6.5 Creedmoor 140gr Sierra Match King issue

[TheDomFather]

Folks,
Loaded up some 140gr Sierra Match Kings over different charges of IMR 4350, It was very hard to close the bolt on these cartridges which were loaded to the Sierra recommendation of 2.810, I had also loaded some 140gr Hornady ELDs to 2.800 and had zero issues with them. Measured to the ogive the Sierra was almost .2” longer than the Hornady. I have a feeling I was jamming the bullet into the lands. I will measure to the lands later but has anyone else had this issue with the 140gr SMK’s? Also if I now have to load them shorter how do you calculate for the pressure increase that may bring at the shorter length?

Thanks for the help,
Dom

 

[Blue68f100]

It's always a good practice to determine the max OAL before you do any loading. I have several min spec 223 chambers that require a shorter than recommended length with some bullets. If you tilt the gun up the round should fall clear. If not continue to shorten the OAL till it does then add at least 0.020"+ more.

You should workup the load with any change of component. Putting 0.2" of the bullet into the brass will greatly increase pressure so you will need to back off the load and work back up.

 

[TheDomFather]

Here is a link to a video of the load testing I did:



Thanks again for the help.
Dom

 

[VoodooMountain]

Did you see any marks in the bullets after clambering?

We’re the shoulders bumped back enough when you sized?

You can also check max oal if your rifle with a cleaning rod and some tape if you are curious about it

 

[Driftertank]

I also consider checking length to the lands to be step one of any new load with a new bullet. Although in my case, the issue is usually the opposite...i have have to load WAY long to get LD bullets anywhere near the lands.

 

[TheDomFather]

Ive tried the Hornady tool and cant seem to get anything consistent. I am going to load 5 dummy rounds with no powder and primer at 2.780, 2.790, 2.800 and 2.810 and see how the bolt closes. These were brand new cases when I loaded them so I didn’t bump the shoulder at all. I used the same die and same die setting for the Hornady ELD I loaded and had no problems closing the bolt on those which makes me think its the bullet and not the brass but I can put the empty fired brass cases in and see if the bolt closes.
Thanks for the tips.
Dom

 

[Blue68f100]

Its better to push them in by hand, then you can feel the resistance. Then tilt the barrel up and see if if fall clear.