Cycling Issue

[LRRPF52]

At the risk of getting yelled at for asking a question that doesn’t pertain to the original question asked to start this thread.

I’ve seen on here several discussions that with the Grendel it doesn’t show over pressure signs until it’s over the line or until it’s running way to hot , but why is that ? Why does the Grendel not show signs of high pressure until it’s over the line ?

I’ve been reloading bolt guns for over 10 years and am always trying to learn, I will start reloading for my Grendel soon after breaking it in with factory ammo but again what is it about the Grendel that makes it not show over pressure signs until it’s over the line ?

It's also important to identify what excessive pressure signs are, which we did in the 6.5 Grendel Handbooks, as has been done in other reloading handbooks from major manufacturers.

Without a chronograph, you are really limited from seeing what you need to see. In gas guns, which require a certain degree of slop in the action to reliably chamber and extract, you can get false excess pressure signs from the abuse that a production-grade bolt face often exhibits, when sharp surfaces shear the brass under bolt rotation, and the treatment of the primer with sloppy firing pin aperture fit to the firing pin head.

Headspace doesn't allow for slip-fit brass like in a bolt gun, so we typically see more back-and-forth shoulder movement and brass growth/contraction in gas guns. With that sloppy headspace for reliable gas gun operation, combined with rapid bolt rotation during unlocking, a lot of little things pop up when just looking at the brass.

My first metric for detecting pressure is the chronograph and known, published loads cross-referenced with my chrono results. Then I start looking at the case head, primer, and other surfaces on the brass.

If I'm seeing book speeds that correlate with book charge weights with a known load in a chamber that allows cartridges to drop free with gravity (not jamming the lands), but am also seeing flattened primers in Grendel, for example, is it because I've reached 60,000psi, or because of gas gun headspace slop?