Sizing die woes

Jdowns0415

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Mar 12, 2023
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Having some issues loading for my 6.5 AR10. Loading ammo to 2.800 COAL, I have a criterion barrel that simply will not chamber All the way with my reloads. It used to fine but now it doesn’t. I suspect my die is not sizing the brass down enough, as factory ammunition chambered fine.

All the rounds fit in my delta 5 pro but they won’t chamber the last .10 inches of the case in my AR10. They get stuck to the point I have to actually pry the bolt back with something to get it unstuck if they don’t fire. If fired they extract fine. Also the brass looks scratched up tremendously.

I’m using hornady match grade 6.5 dies. I had not had this problem with my other 18 inch barrel from criterion, I even sent this barrel in to see if it maybe needed to be reamed out a little more and they said it was within tolerance. Headspaced, bedded it and gave me a free bolt. I ran 5 rounds through it after I returned from the range of standard hornady 140gr BTHP and it cycled fine working the charging handle which leads me to believe my dies aren’t sizing correctly. Anything else I can do to check? Magazines were fine and the COAL was good on all rounds IMG_8484.jpeg
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I have a criterion barrel that simply will not chamber All the way with my reloads. It used to fine but now it doesn’t. I suspect my die is not sizing the brass down enough…

All the rounds fit in my delta 5 pro but they won’t chamber the last .10 inches of the case in my AR10. They get stuck to the point I have to actually pry the bolt back with something to get it unstuck…

There’s a chance that one of your chambers has a narrower base (Criterion barrel) than the other (Delta 5).

You may need a small base die, not sure if they’re common for 6.5mm Creedmoor.

Try sizing the brass down further, to the point of “excessive headspacing.”

Does the brass chamber well afterwards?

Sacrifice some brass, just to see what’s going on.
 
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This is what it looks like if I try to chamber a resized round. After I get the bolt back open the bullet is scratched up and the round looks like it has been sanded with rough sandpaper on the outside.
 

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If your die isn't sizing down far enough you could try this, I lifted this info from @davere in the 6GT thread when he was telling someone how to fix brass that wouldn't chamber in a new barrel with a tighter chamber, 6.5CM uses the same .308-based case so it should do the trick:

The fix for .308 case head size cases is actually surprisingly easy. Get a Lee .45 ACP U-die (undersize sizing die), take the decapping stem out of it, and run your cases through it. It's a carbide die for a straight wall pistol case, so it's just a sizing ring - won't bump your shoulders or anything like that (which is something that *will* happen with cartridges that have a small base die - to full size the base, you end up squishing your shoulders back a lot, too). Then do a normal sizing die pass.

~$25:

 
If your die isn't sizing down far enough you could try this, I lifted this info from @davere in the 6GT thread when he was telling someone how to fix brass that wouldn't chamber in a new barrel with a tighter chamber, 6.5CM uses the same .308-based case so it should do the trick:

The fix for .308 case head size cases is actually surprisingly easy. Get a Lee .45 ACP U-die (undersize sizing die), take the decapping stem out of it, and run your cases through it. It's a carbide die for a straight wall pistol case, so it's just a sizing ring - won't bump your shoulders or anything like that (which is something that *will* happen with cartridges that have a small base die - to full size the base, you end up squishing your shoulders back a lot, too). Then do a normal sizing die pass.

~$25:

Adding that to my cart. The bases of every case are clean and I scratched compared to the rest of the brass so I suspect that final little bit isn’t getting sized like the rest of the cartridge. I anneal every firing and I also make sure the press is actually bumping the shoulder .004
 
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What bullet are you using? What is the BTO measurement on your handloads compared to the factory rounds with the Hornady BTHP bullets?

The Hornady case gauges are pretty tight in my experience. If it goes completely into the case gauge I would think the unloaded but sized brass would drop into the chamber.

What size bushing do you have in your sizing die?
 
What bullet are you using? What is the BTO measurement on your handloads compared to the factory rounds with the Hornady BTHP bullets?

The Hornady case gauges are pretty tight in my experience. If it goes completely into the case gauge I would think the unloaded but sized brass would drop into the chamber.

What size bushing do you have in your sizing die?
Sierra 142gr, Berger 140 hybrid, 147 hornady eldm, 130 ELDM, 130 Sierra. All of them have been used in my other criterion barrel with no issues until recently. My COAL is always 2.800-2.795 to fit in my magazines, I’d have to measure the CBTO but I haven’t had any problems with just overall length in the past 2000 rounds. I use a .288 bushing in the 6.5 die.

The hornady bullets COAL is 2.800 for the 140gr BTHP. After measuring all the bullets the base of the case on the factory ammo is .464 and the fired and resized brass is .471 so I believe my theory about the case is why it’s getting hung up.
 
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