Hot 7-30 load confession
This is somewhat of an FYI/confession. While writing this, I think of my favorite phrase: "There are a lot of old reloaders and a lot of bold reloaders, but not a whole lot of old bold reloaders".
While preparing new loads for my 7-30, I took data from the Contender load data book, but made a rookie mistake. The bullet I chose was the 120 Nosler ballistic tip due to the reasonable muzzle velocity. I might change that later, but a discussion for another time.
Using H335 to max out the potential of the gun, I read the hornady data by mistake (maybe). Nosler section shows a max load of 34.5 grains. Hornady 120 shows 34.8.
It doesn't sound like much but using fireformed brass, I had fantastic accuracy at 34.8.
Last December, I took it to a public range just to get some reps in. After about 15 or 20 shots, I had a blow out that also gave me a pretty cool scar as shown.
I have no doubt the gun can handle this, but I may have done a couple things that would affect this: suppressor, brass, quicker shots.
My 7-30 barrel was cut to 13" and threaded for a suppressor with flash hider mount and has done well. This day I did a few things differently this trip:
-I put the compensator on the barrel that mounts the suppressor rather than the normal flash hider. Maybe there was some extra resistance there. The suppressor already added some extra force on the lugs.
-I was shooting with less time between shots than normal. This barrel gets HOT
-I haven't confirmed it but I think brass fireformed from 30-30 has slightly more case capacity, this was the first time using 7-30 head stamped brass.
I took a few more shots (while ducking and letting it cool and no suppressor) and took some measurements and didn't show any deformations. I talked to a friend at a local reloading store and laughed at me saying he's done that a lot and not to sweat it, just look over it and check for any damage. All is good with other barrels too and this is the one I took to South Africa in August. I've done a ton of shooting with these but just for a couple of years. I know them well, but by no means an expert, just wanted to share for others to do what they will with this.
I think there is probably more going on than a mistake of .3 grains of powder. Based on you report you went from everyuthing is good, no pressure signs to blowing the action open and blowing a piece out of the case. It may be possibile with .3 gr but it might be worth looking into to make sure there are not pressure signs as you work up to 34.8 gr.