Throat Size of M29

[ColColt]

I slugged my M29's throats and came out with a diameter of .432"...not good with a .429 groove diameter. My 429432 mold will drop a BHN11-12 alloy at .430-.432" depending on which band you measure or where you measure around it(it varies). If I beagle it with the .004" tape I have that still won't help as the largest size die Lyman carries that I've got is .431-still a bit undersized. I'm opened to suggestions. I ordered some plug gauges but of course got an email they were back ordered till the middle of next month from Grizzly so I decided to run a soft lead slug through the throat and this was my find.

[cbrick]

.432" throats that are uniform with a .429" groove diameter isn't all the bad. Far better than the other way around for both leading and accuracy.

A sizer die can be honed out, lot's of threads here on how to that. If your brave enough (I am not) you can also re-work the mold. I have several molds that cast too small for the firearm I intended the bullet for, being a coward when it comes to removing metal from a mold and having none of the machine tools to do it right I ship them off to Erik Ohlen and simply tell him what I want the driving bands to cast at. Works like a charm and his prices are reasonable. Plus you then have a mold that casts right to your firearms preferance.

Hollow Point Bullet Mold Service (http://www.hollowpointmold.com/)

Edit to add: The last RCBS two cav I got back from Erik cast round within .0003" on all 6 bands and this bullet no longer leads my 624 cause its now big enough to fit properly.

Rick

[Catshooter]

Pin gauges are very over rated. If the hole you put the pin gauge into is round, and if the hole's finish is as good or better than that of the gauge, you still can't get a .432 gauge into a .432 hole. Even a .4315 hole is pretty iffy.

Actually, your throat/bore relationship isn't bad at all. The trouble would be the mould. I'd Beagle it. Then I would hone my sizer die until it's big enough. Sandpaper wrapped around a steel rod inside the die will do it. Doesn't take all that long either.

That's my suggestion for ya! Good luck.


Cat

[MtGun44]

How would you claim to have this expertise in the accuracy of pin gages? In my experience,
minus gages seem to pretty accurately reflect what you get from slugging a throat, assuming
you clean the cyl very well and have no burrs on the front edge, which I have found in single
action guns from the ejector hitting just at the edge of the throat.

Bill

[ColColt]

I'm a bit chicken to try and mess with a mold myself. Beagling I'd try but not anything to alter the cavity. I'm wondering if honing the size die would be of great benefit in that from what I thought, the inside is hardened and seems honing it out would change the temper a little...don't know if that matters when it comes to sizing lead bullets or not. I did a little research and one fellow made this comment about it....

"If you hone the LYMAN/RCBS style dies very much, the lube will leak around the plunger(?) that goes up and down in the die...especially if you put a lot of pressure on the lube."

That makes sense but I don't know how far it would be until you had that problem. Maybe .002 or .003" or more?

Catshooter-I have to assume the holes are round-that's all I can go by as for using the gauges. They'd better be round after spending $75 on them gauges! BTW what grade of sandpaper are you talking about? 600 grit or maybe 800?

I could leave the bullets unsized as they do mike at .432"(most places) but getting lube in the groove is another thing. You'd have to run it through a die to lube the grease groove(I'm not into pan lubing) and as mentioned the largest die I have is .431". I don't know. Several avenues to take here. I guess I could start with trying to beagle the mold. Unless I don't resize, whatever bullet it will yield at that point I'm still going to have a .431" bullet for a .432" throat unless I go the honing method on the size die.

[462]

Beagling is easy to do and reversible.

Hand honing a sizing die isn't going to change its temper...it's won't get hot enough. It will take a fair amount of time, however. I start with 400-grit wet/dry, switch to 600 when approaching the desired size, and polish with 1200. Oil the paper.

Or, send Buckshot a PM...he'll make any non-catalogued size you need.

[cbrick]

ColColt, you didn't mention if the pin gauge set you ordered were "minus" or "plus". Check on your order and see, if they are the "plus" set and on backorder you should have no problem cancelling and ordering a "minus" set. You do want the minus set for throats.

Perhaps this is where Catshooter got the erroneous notion that pin gauges "quote: are very over rated". I'm with Bill "quote: minus gages seem to pretty accurately reflect what you get from slugging a throat".

My "minus" pin gauge set quite accurately has checked the throats of many a revolver.

