ejection/extraction trouble shooting: adjustable gas blocks and powder burn rates

[44 AMP]

The load is mid point between min and max. I could have pushed it closer to 3000fps, but I had a couple of pierced primers.

We may have a difference of opinion on this, but I'd say if you are getting "a couple of pierced primers" (and there is nothing mechanically wrong with your rifle) then your load isn't midpoint between min and max, its AT MAX, for your specific combination of gun and components.

[tangolima]

Originally Posted by 44 AMP

We may have a difference of opinion on this, but I'd say if you are getting "a couple of pierced primers" (and there is nothing mechanically wrong with your rifle) then your load isn't midpoint between min and max, its AT MAX, for your specific combination of gun and components.

Pierced primers happened when I tried to go further, 1% or 2% below max. No pierced primers where I am. Just barely noticeable cratering.

BTW, load data is from hodgedon website. I do know it is a bit on the aggressive side.

-TL

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[HiBC]

I wonder how many people have and regularly use calibration weights for their powder scales.

[tangolima]

Originally Posted by HiBC

I wonder how many people have and regularly use calibration weights for their powder scales.

Everytime I turn it on. The powder pan weighs 34.34gr. When I lift the pan off the scale, it should display -34.34+/-0.02gr. I will recalibrate if not.

-TL

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[ballardw]

Originally Posted by HiBC

I wonder how many people have and regularly use calibration weights for their powder scales.

Every time I move the scale, which pretty much means at the start of any powder loading session.

[44 AMP]

BTW, load data is from hodgedon website. I do know it is a bit on the aggressive side.

Aggressive or timid, is just a point of view. What matters is the understanding that ALL reloading data, no matter by whom, or where published was NOT worked up in your gun, with your components.

Pressure signs are extremely good and reliable indicators, not of what the pressure amount is (in psi or whatever units used) but of what the pressure is DOING in your gun, with your components.

"Max" loads in the book are the max that they got, using their gun and components, and while one expects similar results, things with your gun and ammo can be different, either on the high side, or the low side.

I've seen (and had) some guns that show pressure signs below listed book max and some that have gone well beyond book max with no indication of high pressure at all.

IF you get pressure signs, no matter where your load is on the published table, STOP, you've gone as far as your gun wants to go. Increasing your load beyond that point because "the book said X was max" is foolishness, and may result in issues you don't want.

[tangolima]

Originally Posted by 44 AMP

Aggressive or timid, is just a point of view. What matters is the understanding that ALL reloading data, no matter by whom, or where published was NOT worked up in your gun, with your components.



Pressure signs are extremely good and reliable indicators, not of what the pressure amount is (in psi or whatever units used) but of what the pressure is DOING in your gun, with your components.



"Max" loads in the book are the max that they got, using their gun and components, and while one expects similar results, things with your gun and ammo can be different, either on the high side, or the low side.



I've seen (and had) some guns that show pressure signs below listed book max and some that have gone well beyond book max with no indication of high pressure at all.



IF you get pressure signs, no matter where your load is on the published table, STOP, you've gone as far as your gun wants to go. Increasing your load beyond that point because "the book said X was max" is foolishness, and may result in issues you don't want.

I did stop. Thank you.

-TL

Sent from my SM-N960U using Tapatalk

[georgehwbush]

Ok, i'm bumbing this thread just to state for the record;

having now ironed the bugs out of two ar-10's both chambered in 243win and both having ejection problems, as odd as it may seem or sound, too much gas entering too quickly through the gas block has been the problem on both of them, by replacing the gas block with an adjustable one, and adjusting it down to the point that they stop showing ejector swipe marks they then eject properly and consistently.

so it seems that not enough and too much gas can both be equally adverse on the cycling process.

not enough gas can equal failure to eject, failure to pick up the next round, failure to lock back on empty...

too much gas CAN equal failure to eject, failure to pickup the next round, and failure to lock open when empty...

the key seems to be in watching for the swipe marks on the case head. if the action is trying to open while there is too much pressure in the chamber, it makes marks and doesn't function properly. if the action is trying to open with too little pressure; either in the gas system or the chamber it will fail to function properly, but no swipe marks.

[jetinteriorguy]

Originally Posted by georgehwbush

Ok, i'm bumbing this thread just to state for the record;

having now ironed the bugs out of two ar-10's both chambered in 243win and both having ejection problems, as odd as it may seem or sound, too much gas entering too quickly through the gas block has been the problem on both of them, by replacing the gas block with an adjustable one, and adjusting it down to the point that they stop showing ejector swipe marks they then eject properly and consistently.

so it seems that not enough and too much gas can both be equally adverse on the cycling process.

not enough gas can equal failure to eject, failure to pick up the next round, failure to lock back on empty...

too much gas CAN equal failure to eject, failure to pickup the next round, and failure to lock open when empty...

the key seems to be in watching for the swipe marks on the case head. if the action is trying to open while there is too much pressure in the chamber, it makes marks and doesn't function properly. if the action is trying to open with too little pressure; either in the gas system or the chamber it will fail to function properly, but no swipe marks.

Hmm, never considered watching for swipe marks to calibrate an adjustable gas block. I just keep adjusting down until it malfunctions, then work my way back up a bit until it functions reliably.

[stagpanther]

I didn't see anywhere in this thread where the OP mentioned the length of the gas system--In my AR 10 builds these days I would routinely choose a rifle+2" for any barrel 20" or longer to go with an adjustable block.

[georgehwbush]

stagpanther: you must not have looked, it's in the first post.

( PSA 243-win 22" SS gasblock is 10" from muzzle. )

[stagpanther]

In other words standard rifle length?

[georgehwbush]

hmmm according to what i just read about the "standard" rifle mid and carbine lengths, i'd say no. probably mid-length seeing that 9.75 11.75 and 15 inchs are the three respective lengths in question.
at any rate it was a complete factory upper, and that is what it is. <shrugs/>