Early Model 29 throat dimensions?

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jphendren

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Hello,

I am curious what the throat dimensions on an early Model 29 from 1961 usually are? What size lead bullets work the best? .430"?

Thanks,

Jared
 
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I assume you mean chamber mouth diameter. My 29 was built in late 1960, .429" was the standard lead gas check bullet specified then, and that is what I have always used. Chamber mouths on a 1961 gun should be uniform and close to .429" also, I think. .430" bullets would be fine, but not over that. There is no leading, with correct lube, and accuracy is superb. Cylinder gap is around .004", when such S&W tolearances were still being carefully held.

.430" lead bullets should be just fine also, but I would not go higher with jacketed bullets.

Have you measured your chamber mouths or cylinder gap?
 
PhilOhio,

Yes, I mean the chamber mouth throats. I have not received the gun yet, and want to get some lead bullets on order from Montana Bullet Works. I am planning on the Lyman 429421 Keith bullet of course, and was unsure what size works best in these old guns. So I should go with .429"?

I am planning on using Unique, and want something with more power than a .44 Special, but not too hot, don't want to knock the old girl out of time. I have read that 9-10gr of Unique works well.

Jared
 
You won't go wrong with a 429421 sized to .430. 9 grains of Unique will cover most of your shooting needs. For most of my target practice if prefer 7.5 grains of Unique...much more comfortable and extremely accurate.

Good luck.
 
jphendren said:
PhilOhio,

Yes, I mean the chamber mouth throats. I have not received the gun yet, and want to get some lead bullets on order from Montana Bullet Works. I am planning on the Lyman 429421 Keith bullet of course, and was unsure what size works best in these old guns. So I should go with .429"?

I am planning on using Unique, and want something with more power than a .44 Special, but not too hot, don't want to knock the old girl out of time. I have read that 9-10gr of Unique works well.

Jared
Click to expand...

Jared--I suggest you look at Green Dot for your .44 mag. I've been using it for over 20 years. A rep from Hercules(now Alliant) once told me that Green Dot is a well kept secret powder for the .44 mag. 8g of Green Dot is "equivalent" to 9g of Unique with the 429421. I suspect the "secret" is that a guy gets more bangs for the buck with Green Dot, and since Alliant sells powder, they'll sell more by down playing Green Dot.
 
41 fan,

.432" Wow! That is quite a bit larger than I had anticipated.

I ordered some 44 caliber 250gr Keith's from Mt. Baldy Bullet Co., theirs are sized .430", and are BHN 11. Hopefully those will work without leading too badly.

Jared
 
I don't think you can say w/ any certainty what the exact cyl throats are form one gun to the next even witin the same manuf year. I have guns that are 0.430 & 0.431". Slightly larger is better than slightly smaller. You want to size the bullet for the groove dia first, then check cyl throats. If your bbl slugs 0.429" & you have throats the same size, then 0.430" bullet will probably be fine. I had my sizing die lapped out a bit to 0.4305" to get a bit closer for a M629 that has 0.431" throats.
 
My 624 measures 0.432

I recently bought a 624. I just cleaned it up. I have not shot it. I took the cylinder to work today. I measured the cylinder throats with a minus gauge pin. The 0.433 would not fit. The 0.432 fit perfectly.

I am new to all this, but wouldn't the critical dimension be the groove diameter of the barrel? Which brings up another question. How do you measure the groove diameter?

I suppose I could use the gauge pins to measure the land diameter?
 
"How do you measure the groove diameter?"

I believe you have to push a soft lead object through the bore, and then measure it. This should give you the groove diameter

Jared
 
I have a 1972 model 29-2 that has .432 chamber throats.
Same goes for my mountain revolver.
I have fired .430 hardcast bullets in both guns before and after 12 rounds or so the first 2 inches of barrel looked like a smooth bore.
Much scrubbing and cussing later I got that mess out of there and now only use those .430 bullets in my Rugers.
You must measure your chamber throats to be sure but most of the older Smiths are larger than .430. If memory serves they stayed around .432 until the 29-5 or so.
That being said I now use a 240grain .432 bullet either from Dardas, or Penn with 8.5gr Unique for plinking or 10gr Unique for a working load that will handle most anything I need to shoot.
The same bullet with 19.5-20grains of 2400 makes a superbly accurate hunting bullet.
 
pop-gunner,

Thanks for the link.

