Why 2 Wraps?

[shell70634]

I've been reading the stickys, bought "The Paper Jacket", and googled. It's always 2 wraps of paper. Why 2? I'm sure somewhere it told why but I missed it.

If my 35 Whelen slugs at .360, should I wrap a 358 dia boolit with 2 wraps of .0005 thick paper?
If I used a 357 dia boolit could I use 3 wraps or thicker paper.

The more I type the dumber I feel

[barrabruce]

Of course you can to all the above.

some use 3x wraps of thin paper with stella results.

Remember that you are trying to a bore riding slug that is wrapped in a paper jacket that has to seal the rifling and grooves all the way to the muzzle.
It is not black powder we are using to relying on bump up does not occur.

So rules of thumb are.
Bore + 1 thou diameter core.
Groove + thou or more patch diameter.
If it takes 2 0r more wraps to reach that diameter so be it.

2 to 2.5 thou paper is pretty common and is about perfect for the 4 thou nominal groove depth of modern barrels.

micro groove and old original barrels had shallower rifling 2 thou maybe to deal with powder fouling and such.
Their geometry were different also.

Now if I could get a one wrap to stay on a core and make it through the barrel and come of in one piece it would be nice.
A chase patch breach seated maybe??

I've had no luck with sewing pattern paper with is thin and tough.
But others have.
I think you have to try a few things to see what works for you.

Now the one and a half wrap is a quick and neat thing.
As they're are no lines to meet up or over lap.
But alas it don't shoot that great.

[Hardcast416taylor]

To better give you an example of double wrappings is my .338 mold drops at .332" and my .416 mold drops at .411". I wet wrap using ordinary copier paper. After drying for a day I light lube with JPW and push thru a sizer correct for those calibers bore size.Robert

[PWS]

I always figured it was to put one full layer across the end seam to ensure full coverage.

The quickest and easiest way I've found to paper patch is one wrap of square ended sticky label or paper tape but the single layer doesn't seem to be as durable and I'm always suspicious that naked lead gets exposed at the seam. The standard double wrap usually shoots a little better than the sticky labels and isn't subject to adverse interactions between the adhesive and any lubes. Anyway, just my 2c...

[6.5 mike]

2 wraps allow the paper to lay down evenly at the seam, if done correctly it's real hard to find the seam. I use a lot of tracing paper, .0015 thick, this pulls down very tightly when dry. I've wrapped first then sized or sized first then wrapped. Doesn't seem to matter for me.
I do adjust my finial DIA with the thickness of the paper I'm using. I've been lucky in that a lot of my moulds drop just right to patch to what I need or want. My Lee 379- rf drops good for my 375 marlin, 2 wraps bring it up to fill the fired cases in my 38-55 without any other work. Cast, wrap, load, BANG, works for me.