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"Over Gassed" AR's Fact or Fiction? Other Perspectives

LRRPF52
Jim Sullivan: "The diameter doesn’t change, it’s the rounding off. There are two things about this event. The gas port in the M16, we didn’t know about this. A lot of the US gas operated guns, the BAR for example, had gas port adjustments on it. You can let the gas port be the initial throttle, but you can compensate for when it rounds off. But in a gas operated gun, if you don’t have a gas adjustment on there, you can’t use the gas port diameter as the metering diameter. You’ve got to go downstream someplace and put something smaller in there that can’t erode that remains the metering diameter.

We didn’t have anything like that in the M16, that part was our fault, we didn’t know it needed to be that way. I went to Colt about the M4, and took the plug that’s in the end of the gas tube and I moved it over this hole, and I made it the restricting hole diameter. No matter how big you make the gas port, or how rounded off it becomes, it’s the hole that is in the gas tube that does the metering and determines how much gas gets back here."
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6gt

B
davere said:
I read that as what he's saying is that he's trying/planning to bump .002, but it isn't clear what he should use as the reference dimension that equals his chamber (because his brass hasn't grown consistently on first firing, which is typical - it usually takes 2-3 firings before it all uniformly matches the chamber). Once his brass is consistent, he can bump .002 from the nominal case length, and be good to go each time.

The bit about being .008 longer - he's comparing his longest fired brass to a brand new case (which is typically .001-.002 shorter than the minimum chamber dimension in the cartridge spec). His chamber has to be at least as long as his longest fired case - so using that as the reference, and making sure all the brass is at least .002 shorter than the longest fired case is a good way to start. But he's not talking about bumping them .008 shorter (that'd severely shorten the lifespan of those cases if done regularly).

That said... While getting dies set, or simply through negligence, it's possible sometimes to over-bump a case by that much... ask me how I know... LOL. So, accidents do happen.
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Precisely. I'm using a comparator on the case shoulder.

The factory brass that I measured was about 1.407" (this is clearly just a reference measurement relevant to my measuring system only). I don't have any more new brass to measure to double-check this.

Most once-fired brass is in the 1.413"-1.414" range, with a couple of cases at 1.415" and a few at 1.412"

I have set the die to bump to 1.413"

I'm still seeing the occasional ejector mark with 1x fired brass loads, which should only have a headspace of 0.002" or so. I don't think it's high pressure based on the powder charge and velocities (I'm in the velocity range other people are getting from short barrels with dasher/BR and even ARC cases). Although I ack that the .236" bore might be fucking me here

I have seen other people saying "this just happens" with Alpha brass sometimes due to the surface finish, or brass hardness not fireforming and gripping chamber walls well. I am looking to see if others have similar experience.
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Your PVA prefit experience

bohem
Gbar222 said:
I have no idea what the secret is, but PVA has 6 Creedmoor barrels perfectly dialed in. My steel prefit (Tikka) Osprey continues to impress me and make me look like a much better shooter than I am. One ragged hole with all factory ammo that I have tried.
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This is one of the reasons why we do not share reamer prints nor are we often going to make changes to prints because the internet opines that something should be done.
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Night Vision Help buying a thermal

Rerun7
As mentioned above, if you’re going to use it on a bolt gun and AR you need to think about form factor. The ones with a traditional scope form like the pulsars are going to be easier to swap back and forth.

For 300yds 640 is plenty so the 1280 is just going to be because you want it. Even a 384 would work fine.

I’d highly recommend splitting your budget across a scope and a scanner. Having to scan with the gun all the time is tiring and you miss stuff. With that budget you could get a helmet mounted scanner and a scope.

Stick with the larger brands and it’s honestly hard to go wrong nowadays. I’ve had thermals from most major brands and they all worked pretty well.

2 vs 3 mag doesn’t matter that much. You’ll like the 3x for coyotes and if shooting hogs the 2x is good for runners.

Everything is a trade off.
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"Over Gassed" AR's Fact or Fiction? Other Perspectives

LRRPF52
Flexible Tangerine Sprite said:
By the way - on that posted video - the bolts on those DPMS big frame AR's (and Armalite AR-10's) are notrious for holding onto brass cases, mainly due to the rubber O Ring added over the extractor spring. I do not know who came up with the idea those were necessary but I have never found they are necessary and what they serve to do is clamp the brass case so hard into the bolt face that the bolt will not let the spent case freely pivot out of the bolt when the bolt cycles back. I have removed them. Easy and cheap fix and you don't need to buy a special gas regulated bolt carrier assembly.
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The Crane O-rings were a band-aid for undersized chambers in the first production run of SOCOM heavy M4A1 barrels in the 2000s. Especially when suppressed with the KAC NT4, those guns would have FTExtract issues, so someone though the O-Rings would help with extraction.

