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Measuring Patch Thickness?

Discussion in 'Blackpowder' started by John C, Aug 2, 2014.

  1. John C

    John C Well-Known Member

    I picked up a new BP rifle, in .50 cal, and was loading up some PRB with some patches that came with the rifle. The .490 balls and patches were EXTREMELY difficult to seat. I think I need thinner patch material, but how do I figure out how thick my current patches are, so I can buy thinner patches?

  2. Plastikosmd

    Plastikosmd Well-Known Member

    Micrometer works best, caliper in a pinch. If not available, local gunsmith or if near a machine shop, they could check it out for u?
  3. BCRider

    BCRider Well-Known Member

    I've just been using a set of calipers. To avoid crushing the material too much put the material deeper into the jaws so it sits on the flat faces instead of on the sharper wedge like ends of the jaws.

    I've been learning a lot about patches recently. Some material, such as flannel, will measure out thicker but it crushes down so easily that it drags in the bore more like a much thinner plain woven patch. I've also got some material here that uses a less tight twist on the threads. Again it measures thicker but it rams home more like a thinner material. So the nature of the weave counts for something as well as the thickness reading.

    CANNONMAN Well-Known Member

    YEP, Micrometer is better than caliper. Probably why they cost so much more. Measure in several spots. How to avoid righteous BCRider's crush problem comment. Measure two flat rigid items, like two pieces of 1" square 18g sheet metal. Place patch between sheets. subtract sheet metal. I doubt you will need the accuracy of Micrometer. Nice to own but $$$ might be better spent on BP.
  5. BCRider

    BCRider Well-Known Member

    That still doesn't tell the whole story. The crushability of the patch material means that the final method is to actually try a piece. Since different density materials will pack differently we can't go just by the measured thickness when the measuring tool has supportive pads.

    Ideally one would have a few of the next size smaller balls to try with a new patch material. If it proves to be just right for ramming resistance with the smaller ball then one can assume that it'll be too thick, when crushed, to work with the desired size ball.

    Another option that I'll need to play with is to use the flats on the caliper jaws to measure the "bulk" thickness and the small contact area wedged ends of the jaws to measure the compressed thickness. Using the small contact size ends should offer up a little feel for how the material will pinch between the ball and the lands of the rifling.

    This crush ability does matter. I found that a patch which measured thicker at around .019 to .020 actually crushed down and rammed more easily than a "hard" weave that measured .012.
  6. swathdiver

    swathdiver Well-Known Member

    Get a micrometer and measure the compressed thickness of your existing patches. Then go to Walmart and find several different samples of cotton/linen/denim that are each .001 thinner than what you started with. Shoot 5 round groups with each sample. When they get easier to load and the groups tighten up, go back and buy a bunch of that material. Just make sure the ball you're using, you can keep getting them in that exact same size! That's why we cast our own, to remove the variables that lead to wide patterns and flyers.
  7. Steel Horse Rider

    Steel Horse Rider Well-Known Member

    I buy cotton cleaning patches to use for patching. They are cheap, readily available, and work great in my experience. I apply just a spot of Bore Butter on each one, put them in a margarine or yogurt container and microwave them for a bout 20 seconds. It melts the Bore Butter into the cloth. I throw a handful of patches and round balls into a Ziplock bag and go shooting. Cheap, easy, and useful.
  8. swathdiver

    swathdiver Well-Known Member

    What do you shoot and what groups are you getting at 50 yards SHR?
  9. BCRider

    BCRider Well-Known Member

    It may or may not be an odd way of looking at it but it seems to me that the patch is very much like a sabot for the round ball. It's the way the patch contacts the ball and the rifling that sets up the spin on the ball as it travels down the bore. Or in the case of a smoothbore perhaps it's more about avoiding any unwanted tumbling.

    As with many things what starts out seemingly simple turns out to be surrounded by interwoven factors.
  10. Steel Horse Rider

    Steel Horse Rider Well-Known Member

    Swathdiver: I have a 50 caliber Lyman Plains Rifle, a Pedersoli 54 caliber Hawken, and a Pedersoli 50 caliber flinter, as well as several 45 and 50 caliber pistols in both flint and cap. My best at 50 yds is about 4" groups for 5 shots from a standing position with the Plains Rifle, but I can regularly hit half gallon milk jugs at 40 yds and I can regularly hit a 3" spinner at 20 yds with the Kentucky 45 caliber pistol.

    I am not a purist and usually look for practical ways to keep my costs down and the round cleaning patches sure beat buying cloth and cutting it up. This weekend I bought a bag of 170 patches for $3 and change, I don't figure I can cut 170 patches for that.
  11. swathdiver

    swathdiver Well-Known Member

    Thanks SHR. Those guns are capable of under 2" groups if you were more particular about patch thickness and lubrication. But that's fine shootin' for hunting and plinking.

    A yard of cloth can yield over 1000 patches for about $6.

    Ever heard of Dutch Schoultz's The System?
  12. BCRider

    BCRider Well-Known Member

    It sounds to me like SHR is shooting from a freestyle standing position instead of rested. If I'm right then this is more about his accuracy then that of the guns.
  13. John C

    John C Well-Known Member

    Thank you, gentlemen, for all of the great information.

    Thank you, Swathdriver, for the info on Dutch Schoultz's The System. I am going to order that tonight. It's just what I'm looking for!

  14. Zeke/PA

    Zeke/PA Well-Known Member

    Ask a Toolmaker/Machinist friend if you can borrow his Dial Thickness gauge.
    Much better "feel" than a standard "Mike".
    The Fabric dept. at Walmart is a good place to find what you need.

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