Throat dia. and bullet dia.

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  • Last Post 05 April 2009
kolar55 posted this 24 March 2009

I have a couple questions about throat diameter, bore diameter, and bullet diameter. I'm just getting back into cast bullet shooting and needed a refresher so to speak, so I found this site one the web. Looked like the place to go for info and after some reading and research, I found out there is a lot to do with revolver accuracy that I didn't know before. All I was really looking for was how to determine what size mold and sizer to get for my Anaconda .44 mag. I'm not looking to hunt with it nor do any competition. And I certainly hadn't thought about going to the extremes like years ago with the benchrest rifles. I'm just looking for the proper size stuff so I can at least hit the paper-mostly at about 25 yds, maybe out to 50, etc,etc. Here are some numbers--the throats of the cylinder range from .4292-.4299 with 2 of them at .4295. I don't have any push through slugs so I poured a casting of the barrel about 1 1/2 inches long at the muzzle end with cerrosafe and it measured .4288.  2 different 240 gn. bullets I have on hand are .4295 avg and .4305 avg. Roundness is pretty good on these and they are very hard. Which of these bullets would be my best choice? Is .0007 range acceptable on the chambers? What mold dia. should I buy? And should I size to .429 or .430? Am thinking about the Lyman 429421 mold. Does anybody make a wadcutter mold in about 210 or 215 gn. I would think something like that would be a good target type bullet. They sure shoot good in my .357 mag.   Thanks  Lonnie

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RicinYakima posted this 24 March 2009

Lonnie,

I get this question often at the range when folks find out I am a cast bullet shooter. The simplest, easiest and best way to 95% of the best accuracy out of your bullet of choice is to make a dummy round of the bullet that you know the size of the front shoulder that sticks out of the case. With the cylinder pointed down, if a dummy falls into the chamber, the bullet is too small. If a dummy can not be pushed in easily with your thumb, it is too big. It is dependent upon hardness and size.

The Lyman 429421 is a great 44 bullet, but you don't know if a mould will make 0.429” or 0.433” castings. It is luck of the draw. I bought and sold several until I found one that casts 0.433” that I need for my S&W 624.

Ric

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runfiverun posted this 30 March 2009

take your cast bullets and drop them into each cylinder if they fall through...too small i would just load up about a dozen of each go shoot them the gun will tell you which will shoot and which won't. i have had cast bullets that were, “what should have been perfect” throat/bbl fit. that didn't shoot worth a darn. but the one that i thought i would just try “cause i had some done” shot the best and are now the regular ones for the gun.

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kolar55 posted this 30 March 2009

Well for the most part that's just what I did. Loaded some of each up and went out and shot them. Couldn't really tell the difference between the two with the smaller diameter looking like they might be a tad better. Wasn't really impressed with either though. Groups were around 1 3/4” at 25 yds. I remember them shooting better than that years ago though. . It was shooting two one hole groups with each cylinder full. So I tried the using only one chamber thingy and it was the same thing-two one hole groups. Hmmnph! Got a bit disgusted and put the whole schmear away. Then yesterday something hit me. I had chronographed these a couple weeks ago and they averaged about 1135 about ten ft' from the muzzle. Now I wonder if some of these were at or just above supersonic speed and some below causing the discrepency? I don't remember what the individual velocities were and didn't record them either. Normally I do. I may have to adjust the powder charge a bit and see what happens. Anybody got any thoughts on this for conversation?

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454PB posted this 31 March 2009

There's nothing wrong with 1 3/4” groups at 25 yards, and that can probably be improved with some “tweaking".

I doubt that being sub or supersonic has anything to do with your groups, but assuming you have some room to adjust the powder charge, try tuning the load up and down.

If you know another shooter, have him shoot your loads to see if the “shooter” is affecting the groups.

A friend once told me his Ruger Blackhawk .357 wouldn't keep 6 shots on a pie plate at 25 yards. I had him bring it over, I cleaned it, measured the throats and bore, then took some of my handloaded home cast boolits out to my 25 yard range. The first group was under 2” from a wrist rest. I then offered to buy this inaccurate gun, and he suddenly decided it was a keeper after all.