The civilian side looked at this and said, “If SOCOM and Crane are using this, then it’s an upgrade we need to adopt in order to justify higher price points in our differentiation marketing approach."

Now it’s harder to find BCGs that don’t have them. They are totally unnecessary in a properly-chambered, properly-gassed AR-15.
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On the 5th visit in 14 days to an abusive home they shoot the baby

lonegunman762x51
Who the fuck watches 43 minutes of this retarded bullshit? 43 fucking miserable minutes of these idiots droning on with drug addled idiots and some fucktard narrating this crap like a fucking idiot.

Most cops are 2/3rds of a retard on their best day. 98% of them have zero skills with firearms and barely pass whatever training they give them. The positive take away here that killing the infant stops cops 15 years in the future from arresting that fucking kid 45 times.

Not one of you democrats would take that shitty cop job. Not one of you could deal with an apartment full of fucking junkies and there soon to be dead infant and if they had removed that fucking infant on the first or second visit every fucking one of you would have advocated for lawsuits and media drama over the evil police state stealing children from well meaning junkies.

It ended exactly as expected given the low IQ's and lack of reasoning skills of all parties involved.
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"Over Gassed" AR's Fact or Fiction? Other Perspectives

LRRPF52
Flexible Tangerine Sprite said:
I guess I might theoretically agree with you if you put your AR up against a piece of concrete (like your ball bouncing on a concrete floor scenario) and pull the trigger, but most people fire AR's from their shoulder and IMO the shoulder also absorbs the force of the buffer hitting the back of the buffer tube (just like it absorbs the rifle recoil). Scenario in my view is more like a baseball going into a baseball mitt.
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Part of the AR-15 cycle of operations involves an often-overlooked event where the bumper pad on the back of the buffer bottoms-out inside the RET, which contributes redirected momentum forward to facilitate more positive stripping and feeding of cartridges from the magazine into the chamber. Excessive cyclic rate can cause faster forward momentum.

Also, with excessive cyclic rate, the BCG can out-run the magazine spring’s ability to lift the cartridge stack quickly enough to present the case head high for the bolt to strip it, and you’ll see the bolt run past the head with the carrier face grabbing the case, and pinching the cartridge between the bolt and the feed ramps.

The biggest challenge is making an AR-15 that runs well in the hot when it’s clean or dirty, as well as in extreme cold when it’s dirty and keeping the gun running within the optimum cyclic rate window in all of those conditions.

Jim Sullivan said what they were always missing was adjustable gas, which could have solved all of this much easier like the FAL does.
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Red dots with good auto brightness

SquarePizza
I’m considering a RMRcc for my Glock 26, but after running this Holosun 407k with manual brightness only, I’m starting to think about the importance of auto adjusting.

This is for my daily CC and it’s also my idpa gun. I’m a middle of the pack shooter with draw to first round hit around 1.5 seconds.

The reason I bring that up is, does the adjustment actually keep up with a shooter’s draw stroke. Or is auto brightness just a sales gimmick?
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Amateur OSINTer posting potential targets in Yemen , US military bombs them

Fig
W54/XM-388 said:
You should look a bit further to the west for that answer.
Our "Friends" the Saudis and the other gulf state ilk like them paid for the pushing of their brand of extra crazy islam all across the western world and paid for mosques and radical imams and various "relation" organizations to help their brand of crazy become dominant.
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True, but the new sheriff pretty much murdered or imprisoned most of that crowd and changed the temperature in the room. Don’t get me wrong, he’s a murderous despot, but he saw there was no future in it and has at least started the process of killing it.
kalashnikev said:
No- "bad people" support genocide and all other kinds of Evil and backwardness, while normal people... well, we just don't tolerate it.

Now go read the Bill of Rights 5 times, and say 10 Pledge of Allegiances, then sing one America the Beautiful and one Star Spangled Banner.
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You are such an obtuse poseur.

You are not a “good person” because of your politics and opinions. In my experience those who pose as being virtuous and go on the internet to pat themselves on the back and feel good about themselves are usually the worst sorts of scoundrels who are smearing a thin layer of frosting on the shitcake.
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