Henry Tatro M16

[nuge]

Here are the RPM numbers which reference the configs above. Since I had some other NFA with me today, I timed them and incldued them for comparison (Ref 1-3).

 

[Bret]

Awesome. You've got me thinking about one. How about some videos next time you go out?

 

[Jmacken37]

Have you been following what Amphibian is doing with the CMMG RDB uppers? I'm waiting on my BCG and BBL.

http://www.uzitalk.com/forums/showthread.php?91585-CMMG-banshe-on-RR-questions

 

[sniperdoc]

Big tears!

 

[A&S Conversions]

I think your LEO carbine approach is the optimum RDIAS configuration, plus the machined FC parts from Joe are to prevent trigger slap and wear and tear on the pins I believe. Are you using a ramped, weighted bolt/carrier with your set up?

The machined parts from M60joe was that I sent him two sets of full auto hammer, trigger, and disconnectors. I also sent him a Colt bolt to be ramped. After the SP-1 series of semi automatic AR-15s, Colt changed the diameter of the fire control pins from 0.155" to 0.169" to make conversation from semi to automatic more difficult. It would be problematic to try to fabricate bushings to use standard fire control parts in a semiautomatic lower receiver with the larger diameter fire control pin holes. So I had M60joe ream out the standard fire control to fit the larger semi automatic fire control pins. Depending on the configuration, I have had some trigger slap even with ramped bolts. Using pictures of the modified patented fire control, I modified a set of the larger diameter fire control for additional clearance. That modification has eliminated trigger slap.

I have several ramped bolts but only one with the tungsten weight. I have found that the lighter strength spring that AAC sells for their rate reducing buffer and the Enidine hydraulic buffer used to be my go to setup. "Amphibian's" Tubbs springs and Kynshot buffer work has me believing in that system. Since your receiver extension is staked on, there is a recommended carbine length Kynshot buffer # RB5004 for that with a Tubbs 300 BLK OUT spring. You might be able to shorten the BLK OUT spring even more to get the cyclic rate even lower. I would buy a couple of springs to test with. You can't put coils back on once they are cut.

I would highly recommend that you fire the original design very little. The nonramped bolt is part of the original design to slow cyclic rate. The hammer is fully cocked with a fraction of an inch of bolt rearward movement. That is very hard on the hammer pin. I don't have an original DOE upper. Garrison Manufacturing did my Colt 9mm upper conversation. I had them shorten a Colt 9mm carbine barrel and install their reproduction front sight and hand guard cap on the Colt barrel. They based the dimensions from an original upper. What got me to do it in the first place was finding an original set of DOE/M261 port door hand guards in perfect condition. The DOE uppers are cool but very pricey. I was tempted to have a little longer barrel with a 3-lug but chose original configuration.

After finding a second set of hand guards and a reproduction front sight and hand guard cap, my plan is to make a modern version using CMMG RDB barrel and bolt group with a flat top upper and 3-lug. I think the RDB system still needs to be further developed for suppressor use though. I think a ported barrel like a SD would give the RDB system lower energy like a short barrel. That might be easier on the ejector spring, which has been problematic in the RDB system.

I will be experimenting with that for sure. Also IIRC you have a custom bbl for suppressing your DOE, maybe tri lug? I want to look into that since I have acquired an early / experimental version of a DOE upper shown below that has an even shorter than standard BBL. This upper is what I would use for DOE suppression, but will need a custom bbl of course...

Personally I am going to stick to the original design for the reproduction upper I already have. The CMMG rotary delayed blowback system uses a different mag height. I don't want to modify the two Colt 9mm lowers I have. I do have a modified Bushmaster lower I had M60joe pin a Colt two part 9mm magwell block. I am thinking of modifying that lower to the RDB system for use with Colt mags.

If that is an original Colt DOE upper, I would not modify it. The barrel is short for a DOE barrel. If you are set on modifying the short DOE barrel, I would think any Smith that could add a 3-lug to a SP89 could add a 3-lug to that barrel. I would look into a custom upper for a change in configuration. Like you, I have a SD. A ported barrel to use with the Colt system would be cool. A ported barrel might be a way to use the RDB system suppressed but still having the operation smooth. I have so many personal projects above the stuff I need to do for the Tenko. I have found a local Smith that is excellent at machine work. I hope to have him work on a couple of these projects. He is only open Saturdays on the weekends and I have been working six days a week for the last month.


Scott

 

[Jmacken37]

Good information Scott!