I took the Model 29 out and shot 50 handloads using .430" 250gr Keith bullets (BHN 11) from Mt. Baldy Bullet, over 9.5gr of Unique. This load supposedly runs a little over 1,000fps. Leading was heavy, it came out in strips. There was not much lead in the throats, but the first 1.5-2" of barrel was heavily leaded.

I have not seen any Keith bullets available .432", most are .429-.430". I may have to try a gas checked bullet, I have always had good luck with those.

Jared
 
Bigger is not better as far as throat diameter goes. All the Classics I have measured are .429 and all the performance center guns I have measured are .428.5. They all shoot very well with .429 or .430 lead. I used to get .432 fom Bob at Penn bullet for an early 629 I had that measured .433. It still didn't shoot very well and was traded. I've found the best accuracy with the bullet being .001 to .002 larger than the throats.
 
Did you ever measure you groove diameter? Without knowing it you will only be guessing. Once you figure out what your barrel dimesions are you can go .001 or .002 larger and your leading problem will stop. You shouldn't need gas checks unless you are reaching 1300 to 1400 fps...at your posted speeds the right lead bullet will shoot great and give you no leading. Take the proper measurments and let your gun tell you what to shoot. Good luck.
 
"Did you ever measure you groove diameter?"

No, I have no idea what the barrel groove diameter is. I always assumed that all S&W .44 Magnum's measured .429". Earlier in the thread somebody pointed out that early M29's had a .432" throat dimension, but again I have no idea what my particular revolver measures. Accuracy was great with the .430" bullets, but leaded badly. I would need some pin gauges to accurately measure the throat diameter, and I don't have any currently. I have used gas checked lead bullets in the past at all types of speeds, and they always work great with no leading.

Jared
 
jphendren said:
"Did you ever measure you groove diameter?"

No, I have no idea what the barrel groove diameter is. ...
I have used gas checked lead bullets in the past at all types of speeds, and they always work great with no leading.

Jared
Click to expand...

Forget about throat diameters...it really doesn't matter as long as your groove diameter is less than your throat. How to check: Take a soft lead bullet or fishing sinker that is larger than your barrel and drive it down and out the barrel with a wooden dowel. Don't worry if it mushrooms in the back end as you force in down your barrel...just keep driving it and it will go. Take a set of calipers and measure the bullet (because Smiths have 5 grooves it is more difficult so be careful where you measure). You can usually catch the edge of one side of the groove on one side of the bullet and the opposite groove on the other side. That should give you your groove diameter. Now take that very same bullet and drop it into each chamber of your cylinder...it should either fall completely through or hang up with most of the bullet out of the front of the cylinder. You should be able to push it all the way through the cylinder with very little pressure by hand. That tells you your groove diameter is smaller than your throats. As long as you shoot bullets that are .001 or .002 larger than your groove diameter you should have no leading at the speeds you mentioned (assuming that your barrel is not the problem). Don't guess or generalize, each revolver is different and what works in one gun may not work in another of the exact same model...you must measure the grooves to be sure.

I hope this helps. BTW...using gas checks to fix a leading problem is only fixing the symptom, not the problem. You will get much better accuracy, etc by using the correct bullet in the first place.

Good luck.
 
Last edited:
Accuracy is in the throat diameters. Within reason the slug will go down the barrel. Bob at Penn Bullet can explain this. Also John Taffin has written articles about throat size. You can search online and find them.
 
There is some good advice here and some not so good. You should match the lead bullet diameter to the cylinder throat diameter. The lead bullet should be the same as the cylinder throat or .001 or maybe .002 greater. It should not be smaller!

You also need the cylinder throat diameter to be equal to or greater than the bore diameter. If this is not true it does not matter what you choose for a bullet diameter, it will still give you leading.

Anytime you put a smaller bullet into a larger hole, the hot, high pressure gases will force their way around the bullet and melt the lead leaving it in the barrel. What you are trying to accomplish is to keep the hot gas sealed behind the bullet if possible.

Most of the leading experienced in handguns does not come from driving the bullets too fast, it comes from escaping gas melting the lead into the barrel.

Ward
 
I see this is an older thread but FYI, my 29-2 and 629-3 chamber throats both measure 0.4310 (pin gauged). My M21 (modern) measures 0.4295.
 
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