Revolver has oversized cylinder throats to smaller barrel rifling

[44and45]

My revolver is a .44 special three inch barrel Taurus model 441.

If one's revolver is going to have oversized cylinder throats at .4335 or .434 diameter, and the gun's rifling is only .429 diameter -- can you expect ignition blow-by gasses to push past the bullet while enroute to the barrel forcing cone???

Is there the possibility that the cast bullet may be a bit off center when entering the forcing cone into barrel rifling??? This could cause bad accuracy if this is indeed what happens.

I've thought about having a seating die made up in .4335 diameter, but this seems excessive diameter to ask the bullet to enter the smaller .429 rifling. I'm not keen on doing this as the strain on the gun is going to be a bit too much. There could be a lot of lead shaving build-up in the forcing cone and rifling.

Therefore, wouldn't it be better to just make my cast bullets in .430 diameter and perhaps make them with a good hollow base of about 1/4 of an inch...hoping this takes care of the excessive oversized cylinder throats by the bullets rear base bumps up to slip through the cylinder throats while the front portion of the bullet remains in hopefully perfect concintricity to hit the focing cone area and the bullets entry into the rifling.

Any thoughts on this scenario, anyone have the same problem with oversize cylinder throats.

Jim

 

[rcmodel]

Over-size cylinder throats used to be quite common on S&W & Colt .45 chamberings. Even Ruger seemed to have trouble with it for a while.

You are right that accuracy will be affected.

You will do best by sizing lead bullets to .430" or even larger, if they don't start bulging the cases and make chambering impossible.


rcmodel

 

[pinkymingeo]

You'll have better accuracy and less leading with .433 cast bullets. The .004 difference is acceptable.

 

[ClarkEMyers]

Try it.

The general rule is that cast bullets do better when they fit the throats.

According to research mostly traceable to Speer IIRC - when folks transistioned from lead crusher to PSIA transducers drilled and tapped into cylinders (see also testing in vented barrels) for pistol loads - revolver pressures hit a peak as the bullet transitions into the forcing cone because the bullet bumps up into a fat middle tapered front and rear a barrel shape fatter in the unsupported middle than either throat or bore and then swages back down into the barrel.

 

[44and45]

So, from what you're saying, I'm correct in applying the hollow basing to my .430 diameter cast bullits of about a depth of 1/4 of an inch.

The bullet will bump up on its rear base and taper to the front as it heads for the forcing cone and the barrel rifling where it swages back down to .429 diameter.

This sounds like a better solution than using oversized bullets that run full length of a .434 diameter.

Jim

 

[tkendrick]

ount your blessings. I bought a Uberti Hartford several years ago that was set up exactly the opposite. I don't remember the exact dimensions, but the throat was smaller than the rifling. Took several dollars to straighten that one out.

 

[ClarkEMyers]

I'm certainly not saying to reinvent the Minie ball.

So, from what you're saying, I'm correct in applying the hollow basing to my .430 diameter cast bullits of about a depth of 1/4 of an inch.

A diameter of .430 and a hollow of .25 might well be worth trying - anything is worth trying - but compare the depth of the hollow base on 148 grain hollow base wadcutters and notice that the hollow base wadcutter has been known to separate in the barrel and so lead to nasty surprises. Notice also that many revolver barrels will show a choke point under the threads and so will sometimes, even often but not always, perform better with the choke point polished out.

I'm certainly not saying to reinvent the Minie ball. What works with blackpowder - blackpowder is more to the explosive side for impact extrusion and smokeless is more to the propellent side - and with pure lead doesn't work with smokeless and harder alloys.

It is certainly true that temper - alloy and hardness to include heat treating - sometimes make a noticable difference in cast bullet performance. A bore riding pilot and a groove riding body with minimal distortion works well. Sadly the oversize throat distorts the bullet and the bullet once distorted never recovers. Even in the best of lubri-sizers sizing changes the bullets and a bullet which is the optimal size as cast will almost always perform better than a bullet which has been resized. A bullet that has been sized in a lubri-sizer is often distorted less than a bullet that is sized and resized when fired.

