Seeking some guidance

[John Shields]

I have been shooting .375 H&H, and .50 BMG bolt guns over the years, and recoil has never been an issue with me. This was no different.

One of my sons, who shoots a Hawken, was the one who suggested that when my 70gr charges were hitting well below the target at 60 yards, that I up the charge, as he shoots 90gr out of his rifle with excellent results.

So I didn't think there would be any harm, and I will say, I can find no damage to my rifle.

I will defer to the experts here though, and go back down to 70gr. and start filing on the front sight.

 

[scotsman]

Apart from everything else, you might consider trying an overpowder wad and see how that could help with your patches.

 

[Hans74]

I call it barrel hang time. The slower the velocity the longer the ball is in the barrel the more the muzzle jumps from recoil making the impact higher.
I find this to be more pronounced shooting the heavier conical slugs than the lighter round balls. The lighter the charge the higher the impact....to a point when this changes by distances.

 

[Dr5x]

Firstget your group. then adjust your sights or powder charge.

Dutch

 

[Billnpatti]

I think you are referring to the Davenport Formula. The Davenport Formula was developed by a man who shot in matches it Friendship. It is a handy formula for match shooters but it has its limits. it is not an exact number because it does not take into consideration the brand nor granuilation of the powder being used. Both brand and granulation will have varying burn rates resulting in different breach pressures. However, the formula does give some pretty interesting data, providing one knows how to use it. One of our forum memers posted the following data back on June 6, 2012:

T/C Hawken 15/16” x 32” x .50cal Flint barrel
1:66” round ball twist
.018" T/C NL1000 pillow ticking
Hornady .490” / 180grn lead balls
Wiped the bore after every shot
Pact Pro MK5 Chronograph at 15 feet
Goex powder charges
Average velocity rounded off to nearest 5 fps

30grns 3F = 980 fps
40grns 3F = 1120 fps (+140)
50grns 3F = 1260 fps (+140)
60grns 3F = 1360 fps (+100)
70grns 3F = 1440 fps (+80)
80grns 3F = 1525 fps (+85)
90grns 3F = 1600 fps (+75)
100grns 3F = 1685 fps (+85)

If one were to calculate the maximum efficient load using the Davenport Formula, one would come up with 72 grains as the maximum efficent load for this particular barrel. Note where the break in change in muzzle velocity occurs. Right between 60 and 70 grains. Not too far off for a forumla that results in only a close approximation.

It is interesting to note that the person who posted these results is one of the people who rails the loudest against the Davenport Formula. :hmm:

 

[don hepler]

I fully understand about shooting large caliber rifles, since I shoot a 45 110 Sharps. But it weights 14 lbs.(I'm guessing) and my custom built flintlock with swamped "B" is less than half the weight. The wrist on the flintlock is basically unsupported and the Sharps and my Hawkens are very large in the wrist and have the backstraps to support a large charge. I"m just being carefull, with a very expensive, and light weight rifle, which is a pleasure to carry as well as shoot. With the large drop in the comb and crescent butt plate, these rifles were shot more on the arm than on the shoulder.

 

[Grumpa]

John,
90 grains isn't going to damage you or the rifle. I often shot 150 gr with a patched round ball in my .58 Harpers Ferry with no ill effects to me or the rifle. More of a shove than a kick.

My previous post was to the point that a 5 shot group gives you a better (more consistent?) record of where your rifle is hitting, than a single shot (which could be affected by any number of influences). But, you know your own shooting abilities, and an increase in powder charge should elevate the point of impact.

Richard
Grumpa

 

[B.Habermehl]

Funny how close this result comes to the old one and one half grains per caliber rule. IE 50 cal one and one half equals 75 gr.
The old rule states thus, one grain per caliber to two, with the best results usually around one and one half.BJH

 

[John Shields]

John,
90 grains isn't going to damage you or the rifle. I often shot 150 gr with a patched round ball in my .58 Harpers Ferry with no ill effects to me or the rifle. More of a shove than a kick.

My previous post was to the point that a 5 shot group gives you a better (more consistent?) record of where your rifle is hitting, than a single shot (which could be affected by any number of influences). But, you know your own shooting abilities, and an increase in powder charge should elevate the point of impact.

Richard
Grumpa

Next time I go out, I am going to do 5 shots with 80gr. and see what happens. :grin:

 

[John Shields]

I fully understand about shooting large caliber rifles, since I shoot a 45 110 Sharps. But it weights 14 lbs.(I'm guessing) and my custom built flintlock with swamped "B" is less than half the weight. The wrist on the flintlock is basically unsupported and the Sharps and my Hawkens are very large in the wrist and have the backstraps to support a large charge. I"m just being carefull, with a very expensive, and light weight rifle, which is a pleasure to carry as well as shoot. With the large drop in the comb and crescent butt plate, these rifles were shot more on the arm than on the shoulder.

I guess I was just taking my sons experience with his, just because it is BP, even though he shoots "fake" BP in it with sabots, and trying to apply it to mine.

It is the only real life experience I have to compare it to.

I really wish I knew some one around here, who shoots flints.