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40-82 hiker
03-29-2016, 12:45 AM
I need a little help to go to the next step, which is to order my mold.

I have never used a chamber cast to spec a new mold, but I have been reading about doing just that for some time on this forum. However, my chamber cast has revealed some info which is confusing the issue more than I can figure out with my limited knowledge.

My first sulfur chamber cast this morning.

http://castboolits.gunloads.com/attachment.php?attachmentid=164797&d=1459224468

rifle: Mark X 30-06 factory barrel
caliber: 30-06

Following measurements were made with a gunsmiths micrometer, but I took the measurements (experienced using one).
Grove diameter: 0.308 (some measurements 0.3075)
bore diameter: 0.300 (some 0.299)
Throat diameter: 0.314 right at the start of the throat, tapering to 0.308 approximately 0.225" to 0.25" from the start of the mouth

Following measurements were made with my dial caliper:
The distance from the start of the throat to the start of the lands different for all four lands:
0.175", 0.198", 0.255", and 0.223"

I used this rifle solely for deer hunting years ago, and was satisfied with its accuracy for such. Since it has been sitting fallow for so long I now want to use it for shooting reduced loads (Bullseye, 1000 to 1250 fps range, 170 gr. bb boolit, COWW), and now need to buy a mold for it. I am not asking about loads, as I am comfortable with where I want to start based on much research on CB. My questions, given the aforementioned measurements are:

1) The throat is so big to start with, and given its large diameter (0.314"), it seems to me a cast boolit of 0.314" would be too large with the bore size I have (0.308"). Would 0.312" be too large given the groove diameter of 0.308"?

2) The throat seems very irregular with the start of the lands. Should I get the throat evened up before I do anything else? Never cast a chamber before, so I just don't know if this is going to real detrimental or not. Guess I could just get the mold and start casting...

3) Would there still be an advantage to a bore riding boolit at velocities around 1100 fps?

4) Do I need to take into account for any shrinkage of the cast? I have found many references saying I do not, but I found one article on LASC's website in which the author said there is shrinkage. ??

Too tired and hurtin' too much to think this through anymore for the moment. I hope I have enough info listed. Just not sure to what to do because of that crazy throat (or maybe it is not so crazy?). Your help is greatly appreciated.

Thanks,
Bob

swamp
03-29-2016, 01:47 AM
Bob,
No help with your questions, but your cast is very nice.
swamp

Walter Laich
03-29-2016, 07:33 AM
Bob,
No help with your questions, but your cast is very nice.
swamp

same thoughts here--that is a first rate one. I've seen some that looked like they were made out of peanut butter...that had been stepped on.

good luck with your endeavor

40-82 hiker
03-29-2016, 09:34 AM
Bob,
No help with your questions, but your cast is very nice.
swamp

Thanks for the compliments Swamp and Walter. Swamp, you suggested a pound cast would be better, and I intended to do just that. However, it started taking on properties I did not want to pursue yesterday and the sulfur cast just seemed easier to do at the time. I'm glad I did do the sulfur cast now, as I've been staring at that bag of sulfur for far too long! [smilie=l: It worked out much better than I thought it would going into it.

runfiverun
03-29-2016, 09:50 AM
what I'm seeing here is that your barrel is mostly straight but the chamber has been cut a little crooked.
and you have a fairly long tapering lead without much of a ball seat area.
your cast demands are not very strenuous in fact they are on the verge of too slow for good stabilization.
personally I would look at 2 different molds 311284 it has some good drive bands that can fill out that throat.
and a 170gr tapered Loverign design which was made for throats just like this one.
seat them both out into that throat as far as you can get 100% feeding from the magazine, and still close the bolt easily and go at it.

guicksylver
03-29-2016, 10:39 AM
WELLLLL....fIRST OF ALL I WOULD BE HAPPY WITH MAKING SUCH A GREAT CAST.

Secondly, too much information can befuddle us (me).

Thirdly, Riverrun made an excellent suggestion, I would start with the Saeco 315 or NOE clone the 311 175 FN boolit.
I would try some sized 311 then move on to 312 and maybe even 313, with 18 grs of 2400 you should get some really fine groups.

Why do I say this ?

Because I have a minty 1917 with an original barrel , the bore is very close to .30, the groves are cut to .311 (starting to sound familiar?).
The bullet cast .312, I sized them .313, how do they shoot, well how's sub MOA @ 100 yds with iron sights sound?

In this game what works works , what should work not so much.

That's the art and magic part of cast boolit shooting.

Don't let conventional wisdom spoil the day, the target will tell you far more than you realize.

Seriously you can't go wrong with that boolit, it will work one way or another, trust me I am not a politician.

164803164809

40-82 hiker
03-29-2016, 10:41 AM
Thanks runfiverun.


what I'm seeing here is that your barrel is mostly straight but the chamber has been cut a little crooked.
and you have a fairly long tapering lead without much of a ball seat area.

