Cylinder throat diameter vs bullet size

[Patrick L]

Sometimes ignorance is bliss.

I own a nice old S&W 5 screw 1955 Target .45ACP revolver. It is a "pre" 25-2, ie no model number, just "1955 Target" on the barrel. Its always been a pretty good shooter, certainly better than I can shoot it.

Inspired by "Duke" Venturino's recent article , I ordered a set of plug gauges to check revolver throats. All six throats in my cylinder will accept the .455 gauge but not the .456 gauge. So I guess I have .455 throats. All these years I have sized my .45s to .452 because that's what the books say to. And, just for giggles, I took an unsized bullet and proceeded to drop it right thru all six holes.

So, my question is, just how important is this? I've gotten acceptable results with my small bullets for years. I could probably size my bullets bigger than .452 (I should have measured their as cast diameter, and will later) but I'll never get a tight fit , at least with that bullet. And then I 'd have to check fit in the 1911's. I like keeping things simple, so I'd rather not have to have separate bullets for each gun.

Advice please?

[felix]

You should follow your own advice, and keep doing what you are doing which would keep things simple. ... felix

[Bass Ackward]

If it ain't broke, don't fix it.

I will add that what you can get away with using 45 ACP or AR brass, is simpler than what it would take if you had a longer, more powerful cartridge.

[missionary5155]

Experiment ! My Colt New Service (123xxx civilian) 44.40 for example. Using as cast .427 boolits from and old Win. Mold gave reasonable accuracy out to 25 yards. I could count on 6 shots in about 4 inches... Then I thought hey.. what are the diameters of the cylinders.. .428 and two are .4285.. So I took 10 of those .427 boolits and bumped then up and sized them through the removed cylinder. Loaded 4 cartriges to 8 grains Unique - my standard plinker load. Those 4 cartriges grouped into 2 inches (actually 1- 7/8) at 25 yards sitting. Nice cluster with 3 shots near 1 inch. Now due to my having to ration Large Pistol Primers I did not shoot 10.. BUT I think I will just continue with Cylinder sizes boolits. Cannot hurt !

[sagamore-one]

I have been working on the same thing for a couple of years.. I have a pre 25 , 1955 target 5 screw and a 25-2. Both pin gage at .456 to .4565. I have tried numerous boolit styles, weights and sizes : H&G 46,34,68,130, 78 and xs242. Weights range from 160 gr to 240gr. Boolits sized .454 or .455 shoot no better than those sized .452 but sometimes cause case bulges to the point of sticky loading into the chambers. As a matter of fact, the .452 may shoot a very little bit better. Lube does seem to make a slight difference. 50/50 alox/beeswax has been the most consistantly accurate with all weights and styles. All hard lubes seem to work equally. The 68 seems to group the best and seems to have the lowest recoil impulse. At least for me.
I have even tried to adjust the alloy from straight wheel weight alloy to straight fresh linotype metal and numerous alloys in between.
It appears to me that as long as the boolit is somewhat hard, somewhat round, well lubed,and is launched at a respectable velocity... the 45 revolver will just plain love them.
As an aside... the heavier projectiles do print quite a bit higher than the sights will adjust for. The 160 to 210 gr range seems to be where the sights are regulated.

[cabezaverde]

My SBH turned into a new gun when I finally made the boolits fit the throat.

[pjh421]

How about Beagling the mould? It's reversable.

Paul

[Patrick L]

Here's just a few more tidbits.

My .45 bullets measure .453 as cast. I have a tumble lube mold from my early days of casting. Just for giggles I'm gonna cast up 75 or a hundred and do some group shooting. My experiences so far agree with sagamore-one, so unless I get some one hole groups with the fatter bullets I'm not going to worry too much.

There is some good news. My Model 66 cylinder gauges a nice .357 for all 6 holes. I ran a slug down the bore. It was tough to measure with the 5 groove rifling, but near as I can tell the bore slugs at .3565, so my .358 inch bullets should be near perfect (they shoot well.)

Thank you all, please keep the opinions coming.

[MtGun44]

I have an old S&W 1937 Brazilian contract .45 ACP, basically identical to
the 1917 model. The throats run .454 and it wouldn't shoot better than
6-12" (depending on the particular boolit and load) at 25 yds with cast.
OK accy with jacketed, but not impressive at all. I figured the throat size
is the main problem, but they also have very shallow rifling.

Keith recommended 7.5 Unique with his 452453 as the most
accurate. I bought some custom cast Keith 452453 and they were sized
to .452" and shot poorly. I finally found a 452453 mold of my own.
I found this mold casts .454 and suddenly it was at 3-4" with almost
any powder, much better but not impressive at all.

Well now my 452453 mold cast about .454" but still not particularly accurate
with normal and light loads. Also, it shot about 6" left of POA.

Checking the load against the load books showed that (as usual) Elmer
was way out there with his favorite load, I was scared to try it in the old lady.
I slowly worked up with the .454 boolit and it started moving closer to POA
as the charge increased until, suddenly at 7.0 gr Unique, it was pretty
accurate and very near POA. I stopped there and could not recommend
the hot 7.5 load for the older guns. Maybe the new production steels
are up to it. Here is the result. :drinks:

I have learned a lot from Keith's book "Sixguns".

Bill

[fecmech]

I can't comment on .45 revolvers as I don't have on but my Ruger SBH in .44 mag has .434 throats.
When shot with magnum loads and wheel wt bullets sized .430 it does just fine. When the same bullets are loaded at .44 spec velocities accuracy is poor (3-4"@25 yds). Bullets "Beagled" and sized to .433 fired at .44 Special velocities group around an inch at 25 yds. My guess is that the magnum loads bumped the bullets up in the throats due to the higher pressures and therefore the accuracy was improved. MY $.02