What diameter for bare boolit?

[dubber123]

I am in the final stages of a project which may require the use of a paper patch boolit. I believe velocities will run in the 1,800-1,900+ fps. range. All I have is plain base moulds, and I have never had any luck getting much more than 1,600 fps. without loss of accuracy.

I have slugged the barrels at .510". If I was to get a mould cut, what size under this is recommended for paper patching? Would you recommend a smooth sided, or grooved boolit? Thanks.

[montana_charlie]

I have slugged the barrels at .510". If I was to get a mould cut, what size under this is recommended for paper patching?

Barrels? As in more than one? Is this a Gatling gun?
Is that .510" dimension the bore diameter...or groove diameter?
Can you describe the chamber(s)?
Do you plan to use smokeless?
CM

[dubber123]

.510 bore(s). I am building a double rifle in 50-90. It should be chambered and shooting this weekend. I ordered a Pacific 50-90 reamer, can't say much else yet. What would you need to know? This is a smokeless powder project. Thanks.

[pdawg_shooter]

For smokeless I size .001/.0015 over BORE diameter and patch to groove diameter+. I try to have enough patch to fill the throats. I want a little resistance when chambering.

[docone31]

Dude! An UberRifle!
I do not know if this will help.
My .30s I run .301 on the nose. My .303 British, I run .304.
Here is where it gets different from the standard.
I use a standard mold for each caliber. I size for wrapping to .308 on both. The .30s I size to .309, the .303 to .314. I do not know what the groove is on my .30s, but, my .303 is .312.
The difference I see is the major size difference.
In smokeless, I might consider a lube land casting. At .501 I would want the nose to be there, You would probably patch at .510.
Definate photo spread!!!!
I want another rifle for my desk top to druel over.
Good luck with the finished product. Something to be proud of indeed!

[dubber123]

I hope I gave the right measurement... If you slug a barrel, the largest measurement is the bore, right? or do I have it backwards... I bought 5 of these blanks, and the measurement of a cast slug knocked through was .510" on my dial guesstimaters, (all 5 bbls).

If I am reading you guys correctly, I would want a .507-.508" boolit, to allow for 2-3 thou worth of paper, for my .510" bore.

This is definately something new to me. Lots of reading up to do... Thanks for the help.

[montana_charlie]

I hope I gave the right measurement... If you slug a barrel, the largest measurement is the bore, right? or do I have it backwards...

You have it backward, but don't stop reading and run away with that information.
Stay around long enough to be able to remember how it goes the next time you need to know.

A barrel starts out as a solid 'rod'.
Then it is bored from end to end.
That hole is straightened, checked for size, and polished.
THAT is the 'bore' of the barrel, and it's diameter agrees with the 'caliber' (45, 38, 7mm, etc) it will be chambered for.

Then, as a separate job, the grooves are cut to a certain depth.
The distance from the bottom of one groove to the bottom of the opposite groove is the 'groove diameter'.

When measuring a slug driven through the barrel, it will have 'ridges' and 'valleys' on it.
The ridges were made by the grooves in the barrel, so if you measure across them, you get 'groove diameter'.

You have to measure across the valleys to find the 'bore diameter'.

You're welcome...

CM

[docone31]

Dubber,
The groove is the largest measurement.
If you got .510, and are useing smokeless, I would go .512.
I would get Lee Precision to cut Sizing Dies for that. They are inexpensive, and you are going to have to experiment. .508 sounds about right, with .512 final diameter.
When I found my diameter with my .303 British, I used Meade Traceing Paper. I started with two wraps at .311. Way too small, I then went three wraps to .3135. Still too small. Same accuracy as small cast. I then used two wraps of lined notebook paper. It wrapped to .319, which I then sized to .314. .314 Was the sweet spot.
With your rifle. You are also going to have to play around. With that large a casting, .511 might be the ticket, or .512 is needful.
Buckshot, here on the forum also does great work. He is easy to work with also.
Looking forward to photos. Double rifles keep me up at night!

[docone31]

Lee Products has two molds. One 450gns, one 500gns. Both drop at .515.
Now, I am in a quandry.
If my .303 British slugs at .312, and I wrap to .314, where is your .50 going to be?
You might be at .516, or .517. That is an intimidating size indeed.
If it were me, and I do some things backwards sometimes. I would get the 450gn mold, and get some sizers. I would first size at .515, just to clean off the lands and smooth the lube. If that works, I would patch to .516, just to try. Another alternative is to get a sizer in .514, then open it up if needed. I would size the casting to .508, then wrap and size to .514. If that gives lousey accuracy, open it up to .515.
You know the drill, watch for pressure signs, etc...
Once you are done, you will have one beautiful rifle.
How large across the lands?

[dubber123]

I have several moulds for my 50-70 Contender, 390,400,425,435,470,and 505 grains. All cast at .513" or larger.

So I have .510" GROOVE, and best I can measure, .501" BORE. 2 slugs measured the same.

The only sizer I currently have is .513". I have had Buckshot make one for me before, and trust his work, if I need another. I can get an EDM mould cut pretty easily for me. Would a grooved boolit be superior in any way? Possibly hold a little lube in the indents?

