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Posted: 6/28/2012 11:03:04 AM EDT
Can anyone recommend a good quality lower parts set, trigger ( comp or not  ) pin set and  buffer ? It will be on a  Sendra rr and  10.5-11.5 gas impeng. Flat top upper . Please keep in mind it will be a shooter and in a dusty  environment . It doesn't have to be the supper high speed low drag  mall ninja edition .  Just  practical  and reliable.
  Has anyone run the comp. style triggers on select/fa ?  What buffer /spring  combos are  available to safely play with cycle rates? I'm sorry in advance for asking so many questions that y'all have probably discussed in detail. Although this isn't my first nfa purchase its my first m16 and I just want to be diligent in my research. Any and all advise is appreciated.
                                                        Thanks

PS,  I will be running a m4-2000 can on occasions
Link Posted: 6/28/2012 11:59:39 AM EDT
[#1]
I would recommend getting all new Colt internals and a set of KNS anti-rotation pins.



I personally run the stock Colt trigger in my M16 RR as it is just a range do for doing mag dumps.



Original Colt parts can be bought a Brownells and Specialized Armament.



http://www.specializedarmament.com/catalog/AR_15_Parts-4-0.html



http://www.brownells.com/.aspx/pid=0/sid=853/schematicsdetail/M16-M4-Lower-Receiver-Fire-Control-Full-Auto


 
Link Posted: 6/28/2012 12:09:11 PM EDT
[#2]
Yeah Colt makes nice parts for sure. I've also used regular cheaper M-16 parts kits from SOG Armory and DPMS and other places with no issues though. I run regular buffer springs, but prefer heavier buffers like a H3 or 9mm buffer. If you want to reduce the cycle rate I'd get an MGI buffer. My favorite trigger is the JP Adjustable single stage trigger for my M-16, but the stock trigger also works just fine. Honestly if you are familiar with AR-15's the M-16 is just like it but has a happy switch, so all your AR-15 knowledge still applies. Then more you shoot your M-16 the more you'll learn about it. And of course KNS pins are nice to protect your expensive lower and also make the trigger pull smoother.
Link Posted: 6/28/2012 12:12:43 PM EDT
[#3]
Link Posted: 6/28/2012 2:48:22 PM EDT
[#4]
Quoted:
I run a JP trigger and Colt factory disconnector, hammer, selector and autosear, with JP springs. This combo has worked for me for more than 50k rounds over the last 15 or so years; I've replaced the springs twice, but there is zero wear on everything else.


Interesting. I got to test drive my Colt for the first time today and discovered that the OEM trigger is pretty bad. It probably will improve since it's not even remotely broken in.  Another guy's well used factory had a much better pull in semi & auto.  I'm already spoiled by the Geissele SSA, so was planning to go with an SSF for the RR. Aside from the 1 vs 2 stage differences, can you compare & contrast your setup with an SSF?  How hard is it to modify the JP stuff to work with auto FCG parts?

When my Form 4 clears, hopefully before 2013, I may try your setup.


Posted Via AR15.Com Mobile
Link Posted: 6/28/2012 5:31:56 PM EDT
[#5]
Link Posted: 6/28/2012 8:17:37 PM EDT
[#6]
Thanks for the wisdom and knowledge. I'm new to this board and it  seems to be the jackpot of real world information already. I would like to say  after  I  test fired the gun ( my sot was nice enough to let me have a test fire) it seemed to have the same cycle rate with several different  uppers. Which I thought was kinda slow. They ranged from 10.5 to 16. Is this common? I kinda like the higher cycle rate guns  like the Nam era XMs
Just for your information this is a completely unsolicited thank you to Guns Plus in Georgetown Texas. My much preferred sot. Great guys that aren't self important or have the personality of a wet rag. I can't say enough for good customer service and  willingness to help. Thank you Kyle and Stephen.
                             Still open to advise and  comments,  Thanks again
Link Posted: 6/29/2012 3:44:32 AM EDT
[#7]
Quoted:
Thanks for the wisdom and knowledge. I'm new to this board and it  seems to be the jackpot of real world information already. I would like to say  after  I  test fired the gun ( my sot was nice enough to let me have a test fire) it seemed to have the same cycle rate with several different  uppers. Which I thought was kinda slow. They ranged from 10.5 to 16. Is this common? I kinda like the higher cycle rate guns  like the Nam era XMs
Just for your information this is a completely unsolicited thank you to Guns Plus in Georgetown Texas. My much preferred sot. Great guys that aren't self important or have the personality of a wet rag. I can't say enough for good customer service and  willingness to help. Thank you Kyle and Stephen.
                             Still open to advise and  comments,  Thanks again


What is your stock/buffer setup?
Link Posted: 6/29/2012 9:42:43 AM EDT
[#8]
Link Posted: 6/29/2012 9:43:36 AM EDT
[#9]
Its a standard crbine tube spring and buffer. H2 I think
Link Posted: 6/29/2012 5:58:13 PM EDT
[#10]
Normally shorter barrels run faster than longer ones (all else being equal) but that is not always the case.  The primary drivers of ROF (in my opinion) is the gas port size, followed by recoil spring weight.

You can always tame down any given ROF by adding mass to the system (i.e. a heavier buffer) or by putting in a weaker spring like an AAC rate reducing spring.

To increase the ROF without monkeying with the gas port size you have two options.  

