slugged my bores

[jeff223]

my 357 max barrel is at .355 and my 445 supermag barrel is at .428

so this means i size my boolits for the max at .357 and i size for the supermag at .430

if i do it that way i should have some accuracte shooting boolits?should have?i have tried some .358s and some .360s in the max with no accuracy.that one or two thousands in size makes that much differance?

i also have some Lee 310gr flat nose boolits with gas checks sized at .430 and they should show signs of good accuracy right from the start?right?from my 445sm

[44man]

I feel you did something wrong slugging your bores. Just pushing a slug all the way through the barrel will wear the slug and give you a smaller reading. Your measurements are too small for the standard bore sizes. I am sure you noticed the slug was easier to push the farther you went down the barrel.

[StarMetal]

I've seen 357 mag bores go as tight as .354. In fact I have seen many that were .357 or so. Most Smiths I've seen were .355. Don't know about the 445 Supermag as I've never owned one.

Joe

[Dutch4122]

My T/C Contender barrel in .445 Supermag slugs at .4295" using a soft lead egg sinker.

[Catshooter]

Quote from 44man:
Just pushing a slug all the way through the barrel will wear the slug and give you a smaller reading.

Now that's an interesting thing. I have never heard this before. The slug wears? So then lead would be deposited in the bore, I guess?

I don't think I can think with that data. Are there any references that you are aware of that talk about this?

No offense intended, just another inquiring mind who wants to know.


Cat

[StarMetal]

Okay 44man, we want you to wear a skull protector when you're shooting those hot 44 mag loads. hahahahahahahaha


Joe

[drinks]

44;
Actually, every barrel I have slugged has had both loose and tight spots, as many people have noticed, there are often tight spots where a sight dovetail or a sleeve type sight band has been installed and where the barrel is screwed into the receiver.
The slug shows the smallest dimension of the barrel.
Using soft lead,there will not be any wear on the slug if it was lubricated properly, just displacement of metal.
One object of hand laping and fire laping is removeing the tight spots and make the barrel uniform in dimensions from breech to muzzle.

[jeff223]

these barrel are both TC barrels and i used a TC maxi hunter boolits for the slug(very soft lead).i just tapped the slug into the bore from the muzzle end about 3/4 of an inch,then i took a wood dowel and pushed it back out.i didnt think i needed to run it all the way down through the barrel.once i got them out i then took the measurements and thats what they were.

both these barrels shoot jacketed boolits very good.maybe this cast boolit shooting isnt really worth all this monkey buisness??idont know for sure??just thought i would try

[HickoryCreek]

:veryconfu i don't think I understand all I know about this. So if I'm slugging a bore I shouldn't put it all the way through? Please elaborate, cause I'm slugging my first bore now. It's a 45-70 and I'm pushing oval sinkers through I did five and come up with 4582ish to 4587ish. Caliper not very high quality.

[jeff223]

i guess i dont understand either??
i think if you slug the way that i did you will get a good honest reading.if your bore have tight spots in it i dont know what to tell you.they say my measurements are kind of small but thats what they are.i see Lee makes a .357 sizer die so there must be bores as small as mine out there.if my bore measures in at .355 then i would say a .357 boolit would be just the ticket from what i have read.i know a .358 sized boolit doesnt shoot worth beans.maybe we can get to the bottom of this?

[44man]

I don't know about you fellas, but every time I push a slug all the way through it will be a little smaller then if it is just put in a little way and pushed it back out and this is even if there are no constrictions that can be felt. I can't say the slug wears or just squeezes a little. Since there are no perfect bores, there is bound to be some change. I have spent hours on one barrel doing it every which way and can get different readings every time.
Just the action of starting a tight slug by tapping it in the barrel will distort it enough so it is no longer tight. Lead will also tend to shave off while inserting it. The most consistant readings come from upsetting the slug once it is in the bore and pushing it back out. This should be done from each end if possible. Just pounding it in and pounding it out will not give as good readings but is much closer then going all the way through. I don't know how any of you figure that soft lead will not abrade or distort some once it is in the bore and moved. You are also making the slug turn as it follows the twist which puts stress on the lead and any difference in a grooves depth can make it smaller.
For instance, my 45-70 BPCR is supposed to be .458 according to Browning. If a soft .458 boolit is pushed through the bore, there will be no marks from the bottom of the grooves on the boolit. Slugging with an oversize slug will give readings from .4575 to .459. The bore size on top of the lands will also vary from .4485 to .449. By upsetting the slug in the bore, I get .4595 which is the actual size as far as I can determine. The bore size on top of the lands is .450.
A bore cast with Cerro Safe will show a bore size of .4608 after the proper time for it to stabilize.
The Pedersoli with a tapered bore will show a MUCH smaller slug no matter which way you push it through so it HAS to have a slug upset just in front of the leade and pushed back out. This is also the case with a bore that has been power lapped.
So after many, many hours and a pound of lead slugs, I have come up with the size of my bore. Now you are telling me that one slug pounded in gave you the exact size!!!! You are talking to the wrong man and barking up the wrong tree!
I am thinking you have magic lead!
Have any of you shot an oversized boolit out of the bore with a 1 or 2 gr load of bullseye, caught it in something soft and measured that boolit?

