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Posted: 3/26/2012 7:10:47 PM EDT
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Hello,
I'm accumulating parts to do my first build. I already own a left hand (LH) AR in .223/5/56, but would like an AR chambered in .22 that mimics it's big brother as closely as possible. But I'm stuck on one or two design issues that have me a bit puzzled and was hoping for some help. And please be gentle here. I am not an expert. Mechanically adept but by no means an AR/long-gun expert. So here goes: My understanding is that there are two design limitations in using a .22 conversion kit with a .223/5.56 gun. Though not show-stoppers, these design issues limit the performance of such conversions. And, understanding these points will make my build questions more clear. 1. There is a small diameter difference between a .22 and .223/5.56 barrel. This may affect performance versus a dedicated .22 rifle (note, this is not an issue for me, I was just being complete); 2. The dimensions of the chamber/feed assembly/etc., even when using a conversion kit (e.g. CMMG) with a .223/5.56 is sub-optimal. As I understand it, there is a gap between the tip of the round, and the beginning of the rifling of the .223/5.56 barrel that diminishes accuracy. Is this so? That is, are there these dimensional differences or does the conversion kit completely mitigate these differences. Here's the reason: I'd like to construct a Stag Arms-design LH .22LR AR to match my Stag Arms 3GL. I've got a Stag lower, will be installing a Geissle S3G trigger, an ambi safefy, basic stock, etc. No questions or issues here. Re the upper, I'm assuming I'd purchase a Stag Arms LH stripped upper, a .22LR left hand conversion kit from Stag as well, and a (likely Tac Solutions if they make them separately) 16" AR style barrel to fit the upper, and the rest of the odds and ends to complete the upper. The question is whether interfacing the Stag Arms LH .22 LH bolt/group to the .22 AR barrel will address this 'gap' issue (#2 above) or will the standard problem of .223/5.56 to .22 conversions remain. Also, will all of this work together? Am I missing something? Thanks, B P.S. Please no flames if I've got this wrong. Consider it a startup transient along the road to greater AR knowledge. P.P. S. And please no flames about wanting a LH AR. I know lots of lefties shoot right hander guns just as some americans drive British RH drive cars on U.S. roads. |
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I'm building a LH upper for my southpaw daughter to use. She asked for an AR (to my surprise and delight) but I want to get her one that's set up for a lefty.
Unless you run a dedicated 22LR barrel, the 22 conversions all have considerable jump-gap. Put a 22LR round next to a 5.56 round. The chamber adapter on a Ciener/CMMG style kit is totally free-bore for the length of the chamber adapter. That means all that space has no rifling, plus the normal lede on the 5.56 chamber before the rifling. In my experience the bore size and rifling "rate" on 5.56 are the bigger issues in terms of accuracy. 1/7 and 1/9 twist is just way to much spin for a soft lead .22 bullet and accuracy will suffer. My thinking is that I'm going to see if CMMG can set me up with a dedicated lefty 22lr barrel AND lefty conversion collar to go in a stag LH upper. THat's my first choice. It also is the answer to the question at the end of your post. Using a dedicated 22LR barrel, there is no "gap" before the rifling other than the correct throat for a .22LR shell –– plus the rate of twist (1:16) and groove diameter (.221) are sized for 22LR. But you have to use a "collar" (pic below) attached to the end of the conversion kit instead of the chamber insert. Unfortunately, no one I'm aware of makes the left handed version of that collar. The lefty kits at stag are just CMMG kits and they have a lefty chamber insert. 
I'll let you know what I hear from CMMG, btw. My second option will be to pick up a 16 barrel in 1:12 spin rifling, and use a left handed conversion with a chamber adapter. Not ideal, but workable, and I believe the rifling will be more important than the chamber lede gap or the slightly different barrel diameter. Still, not ideal. My "last" and least preferred option will be to use a 1:9 barrel on an "as built" stag lefty upper, but I'm trying to avoid that at the moment. |
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The left hand cmmg kit like this one can be made to
work as a dedicated kit if the 223 chamber adapter on it is converted to a collar. And a right hand dedicated 1:16 twist barrel can be converted to a lefty too. |
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Quoted:
The left hand cmmg kit like this one can be made to work as a dedicated kit if the 223 chamber adapter on it is converted to a collar. And a right hand dedicated 1:16 twist barrel can be converted to a lefty too. Funny you should post in this thread... I had intended to PM you based on some other posts to see what you would charge to do the conversion of a left handed chamber insert and machining the left side extractor groove on a dedicated 16" slim profile CMMG righty barrel? Also, I'm in the market for a 5 inch (very) slim profile 22LR barrel for an AR pistol build I am working on. (say .570 all the way from the ridge at the end of the piece serving as barrel extension to the muzzle. Any idea what the cost would be for such a beast? (A quote with and without threading for a muzzle device would be appreciated). Much thanks! |
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Thank you. This is very helpful. But let me make sure I am following you since you used some terms that weren't clear to me.
