Home Forums Hunting & Shooting BPCR Here's a weird question fer ya

I know this will sound like it's from left field, but since I'm about to swear a blood oath to eschew jacketed bullets....

One of you fellas tell me how lube theory works. Knowing that you send a bullet thru a lubrisizer, or pan lube...whatever...fill the grooves, load up and blast away...I'm doing fine with that up until the bullet obturates and starts down the barrel. Anyone know of any serious exploration of what is happening to bullet/lube/barrel in that brief twinkling before the bullet exits?

Sorta like...is the bullet just smearing lube on the bore, is it actully riding on a film of lube, er what? <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />

At least one curious mind wants to know it's more than voodoo.

Supposedly the lube is providing a thin coating all the way down the barrel that keeps the lead from tinning(soldering) it to the barrel, due to the heat and friction.
The lube grooves are supposed to keep "pumping" the lube as the bullet travels.

It's not a wierd question, ...........

but, I would expect some wierd answers..........

Planted the 1st part of the garden, today. Battling dehydration, I got tangled up with quite a few cervezas.

While the garden looks great, My answers might transcend wierdness, so......manana.

GTC

I have no idea whats really happening, but that has never stopped me before!

I imagine that the bullet is being slapped in the rear hard enough to accelerate it to lets say 1200fps in a fraction of a second, I imagine that this much force is trying to smash this bullets length down and so is squeezing the grease grooves and forcing the grease in to the lands and grooves.

I imagine that this is happening, but thats just me

Gary

Gary, that's the oburation thing...happening pretty quick then it's over, even before the bullet leaves the barrel. Hell, even before it goes very far at all. Pure lead obturates somewhere in the 12-14 kpsi range IIRC. Of course, I may not recall correctly at all....
Anyhoo, expansion ratios being what they are in BPCRs the muzzle exit pressure is WAY below that a foot or so down the barrel. So up to that point I sort of think I understand how the lube would find the barrel...after that is when I'm getting fuzzy on it...velocity picking up and needing lube even more I'd think. And I'm completely fuzzed out on just exactly how lube works in that environment as well.

Fuzzy Dan

Dan , This is not a 'teaser'.................I'm a bit swamped.....Garden, new dust collector, etc.

First instant in the launch cycle............base moves, nose , stationary.

Barrel has been prepped with a wipe of lube, or for us lazy types, TC 1000, Bore Butter.........

Me, I shoot an " exposed grease groove", at chamber neck juncture, thereby acruing a Hydraulic seal...........fluid O-ring effect.........defeats "lead ringing", so typical in .22 L.R>...........my reamers are designed with this incorporated., and the "transition area" is in effect ......THE swadge, size die.
Wow, talk about "Never Sweat"........though some just can't seem to get this figgered.

A barrel that is truly sized, bore / groove ( no F38kin' loose spots), in combo with the right wad, or IMHO, one with a bit of "Choke", will take care of the rest of the proccess.

Lube consistancy must vary, and be adjusted, incrementally, for temps, and course of fire regimens. This can make, or break the deal.

Gotta go do a DWG..................

We'll be back on this in the AM............early.

GTC

Thas just cool...the chamber swage thing. <img src="/ubbthreads/images/graemlins/cool.gif" alt="" /> Hadn't considered the point of the choked barrel...gotta get my thinkin' cap back on or so hep me Gawd I'll be soundin' like a genwine idjet. <img src="/ubbthreads/images/graemlins/crazy.gif" alt="" />

Thanks, standing by for verse 2:

There's a bit of angst about.........and some argument over "tight necked"chambers, Not "releasing" the bullet....I've been avoiding the subject, as I went on record (the article series " Big five in cartridge Rifle Accuracy" )..and There's been nothing radical discovered or proven that would change my views............although it DOES get discussed, a lot.

At a match a few weeks back , one character was loudly pontificating to all who would listen as to how he could'nt understand how a bullet could ..........." Bump up, in the chamber neck, and than run into a freebore ( "bumping / swadging a bit bigger yet)..........and than be swadged back down into the leade, and still work "

Well, I'm not sure I understand that either.....But I KNOW that it works...........and I know that's what's happening, all I have to do is measure my bullets, and my brass, and look at my chamber drawings.............Let's just assume that some understanding of the mechanical / physical properies of the materials involved is out on the table, too. Having looked at the chamber Dwg., and measured this and that, it becomes clearly evident, that when you've got this "on the money", and dialed in properly............the bullet is bumping up, AND swadging down, simultaneously.........

Let's design a reamer..........

* first, I need my barrel, or at least its' bore groove specs.
I like to put a .001" of "squeeze" on the slug, during that "first instant".......my best quality match grade barrels , in .45cal , are a .458 on their groove, so I'll pick a bullet that falls at .459", ( most custom Mold makers call out the nom. dia., when cast in 30/1 ).

