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bjornborud
I finally found time to shoot my 30 XCB rifle today, bringing along several loads that I had prepped after last week’s outing. Today I was going to shoot ball powders, both Hodgdon LeveRevolution (LvR) and Winchester 760 have given higher velocities compared to extruded powders in earlier trials. All HV shooting today was done using Tim Malcolm’s breech seater, as max powder capacity and highest possible MV was the goal. To recap, my 30 XCB rifle is a target rifle from the 1950s, built on an FN Mauser blind single shot action. The barrel is a new Shilen Match, 31 inches long, 1 in 14 twist. Tim Malcolm (Goodsteel) recently re-barreled and re-bedded the rifle.
I had devised a “ladder test” of sorts, to figure out at which MV the bullet/lube/powder charge combo would lose accuracy. Not to be confused with the Creighton Audette ladder test, this was simply a series of charges starting at a known level, increasing by 2 grains per charge for the LvR and 1 grain per charge for the W760. Here are the targets for these 2 “ladders”:
At this point I picked one charge from each “ladder” and shot a 10-shot group of each. I picked charges that I believed would stay together:
Finally I upped the charge of the LvR powder by one grain and shot another group. This turned out to be where accuracy went south:
I did not bother to measure this group.
I have to say that this outing was very encouraging, and it certainly proved to me that the NOE 310-165 FN (XCB) is an outstanding bullet, and that White Label 2700+ Carnauba Red is an outstanding lube.
With this shooting I consider myself done with the breech seater, I’m sending it to Larry Gibson in Arizona so he can use it with his Oehler Ballistics Lab to plot the pressure curves in some of these loads. After the 55 grain load of LvR today (MV 3316 fps) the bolt handle was hard to open and I didn’t increase the powder charge any further. Primers were starting to flatten, but I have seen them much worse on heavy jacketed loads.
bjornborud-
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richardshedd
These threads have already been a great tutorial. Once all the testing is complete, it will really be something worth publishing!
Dave
It’s already in the works, in a small way. I’ve been asked by Al Nelson and Wiljen to do some writing for Castpics, and my plan was to collect all the data from the start of this project and turn it into a pictorial about the shooting that was done with my rifle. I’ll also re-shoot all the previous loads to account for what we now know was a bulged barrel when the shooting started.
I’m finishing up a house building project that’s been taking all my spare time, and the Castpics piece will be top priority following its completion.That is great!!
richardshedd
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