Home Forums Reloading Big Game Rifles Hornady 6.5 PRC brass length issue...

I've been loading some Hornady brass in 6.5 PRC. The brass is from the 143 ELD-X and ELD_M factory ammunition. It's been fired twice. I loaded up some 130 Accubonds and 130 Sirocco's a couple of weeks ago, setting the shoulder back by .001. I didn't check the case length before loading them. Saturday at the range I had several rounds that would not load meaning I couldn't close the bolt and several where it was damned hard to close the bolt. The load was 58.5 grains of H1000 and either the CCI-Br. 2 primer or the CCI-200. I got some pretty good groups with the BR-2 at 50.0 and 58.5 grains, but closing the bolt was damned hard. I had some light marks on the case head as well, but primers weren't flat or any other sign of pressure.

I finally gave up and came home. Pulled all the bullets, dumped the powder and checked the case length. Case length was 2.025 and the Hornady website indicates trim length should be 2.015.

My question is would the 0.010 length difference cause a difficult bolt close when the website shows max length as 2.030? I also checked the shoulder length and it was identical to the Hornady factory ammo. Unless I used the wrong headspace gauge when I originally sized the cases I can't figure out the issue.

I went back yesterday and loaded some more. I resized the cases, setting the die to set the shoulder back .001, trimmed them to 2.105 and loaded them up with the 130 AB seated to 2.388 length to the ogive and we shall see what happens. They all chambered with very little difficulty.

For a hunting rifle I usually bump shoulders .003!

Inconsistent trim lengths can cause chambering issues if a carbon ring develops and is not taken care of, a case that is 0.010 to long can be bumping the case mouth against the carbon ring and cause a difficult bolt close and in some cases higher pressure, maintaining a consistent trim length is a must!

Sounds like you were sizing the case just enough to squeeze the body and elongate the case body a bit. You've gotta adjust the sizing die down just a bit more to hit the shoulder and bump it back 0.003" or so, and feeding should be smooth as silk.

I think you're correct. On my next loading I'm going to bump the shoulders back .003. The .001 bump was obviously not enough and I don't want to have chambering issues when I'm 250 miles from home. I usually chamber every hand load after reloading, but didn't this time. If I had, I would have found the problem sooner.

You might also be getting a little bit of the "dreaded donut" at the bottom of the neck. Have encountered that occasionally with Hornady 6.5 PRC brass, even after the first firing with factory ammo.

Remove all doubt as to what's happening - use a Sharpie and blacken the shoulder and neck to see where things are binding. Could be due to a lot of things.

This^^^

I would like to add that not paying attention to whether or not the cases need trimmed can result in a catastrophic failure. Imagine the end of your case being jammed into the throat so it won't let loose of the bullet when you pull the trigger.


Trystan

A little too much donut in the base of the neck can also result in very high pressures.

The standard test for that is sliding a bullet into the neck of fired cases. If it slides in easily, no problem, but any resistance ain't good.

Regarding the trim length. Unless you have a custom reamer most chambers have a generous amount of clearance at end for growing cases. Why not KNOW the dimension? You can make your own or buy Sinclair's chamber plugs. Many chambers are so long that you will never have to trim your brass.

https://www.sinclairintl.com/reload...clair-chamber-length-gage-prod32925.aspx
there is a video showing how they are used.




Varmint Al wrote a good article on chamber length:
https://www.varmintal.com/arelo.htm#Chamber_Length

specs on making your own chamber length gauges if you have access to a lathe
https://www.varmintal.com/alath.htm#Chamber_Length_Gauge