Thanks

[docone31]

Here is where I am the pariah.
I like grooved boolitts. I believe they shrink down on the patch and help hold it. You can see it when the paper is dry.
Do not lube your patch! Just the sizing wax will be all you need.
Ok, you have a .513 sizer. I might just try that one on final size to start. Who knows? That might just be your sweet spot.
To date, and that is many hundred rounds in my .303, and .30s, I have not used lube. I just dab a tad of Turtle Auto wax on my patch, or JPW, and size it. That is all I have ever used.
Paper patching is not like cast loading. No gas check, no lube. In the final sizing, the tail which is pretty much snipped short, is compressed into the base of the patched boolitt.
That is it.
It sounds like you are pretty much good to go.
I would get a sizing die for the prepatching though.
Maybe though, you can final size it and accomplish the same thing. Try one and see. If you can get away with it, why not? The lube lands probably will crush down.
Try one to see if you can size it with paper.

[NSP64]

Dubber, what you need to do is wrap a 50/70 slug you have with 2 wraps, let it dry, wipe it with a little JPW, push it through the sizer, measure the patched boolit. If its .513 great, now unwrap it and measure the boolit, it should now be .502-.503. If not wrap the next one with 3 wraps,repeat. try this until you find the right combination of paper thickness and number of wraps to give you the dimensions you need. The sizing of the wrapped boolit will swage down the boolit.

[dubber123]

Thanks for the help, I'm sure I will have more questions! Just to get it proofed and shooting, I will use conventional cast, but I know I will have to patch if I want full velocity. I hope to chamber Saturday morning, and be shooting by the afternoon.

[NSP64]

good luck and post pics

[docone31]

Dubber, wish I was there!
Definately proof it with cast, then find the sweet spot with paper.
That is going to be an UberRifle with wondernment.
Send PHOTOS!!!!! I want one.

[dubber123]

Nothing to get too excited over, I'm just re-lining a SxS shotgun to 50-90. I will try to take a good side profile shot this weekend. I still need to add sights, and re-finish the whole mess after regulating the barrels.[img][/img]

[dubber123]

[img][/img]

[montana_charlie]

Would you recommend a smooth sided, or grooved boolit?

Would a grooved boolit be superior in any way? Possibly hold a little lube in the indents?

You have asked twice, so you deserve (at least) two opinions.

docone31 patches grooved bullets. I don't think that started on the belief that doing so was especially advantageous as much as they were 'what he had' and he sized them down enough to add paper to.

All things considered (such as profile, etc), smooth bullets are aerodynamically superior to ones with grease grooves. Also, you want the paper to be released instantly as it comes out of the muzzle, so you certainly don't want grease lying in grooves that makes the paper stick to the bullet.

If you are willing to have a mould cut specifically for use in that rifle, I would recommend it be a 'typical' smooth-sided paper patch design.

The 'shape' is left to your preferences, but the 'size' is determined by your rifle...and your paper.

I would start by wrapping different kinds of paper around something...perhaps even on a bullet. But, choose something close to a half-inch diameter that is smooth and close to perfectly round. (The back end of a drill bit comes to mind.)

Measure the naked object for your baseline dimension, wrap it twice with some paper...then measure the increase and record it.
Do that for as many kinds of paper as you have to choose from.

Try it with dry paper and with wet paper so you know how that changes the thickness...which means you have to wait for the wet ones to dry before taking the measurement.
Impatience is not your friend.

[I have deleted the actual size numbers from this post because they were incorrect.]

Once you have found a paper that gives you a thickness that is only slightly thicker than the depth of your rifling...and have assured yourself that you can get as much of it as you need...you can then decide on the diameter of the bullet you want to use.

Since this is a smokeless project, conventional wisdom says the bullet should be patched-to-groove.

Multiply the patch thickness by 2 and subtract that from groove diameter to find a suitable naked bullet diameter.
The total patched diameter may be somewhat larger than your groove diameter, but only if you have a freebore that will accept it.

How deeply you seat the bullet in the case is dependent upon the throat you cut ahead of the chamber. (I use 'throat' to include any freebore that exists and the leade.)
I would advise that the diameter of the chamber (itself) at the case mouth be larger than the freebore diameter only by the thickness of your brass.

If you would like to read further about the choice between smooth and grooved bullets, see this...
http://castboolits.gunloads.com/showthread.php?t=39157

CM

[dubber123]

Well, I just tried a few, using my 470 gr. LBT WFN mould. I wrapped with 2 wraps of regular printer paper. As cast bolit diameter just touches in my .513 size die. I definately need a smaller boolit to start with!

#1 through the sizer just ripped the paper off. #'s 2 and 3 I was more careful to start, and went through, but with way too much effort. Final size was .514", I assume because of boolit spring back, (WW material). I unwrapped one, and the boolit had been reduced from .513" to .505"

[dubber123]

Thank you for the additional info, especially about patch thickness not exceeding the depth of the rifling. The printer paper measured .003", so I was already too thick, plus the oversized boolit=near disaster. Oh, well, at least I only made 3.... It would appear I will need paper in the .002" range. Gotta go shopping I guess.