Initial load for a .62 cal, 1-66 twist, 42" barrel

[nathan.davis]

I just purchased my first flintlock--a .62 cal Jim Chambers flintlock with a 1-66 twist straight octagon barrel that is 42" long. Photos of the gun are listed in the Flintlock forum of this website. The Rice company just confirmed to me this morning that the barrel was made by them. I also bought some .61 RBs and .001 and .0015 patches coated with Wonderlube. I want to select some initial loads to try out for fun practice and for elk hunting.
If I use the Davenport formula to determine a recommended initial load to consider shooting, I come up with a load of 145 grains of FF. My initial reaction is "Wow--that sounds scary big." Some individuals on this forum seem to indicate that they use 90-110 grains of FF for their .62, but I notice a wide range in the different loads that they use, and the postings indicate that the loads vary a lot from gun to gun.
What do you recommend as a starting point for me? I'm planning to try at least 6 different loads in 5 grain increments stepping up from my initial starting load.

 

[roundball]

Don't know what you plan to use it for, but I use PRBs in my .62cal (smooth rifle) for hunting deer sized game in woods settings with shots 100yds or less, and tried 90/100/110/120grns Goex 2F...110grns gave a nice 'crack' muzzle blast and the tightest group at the 50yds I zeroed it...120grns didn't improve it any, so I settled on the following for my deer load.

Rice .620" bore with a Caywood Full Jug Choke
110grns Goex 2F
Oxyoke .60-.70cal X .022" prelubed patches
.600" cast ball from Eddie May (Chatsworth, GA)

 

[BrownBear]

...a 1-66 twist straight octagon barrel that is 42" long....

That's a fair chunk of steel out front, so I'm betting it tames recoil quite well. In my 1" 62 cal smooth barrel from GM (32"?) on a TC Hawken, 110 grains worked out best with PRB, and I can't say it feels any worse than the same charge in a 54 cal. Pretty mild really, when you get right down to it. My 62 cal rifle has a 39" straight 1" barrel, and I don't really feel like it's booting me till I'm well past 120 grains. Coincidence or not, it's favorite load is also 110 grains of 2f.

 

[user 13289]

I just purchased my first flintlock... .61 RBs and .001 and .0015 patches coated with Wonderlube...

you're gonna want some thicker patching eh?

work through as many loads as it takes. the gun will tell you what works best. work it up.

Maybe make 10-grain increments and then try +/- 5 gains for fine tuning.

 

[paulab]

My Jim Chambers early Va. .62 flintlock rifle has a rice barrel also. I started out using .022 thick patches but was getting gas blow-by because the fit was too loose. I got some .035 thick denim and that solved the problem. Cheers Paul

 

[nathan.davis]

It sounds like we have identical rifles. What size ball were you using?

 

[Loyalist Dave]

I'm not super familiar with the "Davenport formula", but I thought it was for even slower twist rates? Dunno...

The standard rule-of-thumb for the smaller calibers is you begin with a load = to the caliber, rounded up or down...so you'd start with 60 grains of 2Fg.

I have also heard that for rifles some folks use 1.5 x the caliber for a starting point on "big game" loads for .58 and larger... so that would be 90 grains.

Work upwards until you find an accurate load that a person standing off to the side by about 20 yards hears it "crack" with the first system. Work up or down until you find a very accurate load at your farthest intended shooting distance with the second system.

LD

 

[Rifleman1776]

LD, we don't always agree. But, this time, we are together. There have been a lot of 'formulas' and theories over the years. A lot of them may be wrong. The best 'formula' is to try the gun and then report back what worked best.
My experience is the slower the twist the heavier the charge is needed for accuracy. I have never found the 'sweet spot' for my .54 cal., 1:72" twist Jaeger because my shoulder makes me quit my shooting session when charges start going north of 100 grains of bp.
But, know this, one day, maybe a hundred years from now folks will look back at our advice and consider us sages whose words are to be heeded, just because we said it one hundred years ago. :wink:

 

[mooman76]

I like to start out with powder equal to the caliber in rifles and half the caliber for smaller rifles and pistols so start with 60gr. and work up in 5 gr increments. Some tend to want to start with heavier loads which is fine but then you won't know what your gun will do with the lighter loads. Nothing says you have to stick with lighter loads and half the fun is working loads up and trying different things to get you at what you want.

 

[BrownBear]

...half the fun is working loads up and trying different things....

Amen and glory halleluya!!!!!! :thumbsup:

 

[Billnpatti]

First, let me clarify the Davenport formula. It is a rather flawed formula because it does not take into consideration some very important factors such as granulation of your powder and the brand of your powder. These factors will effect the burning rate of your powder and, thus, the maximum efficient load for your rifle, which the Davenport formula attempts to determine. We can use the Davenport formula only to get an idea of what the maximum efficient load for your rifle will be.

