Recently, I had a .375/06 IMP barrel made. The barrel maker chambered the body with a .25/06 IMP floating pilot reamer he had. The shoulder diameter has led me to believe it was an ICL chamber as the shoulder dia. is .460" on formed brass with an even .470 base. The normal Whelen Imp. chamber has a .453" to .454" shoulder, some .007" less than mine.
: As I've previously owned and shot a .375 Whelen IMP, I felt a needed another.
: The reason for this post, is I've noticed that some 'writers' have derided the .375/06 IMP as being sub-standard and inferior as far as ballistics are concerned, when comparred to the .338/06IMP and .35 WhelenImp versions. That wasn't my experience before and certainly isn't now, as I've been able to chrongraph the new one.
: Presently, I am fireforming at 2,845fps with 235gr. Speer's without brass loss on old '06 brass and in fireformed brass, I'm averaging 2,470fps with 300gr. Hornady's newer Interlocked RN's. Neither of these loads are absolute max but are probably close. Neither hurt the primer pockets at all - "0" expansion. Both hit the same Point of Impact.
: With a nicley tapered expander, I can expand '06 necks and shoulders (as well as .35 Whelen brass) out straight to .44cal in one pass. The necks are then sized them down for headspacing in an altered, shortened .300H&H mag die with the neck opened up to .401". The resulting cases are ready for priming and loading with the 235gr. fireform load - at 2,845fps and sub-MOA accuracy. All bullet weights tried so far, as with most .375's strike about the same POI and make a 2 1/2" group when shot together - 235Speer, 250SierraBT, 270gr.HornadySP, 285gr.Speer and 300gr. Hornady. Individually, they all make 1" or smaller groups, individually. The 3/8" bore is notably accurate, one and all.
: The reason for the H&H mag die, is the opened '06 shoulder's are contacted when forming, and this keep the necks perfectly square with the case base for fireforming. I assume this is why they are so accurate. A shortened .300 WinMag die was opened to neck-size formed cases while I await custom dies from CH4D.
: I felt the true ballistics of the .375/06IMP chamber had to be known. My big-bore buddy, also with this very same chamber, forms with light loads, yet is still running 2,380fps with 300's, and 2,500fps with 270gr.and 2,725fps with 235's. Even at these levels, there is nothing to sneeze at with the .375/06IMP. In formed brass, mine clocks 2,530fps with 285gr. Speer GS.
: If ft. lbs. energy means power to you, the 235gr. are pushing close to 4,230 ft.lbs. while my other weights, like the 285gr.Speer, run just over 4,050ft.lbs, pretty much the same as factory .338 mag. Out to 300yds, there is little killing difference on game, unless there is a benefit to larger bores as I am want to believe.
: Powerwise, it is on par with the .375 Scovill + a bit which may be a mite contrary to what I've read, also.
: The capacity is an even 80gr. to the top of the case neck.
: It is a worthwhile ctg. for any standard length action with 5 round capability.