I suppose what I'm really saying is there are lots of experiments that are fun to try but the only guarantee is a Freedom Arms or a Bowen custom or another revolver with proper dimensions.

 

[rcmodel]

I would forget the hollow-base thing.
To slow & too much work casting them.
And they won't shoot as well as a larger bullet that fits the cylinder throats correctly.

That gets them started into the forcing cone as straight as possible, and will give the best accuracy.

An under-size HB bullet will start out skipping around in the loose throat, and end up hitting the forcing cone slightly sideways. It will be deformed too the extent that it will not shoot as accurately as an over-size bullet that had no room to get out of kilter in the loose throat.


rcmodel

 

[44and45]

Quote:

A bore riding pilot and a groove riding body with minimal distortion works well. Sadly the oversize throat distorts the bullet and the bullet once distorted never recovers.

========================================================

Well, what about the hollow basing? Which I might add is done by swaging in a bullet swaging die with special nose punch.

The bullet's HB base wall is not thin at the HB 1/4" entrusion, they are nearly 1/8th of an inch thick.

The idea here is to bump up only the HB area up to fit the oversize cylinder throats...while the front part of the cast bullet remains .430 diameter as it enters the forcing cone and thus into the .429 barrel rifling.

At least that is the theory to yet be proven worthy or not.

Wonder what a cylinder would cost to be made by a master craftsman gunsmith, a cylinder made with the proper .430 throats...or, would just lead to another can of worms.

Jim

 

[Jim Watson]

A new cylinder would cost many hundreds of dollars if you could find a gunsmith willing to set up for a cheap gun like a Taurus. Which I doubt.
If Taurus makes the same basic gun in .357 you could have its cylinder rechambered. Probably could part out the rest of the gun and come out a lot cheaper than a custom cylinder.

The hollowbase bullet has a chance. Remington factory .45 Colt bullets have a small hollow in the base to accomodate the differences in cylinders and barrels over the years.

Or you could just load jacketed bullets tough enough to make the jump.

What kind of accuracy do you want, expect, and need (may be three different things) out of a 3" hideout gun?

 

[Vern Humphrey]

Question 1: How is the revolver shooting now, with factory ammo? If accuracy is acceptable, all you need to do is duplicate the factory loads.

Question 2: Have you tried hollowbase wadcutters? They ought to solve much of your problem.

 

[44and45]

It surely is interesting the diversity of opinions expressed on this subject, I certainly thank you one and all for your imput.

But I'll be trying to overcome the oversize cylinder throats with HB bullets, plus avoiding using too big a diameter bullets (.434) to match the present cylinder throats would just be too much bullet swaging entering the .429 rifling.

I've only fired a few test rounds off my front porch, haven't been to the local country shooting range as the weather or my health as precluded getting there. Its been raining a lot up here lately.

BTW, I don't consider this 441 model Taurus a cheap gun, its as good or better than anything I've seen made today by other makes.

It also has a terrific double action trigger pull, very smooth...would make a great carry gun if the politicians would let us have CCW.

More on this if and when I make it to the gun range...weather is still crappy with rain.

Jim

 

[fecmech]

I have a Ruger Super Blackhawk .44 mag that has .434 throats and .429 groove. Using cast wheel wt. bullets at .44 mag velocities (and pressures) sized .430 I had no problems with leading or accuracy in the 1200-1400 fps range. 50 yard groups averaged 3" or slightly less. OTOH light loads in the 900 fps range and less than 20KPSI leaded badly and there was no accuracy. Recovered bullets showed severe gas cutting down the sides of the bullets( blow by in the throats) which caused the leading and destroyed the accuracy. I used a process called "Beagleing" (http://www.castpics.net/, go to articles by members under "Bullet diameter enlargement") to get some .434 bullets because my mould would not cast larger than .431 and sized my bullets to .433.
Voila ! leading disapeared and accuracy returned to <3"@ 50 yds with the mild loads. I use the Lyman "M" die to bell my cases and you will need to bell them pretty good to accept a .433 bullet. Accuracy is slightly better with the full snort loads in that they now average closer to 2" than 3" and I see no signs of excess pressure. IMO lots easier than trying to hollow base some bullets to get them to bump up.

