Converting to a Radial Delayed Blowback PCC Upper

[calicojack]

I have a "can I get there from here" question;

Can I simply replace the BCG, buffer, and spring in my Foxtrot Mike AR9 with a CMMG bolt, and standard buffer and spring, or do I also need a new barrel?

[EDIT] Screw the conversion - I'll just get another PCC or perhaps a braced pistol.

 

[Gcs7th]

No you need the new barrel, it has lugs one it similar to a standard AR15 barrel extension.

 

[teratos]

I have a "can I get there from here" question;

Can I simply replace the BCG, buffer, and spring in my Foxtrot Mike AR9 with a CMMG bolt, and standard buffer and spring, or do I also need a new barrel?

You need the barrel. The barrel extension is part of the RDB mechanism.

Your other option is this:

https://coreys28.sg-host.com/product/cap/

 

[calicojack]

You need the barrel. The barrel extension is part of the RDB mechanism.

Your other option is this:

https://coreys28.sg-host.com/product/cap/

I'll think about that one; might be cheaper than building a new upper. If I could build a new CMMG upper that would give me a 29" OAL, I would love to SBR the thing. Alas, it looks like these are 8" barrels though.

 

[teratos]

I'll think about that one; might be cheaper than building a new upper. If I could build a new CMMG upper that would give me a 29" OAL, I would love to SBR the thing. Alas, it looks like these are 8" barrels though.

Permanently attached flash hider/mount/suppressor.

 

[calicojack]

Permanently attached flash hider/mount/suppressor.

Yes, that would work. Ok.

 

[teratos]

Yes, that would work. Ok.

Stick with me, kid. I’ll help drain your bank account.

 

[calicojack]

You need the barrel. The barrel extension is part of the RDB mechanism.

Your other option is this:

https://coreys28.sg-host.com/product/cap/

At least this option is in stock. The CMMG parts seems to be hard to come by.

 

[calicojack]

Stick with me, kid. I’ll help drain your bank account.

Yeah, you and countless others around here.

 

[teratos]

At least this option is in stock. The CMMG parts seems to be hard to come by.

Yeah. Outrider has been waiting for his order for months.

 

[calicojack]

Teratos, have you successfully run the Scheel option?

 

[teratos]

Teratos, have you successfully run the Scheel option?

I have played with it very little. Going out to play today with all the parts and springs. I’ll give a range report this afternoon.

 

[calicojack]

Ok - even better; I found a 45 ACP CMMG BCG and barrel in stock (with $18 off) that will eventually go on a new SBR; hopefully just in time for the new 45 can due next Summer!

[EDIT] $18, wow, I can get gas for the lawn mower!

 

[John from MD]

You need the barrel. The barrel extension is part of the RDB mechanism.

Your other option is this:

https://coreys28.sg-host.com/product/cap/

That looks like a cost effective way of converting an existing platform. Do any MDS members use one?

 

[teratos]

That looks like a cost effective way of converting an existing platform. Do any MDS members use one?

Playing with it right now. I’ve been going nuts with this thing. I figured it out, and I’m a f’ing idiot. I was playing with a RDB system before this and that requires you to take out the ejector on a Colt pattern lower. Guess what homeboy forgot to put back in?

This thing runs great.

 

[John from MD]

Are the little springs different weights for the rollers? More importantly, does it reduce muzzle climb and felt recoil?

 

[erwos]

Keep in mind that not all lowers play well with RDB uppers. Some people get lucky, but there's no guarantee everyone will.

Glad to hear the Scheel's system is running well, I might give it a try in my loaner PCC... did you take the weight out of the bolt group?

 

[teratos]

Are the little springs different weights for the rollers? More importantly, does it reduce muzzle climb and felt recoil?

There are 4 slots for springs in the buffer. It comes with 4 weak and 4 strong. There are 4 holes where the springs go. I went with the factory set up (1 weak, 1 strong) and it works great. I may play with those some more. Marked reduction in recoil/muzzle climb compared to a straight blowback. I went from a 9 ounce tungsten buffer/.308 spring to taking the weight out of my 9mm BCG and using the included system. Huge difference.

Glad to hear the Scheel's system is running well, I might give it a try in my loaner PCC... did you take the weight out of the bolt group?

I did take the weight out. It’s a different gun. VERY happy. Now that I have the system working, time to take it apart, and polish what I can.

I’ve put a lot of time into recoil reduction on 9mm carbines. I need to get the RDB system out with this side by side. RDB is great for Glock pattern guns. This is a great alternative. I really wanted something to run in a Colt pattern lower, because I have a Colt pattern pre-13 SBR registered at 22”. I can’t reproduce it now.

 

[outrider58]

There are 4 slots for springs in the buffer. It comes with 4 weak and 4 strong. There are 4 holes where the springs go. I went with the factory set up (1 weak, 1 strong) and it works great. I may play with those some more. Marked reduction in recoil/muzzle climb compared to a straight blowback. I went from a 9 ounce tungsten buffer/.308 spring to taking the weight out of my 9mm BCG and using the included system. Huge difference.

Keep killing me...

Maybe Santa will bring me one...or three...

 

[teratos]

Keep killing me...

Maybe Santa will bring me one...

It’s my purpose in life…