Now, let me clarify the meaning of Maximum Efficent Load. The maximum efficient load is the maximum load your rifle will burn efficiently. In other words, it is the maximum load that will be consumed within your barrel without blowing unburned powder out the muzzle. Once you reach the maximum efficient load, the incremental increase in muzzle velocity will no longer be linear with respect to the increase in powder charge. It has little to do with determining the most accurate load for your rifle.

For determining the most accurate load for your rifle, let me refer you to Dutch Schoultz' "Black Powder Rifle Accuracy" www.blackpowderrifleaccuracy.com It is a system that I have and one that I recommend to anyone who is interested in finding the most accurate load for their rifle(s). The price for Dutch's system is only $20 but it is absolutely invaluable. It is, without a doubt, the best $20 I have ever spent on this hobby.

Dutch goes much deeper into determining the most accurate load for any rifle but if I were you, I'd start with a load that is approximately equal to the caliber of your rifle. In your case, I'd start with 60 grains. Then increase your charge by 5 grain increments until you find the load that gives you the tightest group. Fire five shots from a sand bag rest for each charge. Dutch recomends that you wipe your bore after every shot to keep the bore exactly the same for each shot. I concur. So, five shots with 60 grains, five shots with 65 grains, five shots with 70 grains and so on until you reach somewhere around 110 grains. After 110 grains, the recoil and your toleration of it will determine if a larger charge is of interest to you. But, in the final analysis, you will be best served by buying and following Dutch's system. He will go into such important factors as lube and patches in addition to load selection.

 

[nathan.davis]

I notice that you live near Mountain Home AR. Is there a store near there that stocks the real black powder?

 

[Rifleman1776]

I notice that you live near Mountain Home AR. Is there a store near there that stocks the real black powder?

No. pt sent.

 

[paulab]

I'm using a .595 ball.

 

[Loyalist Dave]

let me clarify the Davenport formula. ....thus, the maximum efficient load for your rifle, which the Davenport formula attempts to determine.

OK I had no idea at all what the Davenport formula was.... :redface:

So... the maximum efficient load based on the burning of the most powder within the barrel, and as little as possible being burned after being pushed out the muzzle? Got it....I think....

But, is that the same as the "best" or a "very good" load for targets or hunting? I mean, could you discover when shooting and testing that your maximum burn amount isn't as accurate as a load, say 10 - 20 grains smaller, depending on your normal brand of powder and granulation? OR is the accuracy effected when one exceeds that max efficiency by a good amount?

Or is it back to the good ol' rule... shoot your rifle to know what your rifle likes best?

LD

 

[Billnpatti]

Maximum Efficient Load isn't all that hard nor is it really all that important when looking for the most accurate load for any given rifle. The Maximum Efficient Load is just the maximum amount of powder that will be completely consumed within your bore. Ballistically, after you reach the Maximum Efficent Load, you will continue to have an increase in MV but it will not be linearly related to the increase in powder.

I wish I could find the notebook in which I wrote the results of a MV measurement VS powder charge increase. When you do that, and plot the results, you can see exactly where the Maximum Efficient Load is for any given barrel and powder. The line will be relatively straight up to that point and then it will bend over indicating that you are no longer getting the maximum increase in breach pressure from the powder.

The only way you can determine what the most accurate load is for your rifle is to start with a charge that is equal to the caliber and shoot five shots at a target from a sand bag rest. At this poiint, don't pay any attention to where they are hitting the target, you can adjust your sights to put your bullets where you want them once you find the most accurate charge. Then increase your charge and shoot a fresh target with five shots from a sand bag rest. Keep doing this until you reach a point just beyond 1 1/2 times the caliber of your rifle. Carefully measure the group size and you will see what charge will give you the tightest group. When you have this, you can adjust your sights to put the ball where you want it.

It is a very good idea to buy a copy of Dutch Schoultz' "Black Powder Rifle Accuracy" system. www.blackpowderrifleaccuracy.com Dutch teaches you exactly how to find your most accurate load in the most efficient way and at the minimum cost. He also teaches you the importance of lube and patches in achieving your rifle's most accurate load. It is good, it is worth the $20 that he is asking for it. I have it, I use it and I highly recommend it.

 

[Dr5x]

To me the maximum efficient load is the load that puts the ball where you want it.

Consuming all the powder in the barrel is a tad difficult.
If you live in an area where you could get away with this , Wait til it's quite dark , load your rifle and fire it .
You will be amazed if you have never done this, the flames fly out fro 5 to7 feet in front of the muzzle and this is with the load that you have found works the best with your rifle.

Startled the H out of me.

Dutch

 

[roundball]

Several examples on the Internet:

http://members.memlane.com/gromboug/flash2.jpg

 

[nchawkeye]

If that is a Chambers kit, it is a swamped barrel...

Why not email Jim??? He'll put you in the ball park, he's been doing this for a few years... :thumbsup:

 

[Col. Batguano]

It would be interesting to know if there is a charge that will NOT spit flames out the end of the barrel.