Is this approximated calculated ballistic coefficient reasonable?

[Varminterror]

I know this sounds stupid,

It’s not stupid. Folks have been shooting leverguns like this out to distances much farther than 200yrds for around 150 years, and firearms with even worse ballistics for even longer.

Frankly, the only reason I knew the BC you calculated above was way out of whack is because I’ve been doing this same thing for a long, long time. I shot 44mag for CAS/SASS - which is arguably stupid in itself - but that was coming up on 20yrs ago when I started, and we had LR side matches already back then. It would be around 25yrs ago the first time I would have shot a revolver cartridge levergun to 200yrds, then 250 within minutes thereafter, and attempted 300 within a few more… and a few more minutes, I was sending rounds from my 7.5” Super Blackhawk at the same target distances, and doing much of the same math as I described above to decide how much I would need to raise that rear sight to get there. At one point, I even had a longer screw and an aluminum shim to let me raise my rear sight even higher, rather than swapping to a shorter front blade, and I was notching white lines into the back of my front sight for more and more reach… which I’m told is a technique as old as the West.

The tools you’re seeking already exist, because we already do this. We already have tang ladder sights and fold-up aperture peeps, calibrated and adjustable sights, replaceable front blades of differing heights, stripe-back front sights, etc… You can order this stuff online at big box retailers, ready to go off of the shelf, because we do it, and we need the tools to get it done. So it’s not stupid. It ain’t easy, not as easy as shooting those distances with a modern bolt action in a high pressure bottleneck cartridge - hell, it’s easier to shoot 600yrds with a modern set up than 200yrds with a revolver cartridge levergun, but it’s still fun.

 

[AJC1]

It’s not stupid. Folks have been shooting leverguns like this out to distances much farther than 200yrds for around 150 years, and firearms with even worse ballistics for even longer.

Frankly, the only reason I knew the BC you calculated above was way out of whack is because I’ve been doing this same thing for a long, long time. I shot 44mag for CAS/SASS - which is arguably stupid in itself - but that was coming up on 20yrs ago when I started, and we had LR side matches already back then. It would be around 25yrs ago the first time I would have shot a revolver cartridge levergun to 200yrds, then 250 within minutes thereafter, and attempted 300 within a few more… and a few more minutes, I was sending rounds from my 7.5” Super Blackhawk at the same target distances, and doing much of the same math as I described above to decide how much I would need to raise that rear sight to get there. At one point, I even had a longer screw and an aluminum shim to let me raise my rear sight even higher, rather than swapping to a shorter front blade, and I was notching white lines into the back of my front sight for more and more reach… which I’m told is a technique as old as the West.

The tools you’re seeking already exist, because we already do this. We already have tang ladder sights and fold-up aperture peeps, calibrated and adjustable sights, replaceable front blades of differing heights, stripe-back front sights, etc… You can order this stuff online at big box retailers, ready to go off of the shelf, because we do it, and we need the tools to get it done. So it’s not stupid. It ain’t easy, not as easy as shooting those distances with a modern bolt action in a high pressure bottleneck cartridge - hell, it’s easier to shoot 600yrds with a modern set up than 200yrds with a revolver cartridge levergun, but it’s still fun.

200 yards for lever action is pretty standard. I shoot 357, 45c and 30-30 along with 45-70. I provided my preferred sighting systems for doing that. Tang sights are used, but I don't prefer them.

 

[JimGnitecki]

I took a bunch of the suggestions from the above replies, and especially Varminterror's, and realized this might not be as hard as I first thought.

I found an online trajectory calculator, plugged in a BC = 0.140, and started playing with different zero ranges. It turns out that the range of elevation MOA needed to handle both normal CAS match shooting and 200 yards shooting is about 25 MOA, because the bullet is traveling so slowly (1129 fps at muzzle and under about 900 fps at 200 yards. With 17 inches between the front and rear sights, that means a total vertical movement of about .118" of the rear sight leaf needed to handle the entire range. So there's my starting point.

This iS going to be fun. Thanks again guys!

Jim G

 

[JimGnitecki]

I did some measuring on my rifle's rear sight elevator ramp, and some approximate calculations based on the trajectory data from the online trajectory app. It turns out that if I set my rifle's zero at 50 yards (suitable for CAS), I'll need about another .125" higher setting for 200 yards. But, with my higher than OEM front sight, my OEM rear sight won't go that high. I have my gunsmith checking his supply of rear sight elevator ramps for one that would be suitable! (No more than .097" wide, and a top "step" setting that is at least .306" in height).

