AR15 / .22LR question

[Tony Wells]

OK guys....I know someone will be able to answer this.

I have a Colt AR15 that has a unknown make .22LR upper and we'll call it a "sliding, retractable" buttstock. The spring and buffer are what came with the conversion, but I an seeing a couple of things that make me suspicious. I get a stovepipe pretty often, and even more often, a round is chambered, but the rifle fails to cock, so no fire. I am beginning to think the buttstock bore that houses the spring is shorter than stock, and that changes the characteristics of the spring. If the blowback is not sufficient to recock the firing group, is this a possibility? If so, what to do about it? I do not have the original stock to get any measurements from.

 

[pdentrem]

No experience on this type of conversion. On my 1911, stove piping is an indicator of too heavy spring. Your idea of the spring maybe coil binding in the buttstock may be correct. This would also explain the bolt not moving far enough back to cock prior to the bolt returning to battery.
Pierre

 

[Tony Wells]

I've seen this on a 1911 also, mostly when handloading light loads for plinking. Hard to find a sweet spot to avoid chasing brass all over the place and stovepiping.

 

[george wilson]

My vote is also for too heavy a spring. I take it the rifle is clean and oiled?

 

[pdentrem]

Could also be ammo specific. Regular vs Hi-speed stuff.
Pierre

 

[Tony Wells]

Yes George, cleaned and oiled. Tried it cleaned and dry too, just for kicks. No difference. All of the conversion parts are almost new. This has been a problem from the beginning.

Pierre, I have tried a variety of ammunition. Some does slightly better, some much worse. I am getting convinced that it is the spring.

What to do about it, other than cut the spring..... Seems irreversible for some reason....
I could order a new spring and experiment with it I suppose.

 

[pdentrem]

Just some ideas, as my only experience is a friends Colt HBAR. I can hear that spring go boing fairly well in his.

How much does the spring expand as it is compressed. Is the larger diameter causing a rub condition in the spring tube? That would have an effect for sure. Rough surface? Any kind of drag will cause issues in the available power that the spring can provide to absorb and give back to finish the cycle. Since this is on a collapible stock, is there any kind of lip or parting flash etc that could grab the spring?

Was this kit made for that buttstock? Is there a difference in the lenght available inside the stock for the spring among different makers?

Does the spring have plain open ends or ground closed ends. If open then just remove a 1/4 turn or less at a time.

If you cut the spring back and it becomes too short, you can make or buy a new one or put in a spacer in the butt perhaps. Not the best idea I know but workable. Just think of the shock buffers used on the 1911s, they are simply .125" thick poly of some sort.
Pierre

 

[Morgan RedHawk]

Not for sure is a difference in spring diameters or not, but there might be and it could have something to do with the problem.

There are 2 flavors in buffer tubes when it comes to collapsible AR stocks. Mil spec and commercial. The mil spec tubes are 0.015" wider than the commercial. Have you tried it with the spring and buffer that came with the lower?

I was also wondering, are the spring and buffer that came with the kit for a collapsible stock or a regular stock? Have you tried the upper on a lower with a standard stock?

 

[Al 1]

Try a Remington viper 22 to see if it will cycle.

Al.

 

[Andre]

Try a Remington viper 22 to see if it will cycle.

Al.

Thats half the problem of all rimfire problems, bad ammo.

Try some wolf or SK ammo, more expensive, not high velocity, but great ammo. If it doesn't cycle with that, you need a lighter buffer spring.

Don't think you have to use high velocity ammo, half the fun of rimfire is it's quiet and lo recoil. HV stuff ruins rimfire for me.