chrono and flintlocks

[ebiggs1]

50 cal Thompson Center Hawken with 32” Green Mountain barrel 1/70 ROT.
.490 Hornady round ball
cut patches at the muzzle with olive oil lube
4f GOEX prime
5 shot groups

65 grs fffg GOEX
high 1418 fps
low 1407 fps
average 1414 fps

70 grs fffg GOEX
high 1579 fps
low 1523 fps
average 1560 fps

75 grs fffg GOEX
high 1664 fps
low 1629 fps
average 1642 fps

80 grs fffg GOEX
high 1709 fps
low 1700 fps
average 1705 fps

The gain in fps does go down as the charge goes up. There is a 146 fps gain with the first 5 grains additional powder but only 63 fps for the last 5 gr increase. I am not drawing any conclusions yet as I don't have enough time with the chronograph. It does look like my gun may favor 80 grs, ugh!, :hmm: the spread is tiny being only 9 fps. Onward........................ :wink:

 

[Walks with fire]

What kind of groups are you getting with that barrel?

 

[Dalekg6]

Interesting. I enjoy trying to analyze details like this.

In my 50 cal flinter with a 36" Green Mountain barrel I get an even 80 fps faster at 70 and 80 grains. I'm sure some of the difference is in loading methods, patches, lube and chrono set up. I'm surprised the results are as close as they are, I usually get more variation from one range session to another.

I found my 50 cal likes 70 to 80 gr for accuracy.

I recently chronographed my new 32 flintlock with a 38" barrel. As normal velocity gain per 10 grains went down as the charge went up. What was interesting is comparing identical loads in my 32 flintlock pistol with a 9" barrel. As the charge went up the gain over the pistol also went up. This is an obvious result of the pistol only being able to effectively use less powder.

 

[ebiggs1]

Did not take notice. I was looking for velocity changes, only, with the increase of five grs of powder. I was only 25 ft from the chronograph.

 

[himem777]

Interesting I wonder how the spread would change if you used differing powders.

 

[roundball]

Just some related information you might be able to take advantage of...in running chronograph series like than myself, the use of an OP wad was remarkable in reducing SD.

One rifle, without wads had a SD around 25 fps, then dropped all the way down to an average SD of only 6 fps when I'd use an Oxyoke prelubed wool wad over powder.

 

[paulvallandigham]

+1. :thumbsup: I have seen similar drops in SDV when an OP wad was used as a gas seal. :hatsoff:

 

[ebiggs1]

Guys,
Keep making suggestions (very much appreciated) because this was just the first time out and I have lots of things I want to try. :wink:
Especially separating the myths from the facts. It's gonna be slow because this takes a long time to get everything set up and try to make everything as close to equal as possible so too many variations don't skew the results.
I was going to continue with 5 gr increases but the wind started to pick up and blew the prime out of the pan as I was loading. So 80 grs was the stopping point for the day.

 

[CoyoteJoe]

Well if you want to get technical let's take it a step farther and look at energy numbers.
Looking at the raw velocity number only can be deceiving because a seemingly small difference in velocity can make a surprising difference in energy. Energy is what the burning powder actually releases, velocity is just one aspect of that.
So taking your velocity numbers and since I don't know that exact ball weight I just used 180 grains as a nice round number, I calculated the energy for each velocity as follows.
1414 fps = 799 ft.lb.
1560 fps = 973 ft.lb.
1642 fps = 1078 ft.lb.
1705 fps = 1162 ft.lb.
Now you say the "gain" seemed to be less with each incremental increase in powder but lets look at the "energy per grain of powder".
65 grains = 12.3 ft.lb per grain
70 grains = 13.9 ft.lb. per grain
75 grains = 14.4 ft.lb. per grain
80 grains = 14.5 ft.lb. per grain
So you see the efficiency actually IMPROVES with each incremental increase in powder. That is one reason why looking at only velocity numbers is quite deceptive. The other deceptive factor is that in using constant increments such as 5 or 10 grains, each additional increment becomes a smaller percentage of the total charge so one should expect a smaller percentage of energy gain. :grin:

 

[paulvallandigham]

LOOKING AT ALL THE NUMBERS- YOURS, AND JOES, I think your best load is 70 grains of powder, NOT 80 grains.