Ouch!


your cast demands are not very strenuous in fact they are on the verge of too slow for good stabilization.

I'll keep this in mind when working up loads. Argument of choosing the shorter/lighter boolit?


personally I would look at 2 different molds 311284 it has some good drive bands that can fill out that throat.
and a 170gr tapered Loverign design which was made for throats just like this one.
seat them both out into that throat as far as you can get 100% feeding from the magazine, and still close the bolt easily and go at it.

Just did some research, and 311041 seems to be a popular boolit for this purpose. Due to the large diameter of the throat I guess I'll be getting a custom mold (?). Tom has one that is "based" on 311041 (31-170JG), which is a GC. Would it be good to keep the GC base, or would I be okay/better to get a BB since I'm not going to be using GCs?

What diameter would you suggest? .314 sounds too big, so .312? A suggestion would be appreciated as I'm out of my league at this point. My mold requirements have always been easier than this one.

40-82 hiker
03-29-2016, 10:47 AM
WELLLLL....fIRST OF ALL I WOULD BE HAPPY WITH MAKING SUCH A GREAT CAST.

Secondly, too much information can befuddle us (me).

Thirdly, Riverrun made an excellent suggestion, I would start with the Saeco 315 or NOE clone the 311 175 FN boolit.
I would try some sized 311 then move on to 312 and maybe even 313, with 18 grs of 2400 you should get some really fine groups.

Why do I say this ?

Because I have a minty 1917 with an original barrel , the bore is very close to .30, the groves are cut to .311 (starting to sound familiar?).
The bullet cast .312, I sized them .313, how do they shoot, well how's sub MOA @ 100 yds with iron sights sound?

In this game what works works , what should work not so much.

That's the art and magic part of cast boolit shooting.

Don't let conventional wisdom spoil the day, the target will tell you far more than you realize.

Seriously you can't go wrong with that boolit, it will work one way or another, trust me I am not a politician.

164803164809

Thanks quicksylver! I'm getting the gist of this situation now. This is an incredible site! Just yesterday morning I knew nothing about that rifle regarding cast boolit choices for it.

Great combo you came up with for your rifle. Geez! I'll look into these other molds you listed. Thanks.

40-82 hiker
03-29-2016, 12:44 PM
Just want to make sure this IS a the Loverign design suggested. ?? It is Tom's version of the 311041, and I would order it sized to drop .314 or .313 with COWW and 2% tin (with BB), so I could size between .311 and .313 per suggestions.


Accurate mold #31-170JG
http://castboolits.gunloads.com/attachment.php?attachmentid=164816&d=1459269620

I was looking at the Saeco 315 and NOE clone and will think along that line as well. Just wanting to confirm Tom's design is consistent with what was suggested.

Thanks again for the help.

guicksylver
03-29-2016, 02:18 PM
Nope... this one http://noebulletmolds.com/NV_new/product_info.php?products_id=1184

It works in all my '06's, two groove , four groove, new ,old it doesn't care.

164844

Two groove A4 clone, 100 yds

rwadley
03-29-2016, 03:40 PM
I have a Mark X 30-06. When I slugged it a while back, the groove was 0.3095 and the bore was around 0.302. While grooves and bore dimensions may vary, I think you have a little bit of shrinkage. From what I read, you may have 0.002-0.003" of shrinkage when doing a sulfur cast on 31 caliber rifles. http://www.allaboutenfields.co.nz/links-resouces/reloading/how-to-make-a-sulphur-chamber-cast/

guicksylver
03-29-2016, 04:14 PM
Hiker...If you are looking for an inexpensive mold for your MK x a great start would be LEE's 312 155 2r,
it shoots as good as anything with 18 grs 2400, more importantly it has a .302 + nose and can be sized from .310 to .313.

Time to quit talking and start shooting:bigsmyl2:.

As I said Mr. Target will tell you a lot about your barrel.

BTW , I would suggest a boolit with at least a .302-.304 nose.

This was shot with a well worn 4 groove 1903 , hence the .312 dia. boolit and seating depth.

164859

runfiverun
03-29-2016, 06:01 PM
quicksylver is making some very good suggestions.

my 1917 did not like the 311041 and I measured and bought the mold just for it.
it did not like it.
however my 03A3 shoots those same rounds [leftover from the 1917] into very respectable 1-1/2" groups and I have never looked back or at another load for that rifle.

the 284 is similar to the 041 but is just enough different in drive band length to work better for me.
I would for sure look at that mold in post number-10 it is a very, very good Loverign design
and would be hard to beat in any rifle with a longer throat.
if your dead set on shooting in the 11-1200 fps area then I wouldn't get a gas checked mold or I'd specify the mold as a plain base if I were having it cut.
if I might shoot faster later [IF? I'm always looking to go faster with boolits] then I'd specify a half and half 4 cavity and just cast with 2 of the cavity's.

