AR15 Colt SP 01 full auto

[JDIllon]

I just got a SP 01 Colt, it has a vary high rate of fire on 556/223 what is the best way to reduce the rate of fire.
I have a 9mm upper also It seems to run pretty nice with a heavy 9mm buffer. And I am building a dedicated 22 upper with cmmg barrel and collar.
Any suggestions are welcome.
Any one running cmmg rotary bolt and barrel for 9 mm?
Thanks Jim

 

[chili17]

Whats the barrel length? 16-20" barreled uppers are slow and smooth.

IMHO an adjustable gas block is the way to go. Of course you can play with buffers and springs too. If you can find one, get the Govnah gas block with the appropriate plates.

 

[Battering ram NIB]

308 hydraulic buffer and tubbs flat spring

I can do singles easy . I’d guess 700rpm

Maybe a adjustable gas block. Where’s your empty’s flying out of your gun. Should be around 3oclock

 

[amphibian]

I had a RR Colt SP1 that I egged the hammer pin hole from shooting too much straight blowback 9mm.
At the SMG match I go to, a Doctor had one of those really rare fully transferrable factory Colt 9mm SMG's and it broke the hammer pin during a stage.
I've also seen several other competitors break pins in their lowers. Some were using KNS pins and it would break and they wouldn't know since the KNS design would kind of hold it together for a little while but then it would be digging the holes until they realize it had broken.

I've posted a lot about the CMMG RDB setup and have several setups.
See my site discussing it here: http://www.c3junkie.com/?page_id=164

Basically, myself and others have had issues with the ejector spring dying around 1k rounds and I've resorted to a fixed ejector for my 9mm setup....which is not publicly available.

However, there are a few guys at the match running the CMMG RDB setup with over 1K with no issues but those guys aren't running full auto.....and there are some guys who post on AR15.com saying they are over 3 or 4K of full auto suppressed with the original ejector spring with no issues. I just don't know any of those guys personally......ALL the guys I know personally that run full auto have had the same issues as me. However, even if I had to swap ejector springs every 1K, I'd rather deal with that than running a straight blowback 9mm Colt setup.

Regarding high cyclic rate in 556, yes #1 thing is to control the gas, then mess with buffers/springs.

Lastly, I see that you are in Port St. Lucie? The first Sunday of every month is the Port Malabar SMG match. So there is one this weekend. I should be there. I will most likely be shooting a .40SW CMMG RDB setup. Not 9mm since I'm trying to burn up a bunch of .40SW ammo. I'm still working the kinks out of the .40SW setup. The match is really laid back and people there to just have a good time while being safe. Not many people are super competitive....I wouldn't be bringing a setup that isn't running 100% if I was really concerned about doing well. PM or email me with more details if you want to go.

 

[Gaffshot]

I have an m16 so can speak to high cyclic rate from personal experience. It is caused by too much gas, not enough buffer/carrier mass, too light of spring, or combination thereof. First thing is to look at would be the buffer and spring setup. That is the cheapest and easiest way to begin to address it but may not be the final solution. H1 or H2 buffer with a Springco blue or red spring. It that doesnt get you where you want then replace the barrel with one which has an appropriate size gas port. Centurion Arms and Sons of Liberty are the current hotness and known to not be overgassed.

What barrel is on it now? what gas length? What buffer and spring?

And to go a step further you can replace the entire buffer system with the Vltor A5 system and use a A5H2 with Sprinco green rifle spring. I tried adjustable gas blocks and always a hassle and prone to breakage.

My current set up is Son of Liberty 13.7" barrel with Vltor A5H2 buffer and Sprinco green spring. Cycle rate is almost too slow. About 650. Ejection pattern for 556 is at 4 o'clock. Wolf steel case usually cycles but occasionally won't cycle it all the way. If I wanted to run reliably with steel case I would just drop down buffer weight to H1.

Regarding the Colt 9mm upper: there are reasons why the Colt 9mm smg never became successful. High recoil, crazy heavy bolt, and excessive breakages.