 

[44and45]

fecmech, that is indeed the kind of experience I was hoping to hear about, thank you.

A person who has exactly the same cylinder throat scenario and found a solution to overcome it. GREAT! GREAT!

BTW, I think I have some old Lyman 310 dies that are .44 special M-dies, but don't believe they'll bell the case mouth. Been my experience they kind of crimp an oversize brass case where the bullet is seated.

Jim

 

[fecmech]

BTW, I think I have some old Lyman 310 dies that are .44 special M-dies, but don't believe they'll bell the case mouth. Been my experience they kind of crimp an oversize brass case where the bullet is seated.

The "M" die is a 2 step expander die especially for cast bullets and is currently made for most calibers. The purpose is to expand the case so that cast bullets can be seated without damage. I'm pretty sure they can be bought individually from Lyman.

 

[44and45]

Aye, I stand corrected. My Lyman M-die is on re-examination is an MR-die. Which I assume means muzzle resize.

I'll have to look into getting an M-die in .44 caliber that can resize my brass to take the .433 bullets.

One thing I've noticed, my cylinder chambers are more than adequate to accept the slightly enlarged brass case mouths.

Another thing that has come to my attention, the Taurus model 441 is not the only revolver I have with this .433 oversize cylinder throats. My 2nd model S&W in .44 special has the very same problem...only I didn't realize it before. Always wonderd why there was so much blow-by on the bullets shanks, and the accumulation of powder and lead under the top strap then wiinding up on the top of the cylindere flutes.

Hope to tailor make some bullets that will work well in both of these revolvers.

Jim

 

[Jim Watson]

Back in the old days, when guns were less precisely made than now, and when they were worked hard to where they would be thought worn out today, the roundnose bullet served a real purpose. Diving from case to cylinder to barrel with a little self aligning effect.

 

[brickeyee]

"...too much bullet swaging entering the .429 rifling."

If you have not done some serious checking of accuracy yet, how do you know it will be a problem?
Shoot the thing before trying anything else.

And be glad it is NOT the other way (tight throats/cylinder) since once you swage the bullet down it rarely comes back up.

Throats are normally somewhat larger than barrel diameter to make up for the tolerance in aligning the cylinder and barrel.

 

[44and45]

I have not been to the local shooting range for two reasons, climate and old age problems. It was in the 20's today up here, and don't feel like freezing my nads off.

The gun's former owner told me about the oversize cylinder throats and it shoots best with .434 dia. RNFP 200 grain bullets loaded with 6.0 grains of Unique. Apparantly there is no problem in shooting .434 mild loads in the .429 rifling.

He also said to reload he used a .44 magnum seater die to push the bullet down to the crimping area...but used a .44 special crimping die. This reloading sequence is something I'm not real sure about yet. If necessary a special crimping die could be fashioned.

I still intend to first try hollow basing .430 dia. bullets before using the .433 dia. bullets. I can swage HB on any cast bullet with my swaging equipment, I can bump up any cast bullet with the same equipment.

I really like this revolver, and willing to go the extra mile to make everything work in it...and in due time will try and get it all working including the dang 2nd model .44 spl. S&W that has the same oversized cylinder throat problem.

That's how I know about oversize cylinder throats.

Even if I fall on my a$$ with all this effort, I'll have at least tried...please wish me luck.

If I can cure the 2nd model S&W blow-by problem, it will be well worth the effort...that gun is capable of two inch groups at 20 yards.

Jim

 

[nicholst55]

I have a S&W M25-5 with .456" cylinder throats and .452" groove diameter. When I first discovered this I panicked and looked at hollow base molds and considered trying to use lightweight .45-70 cast bullets sized to .456" or .457" (assuming that they would even chamber). Then I took it to the range and shot some .452" jacketed and .454" cast bullets through it. End of problem.

The gun shoots as well as I can hold right now, so I'm not going to worry about it. Try yours, weather and health permitting, before you rush out and spend a lot of money on something that you may not need.

