Black powder blowgun?

I read David Freeman’s excellent article about the Pietta .36 caliber 1851 Navy Colt Revolver in the Feb 2021 Issue of GUNS. I was interested because I have the same gun with a brass frame I assembled from a kit. I am puzzled by one thing: How did he get his gun to shoot accurately with .38 Special ammo in the conversion cylinder? My gun shoots very well with Hornady 0.357" pure lead balls and 20 grains of Pyrodex. I typically get 6-shot groups of about 3" at 25 yards. I believe the bored diameter of this revolver is about 0.365" but the .38 Special ammo uses 0.357" projectiles. I pushed a 0.357" diameter JHP bullet into the barrel and it slid all the way down and out the muzzle. So, how did you get your .38 Special bullets to engage the rifling in your gun?
Paul D. Ruffle

Your question had me pulling out my digital caliper for some measurements. The bore on my Pietta measures 0.36". The .36 caliber Hornady lead balls I have on hand measure 0.35" and they drop right through my barrel. That’s why we use packing around them. My .38 caliber bullets measure 0.359" at the base and fit snugly in the barrel. They don’t drop through but I can blow one through like a blowgun.
Theoretically, the .38 Specials should be more accurate but I didn’t save my targets or notes so will need to make another range trip to make some comparisons. Darn, I’ll have to shoot the gun again!
—David Freeman