Rick

[geargnasher]

M629 Silhouette model I worked with a while back had .4315" throats and a .4290"groove measured on the corners of the five-groove slug. I honed a .429" H&I set to .4313" and it shoots almost 2moa at 100 yards with the right hardness of boolits. I'd say no problem, just beagle the mould and hone the sizer. If that doesn't work, get Tom at Accurate Molds to make you a mould of your design, or one of his catalogued designs, in the material of your choice and the diameter of your choice with the alloy you specify.

Gear

[ColColt]

Beagling is easy to do and reversible.

Hand honing a sizing die isn't going to change its temper...it's won't get hot enough. It will take a fair amount of time, however. I start with 400-grit wet/dry, switch to 600 when approaching the desired size, and polish with 1200. Oil the paper.

Or, send Buckshot a PM...he'll make any non-catalogued size you need.

Thanks for that info. I think I"ve got some 600 but will have to get the rest.

It was the minus set I bought. I don't know who would need 250 of these things but that's the way they come.

http://www.grizzly.com/products/Steel-Plug-Gauge-Set-250-pc-Minus/G9794


I'd say no problem, just beagle the mould and hone the sizer.

Looks like there's no way out but to do that other than order a custom mold. I now know why many years ago my 4" M29 wouldn't shoot as good as I thought it should. I didn't get into all this about throat diameter back then and no telling what the differences were between the groove diameter and throats of that one. I remember just sizing the bullets to .429", lubing and then shooting them. That was the size die I was told to get and blindly followed that advice.

I'm off to the range in the morning to try out this new beauty but with .430" bullets I'll probably get some leading. It'll still be fun to shoot and afterwards, Chore Boy to the rescue.

[fredj338]

How would you claim to have this expertise in the accuracy of pin gages? In my experience,
minus gages seem to pretty accurately reflect what you get from slugging a throat, assuming
you clean the cyl very well and have no burrs on the front edge, which I have found in single
action guns from the ejector hitting just at the edge of the throat.

Bill
Seriously true. My good friend is a machinist, he uses pin gages all the time for lapping IDs on mat'l. He does my cyl throats & sizing dies for me when I need it, nice guy to have around.
I would size the bullet to 0.432 & shoot em. Over size cyl throat on some smiths are a real PITA to get good accuracy with. You can probably get Lathsmith to open the die up if you don't want to do it.

[GLL]

Take a look at on-line industrial auctions. I picked up this nice Meyer "minus" set (Made in USA)for under $25 because someone had spilled marking dye on a couple of the pins. It washed right off with acetone !

If you only need a few, Meyer sells individual replacement pin gauges.

Jerry

http://www.fototime.com/6B38557F6AEEE8D/standard.jpg

[ColColt]

I never find deals like that. I looked on ebay and they were wanting much more than the price I got mine from Grizzly.

[ColColt]

I posted this on another forum but didn't get any response so I thought I'd post it here. I took the the M29-3 to the range this morning and was surprised at the groups despite the fact the 250 gr boolits weren't the exact throat diameter. I had made about 100 from a mix of BHN12 alloy and the only sizer I had would only bring them to .430" and the throat diameter is .432".

It looks like I'll need to beagle the mold and I've just gotten the largest sizer Lyman has which is a .431". The surprise came when the groups I had were averaging 1 1/2" at 10-15 yards. This was a conglomerate of 11 gr of HS-6, 10 gr of Unique and 8 gr of Universal and of course I had to load up about 10 20 gr of 2400 which gave an 1 1/4" group at ten yards. All these were from the 429421 mold which drops them at on average, 248 gr.

Oddly enough, the leading I got was primarily just into the rifling about 1/2" past the forcing cone. Another surprise came when my last string was with the 20 gr of 2400 load with the same bullet. It actually seemed to clean up 99% of the small amount of leading at the area just into the rifling but did show small traces of leading toward the muzzle instead. Perhaps that clean up was due to it sealing the bore better...just a guess. None of this leading was great and a few swipes with Hoppe's followed by a brush cleaned up most of it.

I still think I should more closely get the sized boolit to the throat diameter of .432" despite the small amount of leading and the great grouping. I'm going to try beagling the mold tomorrow with some .004" tape I have and see what size that produces.If that fails, I'm going to send the mold to Erik to perform his magic on. I'm still curious as to why the good groups with an undersized boolit and particularly how/why the hotter 20 gr of 2400 cleaned up the leading left just ahead of the forcing cone...most interesting. It was like iI shot a few jacketed bullets instead of lead ones.

Another surprise was the 11 gr of HS-6 load. I loaded 15 of those and wondered if I needed magnum primers and decided to load ten of those as well. I could feel a difference in felt recoil with the same powder and charge with the magnum primer (CCI 350). It was like I increased the charge a few grains. Any ideas on that? Maybe it was my imagination.