40-82 hiker
03-30-2016, 12:06 AM
Thanks to all! I've got a lot of really great information to use now.

It looks like the Saeco 315 style boolit is a great suggestion. With my back/pelvis issues nothing happens very quickly, so it will be a little while before I'm shooting boolits out of my rifle. But, I hope the mold is ordered in a number of days.

However, first I want to resolve the dimensions of the cast. This is for my education as well as a tool to order the mold. I've heard much about chamber casting using sulfur, but there appears to be conflicting information about such on CB and other sites as well. The LASC article states -.001". I've read a number of references that state no shrinkage. rwadley states (based on his referenced article) -.002 to -.003. This is a point I would like to clear up, for myself as well as others. No problem, just the way I like to learn. Think I'll start with a bore slug to compare with the cast (I'll drive one in only as far as the cast goes into the barrel, then another all the way through).

I'll be shooting my rifle before long, that is for sure. However, this experience shows me proof positive how valuable a cast of the throat can be. I'm sold! Don't think I will ever order a mold in the future without casting the chamber at the very least.

leadman
03-30-2016, 02:26 AM
Go to the section on boolit swapping and get some samples from members to try. The 311041 would not be my first choice in that chamber, something like the 311299 or 314299 would be what I would load first. I also would start at .309" and go up if needed.

runfiverun
03-30-2016, 11:23 AM
if the casting doesn't shrink it won't come back out of the gun.
how much sulpher shrinks I dunno, but I would be inclined to take the information from the LAHSC site as good.

guicksylver
03-30-2016, 11:01 PM
+2 on leadman.

No way with the 041 or 41 same bullet.

313299 or 314 anything, easy to size down , sizing up is hard.

Plus you get the bigger nose a good thing.

40-82 hiker
03-30-2016, 11:29 PM
Not ignoring you all. Physical therapy today and reacted poorly to it. PT twice a week forever and some days are pretty rough. Tomorrow...

I am very grateful for all the help you all are giving on this project. Very!

Thanks,
Bob

runfiverun
03-31-2016, 01:41 AM
heck were great at spending money.
sometimes we even use our own :lol:
anyway the best way to make your decision is to measure that throat area along it's length then look at the pictures and measurements they show.
then compare the measurements on the drawings to yours and come up with the least amount of air space between the barrel and the boolit.
the closest one is gonna be your best fit [mechanical fit] when the boolit stats moving forward and engaging the rifling and such it needs a place for the excess lead to flow [the least amount the better] this is when the static fitment comes into play and where a flexible alloy is going to help.
the trick is to balance the forward movement and flow of the lead with how it grabs the rifling and holds on to it under pressure.

40-82 hiker
04-03-2016, 09:11 PM
I'm back in business, at least to a certain extent.

1) KCSO was very kind to look up sulfur chamber cast info in an old Dixie catalog:

measurement is -0.003 at 48 hours, but mix 1/2 Tbl powdered graphite with 1/4 cup sulfur and the shrinkage is -0.0015 to -0.0017 at 48 hours. I was looking for confirmation with rwadley's referenced article, and this finally means TWO sources saying the same thing. However, now I have a "formula" for mixing the graphite.

2) I'm going to get some lamp black or some other source of graphite and recast my chamber. The experience can't hurt anyway.

3) I'm leaning towards getting a mold from Tom that will have four cavities, two of which will be a 315 clone, and two will be another, which I have not decided on at this time. Both will have a PB, as I will not be bumping velocities to a point I would need GCs (don't hunt or shoot long distances with this rifle, and don't need to leave that door open).

4) COWW + 2, or COWW,pure, +2? Be fun to find out.

Many suggestions are coming into play here, and all are greatly appreciated. I had to replace a radiator in my car this AM, and that has set my back issues back more than I was hoping for. Oh well, just slow this project down a little more...

More later...

swamp
04-03-2016, 09:17 PM
You should find graphite at the hardware store. Used for lubricant.
swamp

Tailhunter
04-03-2016, 10:40 PM
Where do you get the sulfur for the casting?

runfiverun
04-03-2016, 10:56 PM
garden section.
or a green house.

you can clean your alloy with Sulpher.
it acts as a grain refiner and is a pretty good additive in place of arsenic for alloys that don't have it.

40-82 hiker
04-03-2016, 11:17 PM
Go to the section on boolit swapping and get some samples from members to try. The 311041 would not be my first choice in that chamber, something like the 311299 or 314299 would be what I would load first. I also would start at .309" and go up if needed.

Done! Thanks.

40-82 hiker
04-03-2016, 11:25 PM
it acts as a grain refiner and is a pretty good additive in place of arsenic for alloys that don't have it.

Did not know this... Do I assume it is used as a flux? How much? Also, arsenic is good for water cooling, but does it give any other properties to the alloy in absence of water cooling?

scottfire1957
04-04-2016, 12:38 AM
I need a little help to go to the next step, which is to order my mold.

