Black powder 45-70 velocities or how to chrono black powder?

[NapalmCheese]

Long story short, I loaded some new starline .45-70 cases with 4.0 and 4.3 CC (respectively) of FFFg Goex. This is the same powder I load in my pistols. I didn't have enough FFg, so used FFFg. I'm using a 405 grain Chevy Cast uncoated lead bullet with black powder lube. I was using a Chrony (photo gate chrono).

4.0 CC of FFFg is about 60 grains by volume (I haven't measured) and 4.3 is about 65. I was seeing velocities north of 1700 fps which seems really really fast.

Could it be that I'm actually chrono'ing the smoke or something making it look like I'm getting higher than expected velocities? I was at 10 feet from the muzzle, I didn't push back because it didn't occur to me at the time. I'm getting a new chrono anyway since my buddy decided to shoot the back of my chrony with his last shot, but weird that I was seeing such high velocities.

[classicist]

[NapalmCheese]

I certainly have work ahead of me.

I'm not trying to achieve high velocity, far from it, I'm looking for 1300 fps or so. I was just very surprised to see 1700 fps and just don't understand how I'm getting those kinds of velocities with 3F. Maybe I wasn't.

Ultimately I'm looking for two loads, one that'll carry out to 600 yards for "long range" repeater events, and one that'll be easy and clean shooting at 50-100 yards to the tune of about 30 rounds without having to clean every 10 or so rounds. Well maybe 3 loads, I might put together a hunting load.

I'm not casting right now, so dependent on commercial bullets. Finding 20:1 or any really soft bullet is difficult, especially lubed with black powder lube. I don't mind pan lubing, but I'm not currently set up to lube and size. Most commercial manufacturers seem to drop their bullets somewhere north of 15 BHN. Missouri has their cowboy bullets at 12 BHN, but their .45-70 bullets don't look like they carry anywhere near enough lube. I might try shooting hi-tek coated bullets with a lubed felt wad under them.

[classicist]

[classicist]

I should add that, as I understand it, the biggest cause of leading is using a bullet that is not properly sized. You may have success at 1300fps. But, in my limited experience (with MY bullets, rifles, loads, etc.), keeping speeds under 1200 results in a less lead-fouled barrel, or one without any lead fouling.

[NapalmCheese]

I'm shooting this in a modern, Miroku built, Winchester 1886, though my buddy just got an original trapdoor and will be making some ammo for his. I'll keep the hollow base bullet knowledge in mind when he's buying components. I think Bear Creek Supply has hollow base .459 bullets with a moly/poly coating. With a lube wad underneath that might work well. I've shot bear creek bullets with a lot of APP in other guns, but never with real black. I've got enough FFg to do some experimenting now, so that's nice.

[classicist]

[NapalmCheese]

Hah, I bought that book a week ago!