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1990 IMR data
Posted: Thu Jan 22, 2026 6:54 am
by 375Short
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1990 IMR Handloaders Guide. Yesterday I was searching the junkyard (internet) for slow powder loads and must have read 10 times from on-line experts “ you can’t do that because”. Sometimes we silhouette shooters are trying to do something that’s not common. Like milking a Tigger, it can be done, it’s just rare that someone has a need.
Maybe someone will find this published data useful or interesting.
Re: 1990 IMR data
Posted: Thu Jan 22, 2026 10:29 am
by DAVIDMAGNUM
The following is older but published data. I have shot and chronographed this load in my 1892 Rossi. Very low extreme spread , accurate and hard hitting.
357 Magnum, Starline Brass, CCI Small Pistol Magnum primer, 193gr Hunters Supply hard cast bullet and 16.5gr Alliant RL7. 1,350fps muzzle velocity.
Dents pistol caliber common steel animals. Knocks over all full size rifle caliber animals if the rams aren't set horribly. Impressive for such a little cartridge.
Re: 1990 IMR data
Posted: Thu Jan 22, 2026 7:49 pm
by edgehit
Now I want a 44 mag.
Re: 1990 IMR data
Posted: Fri Jan 23, 2026 7:42 am
by 375Short
D Mag in your RL 7 load development did you get any indication that you could back it down a couple hundred FPS and still get good ES and accuracy? Or maybe it needs a significant amount of compression to behave well. I would guess the pressure was probably still low by .357 standards.
Re: 1990 IMR data
Posted: Fri Jan 23, 2026 8:42 am
by DAVIDMAGNUM
375Short wrote: Fri Jan 23, 2026 7:42 am
D Mag in your RL 7 load development did you get any indication that you could back it down a couple hundred FPS and still get good ES and accuracy? Or maybe it needs a significant amount of compression to behave well. I would guess the pressure was probably still low by .357 standards.
16.5gr of Alliant RL7 with that particular bullet is a 100% fill charge.
Knowing my Rossi, very shallow rifling and slow twist, it only shot cast bullets well if the bullet was hard and pushed hard. I tried the full case load and nothing else.
Since RL7 is a very slow powder for that cartridge if you try a reduced charge weight at least verify that the bullet exits the barrel for every shot.
David