Observations in shooting my 15-22 as an SBR

[RedNeck Jim]

I have posted some of my concerns in other threads but wanted to start over fresh.

Once I decided to SBR my 15-22, I did some research here and a prevailing thought was a 4.5" barrel was the best, for the main reason such a short barrel would allow one to use easier to find high velocity ammo, with it still staying subsonic. Logic being, such a short, pistol length barrel, would not allow HV ammo to get up to the speed of sound... as it normally would. This would give the SBR a nice advantage as it could shoot any 22lr ammo and not have to worry about the sonic crack.

So I sent my barrel off to Adco and had it cut down to 4.5" and threaded to the specs for a Sparrow. Looks nice but danged if I don't have failures to fire. Seems when I shoot subsonic rounds thru it, such as Norma or CCI SV, I get multiple failures per magazine. Lately after the first shot, the next round loads but the gun fails to fire. I assume that means the trigger is not being reset.

I have a spare 15-22, so in testing I have tried all sorts of things, such as cleaning out the firing pin channel & even swapping in the new bolt assembly. No matter what I do or try, subsonic ammo will not always reset the trigger. A few weeks ago I put the 16" barrel onto the SBR gun and since then have had no failures. I have shot well over 500 rounds lately with not a single failure. So today I brought down the 4.5" barrel & its handguard & installed them back onto the SBR rifle. First magazine was CCI SV and the gun shot once but the trigger again failed to reset. Thinking subsonic ammo didn't have enough power to reset the trigger when used with such a short barrel, I then switched to CCI Mini-Mag HV ammo, and then the gun performed flawlessly again.

So seems to me, with my setup, subsonic ammo will not work properly with such a short barrel. Guess I could continue to use it with HV ammo but sure seems considerably louder when firing it plus every few rounds one is very loud... like it is going supersonic.

I use a CMC trigger & keep my gun properly cleaned. Originally some around here thought the issue was with the bolt or firing pin but after all my tests, I know that is not the case. When I drop in the 16" barrel everything works perfectly, as my gun always has. Drop in the 4.5" barrel and the gun fails with SV ammo.

Anyone else has issues with such a short barrel? You notice when shooting HV ammo that it is louder than when using a 16" barrel and subsonic ammo? You have any of your HV ammo going supersonic thru the 4.5" barrel?

So for now I am back to shooting with the 16" barrel. Maybe one day I can swap barrels with someone who wants a 4.5" barrel so that I can try again at say 10" or so.

 

[strobro32]

Q #1. Anyone else has issues with such a short barrel?

Q #2. You notice when shooting HV ammo that it is louder than when using a 16" barrel and subsonic ammo?

Q #3. You have any of your HV ammo going supersonic thru the 4.5" barrel?

Maybe one day I can swap barrels with someone who wants a 4.5" barrel so that I can try again at say 10" or so.

A #1. I have not experianced problems because I use the JP reduced hammer springs. I was considering milling some weight off the bolt like S&W did with the 15-22P.

JP Enterprises Trigger Spring Kit AR-15 3-1/2 lb Reduced Power

A. #2. Yes. HV is louder with the 4.5" barrel too.

Remington Golden Bullet has more powder and creates bolt bark and the cases rupture more often. Remington subsonic is under powered and the case fails to seal against the chamber so it is louder than any other subsonic ammo I've tried.

A #3. Not with anything I've tried. I've heard that Stingers might. I did loose velocity but not accuracy with CCI Standard Velocity ammo. I do not run "subsonic" ammo as Standard Velocity or Match ammo is subsonic.

I love making firearms smaller and quieter. For those who tweak firearms, we know new problems will come up. It's part of the challenge. We enjoy problem solving.

I would trade you a standard barrel in a heart beat if I had one. Sorry for your problems. I've always enjoyed reading your post with the bump stock.

Did you try the bump fire stock on the 4.5" barrel?

 

[RedNeck Jim]

I contacted S&W about purchasing a new barrel but they don't sell them. However if I send the gun in, they will replace the 4.5" barrel with a 16".

Seems odd to do it that way as I was prepared to purchase the barrel. But then again, they may charge for this. I have no idea but will find out pretty soon.

 

[ChattanoogaPhil]

Have you tried the stock FCG in the SBR?

If you want to try the JP springs PM me and I'll drop them in the mail.