I took only 5 grains of powder- from 65 to 70 grains--to gain 146 fps. in MV., and 174 Ft. lbs of energy(FPE).

From 70 to 80 grains- twice the increase in powder, you get only 145 fps. increase in MV., and 189 fpe.

The increase in fpe per grain is much less impressive:

65grains to 70 grains is only 1.6 fpe per grain increase.

But, from 70 to 80 grains, the increase is only .6 fpe per grain. ( 13.9 to 14.5)

The raw numbers increase- I give Joe that-- but I find it difficult to claim that represents an improvement in Efficiency. When you consider the very poor Ballistics Coefficient of any Round Ball, and variations in MV between shots, these numbers approach the insignificant, IMHO.

My suggestion is that you now have a "Ballpark" of powder charges and loads to try in your gun. Stick with the one that proves to be consistently the most accurate for YOU and YOUR GUN( not mine). When I was doing this kind of load development with my rifle, for instance, I found that 80 grains shot very well out to 100 yds with my .50 cal. rifle. However, groups were not significantly better than when I used ONLY 75 grains of FFg powder, and the felt recoil was a lot less. That is my gun, with its stock dimensions- not yours. And my shoulder is Not yours, either!

After considerable shooting, both off a rest, and off-hand, I found I could get better groups with the 75 grain load, and that is what I use in the gun. When looking at not just the MV and energy at the muzzle, but also at the down range velocity and energy figures, The Deer is not going to know the difference. The difference in POI is less than .2" and I can't possibly hold that difference using iron sights.

I personally know shooters shooting similar guns who love 70 grains of FFg for their hunting, and I know more than a few who like 80 grains for hunting. The difference in Velocity at 100 yds is well under 100 fps for the 3 loads, so the deer simply is not going to know the difference.

I also know a few guys who insist that any ball pushed out of the barrel with less than 100-120 grains of FFFg powder will bounce off a deer at 100 yds. That simply is not my experience, nor that of any other successful hunters I know.

Lyman's Black Powder notebook, 2nd Edition, has some information on down range velocities you can consult. Basically, you should expect that a RB will lose 40-45% of its Muzzle Velocity out at 100 yds, depending on caliber. The larger the caliber, the more velocity and energy it retains over that distance.

I hope this helps. :thumbsup: :hatsoff:

Paul

 

[longcruise]

I was only 25 ft from the chronograph.

You might consider moving the chrono a bit closer. Ten or 12 feet is usually far enough away to eliminate the effect of gasses and ejecta.

The further you stretch the distance out, the less you are looking at "muzzle velocity" and energy The faster balls slow at a faster rate than the slower ones. Stretching the distance will accentuate that difference and slightly skew your comparisons. Some ballistics programs have a function that will allow correction to the true muzzle velocity if you have an accurate BC.

I always find chrono results interesting. Much more useful than the tables found in the "bibles"

 

[roundball]

Interesting...never thought of expressing it that way.
:bow:
I did know of course that there was a point of diminishing returns as far as velocity went...saw it in my own numbers.
But in spite of the claims made by some that a theoretical formula says it ain't so, as long as I continued to add powder it continued to burn, and I continued to get incremental steps in velocity with each increase in powder.

And knowing higher velocity meant flatter trajectory & more energy at the target, that was good enough for this settler...

 

[longcruise]

Basically, you should expect that a RB will lose 40-45% of its Muzzle Velocity out at 100 yds, depending on caliber.

This is true and is the reason I suggested that he move the chrono closer and also do MV corrections with a ballistics program if possible.

A .490 ball with a MV of 500fps will be going 306fps at 100 yards. I will have lost about 38% of it's velocity.

