Wrapping as cast?

[Harter66]

I've 2 7x57s 1 is a 1908 Small Ring Mauser the other a brand new Savage re-bbl.

Both bbl show me .278 bore dia w/grooves of .286+ and .284 .

I've aquired an RCBS 270-130 fp mould that should drop at .279-80 .

Is it likely this will work w/o any added sizing steps ? Ie cast cool roll and final size .


I've read it ,but can't find those special consideration for GC boolits. Remind me please?

[45 2.1]

I've 2 7x57s 1 is a 1908 Small Ring Mauser the other a brand new Savage re-bbl.

Both bbl show me .278 bore dia w/grooves of .286+ and .284 .

I've aquired an RCBS 270-130 fp mould that should drop at .279-80 .

Is it likely this will work w/o any added sizing steps ? Ie cast cool roll and final size .


I've read it ,but can't find those special consideration for GC boolits. Remind me please?

That boolit has about 55 to 60% bearing length with a severly undersize nose for your intended usage. I would worry about it tipping somewhat more than anything else. Look at your 100 yd targets when you try it. Try air cooled WW and adjust the patch length so it engraves the throat when seated to the base of the neck. Don't worry about useing a gas check.

[geargnasher]

Wrap wet with two wraps of paper that will get your boolit up to throat size when dry. Basically adjust final diameter using only paper type/thickness until the boolit is a snug fit in the throat when chambered. Don't worry too much about groove diameter here as long as your boolits are patched larger than groove, which they will be if you patch to fit the throat. Bore diameter is key also, your as-cast boolits sound like they are PERFECT.

The GC shank works fine with paper-patch, no drawbacks really. In fact there is some advantage as it makes the patch tail easier to twist around the base without tearing.

I like to final-size my PPCB in a base-first sizer so I can get a little lube on the paper and crush the clipped tail into a nice wad of lube/paper under the boolit, but you don't have to. This almost always requires honing out a sizer die so the sized diameter fits the throat.

You might also need to modify your sizer dies, use a collet or bushing neck sizer, and an oversized expander. Too much case tension on a PPCB ruins accuracy, and a thousandth of interference fit is about as much as small calibers can tolerate.

If you have a throat diameter of (say) .288" and it's long enough to take the nose of your patched boolit, size to .288" and expand your case mouths to .287". Also check the patched boolit for fit in an UN-sized case, often they will fit just fine without sizing and only a slight bellmouth added to ease seating the boolit.

Gear

[geargnasher]

45 2.1 posted while I was typing, and he makes a good point. I've done a bit of work with and had pretty good luck patching "bore riders" with severely undersized noses by wet-patching full length to the "breakover" point on the ogive. I stress WET because the paper must stretch to be tight on the two-diameter boolit. You will also have to make make different angle cuts on the ends of the patches to accomodate the stretch and still have the seam meet up parallel. The paper on the nose will support it somewhat in the "bore" diameter of the barrel, provided the rest of the boolit fits the throat and there isn't much clearance betweent the chamber neck and the neck of the case.

Gear

Edit to add pic, this boolit has a very short bore-riding surface and a high bearing-length to nose-length ratio, but it's the same concept. I don't have a picture handy of some of the silhouette-type boolits I've patched with good success.

http://castboolits.gunloads.com/imagehosting/thum_89094ea39a08d9d9c.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2489)

Here's one for 45 2.1, see, the oversized Midsouth Cruise Missile is worth something!
http://castboolits.gunloads.com/imagehosting/thum_89094e014004bd7b1.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1266)

Speaking of patched bore-riders, this one has a .265" nose patched to .274" and it shoots just fine in my .270"-bore .270 Winchester.

[Harter66]

I went through the full learning curve w/an s k s last winter.

I didn't give any thought to the nose dia being an issue even though I was reading through the slumping threads this morning. I knew it was too easy! :-)

[geargnasher]

Try it and see, all the theory in the world is really pretty much just useless speculation until you pull the trigger. If you tinker with usual suspects of paper thickness, case tension, seating depth, powder type and charge, and maybe even fillers and still can't get it to shoot straight, maybe the nose-slump caution proved itself, but it might work just fine too.

Gear

[Nobade]

Don't know what you'll get with the Mauser, but I'd bet the Savage will work fine with that boolit. I have the same mould, and patch it with onionskin paper to shoot in my 7mm TCU. It's really handy to not have to size anything, just cast wrap and load. I do smear a little vaseline/beeswax lube on the patch, and do run the patch up to just over the break in the ogive to get the nose big enough. But it shoots lights out in my TC and has won a few standing big bore matches so far.

With the Mauser, just use thicker paper. If the boolit doesn't fall through the bore before you patch it, you will probably be able to get it to work if it's long enough to touch the lands and still be in the case. (If not you could still breech seat it. )

[nanuk]

I"ve always wondered how well the patch comes off with the undersized nose....