 

[44and45]

I hope to get out tomorrow if the freaken weather isn't too cold, but them local deer hunters usually have the range benches tied up pretty good for the next month or so.

Don't worry, my first step is I've got some regular .430 diameter loaded ammo ready for test firing, some have hollow basing...going to test shoot both.

Some of these mighty hunters have 375 magnums rifles, blows the wax out of your ears and other places. That's what happen to me the last time I went to the range.

Up here in northern Wisconsin you don't need an elephant gun, just the old 30-30, or a good magnum revolver...the trees are thick as brush.

Jim

 

[44and45]

Well, to all you guys who said "I told you so! " Weeel you did, and you're pretty much right about part of it."

First loads shot were 200 grain RNFP hollow base with red lube, 6.0 grains of Unique that grouped about 3 to 4 inches but extremely fowlling the cyliner chambers and barrel. As did the 175 grain RNFP HB bullets that flew with 4.0 grains of Bullseye...these did about the same group size.

Not only was those powders very dirty, the blow-by of powder soot on the side of the brass cases was horrible as well.

Then I tried an old reliable, 240 grian Hornady factory swaged bullets with my 1/4 of an inch hollow basing added, these babies shot to point of aim and whoa nelly, the 4.1 grains of Clays really shot clean. It actually cleaned all the afore mentioned dirty shot powder and gunk out of the revolver's barrel...plus there was no blow-by soot gunk on the side of the brass cases...amazing.

The gun is down on my garage work bench soaking with Butches Bore shine. This should clean up any lead residue if there is any. Then follow that up with some arromatic Hoppes sweet smelling sauce.

So, the solution to all my fears is to stay with .430 or maybe .431 bullets, as I can still seat those castties with my regular .44 special reloading dies...BUT!

And this is a big butt, er but. The hollow basing is the ticket to cleaner burning, and accuracy with the Clays and Trail Boss powders that worked the best today.

Thanks for all you guys imput, you're a good group.

Jim

Best groups obtained first time out with Taurus...nothing to brag about but I'm happy.

 

[Jim Watson]

I'd try some of the soft swaged bullets without the labor of cutting a hollow base. They might slug up well enough as is.

 

[rcmodel]

+1 to what Jim said.
Or try a softer casting alloy.

Most folks are on a "hard-cast" kick, when in fact they would be way better off with Elmers old 1/16 tin/lead alloy.

Unless you are shooting very hot loads in a .44 Spl. the harder bullets, and even most commercial cast bullets meant for Cowboy Action reduced loads are way too hard.

Blow-by, gas cutting, accuracy, and leading will be a problem because the bullets are too hard to bump up and fill the throats at standard pressures.

Hard-Cast bullets are great for max loads in the .44 Spl. and any of the Magnum calibers, but not in standard pressure or reduced loads where a softer bullet will work far better.


rcmodel

 

[44and45]

I've got a lot of 170 to 175 grain cast bullets that are very soft lead, and some 180 to 185 grainers have the Lyman gas checks which a dimple bumped on their bases. These might be good canidates to use with some clean burning Clays or Trail Boss. Speed them along close to 900 fps should be pretty good.

Today I shot a few 175 grain at around 700 fps, accuracy was good, but powder was very dirty...that can be fixed with some that burn cleaner. Hardly any recoil with those puppies.

Couple of years back I shot some really lite bullets I made up from 158 grain, that were once .358 diameter .38 spl. bumped up to .429 to .44 spl. They flew at nearly 1,000 fps but shot around 8 inches low from POA...but grouped tightly.

Too bad winter is breathing down our necks up here, my shooting season is nearly over as it gets colder and colder.

Now if I could just hit that lotto tickert that brings the big bucks, first thing I do is build a basement with a 20 yard range that is heated, vented, and sound proof. It could snow all it wants to then, I wouldn't care. Heck! With that going for me I wouldn't have to rub elbows with those deer hunters and their blunderblusses giving me the twitches just as I'm about to pull the trigger on my revolver.

Jim