How much B/C gap is too much?

[Super Sneaky Steve]

I recently clocked speeds on my 1861 Navy vs my Remington Navy using equal charges and balls.

Even though the Remington is 1.5" shorter it's giving me 150fps more.

The gap on my Colt is over 0.020". That's my largest shim and it dances around in there.

My arbor has been corrected so it's dead on. I've seen some youtube methods of correcting this which requires filing the barrel by the pins and the arbor at equal amounts. I'm not used to working on these so I'm not sure if it's a sound method or necessary.

Any advise from the experts would be appreciated.

[45 Dragoon]

.020" is huge!! I set them at .0025"- .003".
If your arbor has been "corrected" , it is now too long.

Mike

[Brokenbear]

Yes but ..the bore diameters may be different ..and you may be shaving at loading different amounts of lead upon ramming the ball ..like one may make perfect lead rings 360 degrees and the other is doing thinner or crescent shaped lead rings ..plus you may have one gun whose cylinder chamber mouth cutting the ball too undersized for the bore ..is you velocity statement based on the average of all the shots from a full cylinder ..is every chamber delivering the same velocity ..
Just saying lots of things can cause a loss of velocity ..are your velocity tests conducted from a freshly cleaned firearm where every nipple flash hole is perfectly clear..
All of this is of course not addressing the gap situation which I will leave to the gunsmiths
And I am quite sure everything I have mentioned you have already checked and rechecked ..but I find myself occasionally doing something off key and can only smile at it ..we as humans are all fallible ..some of us like me just don't know it ..yet

Bear

[Super Sneaky Steve]

The colt has had the chambers reamed to .378 for the best seal in the bore. The Remington is way undersized around .363. I'm getting very poor accuracy and I'm going to ream them to .375 this weekend. So the velocity difference will only get worse.

So the big question is do I leave it be or try to fix it? And if I fix it, what's the best way to do it?

[indian joe]

.020" is huge!! I set them at .0025"- .003".
If your arbor has been "corrected" , it is now too long.

Mike

yeah way too much - mine are .003 to .005 - some fellers reckon .012 (too much for me)

I did a Walker that had done a lot of hard work - I think I took .010 off the bottom joint (barrel section) to get it square, drilled the pins out and replaced with a size larger - mistake there! - I made them too neat fit - the gun goes together pretty stiff - needs a tap or two with a plastic mallet to bed that joint. I figured some more heavy loads it proly loosen up soon enough. Did that in the lathe - took tiny fine cuts with a sharp tool and finished by turning in reverse to make sure I didnt get a slope on the cut. Dont think I would attempt that cut with a file!
Like Mike I am puzzled how a "dead on corrected" arbour ends up 15 thou too long?

[Jackrabbit1957]

Indeed, that's a lot! Why not send it my way and let's get it done the way its supposed to be?

[John Taylor]

Cylinder gap should be under .006" for black powder guns and usually about .003" for smokeless ( the Ruger in 357 max is .0015"). Black powder guns usually require a bit more than smokeless or they can bind up a bit. Easiest way to adjust is to take a bit off the bottom of Colt barrels and make a wider wedge. Also there should be a stop added inside the barrel for the cylinder pin to butt up to. Someone did instructions about 40 years back for making an adjustable stop for the cylinder pin but I don't remember how it was done.

[Jackrabbit1957]

The stop is a threaded stud that bears against the wedge. I find the best way to fix it is to weld the end of the slot in the arbor and dress it back to make it fit. Any time material is removed from the frame or the barrel lug the arbor slot is going to change, sometimes by quite a lot. Welding saves me time and effort by not having to make an oversized wedge to compensate for material removed to fix the barrel/ cylinder gap.

[LST-1185]

I also adjust mine between .003 to .005. Anything over .006 is to much for me.