There is in fact an issue because of the cartridge length difference creating a significant gap for the .22lr to traverse. In addition, the rifling rate of a .223 is just non-optimal for a .22 so a 1:14 or so is best. Thus both can be solved by purchasing a .22lr-specific barrel designed to fit an AR upper. That will solve the 'gap' and spin rate issue. Re the left-hand thing, the barrel is not left- or right-handed so there's no issue there. But the bolt must be designed to be left-hand aware. I can either purchase the Stag .22lr BCG or there is something that can be done with a CMMG design? What would that be? (am I getting this right?) Thx, B Edit: looks like this is the right part to make this work with the Stag LH lower. I presume when is says: 'Only for use in 5.56 NATO chambered AR-15 rifles.' that references being used with a .223/5.56 upper (e.g. a Stag LH upper) and does not bear on whether there is a .22LR barrel installed in that upper? |
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Quoted:
Thank you. This is very helpful. But let me make sure I am following you since you used some terms that weren't clear to me. There is in fact an issue because of the cartridge length difference creating a significant gap for the .22lr to traverse. In addition, the rifling rate of a .223 is just non-optimal for a .22 so a 1:14 or so is best. Technically, the dedicated 22LR barrels will be 1:16. Thus both can be solved by purchasing a .22lr-specific barrel designed to fit an AR upper. That will solve the 'gap' and spin rate issue.
Re the left-hand thing, the barrel is not left- or right-handed so there's no issue there. Not quite correct. The dedicated 22LR barrels have an extractor cut. The way it works is the rear of the barrel has a .460 outer diameter nipple that fits through a collar that replaces the chamber insert on a normal conversion. Here's a pic –– see that little reduced diameter bit on the chamber side of the barrel? That fits through the collar, also pictured. 
When used with a right handed bolt conversion assembly and collar, this extractor cut is on the right side of the barrel (and the collar). To use it lefty, another cut would have to be made on the left. Very minor and obviously there are folks who do this sort of work. But the bolt must be designed to be left-hand aware. I can either purchase the Stag .22lr BCG or there is something that can be done with a CMMG design? What would that be?
My recollection is that CMMG makes the lefty bolt conversion assemblies for Stag. But in any case, the only existing left handed conversions use chamber inserts and no one sells (retail) left handed collars. The collar is different left to right not just in where the extractor cut is located –– this is because the rails in an AR15 22LR conversion are not on a level horizontal plane with the gun, but sort of offset (tilted diagonally left to right) to that everything can be included where the designer needed it. On a lefty set up in addition to the bolt being opposite of a righty bolt, this tilted set of rails is opposite. The poster above correctly pointed out that there are folks who can take the left handed chamber adapter and machine it into a left handed collar. I was happy to hear that and am myself interested in the cost of such a thing. (am I getting this right?)
Thx, B You're on the right track: To make the "best" lefty upper, you need: a. Lefty upper receiver. b. Dedicated 22LR barrel –– modified by addition of a left handed extractor cut. c. Lefty 22LR conversion kit –– modified by machining the included 5.56 chamber insert into a left-handed collar that would work with the left handed barrel and kit. d. The lower receiver of your choice. Edit: looks like this is the right part to make this work with the Stag LH lower. I presume when is says: 'Only for use in 5.56 NATO chambered AR-15 rifles.' that references being used with a .223/5.56 upper (e.g. a Stag LH upper) and does not bear on whether there is a .22LR barrel installed in that upper?
The lower you use is immaterial (although you should never build a pistol marked lower into a rifle or you kill your ability to ever use it in a pistol again –– that's a whole mess of ATF law that is generally irrelevant to your project). For my part, I don't like specific caliber marked lowers, however, and recommend you get the cheapest lower you can find for your 22LR project. They all work the same. For a lefty, you'll want to install an ambidextrous selector switch, and possibly the ambi magazine release–– which will allow push button style release by the left trigger finger. Lefties have to get use to simply using the charging handle to release the bolt. |
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Quoted:
Quoted:
Thank you. This is very helpful. But let me make sure I am following you since you used some terms that weren't clear to me. There is in fact an issue because of the cartridge length difference creating a significant gap for the .22lr to traverse. In addition, the rifling rate of a .223 is just non-optimal for a .22 so a 1:14 or so is best. Technically, the dedicated 22LR barrels will be 1:16. Thus both can be solved by purchasing a .22lr-specific barrel designed to fit an AR upper. That will solve the 'gap' and spin rate issue.