[fredj338]

Magnum primers w/ certain powders can indeed bump vel, sometimes quite a bit. I see this w/ AA#9 in the 357sig. It can increase pressures which, all things beoing equal, often increases vel. Add'l. vel will increase recoil.

[Catshooter]

First off I make no claim of being an expert.

However, I used to use pin gauges, then got yelled at by a real machinist.

Most throat are finished well, and of course so are most all pin gauges. Pin gauges are centerless ground and it's a good bet they're round.

But the throats, are they round? Maybe, maybe not. If you start using snap gauges with a good mic you find out that some are and some aren't. They all should be, but then we shouldn't have to measure them, they should be right too.

If the throat isn't round a pin gauge will only measure the smallest diameter.

Maybe I'm just being anal and a pin gauge will be close enough. YMMV.


Cat

[ColColt]

I tried my smallest telescoping gauge and just didn't feel comfortable with that method as I kept getting a slightly different measurement depending on my dexterity. What I mean is if you release the end of the gauge to let the two little...whatever they're called, snap out to contact the throat, and if you tilt it a little this way or that you may get a different measurement one time then another. I did use a relatively pure lead slug I made by putting a small amount inside a 45 ACP brass case and heating it up with a butane until it melted. I let it cool a long time and got it out to slug the "chosen" throat with and miked it at .432". I just wanted to be sure with the plug gauges to see if my findings are true.

[Buckshot]

............Might be usefull to some shooters for measuring bores, throats, and other things is ball guages. I find them a bit easier to manipulate then telescoping guages. Some finesse IS required then with a mic in getting consistent readings, even if the mic has a friction thimble, which some people curse. All that aside, don't let yourself get all tangled up in chasing tenths around. If the revolter's chamber mouth is checking .4317" to .4322" in various places, I'd call it .432" and be happy:grin: Part is technique in using the guage and mic, part will be actual machine work.

Tenths in boolit OD are easy to loose and gain without even being aware you're doing it. Few moulds are that round. A non drastic change in alloy, alloy temp, mould temp, alloy height in the pot (bottom pour), letting or not letting the alloy flow a bit after the cavity fills, and how tightly you hold the blocks closed can easily cause tenths to disappear and reappear in as cast boolit ODs. I have an old model Ruger Vaquero 45 Colt. Best I can figure the groove is .451" and the chamber mouths are .451". I size the slugs .452" and pretty good results with it.

...............Buckshot

[cbrick]

Absolutely Mr. Buckshot. Tenths mean nothing, a change in the temp of the day can cause a few tenths difference in bullet diameter.

Same with alloy BHN, if your alloy checks at 12 today and your next pot full checks 11 you'll never notice the difference. Wide variations in BHN will make a difference just like a much wider variation in diameter will make a difference. A few tenths . . . Never.

Rick

[MtGun44]

Catshooter - I agree that you only measure the smallest diameter, no doubt that this is
correct. However, my experience with snap gages is that I need to spend 2-3 minutes making
4 or 5 different measurements to get self consistentent results, and that I need three hands,
one for the gun, one for the gage and one to twist the lock :-) With a pin gage set, I can
get the "nearest .001" in 20 seconds or less. I think Buckshot makes an excellent point that
chasing anything less than .001 gets you into a tail chase. On the one hand we have folks
using a ".001 marked" caliper (which my tool and die maker friend says cannot be trusted
to closer than +/- .002") to slug barrels and directly measure throats, and criticize their
sizing die diameters. On the other hand, some folks start trying to make something useful
out of the difference between fitting a boolit at .4322 and .4319. Like Buckshot, I can
use ball gages MUCH better than snap - required hand count matches actual inventory ;-)

0.001" is a VERY small distance. Needing to measure 10 times closer is starting to get out
into science fiction, in my experience. It gets VERY hard to actually, intentionally, and
repeatably work to 0.0001". Ask one of our sizer die makers here what they would
charge you to make a die to put out boolits that are .4322", dead on? My bet is that
they would either reject the commision or charge 5-7X because they would need to
account for throwing away 3-4 units that they got to .4324 or something before they
caught it. Do we (as skilled casters) need to have micrometers that measure to .0001"?
YES, but mostly so that we can be essentially certain that we are accurate to the .001"
level, not so much to actually try to be accurate to the .0001" level.

So - yes, no doubt that some throats may be out of round a bit. I think that the reduced
dependence on operator skill to get repeatable results by using pin gages is more useful
than the possibility that I might only be seeing the smaller diameter of an oval hole.