 

[dullh]

I too have an SBR 15-22 (the one in my avatar) but with a 5" barrel and I also have the CMC trigger. Every other magazine or so, I chamber the first round out of the magazine and the second round won't be picked up and chambered...once I get that round chambered by hand, all subsequent rounds chamber and fire no problem. Ammo used is Norma Tac-22...

This is the only trouble I encountered...except for my new (in jail) Warlock not threading onto my barrel...the other jailed cans (Sparrow and TacSol Cascade) thread on perfectly...

 

[RedNeck Jim]

Have you tried the stock FCG in the SBR?

If you want to try the JP springs PM me and I'll drop them in the mail.

I haven't but maybe I'll give that a try. If that helps I'll get with you on the springs or are you saying adding the springs might help the issue? Or do they simply lighten trigger pull?

I wish more folks that shoot the 15-22 SBR would tell their experiences. What length barrel, what FCG & if they have any added issues because of the shorter barrel. My 15-22 with CMC trigger just never, ever fails with a 16" barrel. Granted, I only shoot the good stuff, such as the Norma & CCI but soon as I switch to the 4.5" barrel, I have failures.

 

[RedNeck Jim]

I too have an SBR 15-22 (the one in my avatar) but with a 5" barrel and I also have the CMC trigger. Every other magazine or so, I chamber the first round out of the magazine and the second round won't be picked up and chambered...once I get that round chambered by hand, all subsequent rounds chamber and fire no problem. Ammo used is Norma Tac-22...

That happens to me too & curious what is up with that? 2nd round will not fire, no matter what magazine used.

 

[ChattanoogaPhil]

I haven't but maybe I'll give that a try. If that helps I'll get with you on the springs or are you saying adding the springs might help the issue? Or do they simply lighten trigger pull?

I wish more folks that shoot the 15-22 SBR would tell their experiences. What length barrel, what FCG & if they have any added issues because of the shorter barrel. My 15-22 with CMC trigger just never, ever fails with a 16" barrel. Granted, I only shoot the good stuff, such as the Norma & CCI but soon as I switch to the 4.5" barrel, I have failures.

The JP springs should offer a bit less resistance against the bolt moving reward. Since the issue seems to be not quite enough blowback umph with the shorter barrel, they might help.

 

[BigWaylon]

Every other magazine or so, I chamber the first round out of the magazine and the second round won't be picked up and chambered...once I get that round chambered by hand, all subsequent rounds chamber and fire no problem.

That happens to me too & curious what is up with that? 2nd round will not fire, no matter what magazine used.

Is that happening only with full mags? Or is the 2nd round no matter what?

Can you narrow it down to a specific mag, or couple of mags? If they're 25rd, does the same problem happen if you just load 20? What if you just load 2-3?

 

[telero]

The JP springs should offer a bit less resistance against the bolt moving reward. Since the issue seems to be not quite enough blowback umph with the shorter barrel, they might help.

JP springs can't be used with the CMC trigger though. Unless he's willing to change to another trigger that uses a standard spring set, using the JP springs won't be an option. And with how much he seems to like the CMC, I'm guessing he won't change, even if it would lead to better reliability with the short barrel.

 

[RedNeck Jim]

JP springs can't be used with the CMC trigger though. Unless he's willing to change to another trigger that uses a standard spring set, using the JP springs won't be an option. And with how much he seems to like the CMC, I'm guessing he won't change, even if it would lead to better reliability with the short barrel.

Phil initially mentioned trying the stock FCG and to use the JP springs with it. I have my original FCG plus have a spare 15-22 with stock FCG.

As you state, I have my doubts if I will like going back to a stock FCG, even with the JP springs. But who knows & testing it out will be interesting.

 

[jbarchitect68]

You may find this info interesting.
I used an Innovative Arms 4.5” barrel with silencer for this testing. I did a little research and it seems a silencer does not have an appreciable effect on velocity although I did not test without the silencer.
So here are the chrono results for Federal Champion 22LR 36grain listed as 1260fps:
1055, 1083, 1089, 1130, 1111, 1041, 1077 (the rounds over 1100 had a louder crack but all the rounds had some noise that prevented me from hearing the bullet hit the dirt)
Here are the chrono results for CCI SV 40grain listed at 1070fps:
865, 914, 878, 883, 870 (these were obviously more quiet and I heard the bullet hit the backdrop each time)

Both brands cycled the action without a hitch and I have a CMC trigger too.

Did you shoot your with the Sparrow or is it just threaded for one?
Maybe some backpressure from the silencer is what you need.

