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I can fully see how it wouldn't be a good indicator of gas pressure, due to the variables.
If ejection patten does depend on cyclic rate, though, which I can't envision how it wouldn't after seeing the results I have... Aside from ejector tension coming into play to an extent, it looks like a reliable method of field-expedient cyclic rate observation.
I guess the way to really figure this out would be to examine cyclic rate using a high-speed camera, and seeing how it relates to ejection pattern. Are you implying that that cyclic rate and ejection pattern are two entirely separate issues? I have a hard time believing that. Not saying it isn't true, it just isn't supported by my observations and what seems intuitive.
I'm not saying you are wrong... I very well might be wrong. It's just that the method I have been using has been working for me, and I have been able to make modifications to ejection pattern using it which common knowledge says are influencing cyclic rate.
Excessive extractor tension will alter ejection.
Weak ejector strength will alter ejection .
Excessively fast or slow BCG speed can look different than moderately over or under speed BCG travel.
Raising and lowering buffer weight and spring strength will alter bolt speed and ejection pattern independantly of gas ring function.
Dirty/dry/caked parts will cycle differently than clean, slippery ones.
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I'm not suggesting it is perfect, or that there are NO other variables. And without a whole lot more research and data I don't think either of us is going to come up with conclusive proof either way. (If you have it, I'm all ears.)
My observations, though, with a number of different rifles have been that buffers, carriers, and springs have substantial impacts on ejection pattern through their alteration of cyclic rate.
It isn't a flawless method, and I don't claim it is... but it seems to work, that's all I'm saying and we can leave it there.
Last edited by lamarbrog; 12-05-11 at 18:58.
As with Gunz, I use McFarland gas rings and will continue to do so.
My personal rifle has about 2500 rounds on the ring and it looks almost new.
I also have a buddy who has slightly more (about 2800) through his gun and no visible wear at all.
It is my understanding that the steel used in McFarland gas rings is of a higher grade than the steel used in normal 3-piece mil spec gas rings.
I also understand that McFarland gas rings are part of the PIP of the Mk18 for the Navy to increase the reliability and longevity of the 10.5" Mk18.
My buddy had issues running weak steel cased ammo before installing the McFarland ring. It just wouldn't cycle the gun (short stroking). Buffer, buffer spring (chrome silicon), and carrier all remain the same. Issues disappeared once he installed the McFarland ring.....haven't reappeared since and he shoots both weak Rusky steel cased ammo and XM193 regularly (he's about a 50/50 between the two)
Last edited by BufordTJustice; 12-06-11 at 01:16.
I hope to god that this question answers itself.
Also, I distinctly remember a test someone did, I forget where I saw/read about it. Someone completely took the gas rings off a bolt and went through a course of fire with the weapon without any major issues. Granted, it's not the smartest thing to do, and certainly not every weapon would do it. Statistically speaking, I'm not sure how probable or improbable it would be for a weapon to function without gas rings.
Even if a carrier/bolt collapses under it's own weight, that doesn't necessarily mean the gas rings are worn out. As stated by IG, the proper test is to pull the cam pin out of the carrier, insert the bolt and if it falls free under it's own weight, the rings are considered bad. If not, you're set to go.
Last edited by viperashes; 12-06-11 at 07:51.
I think that might be where the disconnect is.
Having a high or low cyclic rate does not really indicate if the weapon is over or under-gassed, and excessive extractor tension and/or weak ejector strength can indicate something other than what ejection pattern may seem to indicate, and combinations of variables can show wide differences in ejection pattern.
I have had literally hundreds of shooters on a range at once, all with virtually identical mil-spec weapons, with several different ejection patterns, none of which had any issue in function.
If you want to use ejection pattern to diagnose function problems, it's your choice. I prefer to use other methods as recommended by guys that have done it professionally over the course of decades for guys that stake life on the function of their weapons. Doesn't mean it's the only way, but they have a highly successful model that I choose to follow that has worked for me in my 14+ year career.
I'm not too worried about ejection patterns. I did notice it change when we were experimenting with different buffer springs (standard, blue and red) and different weight buffers. I'm now running the rifle with an H3 and a red spring (Springco's recommendation for 16" carbine gas). Had that set up for the TAPS class, just shy of 300rds. The function was flawless.
I'm going to try the McFarland ring and see how it goes. Looks like DSG Arms is getting more of my money.
Thanks guys! Will let y'all know what happens after the next 500rds.
I think we pretty much agree on the technical aspects, but just interpret it differently.
A rifle that is over-gassed will probably wear parts faster, but as long as something is being done to keep the cyclic rate under control it is not an immediate problem in the sense you can likely avoid stuck casings and other failures associated with a rifle that is cycling too fast.
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