 

[A&S Conversions]

I think that the 9mm HT guns are cool. The problem is the hammer pins are brittle and will break. Colt has addressed this somewhat with stainless steel pins that are more forgiving. But with only 100 transferable 9mm Colt subguns in the registry so the market value is very high, I would not want to shoot one in factory configuration much if it were my gun. YMMV.

Scott

 

[mattnh]

Source for the stainless steel hammer pins or just use replacement KNS pins?

 

[A&S Conversions]

SAW might or might not have them. For DIAS use I have had good luck so far from the KNS pins.

Scott

 

[nuge]

Thanks Scott for your experiences and advise above. You read my mind in observing the HT extension ring is staked on and assuming I wouldn't be cranking it off to add a rifle buffer tube & buffer... Yes I will be preserving the original design as I pursue improved performance within reasonable limits for this piece. Right now that looks like it will leave wide open bolts, springs, carbine buffers and FCGs as eligible variables. Also any upper design that is plug and play with the "as is" HT lower will be fair game. Also looking to factor in HT vs 9MM RDIAS comparisons while I'm at it.

Improving controllability and smoothness over the baseline will be my goal for future experiments. Controllability is quantifiable, but smoothness not so much. Yes you can feel differences in SxS comparisons, but I hope to be a able to find a way to measure smoothness of FA fire and put a number to it. Using industrial safety vibration testing equipment may be a way...

 

[nuge]

Pin Breakage

I have broken standard pins working my way through severe trigger slap. First remedy was the SS pins, followed shortly after that by the patented FCG components. I have used SS pins in 9mm set-ups ever since and in tandem with the modified FCG - have never broken any more pins, nor had trigger slap.

One benefit in going back to standard pins with the modified FCG could be earlier detection of stress on the lower components (by breakage) than with the SS pins. If no breakage after a few K rounds then the modified FCG may have reduced the stress to the normal 5.56 set-up range. I haven’t tried this yet but am thinking about it…

Another indicator of over-stress besides broken pins is visible damage to the backbone of the disconnector. With the standard FCG components this is where the hammer reaches its travel limit at the trip and hits the disconnector during blowback. But in the modified FCG components case, much more over travel of the hammer is allowed without hitting the disconnector. In fact the travel limit becomes the backside arc of the hammer hitting the bird’s head of the disconnector (as shown below).

How to test this? The hypothesis could be this: Installation of the patented FCG components eliminates the need for SS pins in a 9mm blowback set-up. One way to test it is by running to failure using the standard pins, or to declare victory if failure is not achieved after some number of rounds. What should that number be? Of course, early round count pin breakage would disprove it...

 

[A&S Conversions]

If you are after "smoothness" within your parameters I would suggest the 5004 Kynshot and Tubbs 300 BLK OUT spring. I would also look into a JP Enterprises trigger. I have heard that the Geissele SSF trigger doesn't like the Colt blowback system. With M60joe gone, I don't know where to buy the tungsten replacement weight for the 9mm bolt. TROS used to make a 5.5" AR 9mm 3-lug barrel. I onc had an original 9mm Raptor can. At the last ISSMC in 2007 I put 357 rounds of 9mm in about a minute and a half. The mount and the first baffle stayed on the 3-lug. The rest of the can went tumbling down range with 3 rounds in the mag and one target left. I was asked to stop and was assessed a 10 second penalty for the single unneutralized target. I sent it to Dr.Dater. He removed one baffle (which is the current configuration of 9mm Raptor cans) and shipped it back, no charge. He said I could buy him dinner. I still owe him.

I don't know as there is much more that could be done with the original HT receiver. You do want to watch PSA for the https://palmettostatearmory.com/psa-9mm-smg-magazine.html Colt style 9mm mags. The only difference I can find between the PSA mags and the Colt pre 94 mags is the base plates. Before the National AWB Colt 9 mm mags were parked with steel followers. After '94 they were blued with a plastic followers. I prefer the steel followers. I bought 10 of the PSA mags for $10 each with free shipping. That was a great deal.

Scott

ETA I searched for the modified M16 fire control, but could not find it for the larger diameter pin size. So I modified a set with a Dremel. They are not as pretty as the ones pictured, but it did work. It is also my understanding that using the stronger hammer spring for Eastern Block primers helps too.

