Modify a Mark III for Subsonics?

MicroGuy · Post by **MicroGuy** » Fri Oct 05, 2007 9:33 pm

I've heard of some people that have a problem with the Mark III cycling while using sub sonic ammo (with a can).

I was wondering, how hard would it be to modify the gun to work better with sub sonics?? Assuming that's all you'll shoot, or you'll have to go back to an un-modified gun to shoot regular ammo again.

Basically, weaker springs.

I guess the main spring, and probably the bolt spring. Of course the mainspring can't be too much weaker or it won't fire the cartridge.

Any suggestions? Ideas?

I'm going to be getting a can fairly soon. And don't know what I'll be using the most of. But it's just that I've heard from some people using sub-sonics that they don't cycle all the time, or at all in some guns.

Georgezilla · Post by **Georgezilla** » Fri Oct 05, 2007 10:21 pm

Well, to say for sure what I'd change I'd have to know what type of cycling problems the pistol is having while using the sub-sonics.
A few problems come to mind but I'd say the most probable is that the sub-sonics aren't pushing the bolt back far enough, in which case I'd just change the recoil spring.

What barrel are you planning on mounting the suppressor to?

Thinking about it, I can't really see a purpose using sub-sonics AND a suppressor with a .22. The suppressor basicly brings the sound down to the mechanical sounds of the pistol. That being said, I'm not sure why someone would want to use sub-sonics (which cost more in most cases) in a suppressed .22.

Post by **Bullseye** » Sat Oct 06, 2007 4:24 am

Buy a second recoil spring assembly and modify it just for using subsonic ammo. I'd start clipping spring coils until I get reliable cycling. Keep the modified spring assembly in a marked box or bag and swap it out only when you need to use it.

R,
Bullseye

MicroGuy · Post by **MicroGuy** » Sat Oct 06, 2007 5:28 pm

Georgezilla wrote: What barrel are you planning on mounting the suppressor to?

Thinking about it, I can't really see a purpose using sub-sonics AND a suppressor with a .22. The suppressor basicly brings the sound down to the mechanical sounds of the pistol. That being said, I'm not sure why someone would want to use sub-sonics (which cost more in most cases) in a suppressed .22.

I've got a Hunter with the 6 7/8" barrel on it that will have one attached to it. Then a little later I'll get a shorter Pac-lite for carrying around (camping)

The reason for using sub-sonics is with regular rounds, even though the silencer brings the sound level way down, you still get the super sonic crack down range (sounds like the crack of a whip).

With sub-sonics, you don't get that, much quieter.

I went to the silencer shoot the other weekend, and the difference was incredible.

MicroGuy · Post by **MicroGuy** » Sat Oct 06, 2007 5:30 pm

Bullseye wrote:Buy a second recoil spring assembly and modify it just for using subsonic ammo. I'd start clipping spring coils until I get reliable cycling. Keep the modified spring assembly in a marked box or bag and swap it out only when you need to use it.

R,
Bullseye

So, you think it would only be the recoil spring eh? I would have figured on the main spring since it's so much stronger (at least I thought it was).

But that would be a hard one to adjust.

Post by **Bullseye** » Sat Oct 06, 2007 5:48 pm

Once the hammer is cocked the mainspring pressure is negligible. The hammer locks into the cocked position fairly early in the ejection cycle. The recoil spring assembly provides the resistance to prevent the bolt from battering on the bolt stop and applies enough force to close the bolt fully on a new cartridge. I'd go slowly removing one or two coils at a time until I get the best cycling. Some people buy reduced power springs from companies like Wolff Gun Springs but then you have to remove the end from the recoil spring assembly and repeen it back on after the spring is replaced.

R,
Bullseye

bearandoldman · Post by **bearandoldman** » Sat Oct 06, 2007 8:02 pm

Remember teh originaly small radius that JMB had on the firing pin stop on a 1911, and the Army wanted it easuer to hanc\d cock so they put onm a larger radius. I seee some of the Ruger 10/22 shooter also radius the bolt face that cocks the hammer to make them run smoother also. Changin the radius greatly affects teh mechanical advantage of the bolt cocking the hammer. Mayb e this is the way to go with the pisto also, do not have abolt to loook at right now, everything ios put away and assembled at the time.