I have never used a chamber cast to spec a new mold, but I have been reading about doing just that for some time on this forum. However, my chamber cast has revealed some info which is confusing the issue more than I can figure out with my limited knowledge.

My first sulfur chamber cast this morning.

http://castboolits.gunloads.com/attachment.php?attachmentid=164797&d=1459224468

rifle: Mark X 30-06 factory barrel
caliber: 30-06

Following measurements were made with a gunsmiths micrometer, but I took the measurements (experienced using one).
Grove diameter: 0.308 (some measurements 0.3075)
bore diameter: 0.300 (some 0.299)
Throat diameter: 0.314 right at the start of the throat, tapering to 0.308 approximately 0.225" to 0.25" from the start of the mouth

Following measurements were made with my dial caliper:
The distance from the start of the throat to the start of the lands different for all four lands:
0.175", 0.198", 0.255", and 0.223"

I used this rifle solely for deer hunting years ago, and was satisfied with its accuracy for such. Since it has been sitting fallow for so long I now want to use it for shooting reduced loads (Bullseye, 1000 to 1250 fps range, 170 gr. bb boolit, COWW), and now need to buy a mold for it. I am not asking about loads, as I am comfortable with where I want to start based on much research on CB. My questions, given the aforementioned measurements are:

1) The throat is so big to start with, and given its large diameter (0.314"), it seems to me a cast boolit of 0.314" would be too large with the bore size I have (0.308"). Would 0.312" be too large given the groove diameter of 0.308"?

2) The throat seems very irregular with the start of the lands. Should I get the throat evened up before I do anything else? Never cast a chamber before, so I just don't know if this is going to real detrimental or not. Guess I could just get the mold and start casting...

3) Would there still be an advantage to a bore riding boolit at velocities around 1100 fps?

4) Do I need to take into account for any shrinkage of the cast? I have found many references saying I do not, but I found one article on LASC's website in which the author said there is shrinkage. ??

Too tired and hurtin' too much to think this through anymore for the moment. I hope I have enough info listed. Just not sure to what to do because of that crazy throat (or maybe it is not so crazy?). Your help is greatly appreciated.

Thanks,
Bob


I'm sorry if I am late. But would this not be a better question for a mould maker verses the kindly hill folk of cast boolits? I mean really, the mould maker will have more info than ANYBODY else on ths site that isn't a mould maker, about moulds, and making them, sizing, and boring and drilling and machining and stufF.

40-82 hiker
04-04-2016, 09:51 AM
Why not ask the experts on CB? Such a world of knowledge that I am getting! Also, it seems the mold makers are SO very busy. Many reasons I can think of to communicate with the people on this forum.

Anyway, the questions I have asked of mold makers in the past are more to the point of the molds themselves. Fitting a boolit to a throat/bore combination is rather what CB is about, and part of MY fun on CB is communicating with people. JMHO.

Also, there are so many opinions on what would constitute a appropriate boolit for a given situation that just one answer may or may not be appropriate (really not known until the boolit is in the gun anyway). I'd say the collective wisdom I have garnered from the people responding to my initial post is knowledge gained from thousands of boolits fired in many different rifles having less than ideal throat/bore characteristics. I'd think this collective wisdom would be very hard for any single person to have. Besides, why question why we post? Is this exercise not at the heart of CB itself? Sharing of projects, and the ability of a neophyte to ask for help? I have been around guns my whole life, but heck if I have EVER scoped out a mold to my exact needs.

All JMHO, of course. As well, I would think if a mold maker is going to start doing consultations on "boolit fitment" we are going to have to start paying a lot more for the molds we order.

blackthorn
04-04-2016, 01:00 PM
I found the info on sulphur shrinkage interesting (thank you) as (up to now) I was under the impression that it did not shrink. I got this impression from literature that said sulphur is used to set heavy machine mounting bolts in concrete because it did not shrink. Thinking about it, a cast of sulphur would likely be impossible to remove if it did not at least relax somewhat.

I think "lamp black" is carbon, not graphite. I might be wrong though.

40-82 hiker
04-04-2016, 01:36 PM
I found the info on sulphur shrinkage interesting (thank you) as (up to now) I was under the impression that it did not shrink. I got this impression from literature that said sulphur is used to set heavy machine mounting bolts in concrete because it did not shrink. Thinking about it, a cast of sulphur would likely be impossible to remove if it did not at least relax somewhat.

I think "lamp black" is carbon, not graphite. I might be wrong though.

The reason I went to the efforts I did to figure out what happens to sulfur when going from liquid to solid is because of the MANY different statements regarding shrinkage, or not, that I have read. It is hard to pen down. If not for rwadley and KCSO I would probably still be bouncing around this issue. Apparently many have used chamber casts, with good results, without figuring in shrinkage. Confusing...

As to using sulfur to set machine mounting bolts in concrete, I am as well puzzled. Just don't know... But it does seem a certainty that sulfur does shrink when solidifying, at least for 48 hours.


