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Thread: Questions on basic theory and technique of paper patching.

  1. #81
    Boolit Master Ricochet's Avatar
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    Smile A Couple of Newbie Questions

    I've shot cast boolits most of my life, and cast for about 25 years, but though I've been intrigued by paper patching since I was a kid I'm only now about to try patching and shooting my first ones. I've read through this sticky, the one on the LASC site by Mollohan and Iong, and lots of interesting threads here. A couple of questions I'm wondering about before I start wrapping: (1) On two-diameter boolits like bore riders, should the patch length be based on the diameter of the smaller part, to prevent patch overlapping there, or would you still base it on the larger diameter? Seems to me like the former would be best, but it will slightly increase the gap over the larger part. (2) If in looking at your boolit diameter, target overall patched diameter, and papers on hand, and see a combination with a thin tough unfilled paper that would give perfect dimensions with 3 wraps, is there any good reason not to try it? Is the double wrap carved in stone and handed down from on high, or just convenient? Thank you for sharing your experience!
    "A cheerful heart is good medicine."

  2. #82
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    I'll take a stab at it, The bore/groove dimensions of most modern rifles have a pretty standard net value, regardless of caliber. You're looking at groove depths of around .0025-.0045" Most rifle throats will allow up to .002" more patch thickness beyond groove diameter. What works for me is sizing the entire core to a thousandth or two larger than bore diameter and patching to just below throat entrance diameter. Groove diameter is really fairly irrelevant here. Size your necks only as much as necessary to hold a patched bullet that is just small enough to go into the throat.

    here's an example of a system that worked for me. In a modern .270 Winchester, a .271" as-cast core with only slightly smaller nose (.269 tapering up) patched to throat entrance diameter of .2785" took two wraps of 100% cotton Vellum or two wraps of wet 16 lb Green Bar printer paper. A .2685" core patched with thicker paper to .2785" printed shotgun patterns in the same rifle. Under-bore cores don't shoot well at all, ever, in my experience UNLESS you're talking pure lead and black powder, which is a whole different plate of enchiladas. Cores much more than three thousandths over bore don't shoot well, either, nor to long, under-bore noses regardless of how fat you patch them. I'm speaking strictly about modern rifles using smokeless powder at factory ammunition velocities.

    Another example is a typical .30-'06 with a throat entrance of .3105-.312", bore of .300-.301" and groove of .308-.309" Again, two wraps of 16 lb green bar, vellum, notebook paper, or Meade Sketch paper will bring a .302" core up to right about .311" and shoot MOA or better at factory ammo velocities.

    .45/90 Winchester, same deal. .453" cores patched to .461" shot best. Name-brand notebook filler paper did the trick, didn't try green bar because I didn't have any when I was fooling with it. .45 Colt rifle: Core at .448", just larger than bore, patched to .456" for a snug throat entrance fit and snug in a fired case shot best. Again, two wraps of just about any common writing or printing paper did the trick.

    I would never say that anything is carved in stone with regard to the paper jacket, but I have done a lot of things the WRONG way, and this method just works. It also happens to be convenient. I don't know of too many papers that are thin enough to make three wraps and come out in the "works best for me" tolerance range or that would be strong enough to withstand the wrapping. Then you add another 50% to the stretch factor and difficulty of having the ends of the wrap come out right.

    Regarding your first question, I personally have had the best luck using a lightly-grooved, torpedo-shaped bullet which has minimal under-bore-diameter nose length. If you do use a sort of bore-rider due to throat shape or short throat situation and thus find yourself patching a tapered bullet, my solution has been to cut a patch with slightly different angles on the ends. If carefully stretched when wrapped wet and allowed to dry, it is possible to achieve a no-gap situation and still have a tapered patch. I think I put up a bunch of pictures here about how I used a tapered patch on the AM-30-160 in my '06. Patch gaps can hurt accuracy a little depending on how large they are, but an overlap, in general, is worse. I try to keep my patch end gap less than a thumbnail-thickness wide.

    Hope that helps. I'm kind of stuck in one way of doing this since it works so well for me.

    Gear

  3. #83
    Boolit Master Ricochet's Avatar
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    Thanks, Gear.
    "A cheerful heart is good medicine."

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check