I recently bought a 2nd 22-250 (a RARP) so that I'd have enough guns for hunting bunnies and yotes with my growin-too-fast boys. I've been reloading for ~10 years, but until recently I've always used my Dad-in-law's or my buddy's RCBS Charge-master. With a new job that takes a lot more of my time, I thought I'd get a scale and the few things I lacked to load in my basement vs. taking time to travel to their houses.
Fast forward to yesterday. I got some chores done and wanted to do some load work on the new 22-250. Last load I wanted to try was the combo of I4895 and Speer 55 SP. Someone had told me I4895 had done real well in theirs, I had some, and never tried in in my other 22-250. I didn't have time to run the whole gamut from bottom to max load (and really wanted to focus on some temp resistant powders like varget anyway) so I only ran a few in the middle of the range. The third round of the 35.5gr load sounded a bit different, and I thought well it's hot out (~95F) and the barrel is quite warm, and then I tried to open the bolt...and it took all the muscle I have (not a lot, really
) to get it open. I had blown the primer!
Had a BBQ with friends last night so I really didn't get a chance to research this until tonight. I first started reading about the temp sensitivity of I4895, and didn't think there was enough variance to blow a primer (note that this load is a whole grain below Hodgdon's max). Then started looking in to seeing actual reports of this combo, and didn't find much. Then I just started trying to research what had caused others to blow a primer and came upon a thread from Dirtfarmer, titled "Whoops....." (April 2015). His scale had a problem with the weight jumping a notch. I then recalled that I didn't fire all the rounds I'd made for this load (who would after blowing a primer?). So I pulled a bullet, and tested the scale, and sure enough that load had been 40.5 grains!!!
The Herters MS4 magnetic scale I'd bought second-hand some light wear on the beam in the lower gradients, but I'd never even thought that the weight would jump as it hit after removing the pan.
I share this as a reminder to be aware of, and double check what you're doing all the time.
I am curious of what pressure this load was running at, if anyone wants to run it through quickload (using 210s, win brass)...yea...it'll probably scare me again, but that's o.k.
Also, should I be concerned about the chamber, have it inspected?
If interested, the primer pocket was blown to .224. The lower section of the web is at .469, and most new brass is measuring about .466. Any input, critique, etc is welcome. I don't want to get anywhere near this experience again. Thanks in advance.