* Now, I like to incorporate a bit of .460 dia. freebore , into my leade / throat equation, which allows me to hang that bullet well out of the case, usually with at least a coupla grease grooves exposed ( and some agrees, some don't)

* I need the brass, that I'm going to run ( particularly if I'm cutting back a longer " basic" case) and , in particular, I need to know its' average (and hopefully very uniform) neck thickness, Degree of taper through the intended Fire Formed neck ................and also have a good "feel" for its' maleability and " springiness".

when you pick something up off a table, or off a rack, you're going to have to work with the chamber you get. With any luck, you'll get things working, and have fine accuracy.........when you have some degree of control over your chamber dimensions................up front, things become a little bit easier ( and somewhat more reliable in terms of accuracy).

This has great appeal to someone with a lazy streak as wide as mine.

No assumption should be made that this chamber design is an easy one to cut, .........it's not.

Good thread, Dan.

GTC

That is just plain neat. A true test of your vision this night, under the full moon of the East and sipping magic tea culled from the pasture across the street...must discuss this with Weohumpkawekia beneath the scuddin' clouds. Or something like that.

You think that up yourself or did the Spirits put you on to it?

Honest to God, I would have never imagined that all those acrobatics would/could be planned...scares me that it makes sense. <img src="/ubbthreads/images/graemlins/cool.gif" alt="" />

Why this fascination with groove diameter? I contend that this is entirely an artefact of most modern shooters earning their training wheels with smokeless and copper.

If you do your historical homework, I think you will find that the most accurate rifles of the day were muzzleloaders. They aligned the bullet with the bore by using land diameter bullets (the WHOLE BULLET not just the nose). NOTHING will align your bullets better. Why not do the same? With bore pigs and a well orchestrated wiping routine, there is no reason why you shouldn't be able to do this today in any competition other than a timed relay.

Never have figured out this fascination with groove diameter bullets.

Brent

OOPSE,

One component you didn't mention, lead angle? <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" />

Brent,

You advocating bore size bullets <img src="/ubbthreads/images/graemlins/help.gif" alt="" /> If you are, won't shoot worth ka-ka <img src="/ubbthreads/images/graemlins/tongue.gif" alt="" />

D.D.,

You stay awake nights dreaming up those, "Weohumkawekia" <img src="/ubbthreads/images/graemlins/confused.gif" alt="" /> or is it your drinking to many magic teas <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> Better yet, you live an a closet and write your stuff and slide the note out under the door and some else sends those,"Weohumpkawekia" off to your readers.

Kelley O.

Kelly, upon some reflection, and a sip of "tea"...I may resemble that remark. The closet part anyway. Mine is a well choreographed life style. Wake up - coffee- faht- coffee - type coded message to "Weohumkawekia" - faht - nap. On odd and unpredictable phases of the moon I shoot guns, murder small animals and eat them. <img src="/ubbthreads/images/graemlins/cool.gif" alt="" />

Putting on a referee's hat, methinks there a substantial difference between disciplines in the BP world. IIRC, BP paper patch calls for something slightly under bore sized, patched up to slightly overbore. I shant mention the godless procedure with smokeless here in this forum. Frontstuffers do load bore sized bullets, perhaps a tad over bore if only to hold them in place. It works with balls because they are usually patched, and in the world of conicals it is necessary if a second shot is desired due to fouling. The truly accurate front stuffers were paperpatched as I recall, whether they were loaded with a false muzzle or not. They also get a wipe between shots. And they get lubed by patch or groove lube on the way down. Another point of some note, front stuffers shoot a diet of pure lead almost exclusively, something I understand is not always the case for BPCR. Different strokes takes different strokes...or so I've heard.

Well, lemme slip this under the door for my savage messenger.

Toodle

Brent, the only luck seen with boresized, in cartridge.....that I've been involved with, was with those fully breech seated, in Schuetzen , loaded / wadded cases loaded seperate.........200yd . Fixed ammo, with bore dia., has to much capacity for losing good co-ax alignment, and one would have to use "everlasting" brass, to get on top of that problem ( and, I reckon, A specific , adapted chamber neck)............working the pee out of regular necks lacks appeal. ( to me anyway)

K.O............I'm using from 1/2 degree ( smaller cal., .38), out to 1 1/2 degree ( .45 cal )...........I guess that's about right, cause they work. I'm wondering about incremental changes ( like 1 degree for .40 cal, 2 degrees for .50cal....??) , as bore size increases , but will keep everything where it's at, for time being. I like to see the ogive lightly suported, and a wee bit "engraved"....some plays with some "jump", and report good results . Was just talkin' to Sreve R., down at Tucson.....he plays with that, a lot....I wish I had more time, for that sorta fine tuning. My short, squatty 440 gr 'chicken bullets' run just fine, through that .460 freebore.....and in that case they are bumping up, prior to starting to swadge back down.

