large cylinder gap loads?

[bushka]

I have an original colt bisley in 38-40[1902] shooter grade vg/exc., with an 18-20 thou.cylinder gap,measured with the cylinder pulled to the rear.
when cocked it pushes forward to give a .000/.001" gap,optimal,but that dont last when you fire a cartridge of course.
The cyl.bushing is 1.842" which is like new from what I understand,and forward play is not the issue,but backplay is.
I dont shoot this gun more than average 500rnds in the past 10 years,which is nothing @ 50 per year,and dont see a barrel setback job happening anytime soon,
so,
what powder/loads would give less so called "spitting"?
been using unique 8.0 grains with a 155 swc,win LPprm,and get alittle back, about 1 in 6 rnds when holding two handed.
nothing when shooting one handed. exc accuracy 2-3" for an nra "good bore".

Other option,being me a machinist/toolmaker,is to make a .015"shim to fit under the ratchet/recoil plate,to keep the bbl/cyl gap closer upon firing.this would also leave me a couple thousandths for fouling too.

thanks for the blah blah:drinks:

[454PB]

The cylinder shim would be the least likely to detract from the collector value and the easiest fix, but I wonder if you might have ignition problems by moving the primers forwards that much.

[leftiye]

I know you won't like this, but if the cylinder is all the way back and when loaded (use empties to test- I know you had that figured out already) with cases rotates correctly, then the fix is to get a washer type shim to hold it backagainst the breech face, and have the barrel set back to get correct barrel-cylinder gap. Your gun may be a collector, so check first to see if this would hurt its value. Ted

[bushka]

thanks all,
leftiye changed me mind abit, re-measured the gap with a cylinder full of empties from last sunday,and the gap came down to .015".
saami max is .012" I read somewhere.
the fired cases act like headspace gages it seems.
Now the blast part of it is actually cool,dont bother me at all.kinda like a 38+p+.
But now I see Taylor forcing cone reamers at Brownells that claim to cure all lead spitting presumably because any shaving is taking place well inside the bbl.
My cylinder lines up perfectly with a little side to side movement,just a bit more than my 2nd generation,but looking at the forcing cone with its almostnon existent 45 degree angle lead,there be some lead built up there,so this re throating seems to be less invasive option than setting back the barrel to
re gain velocity loss shooting at paper targets once in a while.

[montana_charlie]

with a cylinder full of empties from last sunday,and the gap came down to .015".
saami max is .012" I read somewhere.
Are you saying your cylinder is worn beyond maximum acceptable, and that makes you happy?

In my limited experience, it doesn't seem that the case rims should be tightly sandwiched between the cylinder and breech face. There always seems to be a little play there on a properly fitted gun.

I suppose the metal that wore away on yours was on the back end of the cylinder, so will you not consider a shim there? Not one thick enough to cause ignition or headspace problems, but enough to bring the gap down to .010" or (perhaps) .008"...and allow that small movement of the cases?
CM

[bushka]

no,what I am saying is the end of the barrel is the part thats eroded,not totally crazy horrible, not bad enough to warrant a barrel setback job.
and the cylinder bushing front is worn [endshake] to be corrected with the shims.or even a new bushing.
That will move the cylinder back [like "leftiye"said] to where it should be ,because its been creeping forward all these years little by little,
live with the loss of power [did I mention I punch paper sometimes?],and eliminate
lead spitting thru an up to date,more forgiving barrel throat.Taylor throat.
BTW the cylinder isnt worn,just got done comparing it with another first and second generation .same gap showed.

[leftiye]

Bushka, Thanks for all the support! However, with your new info, I think that you should do both ends with a shim. Mt Charlie is right, you want enough room left after the cases are in the cylinder that they can't jam up with a little dirt, or a stuck case. The giveaway is that your cylinder gap came down .003" when there were cases in the gun. That says that there was no extra room in the headspace area at that point, it was all filled with the cases. Case head plus .002" would be a .005 shim. Check specks or with somebody who knows how much extra headspace there should be (case heads may vary more than .002") and bring your headspace into correct clearance, then use shims at the front of the cylinder to bring endshake down to.001 or .002". The bonus on this is that your cylinder gap will then be well within spec. Your idea as to getting an improved forcing cone is real good, should make a big difference.

[bushka]

UPDATE..

Well after speaking with some well known saa smiths about what they would do for me,I went and did it myself-first by going by the"book",Kuhnhausen`s book which I have a couple volumes for other models,and can highly recommend,even if you wont touch a screwdriver-but want insight.I have smoked my share of bolts,springs,etc before,for the saa pattern,but gawdamm..I had to go back and adjust every partsgun colt I have!
What was a forcing cone issue,cured by the taylor reamer,became a bolt engagement,timing,bottom hand carry up/replace,new bushing,new oversize basepin,bolt block fitting,and close inspection of what I had and should have.
More load experimenting shown the unique/185 swc to be the only offender in the "spitting" dept.,maybe I think because it had a short bearing surface.
Switching to hardcast 180tc over 5gr of trailboss proved the most accurate to date and POI right on the money w/2.5-3" clusters@25yds rest.
The taylor reamer that brownells has is easy to work with as advertised.
I have the endplay down to about .002" with maximum headspace and a wee bit larger than saami max cyl gap,but unless the bbl is set back etc,this is what I got.
In all,I would have to say the love of the endeavor is priceless,but let an expert do it if your time matters and want true perfection.:drinks: