Success basics for undersized PP bore-riders?

[mosinman]

Particularly interested in Lee GC designs, C309-150-F thru C309-200-R in ".31" rifles like .303 B, 7.62X54R, 7.7 J, 7.65 Arg/Belg, etc.

There seem to be enough PPers here that use this unorthodox method successfully that I'd like to nail down the loading specifics of each individual in hopes of finding some like practices among them in order to establish some common standards.

Would like to know:

Patch material - thickness, length from base to nose,and no. of wraps

Boolit used - hardness, diameter both pre-patched and post-patched

Lube, if any

Case neck sized or unsized, and any additional flaring or other prep

Powder and charge wgt.

Primer used

Accuracy

Any other special techniques you may use


Thanks very much in advance :) ,


mosinman

[geargnasher]

I haven't used any of those boolits in the calibers you mentioned, but I have paper-patched bore riders with good success. I found it helpful to make sure the bore-riding section is only a thousandth or so larger than the bore diameter when patched, meaning that it will still chamber properly, leaving light, shiny engraving marks the length of the nose part of the patch.

Wet the paper properly and cut the patch crosswise to maximize shrinkage, you will be trying to get a patch tight just past the break of the ogive PLUS shrink to a two-diameter boolit.

Use the weakest paper you can for the pressures involved, since the bore-riding nose portion of the bands doesn't cut the patch through, it will have to unwrap or strip off by itself. Strong, 100% cotton vellum or similar tough paper might give you fliers. Direction of wrap so that the patch unwraps on its own might help, too.

Gear

[pdawg_shooter]

Slug your bore and size the cast bullet to BORE size +.001/.0015. Give it 2 wraps of 16# paper. Let dry overnight. Clip tails, lube, (I use BAC bot most anything will work), size GROOVE diameter or as large as will fit the throat. Load and shoot. Pure lead will work to around 2200fps. WW, air cooled to about 2500fps and a BHN of over 16 will handle 3000fps. You can start with jacketed starting loads and work up from there. Lyman 311414 and 311284 work great. I size min to .304 and load over AA2495 in the 303 Brit.

[geargnasher]

There's a tremendous amount of excellent information in that one paragraph, Pdawg. With that information alone anyone should be able to succeed, I know with about that amount of info and a few years of experience reloading and shooting cast making the transition to PP was easy for me. Most of it is common sense based on what you already know from shooting gg boolits.

Gear

[303Guy]

I seem to be getting fair accuracy with an under-bore Ø nose section that tapers up to a slight over-bore Ø before the step up to over-groove Ø rear section. I'm not sure that the patch is coming off at all and that's ordinary lined notepad paper. I have recovered just the overhang piece of the patch which was just a thin sliver.

http://i388.photobucket.com/albums/oo327/303Guy/BSAMpatchfragment.jpghttp://i388.photobucket.com/albums/oo327/303Guy/BSAMPATCH42GR.jpg

These boolits had a very short base overhang.

http://i388.photobucket.com/albums/oo327/303Guy/pictures002.jpg

On the other hand, when I use wheat bran filler which I'm sure forms a wad behind the boolit, the patch rear section stays on the boolit.

http://i388.photobucket.com/albums/oo327/303Guy/DSCF5574_edited.jpg

This was a lighter load but something similar happens with the higher power loads.