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klausg
05-18-2006, 05:26 PM
Hey gang-

I need a little light in the wilderness here, and I wouldn't be surprised if there is another newbie out there lurking who's wondering the same thing. I understand the need for slugging the barrels, due to manufacturing tolerances, etc.; you really don't know what your groove diameter is until you do that, makes sense. Where I start to get lost is when you guys start talking about revolvers:

a) Should I be measuring the front of each hole in the cylinder and averaging, or tapping a slug down the bore? Or something totally different?

b) I realize that it is one more thing to play around with, but as I understand it, .001" over groove diameter is a good starting point for bullet diameter. True/False or something else?

Thanks for any light you can shed on my ignorance. Take care

-SSG Klaus

felix
05-18-2006, 05:52 PM
Klaus, "for every gun there is a load that will shoot". Finding it might take a lifetime of changing out the variables, but it can be done by chance. You cut this time down radically by sizing the boolit the largest diameter that can be seated in the cases such that there is only a slight clearance in the individual chamber(s) where the ammo is to be shot. For all of our common guns, that final, loaded round has a total clearance of 0.002 inches where the boolit is. Ideally, there should be close to zero clearance tolerance towards the back end of the case. Does this answer you question for ALL situations? Keep in mind that the chamber where the boolit exits the case must be larger than the barrel for the gun to shoot all loads at least half way correctly. ... felix

Bucks Owin
05-18-2006, 09:04 PM
Hey gang-

I need a little light in the wilderness here, and I wouldn't be surprised if there is another newbie out there lurking who's wondering the same thing. I understand the need for slugging the barrels, due to manufacturing tolerances, etc.; you really don't know what your groove diameter is until you do that, makes sense. Where I start to get lost is when you guys start talking about revolvers:

a) Should I be measuring the front of each hole in the cylinder and averaging, or tapping a slug down the bore? Or something totally different?

b) I realize that it is one more thing to play around with, but as I understand it, .001" over groove diameter is a good starting point for bullet diameter. True/False or something else?

Thanks for any light you can shed on my ignorance. Take care

-SSG Klaus

The "hole in front of cyl" is the throat diameter and should be as big as or "slightly" bigger than groove dia. IMO..."Slip fit" is about right.
If throat dia is smaller than the bore's groove dia the throat will "resize" every boolit fired to undersize and accuracy will suffer...

Best way to slug the bore is with a slightly oversize round ball, say .440 to .450 in .44 cal. Oil the bore well and tap the O/S ball into the muzzle with a soft faced little hammer. Once in, it'll push down the barrel easily with a dowel. This'll give you the tightest groove dia when measured and you'll feel any tight spots as you push it down the bore.

Works for me,

Dennis

klausg
05-19-2006, 11:14 AM
felix/Bucks- Thanks much for your replies; I was fairly sure that the 'throat' would be the dangerous end of the cylinder, but didn't want to fully display my ignorance. I now have a fairly good grasp of what you all have been talking about.

One other question, as long as I'm proving my ignorance. Is there a general rule of thumb as to how much you can size a bullet? I suppose that it would be possible to size a .452 down to .225 if you did it in enough steps, (it BEGS the question WHY? though). I guess to phrase my question more accurately: Is there a maximum amount of sizing that can be done; after which it becomes not such a great idea? If so what is that amount? Thanks again guys.

-SSG Klaus

Bucks Owin
05-19-2006, 11:20 AM
You got me there amigo. I would "think" that any more than say .005" or so would result in "unbalanced" boolits....

I'll learn this one with ya! :drinks:

Dennis

Leftoverdj
05-19-2006, 01:59 PM
Some of our member do huge sizedowns after having filled the groove with lube. I do no more than I have to and would consider .005 at or over my outside edge.

Buckshot
05-20-2006, 06:17 AM
...............If done so that it damages the slug ANY sizing is bad. If the sizing does not ruin the boolits form then you may size as much as you like, o rcan get away with. For quite some time I've sized as cast 45 cal rifle boolits (.458, .459",.460") to .452" for paper patching.

I had a cranky M1909 Argentine 7.65x54 it was impossible to feed cast to with any commonly available mould. I figured if I lube-sized the Lyman 323470, 8mm 165gr Loverin to .323" and then sent it up through a .314" push through die it might work. And work it did. Maven double checked by doing it himself. That's a .009" reduction.

I think Starmetal has sized the Lyman 150gr 7mm down from .285" to .266" or so. That's a .018" reduction which is twice what I did.

In any event, such sizing pretty much requires the boolit to be lubed beforehand. One reason is the simple fact of the lube requiring less effort. Secondly the lube filled grooves cannot collapse and it supports the slug.

Now if the boolit is distorted while being pushed into or through the die then it's potential accuracy will probably be destroyed. Distortion can be caused by being pushed in at a slight angle, being bent, or having it's core distorted. The core being the solid central portion of the boolit defined by the bottom of the lube grooves.

The easiest boolits for the largest amount of sizing are the Loverin types, due to their narrower drive bands and the abundance of lube they carry.

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

StarMetal
05-20-2006, 08:26 AM
Yup, I've sized 150 7mm Lyman loverins down to .285 then to .265 and they shot as well as any normal 6.5 bullet. I have also sized .357 pistol bullets down to .331 for use in my 8x56R M95 and those shot really good.

I agree with Buckshot, if they are sized straight and not distorted or shaved, they do well.

Joe

cbrick
05-21-2006, 05:01 AM
StarMetal,

Question, If you size the 150 7mm Lyman loverins down to .285 then to .265, and .357 pistol bullets down to .331, how deep are the lube grooves after this much sizing?

Rick