Same ball starting at 1800fps will be going 972fps and have lost 46% of it's velocity.

To further illustrate the 25 foot rule, here are the percentages of lost velocity for the same two balls at 30 feet (am using thirty feet because Pointblank does not break down to 25 feet).

At 30 feet, the 1800 fps ball has lost 7% of it's velocity while the 500 fps ball has lost 2% of it's velocity.

 

[hanshi]

Op wads do indeed reduce SD numbers and often give a small velocity increase. This is why I use them religiously. Curiously, from my decades of work with Modern rifle rounds I found that small SD numbers didn't always correspond with smaller groups. Whether this happens with muzzleloaders is not clear. This would make a good subject for experimentation.

 

[majg1234]

I agree with hanshi on centerfire stuff over the last 30+ years I have tried to get my centerfires as accurate as possible but have not noted any significant increase in accuracy with decreased SD, But for an unknown reason still load for the smallest SD I can get :youcrazy: what i have noted with felt wads over powder in ML's is increased ease of loading (able to use a thinner patch) and with conicals less leading which in turn relates to easier cleaning and better REPEATABLE accuracy.I'm still struggling with shot loads in my SB however :idunno:

 

[paulvallandigham]

There are so many variables affecting accuracy and group size, IMHO, unless you have a indoor range, too eliminate wind and variations in humidity, I don't know how you could adequately answer the question of whether a lower SDV correlates always to smaller groups, or not. Even in those kind of neutral shooting conditions, you still have the problem of how a given shooter loads and cleans his gun, and any minor( seemingly) differences in components.

The Slug Gun boys at Friendship have been working on this issue for a very long time, with the open class, Bench gun shooters who shoot PRBs also adding their information. I don't see this issue :hatsoff: :hatsoff: being resolved in my lifetime. :idunno: :hmm:

 

[ebiggs1]

There are plenty of published laboratory results to read. I am not in the least interested in competitive target shooting. I want to know what this gun can be expected to do in real world conditions. Whether it be windy, high humidity or the phase of the moon, this is how it shoots. There are many claims that may be just that, claims. :hmm: I load it, I shoot it and I clean it. Nothing more, nothing less.

 

[CoyoteJoe]

I've chronographed lots of rounds from muzzleloaders,and from centerfire rifles and handguns. Every round over the chrono is also aimed at a target so I'm shooting groups at the same time as measuring velocity. I have never found any correlation between standard deviation and group size, the best group may well have the worst SD. Perhaps it becomes a factor at long range, some people claim it does, but if so it only becomes apparent well beyond the range for practical roundball shooting.
I think it's one of those things which seems reasonable but doesn't pan out in reality.

 

[paulvallandigham]

We are pretty much of the same mind about Laboratory testing. I am also interested in what a gun does in the real world, as opposed to lab testing. :thumbsup:

 

[paulvallandigham]

I have shot enough groups off-hand at targets, where I saw my barrel drop- badly-- but the ball still hit center- and, on the other hand, I have fired shots that looked PERFECT, only to find the hole WAY OVER THERE-- often enough, that I take all correlations of data with a dose of my personal skepticism.

When it comes to SDV and small groups, it seems to hold more true than not, shooting off a bench rest( which I don't do nearly enough these days). That is the only reason I have written about the correlation here. With modern guns, I had pretty well decided it wasn't worth the bother. However, when the Black Powder Cartridge Silhouette Shooters began reporting SDVs of less than 10 fps. and less than 3" groups for 10 shots at 200 yds, I began to renew my interest in this issue.

Even Roundball, here, has reported getting a very low SDV, and one hole groups shot at 50 yards with some of his guns. I think we have to pay attention to observations like that. The Correlation between low SDV, and tighter groups may not be yet "proven", but continued reports of these kinds of groups, and low SDVs from skilled shooters has to be given some credence. :hmm: :shocked2: :surrender: :thumbsup: :hatsoff: