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The Colt .22LR AR15/M16 Conversion Kit

This is a re-post from 2013 but because of this weeks theme of 22 rim fire used in the Ar15 I thought I would bring it back for those who hadn’t seen it.


I know I have talked a little bit about the old Colt produced .22LR conversion kit before, but it was not in much detail. I get asked about the conversion units often and they seem to be fairly rare these days.  I am not even sure how popular they used to be since commercial .223 and surplus 5.56 use to be so cheap.  So anyways, I thought I might talk about it a little more now.

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Sorry to say I can not nail down an exact date for when these things first started being produced, but I know I had seen them around for as far back as I can remember and bought one with my first AR15 way back when I was still young and supple. Above is a picture of a conversion kit still in its original plastic blister pack and shot only enough to confirm it works, which is maybe 20 rounds.  You can tell by the crappy art that it was from at least the early eighties.  Nothing on the paperwork even gives a hint of its starting  date of MFG.   The instruction with this one show it was made at least until the end of the 80s but I have no idea when they first made them.

The unit came with  1  magazines that holds ten rounds, the conversion bolt, a chamber plug and the instructions along with a manual for the AR15 of the time, a SP-2  sporter ( A2 ).

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This is actually one of two that I own.  Since it is mint, I do not shoot this one.  But, I do have a second one with spare magazines.  Since it comes with just one 10 rounder, things move a little slow. Though it would be enough for what I am sure they intended at the time of its release, i.e. teaching a kid or plinking at cans, hunting small game, or like me, a broke college student who could barely afford 22LR and had 30 rounds of 5.56 at any one time to my name.

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As you can see, the second kit is  more used and the two mags make shooting it move along a little better.  The mags are easy to load and are about as tough as a AK mag. No joke. They are solid hard plastic with metal  feed lips etc.  Its like a solid block of hard plastic.  You can see in the picture the size compared to a standard colt 20 round magazine.

I actually owned a third kit before these two and one of my best friends owned a kit as well.  All of them work great. I have never had a problem out of them. I remember my friend had a miss feed a time or two but once was from too low powered ammo and the other from a little too much heavy lube.  They work great and are very simple.  The bolt is hardened steel and a file would not make a mark I would rate its hardness just below Chinese algebra.

I did recently buy one of the 30 round mags made by Black Dog Machine and had high hopes only to find out the mag is a POS and BDM would not return my emails about their garbage product.  So, you won’t be seeing it in this post.

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In this picture above, you can see the little metal nub at the chamber end. That is where the charging handle catches to worth the “bolt” and chamber a round or to chamber check or for whatever other reason you may need.  It seems like its not enough and it probably isn’t but it is just a 22 and no one is going to be beating on it to clear a malfunction to save their life.  Its also as hard as wood pecker lips and I have never seen or even heard of one breaking. As a side note, many years ago DPMS copied this kit and sold one. No surprise there.. The end tab is just what you think it is.  The bolt rides on the two rails and it tracks very smoothly. You do feel the fouling of the rimfire after enough rounds but the springs and rails keep it moving great. Its easy to clean and maintain though colt does say absolutely not to take it apart. There really is not need to take it apart anyway. Its just so simple you see everything you need to clean and lube anyway. Brake parts cleaner and oil is all it really needs.  I knew another guy who  is one of those types who just HAS to take something apart. especially if the factory says not to.  He caused a few problems to the one he had but it still worked.

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The magazine does not have a bolt hold open, but its not really needed.  I suppose if you are super into training with a rimfire to simulate what you do with a 556 thats a down side, but with only 10 round mags and the kit being a rare item these days, I don’t care. I am not much  on using a 22 for training anyway. But that is just me.    You can see the steel feed lips. The mag has the ejector on it  on the rear left of the magazine.  It works well and the steel is hard enough.  The plastic nub in front keeps the magazine from going into the gun too far.  You can see a screw on the side of the mag, but it is not for taking it apart.   the mags have never failed me and as I said, they are very tough.  Though 10 rounds is boring for serious dirt shooter and tin can killers.

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I find it interesting the mags are marked “for M16/AR15”.  I do not know if the military ever bought any to supplement the kits they  used at the time, but it looks at least like colt hoped they would. Or, since people could buy a real M16 for just a few hundred more than a semi auto gun at the time, maybe they just marked it for those who may not have known the AR15 and the M16 are the same gun. Whatever the reason, its neat.

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Here is the kit beside its intended home.  The gun is older then the kit by a lot, but the SP-1 and SP2 is  what the kits probably saw the most use in.   As far as  accuracy, its not too bad in the older gun with a 1/12 twist.  Its good enough to hit a rabbit or squirrel out to around 20 yards. I find with good ammo, skeet are easy to hit out to 100 yards and sometimes 200 with really good ammo and some hold over.  Its not MOA  by no means and its less accurate in a barrel with a 1/7 twist, but its still a rabbit killer out to 100 and a ground hog killer to 150 yards or so when you get use to your hold over.  I have not shot it much beyond 150 yards in a barrel with a 1/7 twist.

Back in the late 90s and friend and I did try it in a Colt Accurized Rifle with a 24 inch SS barrel and a 1/9 twist. It was was accurate enough to hit a old stop sign out to 250 yards with a 18x scope on it adjusted for such or course,  If I recall, it would have been enough to keep it on a coyote sized animal 80 percent of the time.  That is not bad considering what the thing is really meant for.

it will work with some of the hotter standard velocity ammo, but they work best with the high velocity ammo.  Using proper ammo, the kits have never failed me.  If you can buy one for a decent price  I would go for it.   I know that there are very few spare mags floating around. Colt did sell them but not many.  If you do get a kit, it will be just with one mag. If you are offered the kit but no mag, I would pass. Its very, very hard to find a lone magazine for sale.  I would not even bother with trying to get a BDM magazine for it without expecting to have to send it back.  Some guys claim their BDM mag worked, but mine did not and since they would not even return any email I sent trying to get some help I would never recommend buying a kit with no mag and plan on using the BDM mag.

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