Another point - pin gages are "digital" - in the sense that, like a digital scale, they can
only tell you to the nearest .001 (readout digit) and have no analog ability to register
"in between" measurements. I think that this is useful for simplicity's sake.

I am not saying that your method is not a good one - for you. I don't have quite enough
patience to do the snap gages, or enough concern for the (assumed) small out of round
for the typical revolver throat. Carry on, sir - your measurement skills and interest in level
of measurement accuracy exceed mine.

Bill

[redneckdan]

0.001" is a VERY small distance. Needing to measure 10 times closer is starting to get out
into science fiction, in my experience. It gets VERY hard to actually, intentionally, and
repeatably work to 0.0001". Ask one of our sizer die makers here what they would
charge you to make a die to put out boolits that are .4322", dead on? My bet is that
they would either reject the commision or charge 5-7X because they would need to
account for throwing away 3-4 units that they got to .4324 or something before they
caught it. Do we (as skilled casters) need to have micrometers that measure to .0001"?
YES, but mostly so that we can be essentially certain that we are accurate to the .001"
level, not so much to actually try to be accurate to the .0001" level.

Bill


Your post reminds me of a time I was working for a professor here in is side company that did machine tooling research. All the prints were to 4 decimal places, the tools measured to 5. Tolerances were in the neighborhood of half thou to a thou. All these tools were to be made with off the shelf sandvik tooling and a well worn Clausing/Colchester MultiTurn 2000. I spent over a week chasing numbers on this one part. I'd set up the tooling offsets, machine a part and verify the dimensions. The do the math to adjust the offsets. Then machine a small batch and take them to the doc to have him verify the setup before I turned more parts. Well, the shop in the summer is darn near 100 degrees and he kept his office refrigerated, I literally kept a parka near the door to his office for when I had to go in there. By the time he measured them the parts would have adjusted and the dimensions changed. They were mostly still in spec but they settled all to the one side and he wanted to know why I set the machine up that way in stead of hitting the middle of the spec. That was the longest summer of my life...spent chasing decimals.

[ColColt]

I decided to try my hand at beagling today. I had put the tape on last night and was ready to go. Once the pot got up to temp and the mold was fairly hot, I knocked out about 35 or so before it started casting good. Not long after this on side of the tape came loose and I had to stop and wait till that side of the mold was cool enough and took it off and put on another piece. It remained there throughout the session which was about two hours.

I waited awhile to let everything cool down and miked one of my first ones and what a difference. Before they were dropping straight from the mold on average about 430-.431" at best. Today they miked at .432-.435" depending on where you miked it. There were some fins here and there but not bad at all and this wasn't alll the time with every bullet. I suppose it's inevitable that I'll have to have a die made but I'm wondering once sized to .432" and that bullet hits the rifling it's going to have to size down from .432 to .429". Is that too much of a swage? I was thinking perhaps .002" was considered about max they should be sized down going from throat to rifling.

[462]

Now, wasn't that easy?

1. If the tape comes loose, again, just close the mould on it or press it back in place with a gloved hand or cotton towel. That should suffice to hold it in place...no need to halt the casting process.

2. The intermittent finning you are experiencing may be due inconsistant pressure on the handles.

3. A mould, properly pre-heated on a hotplate, will produce keepers on the first cast.

[Char-Gar]

Cylinder throats of .432 - .433 with barrels of .429 - .430 were normal for many years in Smith and Wesson sixguns. They managed to deliver sterling accuracy with cast bullets for generations.

Of late, attitudes seem to have changed on this matter. Folks have sorta gone to seed on the notion that the numbers have to match to have a pistol worth owning.

I just have to wonder how so many generations of target shooter, hunters and outdoorsmen managed to hit anything they shot at.

[ColColt]

Now, wasn't that easy?

1. If the tape comes loose, again, just close the mould on it or press it back in place with a gloved hand or cotton towel. That should suffice to hold it in place...no need to halt the casting process.

2. The intermittent finning you are experiencing may be due inconsistant pressure on the handles.

3. A mould, properly pre-heated on a hotplate, will produce keepers on the first cast.

The tape migrated to the outside of the mold and I tried to push it back with a small screwdriver being careful as not to actually touch the mold with it but it crumpled and I figured I'd need to just make another piece as perhaps it wouldn't stay in place. I hope this will last a few casting sessions without having to be replaced.