[jeff223]

44man that was a good read for sure and i thankyou for it.

all i really wanted to do with this topic is end up with a cast boolit that i could shoot that i would be happy with and nothing more.maybe soft lead used for slugging the barrel will tell me nothing but i know alittle more about my bore now than i did before.did i get a true measurement??i dont have a clue??

ive been thinking about this now for some time and i know what im going to do.im going to drop to my knees and pray to the good lord that i find my way to a true measurement.now that will be just the tickethttp://castboolits.gunloads.com/images/icons/icon10.gif

[felix]

The very best way to measure a bore is to shoot the boolit into a swimming pool off of the diving board, straight down, with a couple of grains of BE (rifle case size) with loose tuft of toilet paper against the powder, against the primer. The measured boolit should be the same diameter all around, plus up and down to where the ogive starts. If there is variation, slow the boolit down and reshoot. ... felix

[S.R.Custom]

I feel you did something wrong slugging your bores. Just pushing a slug all the way through the barrel will wear the slug and give you a smaller reading.
No. The bullet will "wear" only to the point of the smallest diameter along the length of the groove; it is, after all, impossible to wear the bullet down any farther than the extent to which the groove makes physical contact with the slug. (Small diameters in the SuperMags are common; I've owned several Dan Wesson barrels that measured as small as .426")

That said, you'll still want to do the tap-in, tap-out thing with the T/C barrels from the breech end... T/C has the annoying habit of making really long leades, and their leades frequently include a tapered groove diameter at the chamber throat as well, almost like a forcing cone. (How they accomplish this during manufacturing is a mystery to me; I just know that it exists.) I think they do this to bleed off excessive pressures at ignition; it seems to be most common with high pressure cartridge calibers...

If this condition exists in your barrel, you'll want to size your cast bullets .001" larger than this leade diameter. If it's really bad, you'll need to hone out the chamber just to get your loaded rounds to chamber, just to accomodate the really large bullets you'll be casting. But the effort is worth it; once you account for all these dimensional quirks, accuracy improves by an order of magnitude. BTDT.

[Singletree]

SuperMag,
Your description of the forward part of a T/C chamber as a leade is much more accurate than calling it a "throat". The chamber is a mirror image of the reamer used for the purpose. On some of T/C's chambering reamers,depending on caliber, there is no "throat" at all. An extended "leade" is used topped with a tapered section, and ending with the bore guide. Since there is this taper on the end of the reamer, barrel diameter will determine the length of leade. No two barrels will have the same length unless the bore dimensions are identical. Why does T/C do this? There must be a reason and better accuracy with cast bullets is NOT one of them.

[StarMetal]

Felix,

That way I slug a bore, by firing with a light charge of Bullseyes, but I wasn't going to mention it here, glad you did.

Joe

[44man]

Star, I mentioned it also and have done it. Works just fine. Problem is having something to shoot into which gets me back to slugging. (No swimming pool and catch box rotted out. I am always out of gallon jugs too.)

[David R]

Gee,

I had some of the same results above. I slugged my 2 groove enfield. the slug started hard, then almost flell until it got near the muzzle and i had to drive it out. It measured 307 X 299. I slugged my savage 200 in 308. The slug drove through the same all the way, but still .2975 X .307. I didn't quite get it.

Today I drove a slug into my "new" Savage 340 in 30-30. I pounded a pure lead 311410 into the throat about 6 inches up the barrel and drove it back out. It measures .309 X .3005, almost .301 but not quite. This is what I expected. I must have upset it quite well, you could see the rod I used had driven into the slug almost 1/4". This is the same slug I used in the above 2 guns.

I am still learning. Probably going to do the enfield and savage 308 again.

David

[jeff223]

i got the OK to shoot into a friends swimming pool but im going to need some help from some of you cutting a hole through the ice and then after the shot will need someone do dive down to the botton to fetch the slughttp://castboolits.gunloads.com/images/icons/icon10.gif

[Bass Ackward]

Slugging by any method almost always gives you an undersized measurement to some degree. Even the firing into water subjects a bullet to the sizing forces of fouling even if it is just a light oil causing the hydraulic effect. Say you get the size right today on a new firearm, at some relatively short period of time in the future you are going to open up to a point where the bore stabilizes after the tool marks are gone in the gun which can easily add up to .001.

But we seldom monitor this effect. I suspect that this is another reason why choking is so popular. It's error free basically.

[StarMetal]

Jeff,

Just get a lead magnet. That ways nobody has to dive to the bottom of the pool in cold water. I believe Buckshot can make it for you.

Joe