Nobade: do your patches shred at the muzzle even with the undersized nose?

[Nobade]

As far as I can tell they do. They shoot really well, and I never find anything but very small pieces of paper on the ground.

[geargnasher]

Nanuk, if you'll look at this confetti from tough, 100% cotton Vellum paper, you can see the larger triangle pieces from the nose section where it didn't get sliced by the rifling. But at 2700 FPS it comes off anyway. The paper from the main bearing bands gets sliced into neat little squares and makes quite a cloud at the muzzle. The base "wad" can usually be found about 10 yards down range with four little "petal" stubs fanning out from it.

When using notebook paper, there's nothing left to recover, but they shoot about the same accuracy/wise, so my conclusion is that rifling doesn't really have to slice the paper on the nose for it to shoot straight.

http://castboolits.gunloads.com/imagehosting/thum_89094e013fb0b7377.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1265)

Gear

[45 2.1]

Nanuk, if you'll look at this confetti from tough, 100% cotton Vellum paper, you can see the larger triangle pieces from the nose section where it didn't get sliced by the rifling. But at 2700 FPS it comes off anyway. The paper from the main bearing bands gets sliced into neat little squares and makes quite a cloud at the muzzle. The base "wad" can usually be found about 10 yards down range with four little "petal" stubs fanning out from it.

When using notebook paper, there's nothing left to recover, but they shoot about the same accuracy/wise, so my conclusion is that rifling doesn't really have to slice the paper on the nose for it to shoot straight. Gear

Yes, but you stated this:
Speaking of patched bore-riders, this one has a .265" nose patched to .274" and it shoots just fine in my .270"-bore .270 Winchester.

His post states:
Both bbl show me .278 bore dia w/grooves of .286+ and .284 .
I've aquired an RCBS 270-130 fp mould that should drop at .279-80 .

Patching his boolit will give a patched nose diameter of bore or under. Not 0.004" over bore as per what you did. He will have to try to see if it works all the time.

Good use for the oversize CM.............:Fire:

[geargnasher]

My RCBS 270-150 mould drops boolits right at .271" on the parallel bore-riding part, I assume the 130 boolit is similar. If one patches the whole boolit with two wraps of 16-lb paper it should bring the bands up to around .287" or so and the nose up to .280", still a couple thousandths over bore, and possibly enough to help support the long nose at least a little bit. It won't keep it from setting back, but it might help guide it if launched gently enough and straight enough to begin with. I have to use very slow powder and some compacting filler to get that CM to shoot straight, fast powders do bad things to the boolit and they don't fly straight after they get out of the muzzle.

Gear

[45 2.1]

Possibly............ IF the throat weren't a funnel. Slug a 7mms throat and see what I mean. The mauser probably is and the Savage might be. Considering the SAAMI specs replicate the military 7x57 chamber, I wouldn't put money on it. He still needs to try it.......................

[geargnasher]

True, there is that. Too bad there's only on boolit designer around anymore who knows how to design boolit noses.

Gear

[pdawg_shooter]

45 2.1 posted while I was typing, and he makes a good point. I've done a bit of work with and had pretty good luck patching "bore riders" with severely undersized noses by wet-patching full length to the "breakover" point on the ogive. I stress WET because the paper must stretch to be tight on the two-diameter boolit. You will also have to make make different angle cuts on the ends of the patches to accomodate the stretch and still have the seam meet up parallel. The paper on the nose will support it somewhat in the "bore" diameter of the barrel, provided the rest of the boolit fits the throat and there isn't much clearance betweent the chamber neck and the neck of the case.

Gear

Edit to add pic, this boolit has a very short bore-riding surface and a high bearing-length to nose-length ratio, but it's the same concept. I don't have a picture handy of some of the silhouette-type boolits I've patched with good success.

http://castboolits.gunloads.com/imagehosting/thum_89094ea39a08d9d9c.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2489)

Here's one for 45 2.1, see, the oversized Midsouth Cruise Missile is worth something!
http://castboolits.gunloads.com/imagehosting/thum_89094e014004bd7b1.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1266)

Speaking of patched bore-riders, this one has a .265" nose patched to .274" and it shoots just fine in my .270"-bore .270 Winchester.

I have taken the time to hone out the bore riding nose section of my molds to bore diameter +.001/.0015/. After sizing the bullet to correct diameter I have a full length bearing surface to patch. No way the nose can slump or sag that way. Allows you to load to full velocity without any accuracy problems caused by bullets that have distorted under acceleration.

[Harter66]

Thanks guys ,
I still haven't gotten around to casting any to see what they really drop.

I won't be hot-roding either 1 of them. I burn a lot of 4350 ,maybe some 4831. I don't expect to push the spaniard much past 2300 or so as its twisted for the heavies . I think the Savage will take them full tilt. I figure on running 50-50 WW 1-20, maybe water dropped,I might have to shoot a critter w/them.