I wouldn't worry to much about D.D.s flights of fancy, he got $hit on by a Duck <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" />, at Shaman's party..........everyone who got anywhere's near it has been a little 'different' since. <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />
I'm glad that we didn't eat the damned thing. I need the Shaman to hurl one of those pyrotechnic thunderbolts over my reamers.....that'll really wake 'em up. <img src="/ubbthreads/images/graemlins/crazy.gif" alt="" />

D.D if you're "Fahting" a lot <img src="/ubbthreads/images/graemlins/blush.gif" alt="" /> , you're going to love the BP game......cuz everything smells like that, and one can do so with relative impunity. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />

GTC <img src="/ubbthreads/images/graemlins/cool.gif" alt="" />

OOPSE,

I like the 1 1/2 lead angle, dosen't distort the bullets nose when it gets slammed into the rifling. Me, I always like the bullet engraved into the rifling about .010 for best results.

I just take into account the D.D. lives in a closet and doesn't get out much, that's why he's moving to Mossouri. Maybe I better be nice to Ole D.D., so he'll invite me to Turkey hunt on his new spread, never been Turkey hunting. Seen a few two legged Turkeys though <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" />.

D.D.,

Thanks for clearing that up, BPCR versa's Muzzle loaders, really.

Have to agree about fahting and B.P.. Nice to let one and no one can tell or hear <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Kelley O.

Kelley,

All turkeys have two legs. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> But some have hair, and some have feathers. The ones with feathers be the ones that taste best...

As for bore (land) diameter bullets in a cartridge gun, if you ain't tried 'em, then you don't know what you are missing. I find them to work just fine thank you. No reason why they shouldn't either.

FWIW, the original Sharps long range bullets were 16:1 alloy, land diameter (after patching), and loaded way out into the lands. Only 0.1" of the bullet remains in a loaded case.

Check out the photos in Grant's first single shot book and you will see what I mean. If yo uwant to load these things properly, forget everything you learned about smokeless reloading. I think that is where the tunnel vision with respect to groove diameter bullets starts.

Brent

Well, thanks and you're welcome. I was planning to have a picture window next to the Throne when we build up there in Missouri, just to keep an eye out for turkeys. Don't see any reason we couldn't have a REAL turkey shoot someday. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Yup, in the lack of an unlimitted stock of custom ground reamers, or a super tooled grinding shop to modify, modify, and than modify again, I'm thinking that the 1 1/2 * is the good bet, too.

That 1/2 * thing works well, but anything but damn near perfect alignment is immediately visually apparent, and looks like Krap ( am not at all sure that a slightly misaligned wouldn't shoot like a house afire, though, check out the way Dave Crosnoe does his liners....and they DO shoot) . I think this is why we see so many of those very sharp, and abrupt angled throats, on the factory products.........easier to cut. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

The "freebore" feature is in the same realm, .......if you are not really confident of being able to get all the parts and tools pointed in the same direction, you should probably best avoid it.

No pun intended, but the capacity to get good tool geometries ground today , and affordable, at that , is a distinct advantage that the guys building the originals didn't have. And so, the quest continues. One can lean outside of the "traditional" envelope, and sometimes get a distinct improvement...................I think the performance of the BPCRS rigs is proof.

wish some of that rain that's pounding California would make it over here, we're getting nuttin'.

K.O...........are you using Carbide, or HSS reamers? Any thoughts , on same, welcomed.

best regards, GTC <img src="/ubbthreads/images/graemlins/cool.gif" alt="" />

OOPSE,

HSS for reamers. Freebore, theres some long range shooters who use a long freebore, more powder. I'm not a big fan because of the case bullet concentric problem.

Brent,

You caught it <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />..

And yes I've tried bore size bullets, shoot them for 6 months trying to work out the bugs, scores to prove it. I've messed with bullets sized from bore size to groove size in .001 increments over a 2 year period. Will have to say groove size shoot the best.

D.D.,

Interesting picture, setting on the throne, fahting, while looking out the window for Turkeys. Makes for a wonderfull start of the day <img src="/ubbthreads/images/graemlins/tongue.gif" alt="" />

Kelley O.

Kelley, I see you are up early today.

Sorry to hear about your bad luck with bore diameter bullets. They sure work for me.

Brent

Digital Dan:
Glen Fryxell has written an article about the function of bullet lubricant. The article may be found at www.leverguns.com/articles/fryxell/lube.htm. I have no experience casting or lubricating bullets myself, so I have no "know how," only "know about." The SPG publication by Garbe and Venturino, the one giving basic loading information for Black Powder Cartridge Rifles, has a detailed discussion of lubrication and cast bullets. Black powder lubricants need to deal with the solid residue of Black Powder combustion. Lubricants used on bullets propelled by smokeless powder don't have to cope with such a large volumer of propellant residue. Good luck sorting it out!