 

[Battering ram NIB]

Here's mine with a Socom Colt 14.5" upper (factory gas block- only mod is a special muzzle brake)

notice how the cases fly out at around 3-4 oclock
to me this speed is perfect...with a geissele trigger i can do singles at will

post a video of yours

https://www.youtube.com/watch?v=to06Jp4B2UQ&feature=youtu.be

 

[A&S Conversions]

It has been my experience that energy into the bolt/carrier assembly and spring pressure are the keys to cyclic rate. There needs to be enough energy into the bolt/carrier to cycle the bolt/carrier assembly fully and a spring strong enough to push the bolt/carrier assembly back into battery and strip and chamber the next round. If there is too much energy into the bolt/carrier assembly then the mass of the bolt group must be increased and/or the power of the recoil spring must be increased so the buffer won't hit the end of the receiver extension (buffer tube) too hard causing stronger perceived recoil. Increased strength recoil spring would tend to have the bolt carrier strike the barrel extension harder as the increased spring pressure returns the bolt/carrier assembly into battery faster. The greater the speed of the impact of the carrier into the barrel extension requires a greater dead blow mass to stop the carrier from bouncing back from the barrel extension causing bolt bounce. Bolt bounce will leave a live round in the chamber with the hammer resting on the firing pin. The more mass moving in the gun, the more wear and tear happens to the parts. Also the greater the mass moving inside the gun, the more the gun is likely to be moved around by that mass.

Compare the mass MP5 9mm bolt group to the M16 9mm blowback bolt group. The MP5 bolt group has 2/3 the mass of the Colt 9mm blowback bolt group. So the MP5 has lower perceived recoil. Why, because the roller delayed system diverts some of the recoil energy from the bolt group into the trunnion/receiver while the entire recoil energy is transferred to the blowback bolt group. More mass moving inside the gun tends to move the gun around.

Can cyclic rate of a M16 be slowed by adding mass? Yes, but having the entire gun absorb more of the recoil will tend to keep the firearm steadier than having the bolt group have to deal with more of the recoil energy. If a stronger recoil spring is required to slow the bolt group's rearward motion, then the stronger spring will tend to push the bolt group back into battery with more speed. That would tend to speed up cyclic rates, not slow them down. At least that has tended to be my experience. YMMV.

Scott

 

[Gaujo]

Whats the barrel length? 16-20" barreled uppers are slow and smooth.

IMHO an adjustable gas block is the way to go. Of course you can play with buffers and springs too. If you can find one, get the Govnah gas block with the appropriate plates.

Do they still make that? Can't find it

 

[chili17]

Do they still make that? Can't find it

I believe they are out of production. Amphibian designed and manufactured them. If you check out his website, he did a TON of R&D while making them. IMHO one of the best gas blocks out there, no fiddle fukin around with screws, knobs, two clicks up three clicks down to remember.

 

[Gaffshot]

you won't need an adjustable block with a barrel that is appropriately ported. So many barrel manufacturers over gas the barrels so that the gun will always work with the lowest powered ammo in worst conditions.

 

[ferndog1]

I don't mean to hijack this thread but I have a question for amphibian's post... 9mm SP1 hammer pin hole elongated... Are you using a ramped bolt?

RE:

"I had a RR Colt SP1 that I egged the hammer pin hole from shooting too much straight blowback 9mm.
At the SMG match I go to, a Doctor had one of those really rare fully transferrable factory Colt 9mm SMG's and it broke the hammer pin during a stage.
I've also seen several other competitors break pins in their lowers. Some were using KNS pins and it would break and they wouldn't know since the KNS design would kind of hold it together for a little while but then it would be digging the holes until they realize it had broken."

 

[amphibian]

I don't mean to hijack this thread but I have a question for amphibian's post... 9mm SP1 hammer pin hole elongated... Are you using a ramped bolt?

RE:

"I had a RR Colt SP1 that I egged the hammer pin hole from shooting too much straight blowback 9mm.
At the SMG match I go to, a Doctor had one of those really rare fully transferrable factory Colt 9mm SMG's and it broke the hammer pin during a stage.
I've also seen several other competitors break pins in their lowers. Some were using KNS pins and it would break and they wouldn't know since the KNS design would kind of hold it together for a little while but then it would be digging the holes until they realize it had broken."

We are talking almost 20 years ago....back then I started out with a standard Colt non-ramped bolt and just thought it was so damn bouncy and didn't have any noticeable damage at the time. Back then ramped bolts were not commonplace like today. Ken Elmore of SAW was pretty much the only source for a ramped bolt and that is who I sent my bolt to along with getting his custom tungsten insert. It was later that I noticed mine was getting egged.

