Thread: My first load development

Originally Posted by zimmer

@Remmodel7 if you haven't decapping those cases yet could you stick up a photo of them.7

Another indicator that you may be pushing the envelop is loosening primer pockets after only a few firings. This can happen without the extractor wipe or ejector plunger ring appearing. A warning nevertheless.

Primer pockets can be quite tight when the cases are new and will loosen up a bit after firing. If however the primers become super easy to seat there may be a pressure issue.

Otherwise, as stated, try and chrony your loads and compare against a couple of reloading manuals. Taking into account your barrel length.

Also, as pointed out, sadly one 3 shot "group" does not constitute game over. I only ever fire 3 shot strings at the early stages of load development and that is to get a feel for velocities. A series of 5 shot groups is my method. With the strings with progressive increases of charge many times I have jumped a charge and gone to the next charge up because I know the velocities are so low and don't wish to waste components. Those loads come home and are stripped.

I am not a huge fan of ladder testing. Old habits/methods are hard to quit.

Yes realize one group is not definitive but I have to start somewhere. Plan on loading a few more, Checking velocity and looking for pressure signs at that load.
How do people calculate velocity change compared to book data from a 26" barrel in the load data to my 20” barrel?

Originally Posted by Remmodel7

Yes realize one group is not definitive but I have to start somewhere. Plan on loading a few more, Checking velocity and looking for pressure signs at that load.
How do people calculate velocity change compared to book data from a 26" barrel in the load data to my 20” barrel?

Greetings Remmodel7,
I have not found ejector hole marks all that reliable as an indicator of pressure. There can be a slightly rough edge around the hole that makes a mark at normal velocities. Another rifle may show no mark, or any of the other "pressure signs" but expand the case head beyond further use with one shot. I've seen both. In the second case the claim was really good velocity with no pressure signs. Old data that had not been pressure tested was a culprit here as well. Velocity is easily the best indication of pressure that can be used by handloaders. Actual tests of velocity loss v barrel length reduction have shown 20 to 30 fps loss per inch for standard calibres with the smallest cases losing the least. I would figure on 20 fps per inch for your Grendel. Hodgdon/ADI book data for the Grendel is for a 24" barrel so 80 fps would be right.
Regards Grandpamac.

Originally Posted by Remmodel7

Yes realize one group is not definitive but I have to start somewhere. Plan on loading a few more, Checking velocity and looking for pressure signs at that load.
How do people calculate velocity change compared to book data from a 26" barrel in the load data to my 20” barrel?

Don't get me wrong, you've made a good start.
What projectile are you using?

If you're willing to divulge your load I'll run the numbers thru Quickload.