Correct muzzle velocity

[Sierra Sherpa]

Hello,


I'm trying to estimate the correct muzzle velocity for a 300-gr. Hornady .45-70 bullet using about 61.0 grs. of Varget.  The data is from a 24" barrel and states 2,020 fps for 63.0 grs. of Varget.  (The 61.0 gr. Varget load also groups well from my Uberti Highwall with it's 30" barrel.)  With the Handi's 22" barrel and 2.5" chamber--19.5" barrel--I'm trying to figure out what the fps loss would be for the 4.5" difference from the test barrel.  The load groups well and if it ever stops raining here in sunny CA I will further confirm it's accuracy, along with other handloads of IMR 4198 and 3031 and H322 using the same bullet.  Does anyone remember what the fps loss per inch is for this caliber?


I'm using a 1.25-4.5X Eagle Eye (IJK) Optic 30mm scope with mildots.  With the Varget load holding the bottom reticle's first mildot on the target puts me 7" high at 100 yds.  Using the JBM trajectory chart calculator, that hold would put me on at 200 yds. with an MV of 1,800 fps.  I would like to confirm load accuracy at 100 yds. with my various handloads before paying additional fees to use the local shooting facility's 200 and 300 yd. ranges for further downrange performance confirmation.  Appreciate any and all help.

[Sierra Sherpa]

Wow, 65 views and no responses???   

[tacklebury]

As a quick guess, I'd say 50 fps per inch.  It varies though depending on caliber and powder etc...  Best bet is to get ahold of a chrony or use a buddies to test it.  There's a lot of variables there. 
 
**edit**
Oh, and I'd never use varget in .45-70.  I like Reloader7 personally.

[Sierra Sherpa]

Thanks Tacklebury.  I was thinking the same thing.  Thought some of the guys here would know for sure so figured I'd ask. 


Varget does real well in my Highwall and all preliminary indications are the Handi likes it as well.  Will know for sure with further testing.  Haven't tried RL-7 yet.  Trying to simplify powder selections for .45-70, .30-30 and .308.  My Rem. 788 and Rem. 700 VS .308s like Varget, RL-15 and IMR 4064; haven't reloaded as much for the Win. 94.  Take care.

[gcrank1]

When I got a chrony I discovered the book data never has matched my actual velo (by more than just a little). It does give me some extra info, but it has never helped me shoot. I suppose at long distance a wide deviation will affect POI.......supposed to anyway, but Im still the biggest problem I think. Ive read that those mid-range trajectory or drop tables are pretty accurate and you can extrapolate velo by them, if you are mathematically inclined. There has to be at least one computer program to do what you want, though it is still not out of your rifle.