 

[nuge]

If you are after "smoothness" within your parameters I would suggest the 5004 Kynshot and Tubbs 300 BLK OUT spring. I would also look into a JP Enterprises trigger. I have heard that the Geissele SSF trigger doesn't like the Colt blowback system. With M60joe gone, I don't know where to buy the tungsten replacement weight for the 9mm bolt. TROS used to make a 5.5" AR 9mm 3-lug barrel. I onc had an original 9mm Raptor can. At the last ISSMC in 2007 I put 357 rounds of 9mm in about a minute and a half. The mount and the first baffle stayed on the 3-lug. The rest of the can went tumbling down range with 3 rounds in the mag and one target left. I was asked to stop and was assessed a 10 second penalty for the single unneutralized target. I sent it to Dr.Dater. He removed one baffle (which is the current configuration of 9mm Raptor cans) and shipped it back, no charge. He said I could buy him dinner. I still owe him.

I don't know as there is much more that could be done with the original HT receiver. You do want to watch PSA for the https://palmettostatearmory.com/psa-9mm-smg-magazine.html Colt style 9mm mags. The only difference I can find between the PSA mags and the Colt pre 94 mags is the base plates. Before the National AWB Colt 9 mm mags were parked with steel followers. After '94 they were blued with a plastic followers. I prefer the steel followers. I bought 10 of the PSA mags for $10 each with free shipping. That was a great deal.

Scott

ETA I searched for the modified M16 fire control, but could not find it for the larger diameter pin size. So I modified a set with a Dremel. They are not as pretty as the ones pictured, but it did work. It is also my understanding that using the stronger hammer spring for Eastern Block primers helps too.

I have 3 or 4 ramped bolts that are tungsten plugged. Will have to check my records but I think Dennis Todd did the work. I used them in two uppers for the baselining tests - #3 and #4. The KAC style upper (#4) was the smoothest I think due to heaviness of the front end, but it also has a ported bbl like the SD and has the tungsten plugged, ramped bolt.

The stronger hammer spring is an intriguing idea - makes sense. Will likely try that along with the spring and buffer your recommend.

 

[A&S Conversions]

It is my understanding that the tungsten weight on a ramped bolt is about the same cyclic rate as the unramped bolt with the steel weight. The only real downside of the extra strong hammer spring is that it pounds on the firing pin. I had thought of doing a SD style ported barrel, but it is still the blowback Colt system. It will never be as smooth as a MP5 SD. I think that the CMMG RDB has more potential as a SD.

Scott

 

[nuge]

I don't doubt the CMMG RDB may the way to go for ultimate performance - eventually I may get there with an RDIAS platform. Meanwhile I hope to map out some of the variable space for the conventional smg platform. Will be looking at at OEM vs RDIAS lower; standard SMG bolt vs ramped/W plugged; std vs enhanced buffer; std FCG vs modified FCG; and std smg buffer spring vs the flat spring. I do have some strong hammer springs coming as well to test at some point. For measurements I will use RPM and some kind of assessment of smoothness which is TBD...

 

[amphibian]

Over a decade ago, there was a doctor that used to shoot a transferrable factory Colt 9mm at the SMG matches I used to go to regularly. I remember the hammer pin broke on him during a stage so obviously his gun went down. It always ran great before that but of course could never come close to an MP5 in terms of smoothness.

Back then, I was trying everything I could to get my 9mm M16 conversions to run as smooth as possible. Closest I think I ever got was my custom ported LRM integrally suppressed upper with an Olympic Pneumatic buffer (which ended up leaking). I was actually running that with no weight in the bolt to reduce reciprocating mass and a RDIAS. I didn't have any trigger slap doing so either. Again, it was all tuned via porting and to my reloads. Even with all that, I still don't think it was as smooth as an unsuppressed MP5. MP5SD forget it, way smoother.

Fast forward to today, I think I have the MP5 beat with the CMMG RDB but only by modifying 5.45 bolts to cut my own angles to further delay the action. I'm going to get my LRM upper rebuilt for the CMMG RDB as well.

If you guys haven't seen the thread, I'm going to be doing a bunch of testing comparing buffers here: https://www.ar15.com/forums/AR-15/DPM-Recoil-Reduction-System-vs-Hydraulic-buffer-EDIT-Armament-LARB-Mod-2-and-3-added-to-the-test-/118-744494/

We will be using an acclerometer to hopefully get quantitative data on the smoothness.
As I discussed in several threads, I think determining cyclic rate is good but it is hard to quantify smoothness. I've gotten my 9mm M16 down to 465 RPM but it was too bouncy.
As discussed in my Guard tuning page: http://c3junkie.com/?page_id=538, I have documented various cyclic rates but the smoothness all varied. I could have the same cyclic rate in two different configurations but one clearly feels smoother than another. I'm hoping the accelerometer can quantify this.

