Ejector swipe on multiple ammo brands

[pnutty]

2 hours ago, 98Z5V said:

That's what I had to come to on both my .260 Rem guns.  20" rifle gas barrels with 0.750" journals,both ported to 0.080"  That's good.

That ammo isn't hot.  Something else is going on.  I have 2650 fps with Hornady 147 ELD-M handloads going through both .260s, and there are no pressure signs.  

I do have a .875 journal but I doubt that would make that much of a difference, any other ideas to check or do I get an adjustable gas block or extra heavy buffer? 

[98Z5V]

1 hour ago, pnutty said:

I do have a .875 journal but I doubt that would make that much of a difference

There it is.  That's it. 

The gas port is too big, for that journal diameter.  

An 0.080" port diameter would be just fine for a 0.750" gas block journal, but it's too much for the 0.875" journal, and the hole isn't gonna shrink.  You need an adjustable gas block, and choke that thing down a little. Not much, but it needs less gas. 

[pnutty]

49 minutes ago, 98Z5V said:

There it is.  That's it. 

The gas port is too big, for that journal diameter.  

An 0.080" port diameter would be just fine for a 0.750" gas block journal, but it's too much for the 0.875" journal, and the hole isn't gonna shrink.  You need an adjustable gas block, and choke that thing down a little. Not much, but it needs less gas. 

Thanks! Would you have any suggestions on gas block brand? I just keep hearing the adjustment screws seize in those things after awhile. 

I do have to ask how journal diameter affects the gas port size, I would figure a hole is a hole that moves the same amount of gas no matter the journal size but you know much more than I. You have me interested in how all this works. 

One last question is would a heavier buffer have the same outcome? I know the higher the weight of the buffer, the more it delays the bolt movement which would let chamber pressures lower and let the case shrink for better extraction. I am going to purchase the gas block, like I said I am very interested in how this entire system works.

 

Thanks again for all your help and troubleshooting.

[98Z5V]

3 hours ago, pnutty said:

I do have to ask how journal diameter affects the gas port size,

That port has a diameter, and a length. Therefore, it has a volume. 0.625" gas block would have a thinner wall thickess, given the same caliber,  right?  In that, it would have a shorter length. A 0.936" gas block would have a greater wall thickess, and a longer length. That volume needs to stay relatively the same,  in order to have the same flow and pressure - because we're working with several fixed gas system lengths.

Would a heavier buffer fix it?  No, but it would mask the symptoms.  The results might look the same, feel the same initially - but the results do different things.  Gas system and Recoil system need to be balanced,  in order to run correctly, smoothly, and have a fully  functioning gas gun.  If you went the direction of a heavier buffer - heavier than H3 here - you would mask the symptoms of an over-gassed setup, but you wouldn't necessarily be fixing the over-gassed setup.  The heavier buffer would just be "putting the bandaid on the wrong cut..."

Here's a good, long read on all this stuff - this was all written years ago,  after years of experimentation, across different calibers,  barrel lengths, gas system lengths, and recoil system components:

 

Edited 22 hours ago by 98Z5V

[shooterrex]

Told yall too much gas.

[98Z5V]

3 hours ago, pnutty said:

Would you have any suggestions on gas block brand? I just keep hearing the adjustment screws seize in those things after awhile.

Well, that's gonna come down to maintenance, really.  With fixed gas blocks,  just regular normal  shiit, you don't really "maintain" them. They work, with little to no  maintenance,  ever.  The mindset has never been, "Man, when's the last time I deep-cleaned my suppressor and adjustable gas block?!!?..."

It's not something that people think about, and honestly not something I thought about,  for adjustable gas blocks, until I saw a DD adjustable gas block fail at the last match last month - it cost that guy, possibly,  the entire match.  No adjustment mattered, until after the match, testing it, we switched it to the "unsuppressed" setting - then the gun ran (with the suppressor on), and it ran a little harder than it normally did - more felt recoil.

That was the first failure of an adjustable gas block that I've ever seen,  in person.  And it was a high quality one. Carbon-locked.

So, keep in mind, internal moving parts with small orifices, that have combustion gas running through them, will eventually need to be cleaned.  How often? I don't think anybody knows. Yet.  What I would do if I was competing with it - upper receiver muzzle-down, I'd block my barrel crown, seal it,  shoot carb cleaner down the gas tube opening in the upper until it filled up, then adjust that adjusting screw several turns clock and counter-clock,  several times. Unseal the crown, let all that shiit out,  and shoot carb cleaner in the gas tube again and flush out any remnants of junk.  Guarantee you I'd never seize an adjustable gas block.  The only reason I have that advice is because of what I saw last match, with a good,  quality part, and a great police sniper instructor running it. Never thought about it before...  Not to the depth of what I had to think about trying to figure out what his gun did, and why.  I talked to him last eek, told him what I thought, and he agreed.  He'd never touched that gas block after setting it initially. 

Now, recommendation for an adjustable.  I use the Faxon adjustable.  I think it's mechanically perfect in it's design, and it never will have carbon buildup in any port or set screw.  It's the perfect design.  However, right now, they only make it in 0.750".  What I see most people use is the SA Adjustable, as one of the best brands out there.  You'll just have to add it to the list of routine maintenance, knowing what's known now... 