Re the left-hand thing, the barrel is not left- or right-handed so there's no issue there. Not quite correct. The dedicated 22LR barrels have an extractor cut. The way it works is the rear of the barrel has a .460 outer diameter nipple that fits through a collar that replaces the chamber insert on a normal conversion. Here's a pic –– see that little reduced diameter bit on the chamber side of the barrel? That fits through the collar, also pictured. http://tactical22.net/cmmg/cmmg_dedicated-22_ar15_barrel_and_adapter.jpghttp://www.bondcar.com/gunstuff/st22/polish_ramp.jpg When used with a right handed bolt conversion assembly and collar, this extractor cut is on the right side of the barrel (and the collar). To use it lefty, another cut would have to be made on the left. Very minor and obviously there are folks who do this sort of work.correct But the bolt must be designed to be left-hand aware. I can either purchase the Stag .22lr BCG or there is something that can be done with a CMMG design? What would that be?
My recollection is that CMMG makes the lefty bolt conversion assemblies for Stag. But in any case, the only existing left handed conversions use chamber inserts and no one sells (retail) left handed collars. The collar is different left to right not just in where the extractor cut is located –– this is because the rails in an AR15 22LR conversion are not on a level horizontal plane with the gun, but sort of offset (tilted diagonally left to right) to that everything can be included where the designer needed it. On a lefty set up in addition to the bolt being opposite of a righty bolt, this tilted set of rails is opposite. The poster above correctly pointed out that there are folks who can take the left handed chamber adapter and machine it into a left handed collar. I was happy to hear that and am myself interested in the cost of such a thing. (am I getting this right?)
Thx, B You're on the right track: To make the "best" lefty upper, you need: a. Lefty upper receiver. correct b. Dedicated 22LR barrel –– modified by addition of a left handed extractor cut. correct c. Lefty 22LR conversion kit –– modified by machining the included 5.56 chamber insert into a left-handed collar that would work with the left handed barrel and kit. correct d. The lower receiver of your choice. bingo! 
Edit: looks like this is the right part to make this work with the Stag LH lower. I presume when is says: 'Only for use in 5.56 NATO chambered AR-15 rifles.' that references being used with a .223/5.56 upper (e.g. a Stag LH upper) and does not bear on whether there is a .22LR barrel installed in that upper?
The lower you use is immaterial (although you should never build a pistol marked lower into a rifle or you kill your ability to ever use it in a pistol again –– that's a whole mess of ATF law that is generally irrelevant to your project). For my part, I don't like specific caliber marked lowers, however, and recommend you get the cheapest lower you can find for your 22LR project. They all work the same. For a lefty, you'll want to install an ambidextrous selector switch, and possibly the ambi magazine release–– which will allow push button style release by the left trigger finger. Lefties have to get use to simply using the charging handle to release the bolt. I posted a link to the left hand cmmg 22 kit with the 223 adapter that can be converted above. and yes I have done lefty's
And NagOrzo15-1 you mail box is full |
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This is extremely helpful. I'll reread a few more times and doubtfully will have a few more questions. The obvious one being where and by whom I can get the machining work done on the conversion kit part? Any idea how much that will cost me?
Also the price of barrels is (understandably) quite wide ranging. Since I'm interested in maintaining the feel of a 3G(L), I'll likely fork over the funds for a bull barrel. But, for .22 in an AR, does it actually make a noticeable difference in accuracy/repeatability? B |
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So a few weeks have passed since this last thread update. I have made only modest progress in that I've purchased all that is needed for the lower, and a Stag Arms LH upper. All vanilla stuff. But now the tricky part begins in that I'd like to spec out both the parts, and locate a competent machinist/gunsmith who can assist with the necessary changes to complete the project.
So, what do you all recommend for a barrel to fit to a standard AR upper? I'd like it to be a lightweight 16" design. I've been all over the web looking at barrels and vendors and presume that the only ones worth considering are 1/16. Should I just buy the lowest price one I can find? Or is there actually a difference in quality that an average person shooting from a bench rest will see? Then comes the bolt/carrier and extension. Who best to turn to here - acknowledging that I need this to be a LEFT HAND rifle? Finally, who do you recommend who could do the necessary machining of the barrel end, and the bolt extension to make this all viable? I really appreciate your help. Thanks in advance, B |
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Get Redtazdog make a left collar (he lights the collar the barrel turned for a tight fit).
Get a left the bolt (conversion kit, and left collar). Need a 6" file for the left extractor (5 minutes). You can work through the port. Barrels are the same ex LH extractor. Use the CMMG light barrel. Parts: barrel LH CMMG conversion kit LH collar from Redtazdog LH upper receiver ($180, I think) Thing else is "vanilla". |
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I got a left handed CMMG collar for sale if your interested., here's a link to my ad in the EE.
Left Handed Collar for sale |
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