groupings with black powder rifles


September 29, 2008, 03:54 PM
I've had a black powder rifle made by Thompson for a few years and shot it with open sights. I have added a scope to it and today went to sight it in. I only managed 3 inch groups at 50 yards..... what kind of groups do you folks usually get with your black powder rifles?

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September 29, 2008, 05:25 PM
Im thinking there is going to be to many variables. Powder type, weight, patch thickness lube. I think you maybe able to improve on your groupings but your going to have to change powder charge and record your results, then patch thickness, then lube types and powder type. You maybe able to improve. More range time for sure.

September 29, 2008, 05:39 PM
3" at 50 isn't terrible, but it's not really great either. If you're just starting out, you're not doing bad at all.

How many different loads have you tried? Most any shooter will tell you that an individual gun will prefer a particular load over any other. How well can you shoot some other rifle? What groups were you getting before you mounted the scope?

Adding a scope will do nothing to the inherant accuracy of the rifle, unless it's mounted poorly or it's defective, in which case it can only ruin accuracy.

The U.S. military requirement for accuracy from the rack-grade M-14 (1950s) service rifle came to about about 6 inches at 100 yards. You're already there, using a more or less ancient technology.

We're talking about a lot of different variables here, any one of which can influence accuaracy.

bullet weight
the consistency of the bullets
rifling twist
charge weight
the consistency of your charge weight
patch thickness (if applicable)
the consistency of your patch thickness
the amount of fouling present in the barrel
the consistency with which you ram each load
condition of the barrel
condition of the all-important muzzle crown
scope mounts
scope rings
scope condition
your eyes
the trigger action
your skill level
barrel to tang to stock fit
lighting conditions

I'm sure there are a lot of others.

September 29, 2008, 05:41 PM
You should tell us which Tompson Center rifle you're using. Someone on here can then recommend a srtarting load for it. Some of the really fast twist barrels, for example, don't do well with patched ball, by most accounts.

September 29, 2008, 06:18 PM
I am using the Thompson Black Diamond Express. I only tried one load. It is 2 50 grain pellets of Hodgon 50/50 pyrodex, 240 grain Thompson Center Mag Express Sabot, and Winchester 209 primers. I'm not sure if matters much with this load, but I was shooting in a 20 mph wind.

With open sights I got about the same results and thought a scope would improve the groups. I am capable of MOA groups with my Browning A bolt, and today before I pulled out the muzzle loader, I was shooting one inch groups at 50 yards with a Yugo 8mm Mauser.

After I got home, I gave this rifle a cleaning more thorough than it ever had and I'm headed back to the range later this week to try again. I'm thinking range time and different loads might be the key.... I'm still curious what size groups others are getting....

September 29, 2008, 06:31 PM
also remember to swab the barrel every few shots to remove fouling other wise you will never achieve any accuracy

September 29, 2008, 06:43 PM
you dont have to swab between shots to get excellent accuracy.

It sounds like you need a thicker sabot.

Try a 240gr xtp in a black mmp-12 or 24 sabot with 100gr pellets (or loose pyrodex rs-select)

September 29, 2008, 06:55 PM
As has been said there are many variables. Twist rate is critical. If you try to shoot PRB out of fast twist for conicals and sabots, you will not get good results. And visa versa. Fit is another factor. Oftentimes the barrels are rattle-loose in their mounts.

Old Grump
September 29, 2008, 07:02 PM
4 shot groups of 4" with 50 caliber patched balls and 90 gr of FFg Goex at 100 yards using an aperture sight. Same group as I get with my Mossberg and Winchester shotguns with slugs. Close enough for me. I'm never going to get 4 shots at a deer anyway. Anything out of that group can be contributed to shooter error. Shoots better when its colder. Because of that I no longer use slugs and I have never tried the sabots because of the cost.

September 30, 2008, 01:24 PM
Game shooters and target shooters are two different breeds. Game shooters know that they only have one chance to kill but the bullseye is much larger than the paper target. The game shooter is less critical because he has even more variables to consider. Distance to target is only one. Estimating distance is really tough in the real world of hunting.

September 30, 2008, 01:26 PM
oh shoot where have you been Pancho have seen you around in a while.

September 30, 2008, 04:28 PM
If you have the 28" twist barrel, that can stabilize full-bore lead projectiles (no sabot) of well over 400 grains. You have some experimentation to do.

Using PRB from my 48" twist barrel with 110 gr Pyrodex RS I was getting 3 to 5" (three shot) groups at 100 yards, which is almost as well as I can shoot any rifle using iron sights.

I then switched to real 2F BP, same charge volume, and I'm getting less velocity with larger groups and have to swab between shots or the tightly fit patched ball will stick on the way down. I could use a smaller ball with a thicker patch, fool around with the charge weight, or go to a conical and readjust the sights. I don't know, but it takes a lot of time to find that sweet load. Going back to RS and changing nothing else, I'd be OK with it.

September 30, 2008, 04:33 PM
Tinkering with the rifle can help too. I recently took the advice of bedding my smoke poles and using epoxy to fix the hook-breeches onto their mounts more solidly. The epoxy will wear out after a few trips, but it should give me better groups. On rifles that don't need a hooked breech there's some merit to just welding them together, though of course you have to know exactly what you're doing.

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