Posted this in a different forum with no responses after 2 days so I'll try here.

For thoses of you with chronographs and 45-70 Marlin Guide Guns what velocities are you getting? I assume the short barrels put a cap on the velocitiy potential but how much? My current handload should be in the neighborhood of 1800 fps from a 22 inch barrel but it gives off a huge muzzleflash from the 18" barrel so I'm sure I'm wasting powder.

I'm particularly interested in cast bullets in the 300 to 405 grain weight range but jacketed velocities would be ok also.

With factory ammo my ported Guide Gun starts a Remington 405 gr soft @ 1200 fps and Winchester or Federal 300 gr JHP @ 1700 fps. So I'll guess the shorter tube and/or the ports are worth about 100 fps.

Full power 45-70 loads average 26 fps per inch of barrel length difference in the Marlin 1895 and moderate loads about 20 fps.

In my 1895GS

Leverevolution ammo averages 1861 fps

Hornady 350 gr JFP over 55gr Varget averages 1630 fps. I does NOT burn completely with many unburned powder zombies left behind. In my 26" 1895CB I get 1773 fps with this load with a clean burn.

Hornady 350gr JFP over 42gr of IMR 4198 I average 1669 fps with a complete burn and very good accuracy. The 1895CB averaged 1820 fps for comparison.

Oregon Trail Laser-Cast 405 gr RNFP over 28 gr of SR4759 averaged 1529 fps with excellent accuracy in my Guide Gun. Very clean burning. The 1895CB gets 1597 fps.

My favorite load is the following, and it has taken everything from feral boars to Bison:
Nosler 300 gr partition
54 grains H4198
Fed 210 primer
M.V. 2150 FPS

this will give you some good info for the 18" barrels

http://www.gunsmagazine.com/taffintable.html

this link has other good links

https://forums.accuratereloading.com/eve/forums/a/tpc/f/4711043/m/253108746

I'm getting 1850fps out of my guide gun with a Remington 300gr jhp over 60gr of Varget. My heavier load is a 425gr Beartooth hard cast lead bullet over 45.5gr of AA2015 which averages 1650fps.

I get 1940fps with 350gr hc bullets with RL-7 in my guide gun.

Is anyone packing IMR 3031? I just worked up some loads using Hornady 350gr FP Iterlocks and 3031 but haven't had a chance to shoot it y et.