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What did I do wrong with GPR

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Sheppsan

32 Cal
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May 28, 2020
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Just finished a Lyman GPR, my first black powder arm, and took it to the range. Very tight group at 25yds with 60gr Swiss 2f, but on 8th round, rifle would not fire. I found patent breech to be totally clogged with fouling. What did I do wrong?? Was using 495 ball with dried moose juice .015 patch and swabbed bore with juice between shots. Any help/thoughts would be appreciated.
 
I'm not sure in what part of the country your in Sheppsan, but up here in Pa. it is terribly humid and that will cause issues with ignition. Just make sure your wiping patches aren't to saturated or you will foul the patent breech quickly. Is this flinter or cap rifle? I have a Lyman Trade Rifle from early 2001 and you have to take a little extra care with these. Did you have a touch hole pick to use? The humidity up here right now will turn my pan powder into goo. By the way I have the flintlock Trade Rifle.
 
Swabbing patch jag combo possibly too tight and you were pushing fouling down the bore. Idea is to have a loose combo that you push down the bore, twist a bit and pull any fouling towards you. Also, being a new GPR kit, was the bore and breech clear of the factory grease?
 
I'm not sure in what part of the country your in Sheppsan, but up here in Pa. it is terribly humid and that will cause issues with ignition. Just make sure your wiping patches aren't to saturated or you will foul the patent breech quickly. Is this flinter or cap rifle? I have a Lyman Trade Rifle from early 2001 and you have to take a little extra care with these. Did you have a touch hole pick to use? The humidity up here right now will turn my pan powder into goo. By the way I have the flintlock Trade Rifle.
In central Florida, so very humid here, so maybe that had something to do with it. I also did have the wiping patches pretty wet. Mine is a percussion rifle
 
Swabbing patch jag combo possibly too tight and you were pushing fouling down the bore. Idea is to have a loose combo that you push down the bore, twist a bit and pull any fouling towards you. Also, being a new GPR kit, was the bore and breech clear of the factory grease?
Bore and breech were thoroughly cleaned, and don’t think the patch was to tight.
 
Run a lightly damp patch down then dry. Set your gun on half cock, make sure you hear wind blowing out the vent, and importantly when you withdraw make sure wind is heard sucking though your vent, a light whistle. Then a dry. Does your jag fit your your breech?
Give it a twist when in the bottom. And get that whoosh.
If needed pop a cap and make sure gas blows out the muzzle before you drop your next charge
In humid weather residue is a wet sloppy mess.
 
I have shot many BP balls on humid days in WV, never a problem, 20 or more shots. I would swab the barrel with a patch wet with soapy water then dry with two dry patches between shots. Powder was Pyrodex. Never a problem. I do recall firing off caps after the two dry patches.
 
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Last time I was at the range with my flintlock(maybe 3 weeks ago), I had to swab the bore every two shots due to the humidity and the resultant fouling. In the fall and winter, I can go 5 or 6 before I swab.
 
Unless doing serious target work you should be able to shoot all day with a wet patch using your favorite moose milk or windshield washer fluid (the blue winter stuff) without swabbing. Wet the patch, a quick squeeze between your thumb and index finger, then load. It works in North Carolina, not quite as hot as Florida, but we have the humidity - didn’t rain this afternoon so only 85% right now.
 
Was using 495 ball with dried moose juice .015 patch and swabbed bore with juice between shots.

It was likely a combination of all three. too big of a ball/ tight patch combo combined with dry lube and improper swabbing.
Just changing how you swab can solve the problem. Use alcohol or MAP and use a really sloppy patch every so often or squirt some down the bore and force it out the nipple. If MAP quirts out the nipple when you swab you'll never have a plugged nipple.

Also it helps to swab using two patches one wet, one dry. I also flip my patches over (that means 4 passes).
 
Keep in mind that your GPR has a patent breech. Your .50 cal jag only allows you to wipe down to the mouth of the patent breech. It's likely that whatever silly-named magic elixir you're using to soak your swabbing patch in is slopping down into the patent breech, allowing wet fouling to accumulate.

In order to mop it out, you'll need a smaller diameter jag - around .38 cal. To avoid losing the patch, I'd suggest you use a slotted tip.
 
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So it's that narrow channel just beyond the tip of the rod that can become gunked up with black powder residue. I have a GPR which I haven't shot yet. I used to have another a number of years ago which I absolutely loved, and was the reason why I bought this one recently from a member. As near as I can recall I never had a problem with ignition nor with residue build up in the older rifle. Am kicking myself for ever selling it. Kicking myself. Kicking myself.

No. but there are different configurations. Thompson center has a patent breech, so does Traditions/CVA and some others.
The lyman GPR is made by Investarms of Italy.
 
The breech designs vary but generally they are cone shaped of some sort before transitioning to the flash channel.
There are many factors that can contribute to a misfire/breech clogging.
weather
powder
lube
improper swabbing
corrosion
poor cleaning
etc.

You can either track down the culprit(s) and fix or just address the clogging directly.
I prefer the latter, because it allows me to shoot whatever I want out of my gun.
 
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