Cylinder Throats

[siamese4570]

Don't know if this is the right place for this but I saw the sticky about cylinder throats so here goes. I'm pretty sure that the throats on my 44 redhawk are too tight. I still have to measure to confirm but it has always leaded with non-gc lead bullets. Does good with gc-cast and jacketed. If the throats do measure tight, does anybody know a goo gunsmith that can open these up for me? I've been to the Cylindersmith's web site. Anybody familiar with his work? Thanks

Siamese4570

[454PB]

What does the bore measure? What are you sizing your cast boolits?

It's possible that the cylinder throats are fine, but the bore is bigger than you are sizing. A .430" boolit can cause leading in a .431"-.432" bore.

Even if the boolits fit the throats and bore, there are limits to how hard you can push a plain based boolit.

We need more information.

[rvpilot76]

He did my 45 Blackhawk with 45 Colt and 45 ACP cylinders. Highly recommended!

Kevin

[MtGun44]

You need the measurements to judge. The 'diapers' (as Elmer called GCs) and
jackets will cover up poor fit between throat and groove diam.

It can also be poor lube, too hard a boolit, esp if throats are undersized, too
soft (this tends to be blamed a lot more than is real) or undersized boolits
in big bore with properly matched (but bigger than boolit) throats.

Many things . . . . . .

Report back the groove diam of bbl, and throat diam of cyl and we may
be able to help. Generally, you select the boolit diam to be cyl throat +.002"
or 0.001" and the groove diam should be about .001 smaller than cyl
throat diam. Variations will sometimes work, but these are the recommended
sizes. Of course, tight chambers can prevent using a 'large enough' boolit,
too.

You can do it yourself if you are so inclined - refer to my thread on opening
the throats in my BH .45 ACP/.45 Colt in Gunsmithing - find it with search.

Bill

[runfiverun]

might want to check the cylinder gap also, too hard of a lube can be blown out of here
and a naked bullet will lead also, but i would definately look at the other stuff first.

[siamese4570]

Went home last night and measured the bore dia and cylinder throats on my redhawk. The bore was .4305. The throats measured .432 - 4325. This should be good. I've been sizing bullets to .430. Use straight wheel weight metal. I've also tried unsized boolits (.434) with the same result. Don't believe that I pushing them too hard (700-800 fps). The leading occurs just past the forcing cone. So the boolit is probably skidding when it hits the rifling. Should I go up to .431-.432 on the sizing? Hard to think that .001" would make that much difference.

Siamese 4570

[felix]

Siam, it makes all the difference in the world. All the following must be commensurate: diameter, hardness, powder speed & amount, primer, boolit design & weight, recoil with boolit internally & externally. ... felix

[9.3X62AL]

Check also--diameter of the expander spud in your expander die. If the diameter is .426", the expanded cases could be down-sizing boolits any larger than .429" during seating. Buckshot is going to make some more pocket money from me with his M-die and RCBS Expander Die spuds. I like the spud to be no more than .002" smaller than the boolit's sized diameter, maybe .003" with H-110/WW-296 loads at max pressures in Mag revolvers--and those loads have gas checks to guide the way into the case and later out of the barrel, and usually harder alloy too.

Over time, I've found the plain bases and sidewalls of cast boolits to be a bit more delicate than I initially thought. All those "hard cast" boolits may be doing good work NOT because they resist gas blow-by so well--but because the harder alloy isn't swaged down as severely during boolit seating.

[runfiverun]

yep
the g/c ones could be opening the cases up a bit when seating also.

[MtGun44]

Felix and 9.3x62Al are right on -

A couple thousandths will really make a difference. Al is helping you to find
a often overlooked way that "right sized" boolits somehow wind up too
small.

Also, if you add some pure lead to your wwts, you may get them to bump
up to throat diam (proper fit) with all other system varialbles unchanged.

Softer is often better, esp at low vel like you are using. Too many read the
"super quality HARD cast !" ads by commercial boolit sellers and assume that
hard=good, which is not necessarily so.

Bill

[fourarmed]

You have excellent information here. Assuming your measurements are correct, you should get best results with bullets sized .432 to .433. Another thing to consider is the powder you are using. Fast burning powders aggravate the problem. If you are using powder faster than Unique, even at these low velocities, I would try something slower and see if that helps.

Back on the topic of measurement, getting those diameters accurate to a thousandth is not trivial. If you are doing it with a dial caliper stuck in the hole, you may be off by a significant amount. Pin gauges are the quickest and easiest if you have them. Miking an EXPANDED slug is fine too.