I plan on putting the CMMG RDB in the mix as well as 5.56 configurations.

 

[nuge]

In Search of Smoothness

Wonder if the Dr was using SS pins...

Regarding the accelerometer set up you plan, will this be a custom set up or something off the shelf from Larson-Davis etc?

Smoothness as attribute data in an experiment is OK imo if you have a relative scale established. One that comes to mind for my purposes is a 1-10 scale for example, with 1 being extreme choppiness, even painful to shoot, and 10 being better than an MP5. I would place the painful extreme trigger slap, 9mm smg from my experience at 2, in contrast to an MP5 at 8 or 9.

Curious what would fall in between and the relative placement in terms of other 9mm smgs like Sterling, Swed K, Uzi, Lage M11, Colt HT, MP5 & variants.

 

[nuge]

Wonder if the Dr was using SS pins...

Regarding the accelerometer set up you plan, will this be a custom set up or something off the shelf from Larson-Davis etc?

Smoothness as attribute data in an experiment is OK imo if you have a relative scale established. One that comes to mind for my purposes is a 1-10 scale for example, with 1 being extreme choppiness, even painful to shoot, and 10 being better than an MP5. I would place the painful extreme trigger slap, 9mm smg from my experience at 2, in contrast to an MP5 at 8 or 9.

Curious what would fall in between and the relative placement in terms of other 9mm smgs like Sterling, Swed K, Uzi, Lage M11, Colt HT, MP5 & variants.

Took out some 9mm smgs this am for assessment on the smoothness scale. As arbitrary as it seemed, took a stab at it with these numbers: OEM HT 4.5; Uzi 5.0; RDIAS 9mm (#3 above) 5.5;RDIAS 9mm (#4) 6.5; CPS Sterling 7.5. Didn't bring an MP5, but need to factor it in next time - especially comparing it to a sterling to see if it is that much smoother. Definitely left with the feeling that a quantitative measurement method for 9mm FA smoothness is a MUST HAVE.

 

[nuge]

Over a decade ago, there was a doctor that used to shoot a transferrable factory Colt 9mm at the SMG matches I used to go to regularly. I remember the hammer pin broke on him during a stage so obviously his gun went down. It always ran great before that but of course could never come close to an MP5 in terms of smoothness.

Back then, I was trying everything I could to get my 9mm M16 conversions to run as smooth as possible. Closest I think I ever got was my custom ported LRM integrally suppressed upper with an Olympic Pneumatic buffer (which ended up leaking). I was actually running that with no weight in the bolt to reduce reciprocating mass and a RDIAS. I didn't have any trigger slap doing so either. Again, it was all tuned via porting and to my reloads. Even with all that, I still don't think it was as smooth as an unsuppressed MP5. MP5SD forget it, way smoother.

Fast forward to today, I think I have the MP5 beat with the CMMG RDB but only by modifying 5.45 bolts to cut my own angles to further delay the action. I'm going to get my LRM upper rebuilt for the CMMG RDB as well.

If you guys haven't seen the thread, I'm going to be doing a bunch of testing comparing buffers here: https://www.ar15.com/forums/AR-15/DPM-Recoil-Reduction-System-vs-Hydraulic-buffer-EDIT-Armament-LARB-Mod-2-and-3-added-to-the-test-/118-744494/

We will be using an acclerometer to hopefully get quantitative data on the smoothness.
As I discussed in several threads, I think determining cyclic rate is good but it is hard to quantify smoothness. I've gotten my 9mm M16 down to 465 RPM but it was too bouncy.
As discussed in my Guard tuning page: http://c3junkie.com/?page_id=538, I have documented various cyclic rates but the smoothness all varied. I could have the same cyclic rate in two different configurations but one clearly feels smoother than another. I'm hoping the accelerometer can quantify this.

I plan on putting the CMMG RDB in the mix as well as 5.56 configurations.

Will check it all out - looks like good work. Quantifying smoothness will be an important nut to crack.

 

[nuge]

Narrowing down the variables and experiment designs... I think I will go with a two level factorial design around these five variables: Bolt, FCG, Buffer Spring, Buffer, and host (HT vs RDIAS). Will measure RPM and determine smoothness judged by the shooter against an attribute scale.