Georgezilla · Post by **Georgezilla** » Sat Oct 06, 2007 9:27 pm

I'm not sure what can you plan on getting, but with most of them wouldn't you need to get your barrel threaded? Just a thought, I know I wouldn't trust any of the smiths near me to do that

MicroGuy · Post by **MicroGuy** » Sat Oct 06, 2007 10:22 pm

Georgezilla wrote:I'm not sure what can you plan on getting, but with most of them wouldn't you need to get your barrel threaded? Just a thought, I know I wouldn't trust any of the smiths near me to do that

I'm not exactly sure what I'm getting yet either, probably an AAC Pilot.

And yep, has to be threaded. But there's plenty of places that do good work. I'm looking at Tornado Tech for doing it. He will thread the barrel, and add a "concealer" ring to protect the threads when the silencer isn't on there. And when it's on, you can't even tell it's been threaded.

MicroGuy · Post by **MicroGuy** » Sat Oct 06, 2007 10:41 pm

Bullseye wrote:Once the hammer is cocked the mainspring pressure is negligible. The hammer locks into the cocked position fairly early in the ejection cycle. The recoil spring assembly provides the resistance to prevent the bolt from battering on the bolt stop and applies enough force to close the bolt fully on a new cartridge. I'd go slowly removing one or two coils at a time until I get the best cycling. Some people buy reduced power springs from companies like Wolff Gun Springs but then you have to remove the end from the recoil spring assembly and repeen it back on after the spring is replaced.

R,
Bullseye

I would have expected the main spring to take the brunt of it from the cocking action.

That's just from judging the difference between cocking by hand, and pulling the bolt back when it's already cocked. Big difference.

But yeah, getting a whole spring assembly sounds like the way to go, IF I do it.

I tried some sub-sonic on the range today, and had more trouble with it than anything else I've shot through it.

But, I don't know for a fact that's because it was sub-sonic or not. I'll have to try it again a couple of times and get the same results before I blame it on the SS.

jjfunk · Post by **jjfunk** » Sun Oct 07, 2007 1:22 am

What kind of subsonic ammo are your trying? I have tried a few boxes in my MKIII512 and it hasn't balked once on cycling. Just wondering.

Post by **Bullseye** » Sun Oct 07, 2007 11:00 am

Let me pose this question instead - When the sub-sonic cartridge fails to eject is the hammer cocked or not? If the answer is yes but the casing is jammed in the breech, then the answer is the recoil spring tension. If the answer is no the hammer did not cock, then mainspring tension is the culprit.

R,
Bullseye

MicroGuy · Post by **MicroGuy** » Sun Oct 07, 2007 5:57 pm

Bullseye wrote:Let me pose this question instead - When the sub-sonic cartridge fails to eject is the hammer cocked or not? If the answer is yes but the casing is jammed in the breech, then the answer is the recoil spring tension. If the answer is no the hammer did not cock, then mainspring tension is the culprit.

R,
Bullseye

JJ, I was trying out some Remington I think it was, green box. Some I had for a little while and wanted to try on a different range.

Bullseye, I had several different problems, but a couple of times, I pulled the trigger and nothing. So I'm guessing it didn't cock. Strange because A) I've never had that many issue, or that many different issues, and B) it's never "not cocked" like that before. (assuming that's what it did).

I'd certainly try some different ammo before I go whacking springs. Just shooting it, and having those problems, and remembering some other thread about problems with SS ammo, just got me to thinking.

instead of fighting it, IF it did cause a problem, why not modify it so it would work better. Being a simple gun there's not much you'd have to do

But I'd certainly try different ammo first. I only got those because they were there at the time and for just over a dollar a box. I do like the Sniper Sub-Sonics, but I'm not sure I can use them in the can I get.

Post by **Bullseye** » Mon Oct 08, 2007 7:01 am

When nothing happens try retracting the bolt, you can easily tell if the hammer did not cock by the tension of the bolt. Trying out different ammo is also a good idea.

R,
Bullseye

MicroGuy · Post by **MicroGuy** » Mon Oct 08, 2007 3:31 pm

Bullseye wrote:When nothing happens try retracting the bolt, you can easily tell if the hammer did not cock by the tension of the bolt. Trying out different ammo is also a good idea.

R,
Bullseye

Yeah, had I known I would have had that many problems I would have paid more attention to what was going on. But as it was, I didn't, I was just more concerned with shooting. Next time, I'll pay more attention to it.