I have to wonder with all this preparation into making a proper size boolit how we ever got along with jacketed boolits since none of them, in case of the 44 caliber, are going to be .431, .432, etc., but most all are .429". If the throats are .432" I guess it doesn't matter with jacketed boolits-they're still going to hit a .429" rifling.


Cylinder throats of .432 - .433 with barrels of .429 - .430 were normal for many years in Smith and Wesson sixguns. They managed to deliver sterling accuracy with cast bullets for generations.


I hear what you're saying. I believe today we're trying to get this down to miniscule amounts of this and that and worry about dimensions and alloys all too much in comparison with those that were before us...sign of the times.

[MtGun44]

Depends on what level of accuracy you choose to try for. Many folks were and are pleased
to shoot a 3-4" group at 15 yds, and call it an accurate gun and load.

Others want to shoot 1" at 25 yds or 2" a 50 yds, or some want 2" at 100 yds with a pistol.

As we seek tighter and tighter groups, the need for precision in the dimensions of the
gun and the dimensions and design of the boolit, lube type, powder, brass, crimp, etc
all become critical variables.

Mandatory to have a useful tool? Of course not. Fun to fiddle with to try for a very high
degree of accuracy if you are a hobbyist? Yep. You can sure kill a deer or protect yourself
with a lot worse than 2" at 25 yds, but it can be fun to fiddle with it.

Bill

[Catshooter]

Well, I guess I'd better just break out my pin gauges! :)

You're right, a tenth isn't important here. And the pin gauges are much easier & quicker.


Cat

[Mal Paso]

I am using a recent Lyman .430 Die to get .431. Whether lead springback or die streaching it seems to be the rule from .428 through .431 Dies. ( Water dropped 94/4/2 Alloy )

SAAMI Specification for 44 Mag Throats is .4325.

[MtGun44]

INTERESTING! I have never looked at the SAAMI drawing for a .44 mag chamber.

Is .4325 max allowable or the nominal?

Bill

[geargnasher]

Depends on what level of accuracy you choose to try for. Many folks were and are pleased
to shoot a 3-4" group at 15 yds, and call it an accurate gun and load.

Others want to shoot 1" at 25 yds or 2" a 50 yds, or some want 2" at 100 yds with a pistol.

As we seek tighter and tighter groups, the need for precision in the dimensions of the
gun and the dimensions and design of the boolit, lube type, powder, brass, crimp, etc
all become critical variables.

Mandatory to have a useful tool? Of course not. Fun to fiddle with to try for a very high
degree of accuracy if you are a hobbyist? Yep. You can sure kill a deer or protect yourself
with a lot worse than 2" at 25 yds, but it can be fun to fiddle with it.

Bill

Amen. I have personally eeked several fine 2" groups out of one at 100 yards many more in the 3-4" area, just to prove to myself that it was possible and that I could shoot that well from bags. Really, I learned that I can't regularly shoot as well as that gun can, even on a perfect day. My trigger control and eyes (even with a quality red dot sight) just aren't as good as the gun and load proved to be. If it's going 2" at 25, I'll bet it can do a lot better, but only if you think it needs to.

Gear

[ColColt]

I'd be tickled pink to get 3" groups at 25 yards...from a pistol rest, of course. If I can get that at 15 yards I'm content using my own cast boolits. As yet, I haven't fired any jacketed boolits through my M29 and probably won't. I am considering, however, reaming the forcing cone to 11 degrees which is preferable if you're using primarily lead boolits. That should aid in the accuracy department along with the proper size boolits.

[geargnasher]

I was just trying to provide a little perspective here. 44man really opened my eyes a couple of years ago when he told me that 25-yard groups were useless indicators of accuracy. Whil I don't necessarily believe that is true in all instances, it served to show me what CAN be done, and that you never really know how a load is doing until you check it further downrange, where you might find it tumbles or keyholes, who knows. I had come to expect 3" groups at 25 yards were about normal with most revolvers. Now, I have my wife's Model 36 Chief's Special shooting into three inches at 25 yards with it's 1.6" barrel.

Gear

[Mal Paso]

INTERESTING! I have never looked at the SAAMI drawing for a .44 mag chamber.

Is .4325 max allowable or the nominal?

Bill

I believe that's the Standard but here's the link http://www.saami.org/PubResources/CC_Drawings/C%20and%20C%20Dwgs%20-%20TOC%20-%20Pistol.pdf

I looked it up in the process of throating 2 44s. I cut mine .4312 with a Manson Reamer.

Both guns were late models. I'm sure the narrow throats of later years was to improve the performance of jacketed bullets.