 

[RedNeck Jim]

Did you shoot your with the Sparrow or is it just threaded for one?
Maybe some backpressure from the silencer is what you need.

Always shoot suppressed with the Sparrow.

Your test matches up to what I have been hearing when I shoot. The HV ammo is rather loud, much louder than subsonic, plus occasionally some appear to give off the sonic crack. They might not do so in the summer but seem to do so when chilly.

 

[little_airwolf]

We arent allowed suppressors in Canada. So I went with a 10" barrel for less weight.
I hope it wont be crazy loud with SV ammo.

 

[RedNeck Jim]

We arent allowed suppressors in Canada. So I went with a 10" barrel for less weight.
I hope it wont be crazy loud with SV ammo.

It is loud... relatively speaking. Just got done shooting using the Norma subsonic ammo, and let off a few shots without the suppressor. Was so loud, almost wet my pants. Was not wearing hearing protection, as not needed with the suppressor.

 

[RedNeck Jim]

Have you tried the stock FCG in the SBR?

Well it is a beautiful day here, in the upper 50s without a cloud in the sky, so I took a half day off work to do some tests. I'm still confused.

So I started shooting the 4.5" barrel using the stock FCG. Trigger felt surprisingly good but on first two magazines, the second round would not fire. The trigger did not reset after the first round and the gun would not go to safe. Rack in a new round & in both situations, all other rounds went off perfectly. Then the next 4 magazines shot perfectly.

So went to the house to reload those magazines & get some more. Before trying the CMC trigger, I decided to try a magazine with just 5 rounds in it & danged if I didn't get the same failure on the 2nd round. Odd thing is, the next 6 magazines with the CMC trigger fired perfectly.

So I'm wondering something. Why is the 2nd round not resetting the trigger? Has to be something to do with not enough pressure, as when I shoot HV ammo, I have no issues, but why on the 2nd round with subsonics? I have a theory & it might explain my results. I know many suppressors, such as the Sparrow have a noticeable first round pop (FRP), especially when shot using a pistol barrel. I get almost none with a 16" barrel but on my pistols & this SBR, it is noticeable. So I wonder if whatever causes the FRP, which I think has to do with more oxygen inside the suppressor, could likewise cause less back pressure? Might also explain why the problem went away after the first 2 magazines, as I was shooting rather quickly with quick magazine changes.

I did note, on my second trip down today to shoot, that the FRP was loud on the first shot on that magazine with 5 rounds in it. And as I stated, I did get a failure to reset the trigger on that shot.

This make any sense or anyone have any other ideas? I think next time I shoot, I'm gonna try squirting some water in the suppressor to see if I can remove the FRP and to see if that allows the trigger to reset.

 

[BigWaylon]

So I'm wondering something. Why is the 2nd round not resetting the trigger? Has to be something to do with not enough pressure, as when I shoot HV ammo, I have no issues, but why on the 2nd round with subsonics? I have a theory & it might explain my results. I know many suppressors, such as the Sparrow have a noticeable first round pop (FRP), especially when shot using a pistol barrel. I get almost none with a 16" barrel but on my pistols & this SBR, it is noticeable. So I wonder if whatever causes the FRP, which I think has to do with more oxygen inside the suppressor, could likewise cause less back pressure? Might also explain why the problem went away after the first 2 magazines, as I was shooting rather quickly with quick magazine changes.

FRP is caused by the oxygen in the can. After the first "explosion" it's usually burnt up. I don't remember enough from honors physics 20 years ago to tell you if that would cause the problems your having or not.

In case you missed it, I asked a question earlier about the 2nd round not loading. If you don't mind, will you scroll back and answer it? (The one about full mag vs partially loaded mag)

 

[RedNeck Jim]

In case you missed it, I asked a question earlier about the 2nd round not loading. If you don't mind, will you scroll back and answer it? (The one about full mag vs partially loaded mag)

I have not had an issue with loading, only with the trigger not resetting. I saw your question and that is why I stated I ran a test with 5 rounds in the magazine. As I stated, I had a failure to reset after that 1st round.

 

[ChattanoogaPhil]

That's interesting.
What does it do without the can?

 

[RedNeck Jim]

FRP is caused by the oxygen in the can. After the first "explosion" it's usually burnt up. I don't remember enough from honors physics 20 years ago to tell you if that would cause the problems your having or not.

I went back & looked at your video from your SBR project, where we noted the FRP on your first round shot suppressed. When looking at your video, there is obviously a lot of "energy" leaving the suppressor as opposed to the following rounds.