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Posted: Yesterday 1:34:23 PM EDT
[Last Edit: vagrenadeer][Edited]
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Hello! I'm having a lot of trouble working up a decent load for my psa ar10 (18 inch stainless bbl, gen 2 shooting suppressed). I have a pile of pull down 308 soft points with cannelures that perform well in my bolt guns, and was hoping to get a reliable budget deer load for the ar10. I've tried both wc844 and reloader 15. My jug of wc844 has been loaded using h335 data in other calibers with no issues, albeit a little slower than same charge in h335. I tried mild, medium and 44 grain max loads per Hodgdon (Speer goes as high as 47 gr for h335). Hotter loads seem to group best, but almost everything down to 2300 fps is giving me mild pressure signs on the brass (including cracked necks and divots on the hotter end, shiny swipe marks on middle and lower end). Brass is once fired and fl resized before use, bullets seated to cannelure. I understand hornady brass tends to be softer but seeing swipes on everything but factory PMC. I previously shot this gun only a few times with 2 factory loads- pmc 147 grain fmj (slow stuff 2500 fps in this gun- brass looks good) and steel cased soft points but my reloads are chewing up the brass even down to 2300 fps loads. Does this gun just beat up brass? Anyone else loading for one of these? I'd love to see what your fired brass looks like out of the same gun. Any assistance would be appreciated- I might be worried about this needlessly.  ^ This is what 42 grains reloader 15 (< 2300 fps) and factory steel looks like  ^ 44 grains wc844/h335 2600 fps in 18inch barrel- best grouping out of my trials  ^ 43.5/42/41.5 grains wc844 2600-2500 fps 18 in bbl |
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KY, USA
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My expirience with the AR10 platform is limited to 4 or 5 rifles. A couple in 308 and a couple in 6.5cm. Every single one needed an adjustable gas block. I say this as someone who thinks they are vastly overused on AR15s. I would make sure the ejection is going to the 3:00.... 3:30 area. If your brass is getting thrown in front of your firing position, you need much less gas, as many of these rifles do. A heavier buffer might also help slow down the bolt. Brass seems to look healthier after the rifle is tuned. But yes, generally speaking, the AR10 is rougher on brass, than say an AR15. |
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What Willie said. Looks like a tuning issue to me. I think you have too much gas vs buffer+spring, causing the bolt to try and unlock+extract under excess pressure. You need to slow the operation down. If fixed-gas, just go to a heavier buffer. If adjustable gas, put in a heavier buffer anyway. Standard carbine buffers (ar10 and 15) are too light for most builds IMO. |
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Originally Posted By vagrenadeer: Thanks for all of the input and advice. I'm getting 3 o'clock ejection (albeit not going very far) and will try a heavier buffer. If the ejection pattern looks good, take a small punch and make sure the ejector is physically able to be depressed all the way into the bolt and its not standing proud on a live round when firing. If it wont go all the way in, remove the ejector and spring and check the hole for obstructions from the manufacturing process. |
| A couple of buddies have ar10s that have been tuning nightmares as well. Awful hard on brass, we've messed with them a lot.I'll second adjustable gas plus buffer weight tuning. Will also add that ejection patterns can be misleading if the brass is bouncing off the receiver/deflector as well. They often cycle so fast it is impossible to tell unless you check for marks on brass/deflector. Can cover with something that is easily marked up to get a better idea there too. |
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