While I am confused as to the difference between lamp black and graphite, graphite is made out of carbon, though in a unique state. I may very well not want lamp black, so thank you for bringing this up. I will certainly use graphite, regardless of what lamp black is. I did confuse the issue when bringing lamp black into the game. Thanks for pointing this out.

runfiverun
04-04-2016, 05:39 PM
they are both carbon the size is the difference.

sulpher is a good cleaner in that it will grab onto impurity's in the alloy and help them float to the surface. [it's also good at pulling zinc from an affected alloy]
sulpher becomes part of the alloy, modifying the structure allowing the particles to pack together into a tighter grain structure.



Yeah I'm sure none of us have ever designed a mold or figured how to get a certain diameter from a certain alloy.
it's only the specialists with design programs [like the one that I got from Tom at accurate molds] that can do that kind of stuff.

40-82 hiker
04-04-2016, 06:58 PM
Yeah I'm sure none of us have ever designed a mold or figured how to get a certain diameter from a certain alloy.
it's only the specialists with design programs [like the one that I got from Tom at accurate molds] that can do that kind of stuff.

I'm glad you responded such. I am fried from yesterday and not hardly on my feet today, so keeping the computer time to a minimum as it's uncomfortable using lying on my back. Didn't feel like going into that topic anymore than I did...

Since we're on the topic: While I have been shooting off and on most of my life, I really got into my BP guns a few years ago when a friend suggested I start casting again, and join CB. The help I have received, and the knowledge base shared (readily!) by the members here is absolutely unbelievable. I escalated this hobby as a means of physical therapy (as well as the fun of it), and it has been greatly beneficial. I could not have accomplished what I have without the help of so many people, so knowledgeable in what they do. Period! Kudos to all!
Runfiverun, I'm glad you have that software so you know what you are doing. :kidding: Did I use the correct color (sorry if I did not)? First time for everything...

4719dave
04-04-2016, 07:23 PM
Yes ...I love this place I read all night spend money I don't have ,beat the wife home to get the mail....:bigsmyl2:
This was great info

blackthorn
04-05-2016, 02:34 PM
So-- I learned two things from this thread. Sulphur does shrink and Lamp-Black is a fine rendition of Graphite. Thanks. That means I have another use for the thirty year old, two pound box of Lamp-Black sitting on the shelf in my shed.

whisler
04-05-2016, 09:02 PM
2 pounds of Lampblack can cover about 2 acres if the wind is blowing. :bigsmyl2:

blackthorn
04-06-2016, 01:15 PM
Quote "2 pounds of Lampblack can cover about 2 acres if the wind is blowing. :bigsmyl2: "

Just 2???? LOL

whisler
04-06-2016, 09:34 PM
I didn't want to exaggerate but it is probably closer to 4 acres. It also has another name -Jump-on-you Black". Don't ask me how I know!

dondiego
04-07-2016, 02:36 PM
Lampblack can also be used in fireworks formulas.

40-82 hiker
04-12-2016, 12:08 AM
Been under the weather, but poking my head out now, and asking a few last questions. Things just go slow for me...

I'm ready to order a mold, thanks to so many who have helped, and will order from Tom, getting a 4 cavity mold with two different boolits.

1) Both will have a plain base. I'm committed to the idea of the loads with Bullseye. I need something to shoot on days my spine and pelvis are bothering me. If these boolits do not work out, I'll sell the mold and start over.

2) Boolit 1 is a .314299 clone. I changed a couple of the dimensions of Tom's 31-200L so the boolit is:

diameter: .314"
nose diameter: .303"

166016

3) boolit 2: a Saeco 315 clone, but:
Diameter: .313"
tapering to: .303" bore rider

The chamber neck seems to have plenty of room for these boolits, but I can always inside neck ream if needed. Chamber neck measures .345" in diameter.

Questions please:

1) given a bore of .303 max, should I bore ride with a .303" or go with .304" (small difference, but from what I understand pretty important).

2) alloy: COWW plus 2% tin about right for 1200fps range?

3) Should I drill out the flash holes? If so, what size bit?

Any comments will be appreciated. Casting and reloading are very hard on me, but I really enjoy it greatly. I just need to narrow down issues before I get started, or at least as many as I can. Don't know anything really until I'm launching them downrange. So, I'm in debt to many for help given here.

Thanks,
Bob

HangFireW8
04-12-2016, 12:43 AM
Before you order that mold, consider a few things first. Since you have the chamber cast... but you didn't post the chamber neck diameter. If you take .314" and add .012"+.012" plus .001" minimum for boolit release, that's .339", is your chamber neck at least that size? If not your loaded cartridge won't fit.

Second, to seat a .314" boolit, you won't be using a conventional set of dies that leave the neck inner diameter at .307" or so. What's your plan for neck sizing and expansion before seating the boolit? Is it a plan consistent with good brass life?