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CB posted this 31 March 2009

Lonnie, the 429215 mold drops at about 210gr, it is a GC bullet , but I have had good success with out GC's, been using it forever, if you want a liter bullet than the 429421. Bullet size is variable as you know,IMHO .002 over size works best for me. If you want a wadcutter mold in 44 you may have to a custom mold maker.

I think I saw a 44 WC on e-bay awhile back , but can't remember what flavor it was...Good Luck

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kolar55 posted this 31 March 2009

Thanks Guys. I was a little concerned about getting lube underneath the bullet in place of the gas check when sizing and lubricating with a lyman 4500. Is that a problem? I guess I'll find out when my 429215 gets here. As to playing around with the powder charge on these 240 SWC's, I think I'm going to do just that as soon as I get a good day again. This time I will pay a little more attention to and record the velocities etc. The weather is being kind of a pain. Probably should have done it yesterday instead of alloying. Which brings me to another question. I have a mix of range lead and Linotype water cooled that shows 20bHN on an LBT tester after 7 days. Is this a little too hard or about right. These all will be run through handguns and lubed with White label 50/50.

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runfiverun posted this 31 March 2009

that is a bit too hard for my tastes. especially if they are too small. if you had a 429 bbl and 430 throats and a 430 boolit i don't think hard is a problem. but if things are wrong and your load is too light you will have accuracy issues. i push plain based nominal weight boolits to 1600 with no problems at a bhn of 10-12.

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kolar55 posted this 31 March 2009

Thanks Run. I was thinking that might be a bit too hard and not being able to seal the bore, chambers or whatever and getting gas slipping by. I'll just have to experiment with this I guess. I've had some leading issues but everything I have shot through this thing has been bevel base. I'm not much of a fan of bevel base boolits. They were about 13BHN, 240gn SWC, ahead of 9.0 Unique for about 1135 fps. I wouldn't expect them to lead the bore. However I recently JB'd the S$%$ out of it and the last 50 rounds left it pretty clean. So maybe there was something built up in it from years ago. Who knows. That's what I get for being away from this for so long.

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mtgrs737 posted this 01 April 2009

The rule of thumb is .001” or greater over actual groove dia. I personaly like .002” but don't always get it as the mould must drop the slug oversized. In your situation the cylinder throats will be the limiting factor, they must be .001” over groove size or .4298 minimum. You may need to have the throats reemed to .431” if you can find someone with the proper reamer. I have had three cylinders done by the cylinder smith at http://www.cylindersmith.com>http://www.cylindersmith.com with sadisfing results. Good luck and enjoy a fun hobby!

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kolar55 posted this 01 April 2009

Wow! Thanks for the info. I was thinking .430 sizer would be about right. I think my bullets are going to be a bit on the hard side. I've got some test ingots (about 3/8” thick) that were water cooled and some air cooled laying here. They need a couple more days before checking hardness again to see where the end up. It will probably be a week before I have time to cast some and do a little testing. Right now all I have is a .429 sizer. The mold should be here in a couple days.

In a couple weeks my time will become very limited. Planting season is approaching soon.  Thanks again to all. You have been very helpful.

Lonnie

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kolar55 posted this 05 April 2009

Well, the mold came and I made a batch of bullets. Sized and lubed them and couldn't wait any longer. Worked up some loads with three powders and tried them Saturday afternoon. I thought I might as well try them at .429 and they seemed to shoot pretty good. W-W 231 came in the best with two of the loads giving only 14 and 17 FPS spread. This was only for 5 shots and may or may not be accurate. However the others varied WAY more than that. These two groups were the best also. One was Right about 1 1/8” and the other went about .920". Unique had two at 1 1/8". Bullseye didn't fare quite as well. Of the ten groups fired only one was over 2” and the others in the 1 3/8"-1 5/8"range. 2x Leupold at 25 yds. off a somewhat flimsy plastic rest. (That needs replacing!!!) I also think I have uncovered the leading problem. There is a loose spot in the bore about 3/4"-1” from the forcing cone. The rest of the barrel is glass smooth-even the part between the forcing cone and the loose spot.  I'm pretty happy with the accuracy but wish the leading wasn't there.

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