A. Remove Mass from the system by going with a lighter buffer.  Since you are already running a pretty light buffer your only remaining safe option is a standard H.

The upside to this option is it is cheap (like $30 bucks for an H buffer).
The downside is that you could end up with "bolt bounce" now that you have a lighter amount of reciprocal mass inside the buffer as an H buffer has two steel & 1 tungsten weight vs  1 steel and 2 tunsten in a H2.
Unfortunately there is no way to predict whether you will have a bolt bounce issue now or when you upper and BGC gets more broken in.

B. You could put in a stronger recoil spring to speed up the bolt return speed.  
Once again the upside to try this is cheap ($30ish)
The downside is that you will need enough gas to compress the recoil spring and the only way to find out is to put a stronger spring and see if it works.  If you dont have enough gas to compress the new extra power spring completely you will end up with a short stroke condition.

So for roughly $60 you could invest in an H buffer and a Sprinco enhanced (aka blue spring) or extra power (aka red spring) and experiment and see what happens to the ROF using one the other or both in conjunction.

If either of those options fail to produce the desired results or induce reliability issues, than you only option is to drill the gas port out until the desired ROF is acheived along with proper reliability.  Obviously, there is going to be a point of diminishing returns where you are only going to be able to boost the ROF on a M16 to a certain level and maintain any sort of reliability.  i.e. if you want MAC speed than you probably are going to need to by a MAC.   However, anything between 650 and 900 is pretty safely acheivable if you go slow and don't do anything drastic.

If you need help I am in Central Texas as well and could help you out at one of the local ranges once your transfer is complete.  

I have just about every "normal" buffer there is (Carbine, H, H2, H3, B, X), as well as  Colt OEM M4 springs, both Sprinco springs (blue & red) and well as AAC reduced power springs, and have every gas port drill bit from wire size 55 to 35 if you want to drill it one wire size at a time.

Just shoot me an IM once your transfer comes through if you need or want help and we can figure out a time to meet.

James

Link Posted: 6/29/2012 6:23:55 PM EDT
[#11]
im sent
Link Posted: 6/30/2012 6:34:42 AM EDT
[#12]
Would using a 16 inch barrel with a carbine length gas system on a a2 lower with rifle stock and buffer make the gun run faster?
Link Posted: 6/30/2012 11:29:53 AM EDT
[#13]
Link Posted: 6/30/2012 5:48:08 PM EDT
[#14]
Quoted:
Because carbine receiver extensions/springs/buffers are shorter than their rifle counterparts, in effect they short-stroke compared to the rifle system. And a shorter stroke speeds up the ROF (just like putting a buffer in an Uzi speeds it up by shortening the stroke). And yes, I know one is open-boltand the other closed-bolt, but the principle stands.


Shorter buffer, but also a shorter tube, so not a shorter stroke, Tony.  Stroke length is exactly the same, and bounded by the carrier key and the inside of the upper receiver.

Shorties are faster because of less spring and less moving mass.
Link Posted: 6/30/2012 6:40:43 PM EDT
[#15]
Link Posted: 7/2/2012 10:39:40 PM EDT
[#16]
Quoted:
If the stroke length is exactly the same, why is the carbine spring shorter than the rifle spring? There definitely is a difference in dwell time. That's why the Vltor A5 system works in applications where the carbine system does not: It uses a rifle recoil spring, unlike the carbine receiver extensions.

we may just have to disagree on this one.


Shorter tube needs shorter spring, too, of course.  I went and measured the stroke length of four full-stock and three telestock rifles, and they're all the same - about 3 3/4"
Link Posted: 7/3/2012 6:26:48 AM EDT
[#17]
Quoted:
Quoted:
If the stroke length is exactly the same, why is the carbine spring shorter than the rifle spring? There definitely is a difference in dwell time. That's why the Vltor A5 system works in applications where the carbine system does not: It uses a rifle recoil spring, unlike the carbine receiver extensions.

we may just have to disagree on this one.


Shorter tube needs shorter spring, too, of course.  I went and measured the stroke length of four full-stock and three telestock rifles, and they're all the same - about 3 3/4"


IIRC, the spring length doesn't have bearing on the stroke length of the system.  It's been a while since I studied spring physics, so my post may have some errors. The VLTOR A5 uses an intermediate buffer - weight and length adjusted to allow use of a rifle length spring in a shorter tube.  That compresses the spring a bit, and the resulting preload allows use in a shorter tube, being effectively a spring of weight somewhere between an uncompressed carbine & uncompressed rifle action spring with the bolt closed.  It is, to my rough understanding, the buffer/action spring/receiver extension cousin to a midlength gas system. Neither rifle nor carbine.

The carbine spring is shorter but heavier at rest, along with a generally lighter buffer (until you get into the H3 range).  The rifle length has a softer spring but heavier and longer buffer. The net effect is same cycle length with different characteristics to the recoil impulse.  The subtleties of ROF come about from the interaction between spring rate, buffer weight, and gas system (port size, dwell time, powder, etc.).  Beyond that, I would need to research spring compression & buffer weight to understand it better. Dwell time within & between systems changes, but not AFAIK the actual BCG travel distance.

Without knowing the UZI system, I would hypothesize that the buffer speeds ROF not by making the bolt cycle shorter, but by compressing the spring a bit & effectively making it a higher rate spring. But again, that's just from my understanding of spring physics, not the workings of the UZI.

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