Third, it's only .250" until the bore is .308", or whatever it is for the rest of the barrel anyway, right? If the boolit sticks out of the case that much, it'll seal the bore immediately on firing, if not on chambering. Bore sealed, boolit centered, no blowby, mission accomplished. In other words, fitting boolit to throat is one plan, and a plan that works well with large throats & bores and small throats & bores... but it's not the only plan. Plenty of us get good accuracy and no leading by sizing to the bore diameter, especially when it's a short hop and a long seated boolit.

40-82 hiker
04-12-2016, 01:08 AM
Before you order that mold, consider a few things first. Since you have the chamber cast... but you didn't post the chamber neck diameter. If you take .314" and add .012"+.012" plus .001" minimum for boolit release, that's .339", is your chamber neck at least that size? If not your loaded cartridge won't fit.

Stated above: Cast shows neck diameter is ..345". Plenty of room. Can inside neck ream if needed.



Second, to seat a .314" boolit, you won't be using a conventional set of dies that leave the neck inner diameter at .307" or so. What's your plan for neck sizing and expansion before seating the boolit? Is it a plan consistent with good brass life?

It seems plenty of people here on CB manage this, as I won't be seating a .314" boolit. Maybe .312, or even .311", or even .313, but not .314. Brass life? Good point, but using a separate sizing die, I can't believe sizing to .312 is going to be a big deal. Again, others do it...


Third, it's only .250" until the bore is .308", or whatever it is for the rest of the barrel anyway, right? If the boolit sticks out of the case that much, it'll seal the bore immediately on firing, if not on chambering. Bore sealed, boolit centered, no blowby, mission accomplished. In other words, fitting boolit to throat is one plan, and a plan that works well with large throats & bores and small throats & bores... but it's not the only plan. Plenty of us get good accuracy and no leading by sizing to the bore diameter, especially when it's a short hop and a long seated boolit.

I'm thinking you have missed the point of my mold dropping at .314". I can size to .312", .311", or even .313". I do not intend to actually size as cast. If many people size to .311" for a .308" groove, what is the problem with sizing to .312" for a .309" groove diameter? Or .313 if needed? However, I do want to plug that throat, or as much as I can, on chambering.

Thanks for the response. I have countered your thoughts, but in kind. Who knows, it might turn out you are correct on some of your thoughts, but I'm going with what I consider to be the pathway thought of by many, and one I feel comfortable given this crazy throat I can drive a truck through. Until I shoot the things, it's all a guess anyway. Told that by a sage on this thread.

runfiverun
04-12-2016, 10:54 AM
I can see his point.
your kinda making this hard, and it should be pretty simple.
you have to take into account where all that extra lead will be going as it flows through the throat.
it will be pushed somewhere, just like it does in the sizer.
if it all goes backward you'll end up with a trailing edge that's pretty ragged and that will not be good for accuracy.

I would target the 315.
order it with a plain base.
and spec it to Tom to pour with WW alloy alone at 301 on the nose and 311 on the main bands.
what this does is allow you to add the tin in as needed to change the diameter slightly or to add some softer lead in the mix to change the diameter slightly.

now the 311299 mold has a slightly different purpose here.
you want the nose about .0005 over your bore diameter so it slightly engraves the rifling evenly on all points of contact.
and the body just big enough to fill the grooves plus.001-2 [310 once again]
the nose will help align the cartridge if the case/body is filling the chamber reasonably well.

then you can dial the mold into the rifle where the nose gets a slight amount more or less engraving and the body can move forward into the throat and fill it up without getting mushed up in the process.

the whole trick is to get the boolit from the casting pot to the target with as little damage to it as possible.
mashing it up and down a few times is not helping it.

now what would help, is using the case and partial neck sizing to hold the boolit square with the centerline of the barrel.
sizing to about 310-11 from a 311ish diameter.
finding the most consistent ignition, and using boolits with the most square bases possible.
don't use a gas check mold, get a real square bottom mold and control your casting quality.

if you do those few simple things I promise you will have good 50 and 100 yd accuracy at 1200 or so fps.
with a gas check I'd go to 1900 fps and expect the load to shoot well.

40-82 hiker
04-12-2016, 12:28 PM
I can see his point.
your kinda making this hard, and it should be pretty simple.
you have to take into account where all that extra lead will be going as it flows through the throat.
it will be pushed somewhere, just like it does in the sizer.
if it all goes backward you'll end up with a trailing edge that's pretty ragged and that will not be good for accuracy.

