Sizing die woes

Jdowns0415 · Nov 1, 2024

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

Edsel · Nov 1, 2024

Jdowns0415 said:
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.

Jdowns0415 · Nov 1, 2024

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.

Edsel · Nov 1, 2024

I suppose you could try using Dykem or a sharpie to see where the deficiency in sizing is, if you’re hesitant to fiddle with your sizing die.

smoothy8500 · Nov 1, 2024

Does your clean, resized brass pass the "plunk" test in a clean/scrubbed chamber? Not loaded, just the brass. Drop in, drop out easily?

Jdowns0415 · Nov 1, 2024

smoothy8500 said:
Does your clean, resized brass pass the "plunk" test in a clean/scrubbed chamber? Not loaded, just the brass. Drop in, drop out easily?

In the Delta 5 pro yes, in the criterion no. It passes a hornady case gauge as well.

Doom · Nov 1, 2024

You need to make sure the neck of a fired case didn't separate and stay in the the chamber.

CK1.0 · Nov 1, 2024

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:

Lee Undersize Carbide 45 GAP, 45 ACP Small Base Sizing Die

Lee U Carbide Undersized Sizing Dies are great for reloaders looking for ultimate feeding reliability in their handgun. These dies undersize brass...

www.midwayusa.com

Jdowns0415 · Nov 1, 2024

CK1.0 said:
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:

Lee Undersize Carbide 45 GAP, 45 ACP Small Base Sizing Die

Lee U Carbide Undersized Sizing Dies are great for reloaders looking for ultimate feeding reliability in their handgun. These dies undersize brass...

www.midwayusa.com

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

AllenOne1 · Nov 1, 2024

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?

spife7980 · Nov 1, 2024

Provide actual measurements of the headspace length and then diameters for base shoulder and neck. For both fired and sized.
The answer is in the measurements.

Jdowns0415 · Nov 1, 2024

AllenOne1 said:
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.

Edsel · Nov 1, 2024

Looks like RCBS does have a small base FLS die in 6.5mm Creedmoor.

This would probably be preferable as your case does have some taper to it.

davere · Nov 13, 2024

Edsel said:
Looks like RCBS does have a small base FLS die in 6.5mm Creedmoor.

This would probably be preferable as your case does have some taper to it.

That's fairly new, I guess. You could theoretically also use a small base .308 die. My issue with those is... if your headspace isn't on the shorter side of the spec, you might have to bump your shoulders farther back than you'd like when you use the small base die. That's why I settled on the Lee .45 ACP U-die. It only sizes the bottom of the case, leaving the shoulder untouched - and it seems to work a treat there.

Jdowns0415 · Nov 14, 2024

davere said:
That's fairly new, I guess. You could theoretically also use a small base .308 die. My issue with those is... if your headspace isn't on the shorter side of the spec, you might have to bump your shoulders farther back than you'd like when you use the small base die. That's why I settled on the Lee .45 ACP U-die. It only sizes the bottom of the case, leaving the shoulder untouched - and it seems to work a treat there.

I used the RCBS Small Base die set and it worked like a charm. It doesn't have the bushing option so the neck tension is different than what I used for my load development. The rounds chamber fine for the most part but sometimes they still dont with both factory and reloads. I'm starting to think that the Tubb spring and buffer I am using aren't slamming the bolt home with enough force or the chamber is still too tight and I need to polish it up somehow. My last criterion barrel took about 200 rounds to break in to where it would cycle and chamber every round so maybe the criterions are just tight? Its accurate enough for my use case because the 20 round groups are sub MOA with 142gr SMK's.

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