Groups - Good to Bad

[muzlodr]

I received so much good advise over on the Flintlock side re: a poorly functioning lock, that I thought I'd pick your collective brains about another problem I'm having
The old CVA Hawken I acquired after much abuse is now rebuilt (not restored - I don't have those skills). Firing it last week it grouped very well, for me, 1 1/2 to 2 inches at 50yds. My load was 60gr Geox 3f, .490 Hornady ball, .025 (as measured with a thickness guage) mattress ticking soaked in Moose Milk.
The weather was approx 25 degrees with light snow falling. Now to the question. Because I have advanced arthritis in my fingers, I sometimes have trouble fumbling with #11 caps. I swapped my normal nipple for a Musket size because I don't drop those caps as often. This Sunday when I went out to try it again my groups went to he**. That nipple/cap combo was the only variable. Even the weather was similar. Could this be the cause. I know that as a nipple burns out the impact point changes, but my balls were all over the target? (no pun intended). Any comments greatly appreciated.
:hmm:

 

[Rebel]

It is quite possible that the musket caps are the cause. They are a lot hotter than a standard #11 cap, thereby causing a velocity variation from what you were getting with the #11's. If you have trouble handling #11 caps why not use a brass straight capper, or a Ted Cash capper, or even a leather capper? Makes it a lot easier to manage the caps.

 

[Tahquamenon]

By going to a much hotter ignition, you will need to start over on load development and work your way into a load for the musket cap. You also might find that your rifle will not work well with one.

Have you tried using a capper for the #11 caps? I use a Ted Cash capper and it works excellent.

 

[muzlodr]

R & T
Yes, I've tried my Ted Cash Capper. It stays in my range box because the caps always seem to turn on their sides. I do have an old plastic T/C capper shaped like a star. I'll put the original nipple back in and try that. Thanx

 

[Stumpkiller]

Musket caps may be hotter, but the hole in the nipple is bigger. What this does is gives you a spike in pressure at ignition that drops off quicker than with the regular #11 caps.

It's not that it's better or worse, just a very different profile to the burning rate & pressure graph. The effect is like you moved to a faster burning powder. In this case, it looks like your set-up didn't like the change. Try moving the powder charge up and then down 5 gr and shooting a few more groups. I will gamble and say one or the other will produce a better result, and I'd bet 5

 

[Tahquamenon]

Even without arthritis, those pesky little caps can be tough to keep ahold on with cold fingers. I almost always drop a cap if de-capping with cold fingers.
::

 

[muzlodr]

Thanx, Stumpy
The twist appears slower than my known 1:48 bores, but I'm just eyeballing. It is old enough that it does not have any reference to being made in Spain on it anywhere. I'ts not near as well made as my old .45 T/C Hawken nor even my Cabela's .54 , also a Hawken. Definately no where near my custom John & Caleb Vincent 1847 Ohio rifle, but I have a fondness for it and really enjoy shooting it. I guess I'm just sort of partial to other peoples castoffs. It must have something to do with my age.

 

[Rebel]

It is probably a 1-66 twist. CVA used that twist in a lot of their older rifles. A good round ball twist.

 

i bet your pressure is spiking IE your not getting an even burn .
With the hotter cap your going to need to re work your formula some what to bring her back to what your used to