I would target the 315.
order it with a plain base.
and spec it to Tom to pour with WW alloy alone at 301 on the nose and 311 on the main bands.
what this does is allow you to add the tin in as needed to change the diameter slightly or to add some softer lead in the mix to change the diameter slightly.

now the 311299 mold has a slightly different purpose here.
you want the nose about .0005 over your bore diameter so it slightly engraves the rifling evenly on all points of contact.
and the body just big enough to fill the grooves plus.001-2 [310 once again]
the nose will help align the cartridge if the case/body is filling the chamber reasonably well.

then you can dial the mold into the rifle where the nose gets a slight amount more or less engraving and the body can move forward into the throat and fill it up without getting mushed up in the process.

the whole trick is to get the boolit from the casting pot to the target with as little damage to it as possible.
mashing it up and down a few times is not helping it.

now what would help, is using the case and partial neck sizing to hold the boolit square with the centerline of the barrel.
sizing to about 310-11 from a 311ish diameter.
finding the most consistent ignition, and using boolits with the most square bases possible.
don't use a gas check mold, get a real square bottom mold and control your casting quality.

if you do those few simple things I promise you will have good 50 and 100 yd accuracy at 1200 or so fps.
with a gas check I'd go to 1900 fps and expect the load to shoot well.


HangFire did have me thinking about this much of the night. I wish I had not responded so quickly, but maybe it is for the better. Rough night, and on top of it I had a fire alarm malfunction at 3AM! I had to finally take it down (a number of others are near it).

So, I was taking the "go bigger" advice too much to heart. I will take your, and HangFire's suggestions to heart and use the advice to the tee. Thanks guys. I try to take as much common wisdom as I can in such affairs, as casting, reloading, etc., is just too hard on me (though I still really enjoy it!), so I try to deal with as many potential pitfalls as early as I can.

Will keep you all informed as the project progresses.

Oh, BTW, some seem to drill out the flash holes for such loads with pistol powders. Any advantage/disadvantage to doing such?

Thanks,
Bob

HangFireW8
04-12-2016, 01:26 PM
No problem, and you're welcome.

I too get caught up in "analysis paralysis" whenever getting started on a new rifle/cartridge. Sometimes just trying stuff works as well as following "best practices" to the letter, especially when the letter involves a lot of custom ordered hardware.

The problem of pointing that out simpler alternatives is this... it returns the OP to analysis paralysis.

About flash holes. I would try without drilling first, which usually works well for me. If you have the problem of cartridge headspace reduction (shoulder shrinkage), then try drilling.

Your sizing plan can work. Here is the known issue with sizing: the more you do it, the more accuracy drops off. Thus, custom molds, sizing just noses and/or bases separately, etc. R5R got into some of the reasons for accuracy drop-off.

PS replace all batteries at once with all fresh ones. If detectors are just over 5 or 10 years old (the two most common lifetimes), replace them all at once.

40-82 hiker
04-12-2016, 05:02 PM
PS replace all batteries at once with all fresh ones. If detectors are just over 5 or 10 years old (the two most common lifetimes), replace them all at once.

Great advice, but am actually replacing the one from last night within the hour. The problem was not the battery, but it just started going off as if smoke was present. We spent some time searching the house for a problem, and during the entire time the alarm would go off, then not, then go off, then not. Since none of the other alarms were going off I just declared it defective. So, I just took it down and put it in the garage figuring I would replace it today. My sleep is too hard to come by, and not chancing it again for tonight, even if I cleaned it out. My wife asked me this morning if I should just replace them all, and I thought that was a great idea since they are going on 20 years old. !! Think I'm a little late with that chore?

Thanks again,
Bob

40-82 hiker
04-12-2016, 05:27 PM
I slugged the bore this morning with a lead slug, and here is the result:

Sulfur cast at 3 hours
Bore: .300"
Groove: .308"

sulfur cast weeks later (max. at 48 hours)
Bore: .299"
Groove: .306" to .307"

Lead slug:
Bore: .301"
Groove: .309"


So, given this limited sample, it looks like I experienced a .001" shrinkage at 3 hours, and a maximum .002" shrinkage sometime after then (I'll assume it was at 48 hours as suggested earlier in this thread).

Hope this helps, but with such a small sample, I am not sure exactly how definitive this exercise is. It is certainly right on the money, however, for the expected .002" to .003" shrinkage at 48 hours.

runfiverun
04-12-2016, 08:03 PM
I know how you feel.
I was working on a design for the 30X40 round which is used in semi-auto AR type rifles.
all I had to work with is the chambers throat drawings.
I had no rifle in hand, and no actual chamber measurements.
now that's pressure.
getting things correct and telling someone that what you drew, and drew with specified angles and diameters.
will not only work in the barrel and throat but will feed from his magazine.
then to top it off you have to work with the mold maker and specify the alloy and mold specs with either a plus or minus diameter to the mold.
you also have to determine the alloy you specify from the design and shape of the mold.
one that allows the boolit to glide into the throat under lower pressure before gas volume is generated to accelerate it along, will do better with a softer water manipulated alloy.
one that needs a tighter mechanical fitment [sharp nose shape]and is gonna get booted along by 20 grs of 4198 or something similar needs to be specced to a harder more tin and antimony bearing alloy type.

now somehow you have to make it work in not only the one gun you have the information from but in the next guy's cut by a different gunsmith with a different reamer.
it's no wonder commercial casters/mold makers make their stuff smaller and more generic.

