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Maxamundo

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Posts posted by Maxamundo

    Let's talk about different gas lengths with adjustable gas blocks

    in Rifle - Technical

    Posted · Edited by Maxamundo

    This has been something I've been trying to wrap my head around for a long time as I'm trying to build the softest shooting AR-15 possible.

    There is so much incomplete info on what it means to have midlength vs rifle gas and etc etc and which is softer shooting and all that. I'll ask my question and then talk through my thought process so far, and hopefully someone can help me get a more complete understanding of the platform.

    Basic question: 

    • Assuming all other components of the AR are kept constant, and the only thing we change is the gas port location on the barrel, why should there be any difference in felt recoil at all, given that we adjust the gas block to just lock the bolt open at every gas port location?

    I've made an assumption here, and that is that even when running an adjustable gas block, there WILL be a difference in felt recoil depending on gas port location. I feel that this is a pretty safe assumption to make since I've seen an overwhelming amount of recommendations, specifically from the 3-gun community, for choosing an 18" barrel with rifle gas and an adjustable gas block to get the softest shooting rifle. Not only that, but I've NEVER heard anyone claim that mid length or carbine gas feels exactly the same as rifle given you adjust your gas block accordingly.

    What I know so far: 

    • First, lengthening the gas system essentially does only one thing at the basic level - changes the pressure at the gas port as the bullet passes. Approximate pressures are shown on this graph.
    • Second, the BCG will not start rearward movement until pressure at the carrier reaches a certain value (determined by the force exerted on the carrier by the buffer spring).
    • Third, adjusting the gas port hole size (through an adjustable gas block) changes the rate at which pressure builds up at the carrier.

    What I don't know so far:

    • How does the time required for pressure building up at the carrier compare to the dwell time? Are they on a similar scale, i.e. 100-300µs, or does pressure at the gas key build nearly instantaneously after the bullet passes the gas port, or does it not reach it's highest pressure until well after the bullet has left the barrel? Again, here is another graph that will help.
    • Why would a more open rifle length gas port cause the carrier to accelerate any differently than a more closed mid or carbine length gas port, given that we close the gas holes enough so that the time it takes for pressure to build up at the carrier is the same as with the rifle length system?

    Intuitively I feel that the lower pressure at the rifle length gas port will accelerate the carrier more slowly/smoothly than the higher pressures of the mid or carbine, even if total rearward kinetic energy of the BCG is the same for each system. But I still feel like I'm missing a lot of what is going on inside the gas tube, and specifically I hope someone can shed insight onto what a pressure graph at the carrier might look like with each gas system.

     

    SP-01 shadow doesn't catch in DA when held vertically?

    in CZ

    Posted · Edited by Maxamundo

    What is going on here? 

    Internals include the original sear and trigger bar, original sear spring and trigger bar lifter spring, cajun type 1 disconnector, original CZ race hammer, CZ 85 trigger, cajun reduced power TRS. Gun has over 15,000 on the original parts listed above. This did not start happening after a part change, but just recently after no parts had been altered for a while.

     

    Shadow Custom - Pressure on slide release causes hammer to fall to hal

    in CZ

    Posted

    I've been having this issue with my P-01 and could not figure it out for the life of me. As soon as I get home I am going to check the slide stop clearance. Fingers crossed this is the issue with my gun as well, although it happens to mine sometimes even pulling the trigger strong hand only.

    I know this is kind of late but when I took the slide off it was very apparent where the trigger bar was contacting since the fouling had been rubbed off and that section was shiny. So I just ground that bit down maybe 1/16-1/8" or so.

    Another weird thing is that sometimes I would drop the slide when the gun was empty (like after unload and show clear) and the hammer would follow to half-cock too. But this seemed more random and wasn't as easy to replicate as putting pressure into the slide stop.

    For those that shoot the Precision Armament M4-72

    in Rifle - Technical

    Posted · Edited by Maxamundo

    With the exact same setup you mentioned, I didn't actually notice this until I tried a different comp. It definitely is the M4-72. I shoot with both eyes open and don't blink, but I noticed with the M4-72 I would always blink on first shot and after that be squinting very hard.

    It is probably something you can train around, just as new shooters who always blink can train themselves to shoot while keeping their eyes open. But I will probably not put it back on my rifle.

    Here is a video with slomo where you can clearly see the gas flying backwards to my face: https://www.instagram.com/p/9SdbQuiH_e/

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