RB Trajectories?

[Thunderhawk1828]

I've read that by sighting in at 17 yrds you are also dead on at 75 yds. Are there any charts for BP to show the over / under tajectory at 25, 50 and 100 yds? I have the Lyman BP handbook & manual but it gives velocities. Anyplace give the trajectory information for 50 / 54 cal RB??

Thanks.

Thunderhawk

[Bigsmoke]

In the book Sporting Rifles and their Projectiles, Forsythe gives the advice that it is pretty simple to determine that precisely.
Construct a series of target frames and put them in a row in front of your shooting position.  Then shoot through them.  Presto, there is your trajectory pattern for your own rifle with your own load.  No questions asked.  I think Forsythe suggests placing them every 10 yards out as far as you want to know.  You could also determine the trajectory of a series of different charges as well.

[Uncle Russ]

Thunderhawk, I could give you a "fair estimate" if I knew the velocity of your roundball. (Actual velocity, not book velocity.)
Don't know if you have access to Sierra Infinitive (a ballistic program) but, if you know the velocity and shape of a projectile, you can tell "pretty darn close " what its trajectory will be.

I have posted a couple of trajectory charts, based on my own chronograph readings, here on the forum... but I am unable to find them this morning.

Let me know the velocity, and I will run a trajectory course for you.....However, most often, the real picture is not what folks want to see when it comes to round ball ballistics.

Uncle Russ...

[biliff]

It's a little cumbersome to use at first, but it lets you play around with different scenarios.

http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/rbballistics.html

[vermontfreedom]

DEFINITELY download the ballistics calculators biliff posted.
 
I use it all the time and it is excellent.

My own empirical data corresponds very well with what that program produces for my .54.

I will also say that 17/75 yard thing is pure ballocks. It might work for one particular load in a particular rifle, but the same load won't necessarily work in the next rifle and a different load certainly won't work inthe same rifle.

If an 80-grain charge under a 0.535 fits that  rule of thumb, certainly a 60 or 95 grain charge won't.

[Sir Michael]

All the calculations and formulas in the world are no substitute for going to the range and shooting.  

Practice at the range you intend to shoot.  25 yds, 50 yds, 75 yds, 100 yds.  Once you get your sights on line then it is simply a matter of adding or subtracting powder for the range.

Ezekiel Baker a prominent English gun maker from 1800 to the 1830s once said that it was essential that every rifleman MUST learn to gauge distance and adjust the point of aim to hit the target.  

You have choice.  Learn to adjust your aim point or adjust your powder charge.  Adjusting the aiming point is the most practical for hunting since you never know in advance what the range of the animal you want will appear.

Formulas and rules of thumb are great starting point but the proof as they say in the pudding.

[vermontfreedom]

Couldn't agree with Sir Michael more.

Also meant to throw in to use the fastest load you can shoot accurately and precisely. Higher velocity loads produce the flatest trajectories, all else considered.

So if you get  a fast, precise load, you may be able to hold point of aim = point of impact from 15 to 60+ yards (give or take 1/2 an inch or so).

I tend to sight for zero between 25 and 50 yards because I rarely shoot at game beyond 40. My .54 is about 1/2 inch low at 25 yards and on at 50 but is about 1 -2 inches low at 75 - still not too bad. So I really don't need to think too much about range, but I hunt steep ground and I take that into account along with shots at the extremes of my comfort zone.

If or when I decide to take that 75- or 100-yard shot, I will hold high as appropriate, like Sir Michael suggests.

[Thunderhawk1828]

Thanks all for the responses and advise.

Russ B - sorry, but I have no idea as to the velocity.

I will try the ballistics calculators and see what they come up with.

I do shoot at the range as often as possible (not a lot of chances) and normally sight in at 100yds. I was mainly asking for our monthly shoots, not for hunting, as the tagets can range from 15 yds to about 150 max. Normally I do hold over / under as I feel appropriate and I am missing but its by a small amount and usually a bit low. So its not really a question of missing by a lot, but am looking to fine tune so I can hit more silouhetts (sp?) that I am now missing.  

I have just changed rifles (have not shot it yet) and am now using a 50 cal flint (Traditions Kantucky). I plan on using 60grains 2FF w/ 4FFFF for the pan.

Another thing that throws me off is uphill / downhill targets. Half the year we shoot in a gravel quarry and have a good amount of downhill shots at approx 50-75 yds. Whats the advise here as far as hold?

Thanks.

Thunderhawk.

[vermontfreedom]

If you're missing my "just a little bit", increase or decrease your charge but 2 or 3 or 5 grains and see how you do.

Filing the front sight down 1/128 (or just 1 or 2 draws of the file at a time) will work if you're always low.

As for up/down hill, drop is always less when shooting up or down, so you need to compensate less. Just remember your trigonometry: a^2 + b^2 = c^2. You're estimating distance to target along the hypotenus (c) but you need the true horizontal distance (b), which you can calculate with C and and estimate of the vertical difference between you and the target (a).

Or, you can just 'wing it'. You're really only talking an inch or 2, probably, under 60 or 75 yards, at most...but that does depend on how steep the slope.

[Thunderhawk1828]

Vermontfreedom - WHAT??  OK lets skip the math (I never did understand it) and I'll go with the "wing it" - understand that part and I do thank you for the explanation.

Thunderhawk