The Doctor that had a snapped pin was running all factory Colt which was not ramped.

 

[SecondAmend]

The 5.56 upper that I use most often on the M16 carbine is a 10.5" with screwed on suppressor barrel with standard gas block. After using a standard "9mm, two-piece, mechanical" buffer and standard carbine recoil spring for a number of years, for ROF reduction and gas blow back reduction I've gone to a 5.56 carbine hydraulic buffer and extra power spring. For 9mm and .45 ACP, I also use the same recoil spring and buffer without adding a spacer in the buffer tube as I do not have LRBHO in either 9mm adapter. The spacer delete adds to the stroke length in the pistol calibers which inherently reduces their ROF. The hydraulic buffer eliminates the hard impact at the rear of the buffer tube and at the barrel extension as well as prevents bolt bounce in all calibers as much of the buffer mass is coupled through the buffer's internal spring and fluid system.

For .22LR, I've used a conversion unit in various lengths of 5.56 uppers from the aforementioned 10.5" suppressed bbl. upper to a 20" Model 601 bbl. and others in between. I also have 4.5" and 9" unsuppressed bbl. dedicated .22LR uppers. For the last couple years I mostly use the 9" bbl. dedicated .22LR upper on the M16 as it is most comfortable for most shooters and has worked well with many different types of ammo. I use CMMG (0.8 oz.) and Atchisson pattern (1.0 oz.) anti-bounce weights interchangeably as they also have worked well with many different types of ammo.

Best of luck with your M16 however you decide to configure it.

MHO, YMMV, etc. Be well.

 

[JDIllon]

Thanks for all of your help! Waiting for some parts to slow down the 556. Got the blow back 9mm running great just added a heavyPSA 9mm buffer . Trying to get the 22 dedicated upper running? Tried 5 different ammo,run with the Mil spec hammer spring. If I turn the hammer spring over ,it will auto but not consistent with any ammo? Using cmmg’s auto trip and bolt bounce weight. Any thoughts on why it won’t run with a mil spec hammer spring? Thanks JD

 

[Battering ram NIB]

I use cci blazer .22 It runs 100% in my cmmg upper . I bought the upper complete, not just their bolt

The blazer feels slippery to the touch. I’ve tried other .22 ammo and it wouldn’t feed at all. I’m using S&w .22 black dog drums and the mag well adapter. I run 10 drums/500 rounds and maybe get 1-2 failures due to duds. You want a heavy buffer installed so the bolt doesn’t move it. The buffer should be like a wall/solid. I’ve got a geissele trigger in my gun w no issues For .22. Hammer spring isn’t an issue for me.


.22 is fun about once a year. Worth having but not too exciting

 

[JDIllon]

I want to thank all of you have contributed to helping me solve the problems. I am coming along, it is shooting pretty well on 556 and 9mm by adding a Kynshot 5007 and Tubb flat spring with 3 coils cut off. I am still trying many of your suggestions on the 22 and so far it is not shooting full auto. I have some new parts coming from CMMG and will try it again this week and see how that goes. Thanks again, JD

 

[Battering ram NIB]

Is your cmmg upper a complete upper from cmmg ? Or is it parts tossed together with a cmmg bolt?

Should be plug and play. I bought a complete cmmg upper so I could call them to help get it running

What .22 ammo are you using

Share your setup

 

[Jmacken37]

I am a big fan of Amphibian's CMMG RDB 9mm setup. It ran great until it didn't. I plan on just replacing the extractor spring every 1K rounds.

Also, my CCMG 4.5" bolt/BCG .22LR kit in an Aero Precision upper runs great.

 

[JDIllon]

Is your cmmg upper a complete upper from cmmg ? Or is it parts tossed together with a cmmg bolt?

Should be plug and play. I bought a complete cmmg upper so I could call them to help get it running

What .22 ammo are you using





I’m runny cmmg collar and barrel and a new upper. It runs semi flawlessly. It run the same no matter what ammo. 2 or 3 rnds auto then stop rnd in chamber with a light hit and some times a solid hit but a live rnd. I think I’m getting sever bolt bounce. Considering heavier weight or ball detention? JD

 

[amphibian]

https://www.ar15.com/forums/Armory/New-Anti-bounce-weights-for-Ciener-Spikes-CMMG-kits/23-512258/