This would be a minimally low cost solution.

Jim G

 

[AJC1]

I did some measuring on my rifle's rear sight elevator ramp, and some approximate calculations based on the trajectory data from the online trajectory app. It turns out that if I set my rifle's zero at 50 yards (suitable for CAS), I'll need about another .125" higher setting for 200 yards. But, with my higher than OEM front sight, my OEM rear sight won't go that high. I have my gunsmith checking his supply of rear sight elevator ramps for one that would be suitable! (No more than .097" wide, and a top "step" setting that is at least .306" in height).

This would be a minimally low cost solution.

Jim G

I've herd of custom ramps where they are made for a specific bullet in your case a 405 grainer. It's not terrible math, but there is a height limit. If your long term plan is long range 600 ish yards, you may look to get a front post zeroed with the elevator removed at 50 or 100.

 

[JimGnitecki]

I've herd of custom ramps where they are made for a specific bullet in your case a 405 grainer. It's not terrible math, but there is a height limit. If your long term plan is long range 600 ish yards, you may look to get a front post zeroed with the elevator removed at 50 or 100.

Oh, I would never shoot this Uberti lever action .357 Mg at 600 yards! That's a job for my Pedersoli Sharps rifle, and even that will need a nice quality MVA rear sight and tunnel front with the right inserts! But the club is talking about 200 yard side matches for the lever rifles, and I figure just spending a few bucks gets me into that game with just a higher than OEM elevator ramp!

Since the rifle is proofed for full power .357 Mag loads, I could also make the mission easier by loading a stronger handload than my current 1129 fps 158g load that I use in the regular CAS match stages. If I can keep the hotter load under about 1400 fps, I can still avoid leading the barrrel, right?

In fact, with a 1400 fps muzzle velocity load, I could avoid needing the higher elevator ramp at all, simply by centering my .150" gold bead on the 200 yard target versus using the six o'clock hold that I use in the regular match stages for quicker and better visibility. In the side matches the need for quick sight picture acquisition is a lot less urgent, and I'd have the time to do a slower centered bead sight picture.

This is possible because if the rifle is zeroed for 50 yards, and is shooting with a 1400 fps muzzle velocity, the trajectory chart says I need to add about 17 MOA of height. Using the center of the .150" front sight bead instead of the top gives me very close to that extra 17 MOA, without having to move the rear sight.

Jim G

 

[AJC1]

Oh, I would never shoot this Uberti lever action .357 Mg at 600 yards! That's a job for my Pedersoli Sharps rifle, and even that will need a nice quality MVA rear sight and tunnel front with the right inserts! But the club is talking about 200 yard side matches for the lever rifles, and I figure just spending a few bucks gets me into that game with just a higher than OEM elevator ramp!

Since the rifle is proofed for full power .357 Mag loads, I could also make the mission easier by loading a stronger handload than my current 1129 fps 158g load that I use in the regular CAS match stages. If I can keep the hotter load under about 1400 fps, I can still avoid leading the barrrel, right?

In fact, with a 1400 fps muzzle velocity load, I could avoid needing the higher elevator ramp at all, simply by centering my .150" gold bead on the 200 yard target versus using the six o'clock hold that I use in the regular match stages for quicker and better visibility. In the side matches the need for quick sight picture acquisition is a lot less urgent, and I'd have the time to do a slower centered bead sight picture.

This is possible because if the rifle is zeroed for 50 yards, and is shooting with a 1400 fps muzzle velocity, the trajectory chart says I need to add about 17 MOA of height. Using the center of the .150" front sight bead instead of the top gives me very close to that extra 17 MOA, without having to move the rear sight.

Jim G

Sorry I got confused but the custom elevator still applies. 200 yards is long in a 357 if you have any energy requirements (I do in metallic Silhouette, I have to knock down the heaviest animal rams). If your poking paper or just marking the target, it should be a lot easier. 357 is absolutely my favorite and I believe is perfect for all ages, because even max power loads don't beat you up. 45-70 is fun, but takes much more conditioning to be consistently accurate.