazine. This distance is normally set to 0.020”. To adjust the magazine height, bend the tab on the mag catch that engages the magazine slightly upward or downward. (The magazine release on the Uzi is regenerative. In other words the magazine must move upward before it can move downward. This will limit how much you can raise the magazine by bending the tab that engages the magazine. You know when you have gone to far when you can not remove the magazine as the stops on the magazine hit the bottom of the grip assembly before you get the mag released!) 9X19 is normally not effected by slight changes in magazine height. 22RF is not as tolerant.

Step 9: Lubricants, The Gun – I have had the best luck with Teflon based lubricants. Apply sparingly on clean surfaces. If a dry towel wipe is used to clean out the powder residue in the gun, re-lube is not necessary each cleaning.

Step 10: Lubricants, The Magazine –Clean & dry the inside of the magazine by pushing patches of paper towel or your favorite cleaning patch. Spray a little Teflon lube on a patch and run it threw the magazine. You want a very thin film of lube on the inside of the magazine. If subsequent cleanings are done with a dry patch to get powder and lead shavings from the magazine, re-lube is not required unless sticking occurs.
 
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tsonda4570

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at step #4 My problem seems to be that when assembled the extractor hits above the extractor grooves. Step # 3 however is performed without a hitch. I have not yet cut a spring down, could that be the issue? Nor did I check to see if it was straight yet.

When you install the .22 extractor there should be no gap between the bolt body and the extractor correct?
 

K2

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Hi,

If the extractor hits above the extractor groove in the barrel (and you have the extractor installed correctly), shims must be added between the bolt body and the extractor/firing pin subassembly. (Take out the 2 screws that hold the extractor/firing pin into the bolt to get the shims in.) I can post some pictures tonight if you like.

Good Luck,

K2
 

tsonda4570

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Photos would be appreciated. I will try and post some as well. I may have the extractor installed incorrectly, hard to tell from the photos I have seen on the internet.
 

BWE Firearms

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As stated in step 4 you need to place shims between the firing pin/bolt face insert and the aluminum bolt body to center the extractor in the barrel extractor groove.
 

tsonda4570

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I will try and find dye tomorrow. Thanks

eta
I changed the spring and it seems to be fitting in the barrel extractor groove now.
 
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K2

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Adding shims

Hi Everyone,

I figure I'll post a few pictures on shimming the firing pin/extractor assembly into the 22 bolt. The shims are easily cut with a good pair of scissors and a paper hole punch, and a clean, empty aluminum soda can. I start by cutting a nice clean square about 2" x 3" from the can w/o wrinkling the aluminum. You will see what the shims look like in a bit.

1.) Remove the firing pin/extractor assembly from the 22 bolt by removing the 2 SHCS's from the top of the 22 bolt. Normally these have a bunch of loctite on them but don't worry about cleaning them up just yet.

remove_screws_small.jpg


boltface_out_small.jpg

2.) Cut out shims that look like the ones in the picture. Depending on how high your extractor is in the extractor groove, add shims 'till the extractor is centered in the groove.

INSTALL_SHIM_SMALL.jpg
.

3.) Install the firing pin/extractor assembly back into the bolt and snug up the screws. Note the location of the shim under the firing pin/extractor assembly.

Oops, only three pictures per post. I'll post one more in the next frame?



Take it out to the range for a test drive. If it works well and the extractor rides where it should, I take the screws back out and loctite them back into the bolt.

Enjoy,

K2
 
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K2

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Assembled Bolt W/Shim

See the shim.

Hope this helps,

K2

shim_installed_small.jpg
 

edo-artneon

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Greetings all...

I have been away from this site for quite a while now and now is the time to get my IMI .22 conversion kit running in my Uzi model A. First of all my Model A is a semi build with a blocking bar installed. The bolt is a registered postie with a groove cut in it to operate with the blocking bar. First of all, did IMI make 2 .22 conversion kits, one for FA and one for Semi? I think I may be on the wrong track if I have the wrong kit for my application. It would help me a lot if someone could straighten me out on my questions above/. Thanks for any help on this.

Ed Biggar

Biggar Custom Mfg. Draper,VA. 24324

276 620 8595
 

Warren

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.22 Conversion Spring Tuning and Runaway

Post #1 in this thread talks about removing coils from a recoil spring. That pretty much confirms what I was thinking.

Years ago when I bought a Vector .22 cal conversion kit for my FA Vector Uzi, it came with a recoil spring assembly. The written instruction sheet said to use the regular 9mm recoil spring assembly with the .22 conversion and only use the spring that came with the conversion kit if the regular 9mm spring caused the .22 to runaway fire.

So, is the spring that came with the conversion kit lighter or heavier? I'm thinking lighter than the 9mm spring.

My theory is this: A too-heavy spring might allow the bolt to recoil only far enough to eject a round and feed a new round, but not far enough to allow the sear to re-engage the bolt.

I can think of no theory that would explain how a too-light recoil spring might permit runaway. Thus, I reason that the kit spring must be somewhat lighter than a standard 9mm spring.

Is my theorizing correct? Or is there another explanation for how a recoil spring could allow runaway?
 
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K2

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Hi Warren,

The spring that came with the Vector 22 conversions was lighter (it had fewer coils) than a stock 9mm recoil spring. The Vector spring appears to be a standard spring w/coils removed resulting in a weaker spring. The balance you aim for is a recoil spring that will have enough force to have the bolt strip rounds, chamber, and fire with low enough force so the fired round can push the bolt back far enough to catch on the sear.

Enjoy,

K2
 

Warren

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As stated in step 4 you need to place shims between the firing pin/bolt face insert and the aluminum bolt body to center the extractor in the barrel extractor groove.
How "centered" does it have to be? In mine, the extractor touches neither the top nor the bottom of the groove (leaves no dye mark) but does not appear exactly centered in the extractor groove (near as I can tell by peering into the mechanism).
 

SecondAmend

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"Chasing" the chamber with a .22 LR finish reamer may improve feeding and extraction.
 

Naginata5

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I picked up a last generation vector kit and put it in my IMI. I walked through the tuning instructions and the only thing I found was the extractor was a little loose so I tightened it up. It came with black dog mags and 90% of them will not feed the last 3 round and the amount of rimlocks are ridiculous. Is it possible the mags need to be rebuilt, or is there another issue?
 

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