Firelapp first or ream cylinders first?

[shakey]

Veral,   

I've got your lap kit and trying to get squared away to slick up a few Ruger .45 Colts.

One of them has cylinder throats measuring around .4525 but a couple have cylinders that are pretty tight... some as small as .450. The undersized ones obviously need reaming but, my question is, should they be reamed before or after firelapping? 

I am probably over thinking this but, it seems to me that running a lap bullet through a very undersized cylinder would not allow it to lap the barrel very well and might require a great many lapping shots.  On the other hand, running the lap bullets through a properly sized cylinder would lap the barrel better but might open up the cylinder too much. 

Is this analysis correct and, what's the general rule here?  Do I firelapp first or ream first?

[Veral]

  You have thought the situation out very well.  The cylinders must be larger than the barrel or lap bullets won't do their thing.  If the 45's are all yours, I suggest that you open them all up to the same size so you can standardize your ammo.  If throats are opened very much over standard jacketed diameter, it will hurt accuracy with jacketed, but most casters don't get cramps over that as they never shoot jacketed anyhow.
  Point here is, if you do shoot jacketed and have a gun that is good with them, maybe you'd like to keep it just for jacketed.  Time to keep it is before opening the throats!

  My recommendation is to measure the barrels at the muzzle, then open cylinder throats at least .001 larger, then lap.    Lap bullets produce almost no change in cylinder throat diameter, but only polish them a little, mainly because each throat only gets one while the barrel gets six.

[shakey]

Thanks Veral, 'bout what I thought.  I'm not worried about jacketed bullets so I guess I just need to get on with it. 

I had in mind to let the folks at http://www.cylindersmith.com/  ream my cylinders for me but, after reading your instructions, I'm trying to work up the nerve to do it myself.  I've got a while to decide yet 'cause, which ever way I go, it'll wait till after hunting season.

Thanks again.

[cinosbus]

I used 240grit, then 320 on a split rod, per the instructions in either Veral's book or the papers that come with the lap compound. It worked quickly and accurately for me - much better than I had expected. Took about 1 and a half strips of 240grit per hole followed by a light going over with 2 strips of 320 for all 6. Now .4525" fits, .453" does not. That's PERFECT! I'm hoping jacketed bullets will still shoot OK like this, since they are only .4515" and there's still not much slop there.

Next step is to have the forcing cone cut if accuracy is not what I want.

[TommyD]

Thanks Veral, 'bout what I thought.  I'm not worried about jacketed bullets so I guess I just need to get on with it. 

I had in mind to let the folks at http://www.cylindersmith.com/  ream my cylinders for me but, after reading your instructions, I'm trying to work up the nerve to do it myself.  I've got a while to decide yet 'cause, which ever way I go, it'll wait till after hunting season.

Thanks again.

I had cylindersmith.com open my Ruger Blackhawk cylinders (45 Colt and 45 ACP) to .452. Both were too tight. My group sizes in that revolver are now half of what they were.

Tom

[shakey]

I sure will be tickled if I get such an improvement.