40-82 hiker
05-28-2016, 09:50 PM
It has taken me a while with my problems giving me grief, but I want to relate what has transpired with this project. Great news at that!

All following would not have been possible without the help from all who helped me in this thread. All I can say is how much I appreciate it. Very! I am going to be exacting in my presentation, as I attempted to put all suggestions I could to my approach in this project. Geez! It really works!!

I have three boolits to work with now, the third being a 300 BO boolit I was given some of. I took them to the range to test yesterday along with the 200 grain boolits, but after 20 boolits fired my back and pelvis gave out (still climbing back out!) so I will take them to the range after the long weekend to test. I'm hoping they work out just as well, as if they do I'll have a different style to shoot (spitzer). I feel bad not testing them as a member on CB mailed them to me, and not being to test them yesterday leaves me lacking, though not in appreciation.

I got my mold from Tom, with some difficulty on his part as he had to help me understand how to put his machining tolerance to my benefit with the mold dimensions. The communcations we had via email concerning this would be embarrassing on my part, and very generous on his part.

I ordered two different boolits in a four cavity mold, two for each boolit. On his website they are 31-175BP and 31-200LP. I used graph paper to draw my throat (as suggested), and used those pages to draw, and then size the boolits for the mold. I planned on stuffing the boolit into the throat on chambering, so as to fill the throat as much as possible, and have the bore rider nose properly etched by the lands, all as suggested. All of this worked out precisely! However, compared to the dimensions shown on Tom's website, the dimensions I ordered are (with an alloy of COWW plus 0.5% tin, however, I started casting with 2% tin, thinking I would go down if needed to cast smaller boolits, but that is not needed, to say the least):

169101
31-175BP:
This bullet will not be sized.

Bottom Bands 1-4: .3110 with the positive tolerance (+) (Edit: once band 5 fit as far into the throat as possible, I felt I did not need anymore tapered drive bands so I ordered the mold with this final drive band size)
Band 5: .3040 (+/-), center tolerance.
Bore rider nose: .3010 (-) (negative tolerance)

Grease grooves between bands 1and 2, 2 and 3, and 3 and 4: .271"
This boolit drops .312 by my calipers.

169102
31-200LP:
2) #31-200LP
This bullet will be sized

Bottom Bands 1 and 2: .3115 with positive tolerance (+)
The bore riding nose .3015 (- tolerance)



For those not familiar with Tom's nomenclature, he uses the designation of the "ten thousandths" place as a way to determine where he puts his .002" tolerance window (he moves the window over to that position).

So, I used the alloy of COWW plus 2% tin to cast these boolits. The 175 grain unsized boolits I lubed with Lee Liquid Allox, and the 200 grain boolits sized to .312 to start, and I lubed with Lyman Moly. The 200 grain boolits do get sized somewhat at .312, but not completely. I could shoot them as is to be sure, but I must lube them, and the results seem to state that what I did was great, so no need to not size and lube as I did.

175 grain boolit (I forgot myself when I labeled the target "170gr.) sitting position, three shots, 50 yards (first three shots after two fouling/lubing shots), 8.5 grains Bullseye, WLR primer, Lee Allox, group is 0.68" C to C:
169104

Next 7 boolits, same load, sitting position, 50 yards (not as good, but dealing with a lot of wind pushing me to port):
169105


200 grain boolit, 50 yds., 8.5 grains Bullseye, WLR primer, Lyman Moly Lube, on bench with sandbag under forearm, sized .312, 0.55" C to C:
169106

75 yds, 200 grain boolit, 8.8 grains Bullseye, 9 shots fired from the bench with a sandbag under the forearm (two boolits together at 7 o'clock), did not change scope setting, the six boolits together are 0.8" C to C:
169107

While I do not detect any obvious yawing, I took some photos of the back of targets shown, and added some very odd contrast to see if the raised paper shows any lopsided indications, and I declare them okay, but show them for scrutiny. I "flipped" the photos so they actually match the fronts of the target. First target is 50 yards, the second is 75 yards.
169108 169109

Now, I still have a problem needing a fix: the primers are backing out, and the OAL of my brass is shrinking. I have not fired any brass more than once, so I do not know if this will continue, but all I fired are now shorter than the trim to length. I do not know if drilling the flash holes will fix both issues, as the shortening of the brass seems to have come out of nowhere. ?? I have been told the shoulder can be set back, but the entire case shrinking?

Given the "benched" loads at 50 and 75 yards, I seem to be hovering at 1 MOA, though I have not tried 100 yards yet, or the "third" boolit yet.

So far this project has been a great learning experience for me. I can truly see the GREAT need for a chamber/throat cast to do this, along with the knowledge supplied by all as to what to do with the dimensions. I seem to listen well. It works!!