Good 4" groups sfter 2 or 3 shots/

[Texas Gil]

My 20ga shoots 4" groups only after the chamber gets dirty. I sent the barrel to a smooth bore gunsmith to inspect the the chamber diameter . I suspect the chamber is somewhat larger than the .6125 bore diameter at the muzzle. The first 2 or 3 + shots is blowing the ball out and the patch is slipping off??? I think. Don't know if anyone else had this issue ever happen. I can feel the tight fitting ball/patch release about 4 in from the powder and then moves very easily down to settle on the charge. I will get a report soon on his findings. The barrel had to be back bored I assume for this to be the case. If so why would it be larger in the chamber? However, this is only my assumption not fact until I get a report. After owning the gun for 15 years I mostly shat bare ball .60 ball op leather wad and ob wad or card and got 5 to 6" groups at 50yds. My brain is spinning.

 

[smo]

My Colerain barrel does the same thing,
My patched .626 ball goes down easily, once it’s started.
As the bore becomes fouled, thus is a plus in my book.
My bore mics at .653. I use .0016 patches.

it doesn’t effect accuracy any that I’m aware of..

 

[bigted]

I think my best 40 yard group has been 3.5 inch shooting my 20 smoothie flinter.

Load is 80 grains Old E 3F powder under a .595 patched RB wrapped in a greased .015 to .018 cotton patch. Starts very easy with thumb preasure and seems like I can shoot all day long.

I keep searching for the best this smoothy has but this so far has been my best. Funny part is outta three shots, 2 seem to touch and the third wonders out. Not in any particular order ... the two that touch can and do happen different each time.

I sure like this shooter. She gives me tranquility and a sense of pride.

 

[hanshi]

I think my .62 may be a bit more consistent but I get about the same accuracy as you. At any rate it's been accurate enough to take deer.

 

[deerstalkert]

My 20ga shoots 4" groups only after the chamber gets dirty. I sent the barrel to a smooth bore gunsmith to inspect the the chamber diameter . I suspect the chamber is somewhat larger than the .6125 bore diameter at the muzzle. The first 2 or 3 + shots is blowing the ball out and the patch is slipping off??? I think. Don't know if anyone else had this issue ever happen. I can feel the tight fitting ball/patch release about 4 in from the powder and then moves very easily down to settle on the charge. I will get a report soon on his findings. The barrel had to be back bored I assume for this to be the case. If so why would it be larger in the chamber? However, this is only my assumption not fact until I get a report. After owning the gun for 15 years I mostly shat bare ball .60 ball op leather wad and ob wad or card and got 5 to 6" groups at 50yds. My brain is spinning.

could be the problem?

 

[jackpine54]

My .62 smoothie FDC was challenging to work up loads for accuracy. I probably went through 200+ round balls and finally found what works. My gun likes ffg, op card, .595 ball and .010 patch. Stiff charges seem to provide more consistent groups for me.

 

[Texas Gil]

Got the answer from my gunsmith!
Chamber diameter is ,624
Bore at muzzle is .612
For 12 + years I shot .60 rb bare leather wad both sides and got descent groups, only when I started testing loads with patched balls did this become a problem . Now we get to ream the bore all the way to the muzzle to get closer to the breach diameter and hopefully much better results with patched ball. Then the ball should stay patched when fired.
Are smooth bores fun? you bet, I've not quit learning since i bought one.