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I have a Henry X Model and a Marlin 1895 lever actions. I am shooting a 350gr LFN gas check bullet and I have to seat .10" deeper for them to cycle. Book says to seat at 2.55" and I have to seat at 2.45". I have not attempted to try them, not knowing what the pressure will do. I used 38.8 gr of IMR 4198 and a factory crimp. The crimp groove is inside the case by about 1/8th of an inch. Are they safe to try? Also, does anyone have 50 fired Hornady 45-70 short brass?
I believe I have a box of 20 of the shorter Hornady brass. PM me your address and I’ll send them to you.
if your load is..by the book...well down as its a starting load,you should be fine...if however its up near top pressure levels,all bets are off.
what your doing is not a lot different to 44 special vs 44 mag or indeed the 45/70 vs 45/90 slightly shorter case= slightly lower charge of powder.
if Im reading your post right...your using normal brass/full length so going to the shorter hornady brass will if anything make issue worse if you seat to same depth inside the case..if you want it so the crimp groove is closer to lip and still seat out long..all good. the distance from base of case/primer to base is your important bit..its the "engine CC rating" for want of better way to put it.
If you are substituting a different bullet the reloading data OAL listing is little more than a recommendation since every different bullets ogive is different. What matters more is how far the bullet sticks into the case and how far it is from the lands. Where did you get your OAL measurement from? From a manual loading a different bullet? If so the OAL is meaningless.
You need to load the OAL that functions with your rifle with the bullet you use. As long as your new seating depth is not jammed into the lands and cycles in your rifle ignore where the crimp grove is. Start out with low trap door loads and as always work up.
45-70 is a long case. Seating 0.1 deeper only changes the internal volume about 5%. Unless you are loading near the max load it should not be a problem, and, according to my copy of the cast bullet handbook, 38.5 gr 4198 is near the starting load.
i just checked my load data for the a 350gr...38.8gr of IMR4198 shouldn't be a problem. It's a fairly light load. Pressure should not be a problem with this load with the bullet seated 0.1" deeper.
As always...check for signs of pressure after the first shot. One of my pet loads for the Henry 45-70 is 38.5gr or IMR4198....and it's mild.
redhawk