Keep in mind, this is something that most shooters will never face - they simply just don't shoot enough, literally.  #1 pile of dudes that would find this out is military in combat arms units, that have a heavy firing schedule.  #2 pile of dudes that are gonna find this out are competitors, that are out there every month, or multiple times a month, shooting anywhere from 100~250 rounds a match.  Not many other people really shoot that much, when you think about it.  Next weekend, I have a 10-stage match with a cap of 20 rounds per stage - I can potentially shoot 200 rounds, so I'm taking a spare mag or two of 20.  I'm taking 240.  I'm completely screwed if I need that many, and something else is WAY SIDEWAYS for me, if I actually need that many.  But, they have to go... in 3 weeks, I'm shooting 2 matches in 2 days, 10 stages each.  20-round cap per stage.  Well, there's 400 potential rounds, and I'll take 460 with me. The week after that one is my Fall Shoot, and I'll bet I shoot 1k rounds over those 4 days.  Hopefully not, but it's happened before, just not all from the same gun. Weekend following that, I'm in another 120-round match...  This is how we find problems, diagnose them, and figure out how to not let them be problems again, when you're on the clock.

 

[pnutty]

7 hours ago, 98Z5V said:

Well, that's gonna come down to maintenance, really.  With fixed gas blocks,  just regular normal  shiit, you don't really "maintain" them. They work, with little to no  maintenance,  ever.  The mindset has never been, "Man, when's the last time I deep-cleaned my suppressor and adjustable gas block?!!?..."

It's not something that people think about, and honestly not something I thought about,  for adjustable gas blocks, until I saw a DD adjustable gas block fail at the last match last month - it cost that guy, possibly,  the entire match.  No adjustment mattered, until after the match, testing it, we switched it to the "unsuppressed" setting - then the gun ran (with the suppressor on), and it ran a little harder than it normally did - more felt recoil.

That was the first failure of an adjustable gas block that I've ever seen,  in person.  And it was a high quality one. Carbon-locked.

So, keep in mind, internal moving parts with small orifices, that have combustion gas running through them, will eventually need to be cleaned.  How often? I don't think anybody knows. Yet.  What I would do if I was competing with it - upper receiver muzzle-down, I'd block my barrel crown, seal it,  shoot carb cleaner down the gas tube opening in the upper until it filled up, then adjust that adjusting screw several turns clock and counter-clock,  several times. Unseal the crown, let all that shiit out,  and shoot carb cleaner in the gas tube again and flush out any remnants of junk.  Guarantee you I'd never seize an adjustable gas block.  The only reason I have that advice is because of what I saw last match, with a good,  quality part, and a great police sniper instructor running it. Never thought about it before...  Not to the depth of what I had to think about trying to figure out what his gun did, and why.  I talked to him last eek, told him what I thought, and he agreed.  He'd never touched that gas block after setting it initially. 

Now, recommendation for an adjustable.  I use the Faxon adjustable.  I think it's mechanically perfect in it's design, and it never will have carbon buildup in any port or set screw.  It's the perfect design.  However, right now, they only make it in 0.750".  What I see most people use is the SA Adjustable, as one of the best brands out there.  You'll just have to add it to the list of routine maintenance, knowing what's known now... 

Keep in mind, this is something that most shooters will never face - they simply just don't shoot enough, literally.  #1 pile of dudes that would find this out is military in combat arms units, that have a heavy firing schedule.  #2 pile of dudes that are gonna find this out are competitors, that are out there every month, or multiple times a month, shooting anywhere from 100~250 rounds a match.  Not many other people really shoot that much, when you think about it.  Next weekend, I have a 10-stage match with a cap of 20 rounds per stage - I can potentially shoot 200 rounds, so I'm taking a spare mag or two of 20.  I'm taking 240.  I'm completely screwed if I need that many, and something else is WAY SIDEWAYS for me, if I actually need that many.  But, they have to go... in 3 weeks, I'm shooting 2 matches in 2 days, 10 stages each.  20-round cap per stage.  Well, there's 400 potential rounds, and I'll take 460 with me. The week after that one is my Fall Shoot, and I'll bet I shoot 1k rounds over those 4 days.  Hopefully not, but it's happened before, just not all from the same gun. Weekend following that, I'm in another 120-round match...  This is how we find problems, diagnose them, and figure out how to not let them be problems again, when you're on the clock.

 

Thank you for putting all that information into something I can understand and read up on.

I also looked at faxon’s website and they now sell their adjustable gas blocks in .625” .750” and .875” diameters so I will pick up the size I need. It is a pretty ingenious design keeping the screw out of the gas port and adjusting it by moving the gas tube.

I will report back once everything comes in and I get out to test it again. Again thank you for figuring this out for me, I would have been running around in circles trying to get it to run correctly.

[98Z5V]

This is good news, man - keep me updated!  

[pnutty]

31 minutes ago, 98Z5V said:

This is good news, man - keep me updated!  

Absolutely, my local dealer has a adjustable gas block in stock as well so might go that route just because I am impatient haha . 

I happened to stumble upon these modified gas tubes that have the gas hole drilled to the size you want, I wonder if these would be a better alternative to an adjustable gas block as I doubt these could fail like the adjustable gas block you described at your match. The price seems expensive for what you get though...

 

https://blackrivertactical.com/WP/BRT-EZTUNE-Gas-Tube-Configurable-Rifle-p334967178