.54 Cal Ball Trajectory

[GregC]

I finally got my new TVM Iron PA. Its a .54 cal. I got out to shoot it today and started at 25 yards to work out my load. I started with 80 grains FFG. At 25 yards I was about 6" low and 4" left. I took care of the left right issue with no problem but left the gun low as I expected it to shoot higher at 50 yards.

When I moved out to 50 yards the rifle shot even lower. I expected the arc of the ball to move the impact higher at 50 yards, not lower. What am I missing?

Also, the 80 grains of FFG gave me a really nice grouping at 25 yards. All shots touching. How do you know when you found THE LOAD that the gun likes?

 

[roundball]

What am I missing?

The sights come full size as the builder doesn't know what load you're going to use, etc...so you need to start filing the front sight down a bit at a time to raise the POI

 

[DrLaw]

I know I am a newbie at this, but I also have a .54 that shot low for me at 50 yards. I was starting with 80 grains of FFG as well. I upped the load to 85, and though it felt as if I had doubled the charge, the POI went up to POA.

What I did was raise the front sight for the rest of the day in relation to the rear notch, and went back to 80 grains. Then later on I filed the front sight a tad and sooner or later, I will be trying it again.

I should be right back to POI at POA now in any event.

IIRC, the recommended load for the gun was 90 grains, but I have not done that, yet. I was using a Lee Conical R.E.A.L. ball and a Speer .530 round ball with a lubed .015 patch. (all I had - made for a tight fit)

The Doc is out now. :v

 

[rabjr]

It seems 90gr with a pillow ticking patch with my lube works very well through both my .54 rifles. I say this because I found a big difference between 80gr and 90gr accuracy wise at the max range I wanted the gun sighted for. Others findings may vary.

 

[BrownBear]

Coincidence or not, my 54's like 90 grains of Goex 3f, too. For reference, with that load I have mine sighted in dead on at 75 yards, which puts it more or less right on at 25, barely and inch high at 50 and about 3 low at 100. Works for me.

 

[Trench]

If you're sights aren't set to throw the ball at an upward arc, then your POI will be lower at any range farther than 25yds. The ball is falling at the same rate as anything else would.

My sights are set so that my .58 hits POA at 75 yards. At 25 yds it's about 1.5 inches high and 2 inches high at 50yds with 80gr of FFg.

 

[Many Klatch]

I only shoot offhand, I never seem to have any luck benching a gun. My .54 likes 55 grains of 3F at 25 yards and 75 grains of 3F for everything beyond that. I am able to keep the ball on a paper plate at 100 yards by holding dead on. That is about all I know about trajectory.

Many Klatch

 

[Billnpatti]

Determining the exact trajectory for a projectile is not a simple thing. You can find information about it in a book entitled "Understanding Firearm Ballistics" by Robert A. Rinker or you can find computer programs that will do it for you. You will need such info as the ballistic coefficient for your projectile (a .54 cal. round ball is .075 and the sectional density is .115) You will also need the measured muzzle velocity using a chronograph and the angle of the bore relative to the horizon. Plug all of this in along with air temperature and humidity and you or the computer will calculate the trajectory.

Is there a simpler way? Well hell yes!!! A new rifle will arrive with a front sight that is too tall (on purpose). Take a few shots from a sand bag rest at 25 yards to see how low your ball is hitting. Now just file a little off your front sight and shoot a few more shots to see how much you have raised your POI. Keep doing this until you have your POI where you want it. Yes, there is a way to calculate how much to take off your front sight and save a lot of shooting.......if you want. Here's how: First measure the distance from your rear sight to your front sight in inches. Write it down. Determine how far it is in inches from your muzzle to the target. If you are shooting at a measured 25 yards, that will be 900 inches. Okay, using a calculator, divide the distance from your front sight to the rear sight by the distance to the target. Write this number down or save it in your calculator. NOw measure how many inches up you want to move your POI. Multiply this measurement by the number saved in your calculator and you will have the amount, measured in thousandths of an inch, of front sight you will need to remove with your file. Use a michrometer to measure the heighth of your front sight and then start filing and measuring until you have removed the calculated amount of front sight. I like to stop a bit short of removing all that I calculated from the front sight and fire a few rounds just to make sure of where I am. Yep, it's just that simple!! :thumbsup:

 

[longcruise]

Get the Point Blank software that is free on the net. Use .061 as your BC. Remember to enter the height of your front sight from the centerline of the bore!

As Trench explained, if your front sight is too high your trajectory will always be below the line of sight. Do a bit of filing till you bring it up a bit, but remember too that you might be filing to a load that is not the best for your rifle! :shocked2:

Better to leave it as is and shoot for groups till you find "the load" and then file sights to match. If you file to the point where your are hitting about one inch high at 25 yards, you will be ready to start comparing poi at longer ranges.

 

[bigsam]

if you go to tvms web sight there are directions on how to sight in a new rifle written by mike nesbitt. as mentioned earlier shoot for group then poi and i would not worry about getting it too close until i had a couple of hundred shots fired. things can change while the barrel is seasoning and its a lot easier to file metal off of a sight than it is to put back on.

 

[Semisane]

The targets below show the actual trajectory of patched balls (in 5-shot groups) from my TC Renegade with a .54 Green Mountain barrel at 25, 50, 75 and 100 yards. The last target is a composite of all twenty shots.

The load was 85 grains weight of GOEX FFFg, which fills my TC U-View powder measure to the 95 grain volume mark. Point of aim on all targets was the center of the black dot.

So, if I adjust my sight to be "dead on" at 25 yards, it would hit a tad over an inch high at 50 yards, about two inches high at 75 yards, and close to dead on at 100. Ya` can't beat that.

 

[roger sells]

I am a big 54 cal fan for target as well as deer hunting. One of the best most accurate rifles I have ever had is a Hawken I made for myself using a Douglas .54 cal 34 inch long 1 1/8 barrel. I spent over half a day at the range working up a load. I worked up a load at 50 yards, and the rifle would print groups all touching at 25 and 50 yards and a 1 1/2 five shot group at 100 yards using 70 grains of FFF and pillow ticking for patch material. Once I found the load it liked, I adjusted my sights so it would print spot on at 25 and 50 yards using 70 grains of FFF. It would drop 2 inches at 75 yards, and 5 1/2 inches at 100 yards. I never change loads when going from target work to hunting, I just spend a lot of time shooting and knowing my rifle. I spend a bunch of time shooting matches at unknown yardages so I can learn how to judge distances in the woods. This rifle load combination has been very successful for me in both target competition and hunting. A lot of work, but it builds confidence and is a bunch of fun. Good luck and enjoy shooting.
Roger Sells

 

[Russ T Frizzen]

Hi Roger. Good to have you here. Do you happen to have any photos of your Hawken? We--well some of us--tend to spend lots of time poring over photos of muzzleloaders! Dan

 

[roger sells]

I was stupid and let one of my friends talk me out of the rifle. I had used it for over 15 years and let him have it under the agreement I could borrow it if the need ever came up. I should have kept it. It was like loosing a friend, and haven't been able to keep one of my rifles since. I will see if my friend will send me some digital photographs.
Roger Sells

 

[Russ T Frizzen]

Thanks, Roger. There's just nothing like a Hawken! I plan to be buried with mine. I would dearly like to know who made it. It's a Great Migration Era S.Hawken and to my eye it is perfection. The most accurate patched ball rifle I've ever owned! Dan