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Posted: 1/3/2017 5:20:59 PM EDT
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I just started reloading for my M1 and realized that I used Hornady's data for H4895 when I was actually loading IMR 4895.
I started with the minimum published load of 43.2 gr. Are there any safety/ accuracy concerns with this switch? Most informal discussion I've read on loading for the M1 with these two powders indicates that people generally use slightly higher amounts of IMR4895 to get the same velocity as the Hodgdon equivalent, so I'm assuming I'm still well within a safe pressure range for the Garand, but I can't seem to find any published M1 load data using IMR 4895 to confirm this. |
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H4895 and IMR-4895 are nearly identical to each other in burn rate when used in .30-06.
46.0 grains of either is considered a standard match load for M1 Garands that can be used for 150 grains, 155 grain and 168 grain bullets. It's a maximum load with 173/175 grain bullets. |
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They are close but not the same. At M1 Garand charges there's not much difference. For bolt rifle tests and loading to maximum charges you need to watch when switching from IMR and Hodgdon. In Hodgdon's 2013 Annual Manual an article by James Tarr tested them at the same charges in a Garand. Using Win brass and Fed 210M primers his results showed H 4895 had slightly better Standard Deviation, with H4895 giving a few feet per second more velocity indicating that H4895 is slightly faster. H4895 is a little denser filling up the case just slightly more than IMR.
His results in an M1 Garand: Sierra 168 gr bthp-----40 grains------IMR 4895 -2322 fps-------H4895 -2333 fps Winchester 147 FMJ------43 grains-----IMR4895-2389--------H4895-2402 Sierra 168 bthp---------46 grains-------IMR 4895-2590------H4895-2634 Win 147 FMJ---------------46.5 grains------IMR 4895-2679-------------H4895-2705 fps Accuracy was close for both. My Garands with M2 150 gr. and Hornady 150 FMJ's don't start shooting well and consistently until about 45 grains of IMR 4895. At your lever with 43.2 grains of either would be very light. May cycle a Garand but a light load. With IMR 4895 and 150 grain bullets 48.0 grains should be maximum. Careful using the wrong data or wrong powder though. |
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The max under the 168 grain match loads in the hornady manual are about half a grain apart. Using less H than IMR for the same max speed.
There also published reduced loads with IMR 4895. You're way fine at the book start load no worries. All that said be careful and read your manual closely. Confirm with a second source whenever possible. (You will see manuals don't all agree to the tenth of a grain but that's due too differences in testing, guns, bullet makes, powder and primer lots plus other intangibles. ) |
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Quoted:
I just started reloading for my M1 and realized that I used Hornady's data for H4895 when I was actually loading IMR 4895. The powders are almost interchangeable. Certain manuals even indicate that their loads are developed with H4895 so that IRM4895 can be substituted. Going the other way is more problematic, but safe enough as long as you are not near a max load. Max difference in 308 or 30-06 is usually around 0.5 grains. My normal load for the M1 with 150 grain bullets is 47.5 grains of IMR4895. This is well under maximum. |
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