Pellet Rolling - theoretical question

Here’s the way I do it, fwiw:

>Start by sizing the skirts - I don’t mean checking the size, I mean pushing them all thru a sizer for uniformity. You can use a smooth-walled rotary magazine of any brand, as long as the chamber bore is just tight enough that pellets have to be pushed through. Example - Leshiy 2, I pick one chamber on one magazine (for consistency) and push pellets through with a piece of dowel. It goes pretty fast.

>Now that all of your pellets have the same skirt diameter, now it’s time to roll-test! And here’s the fun part..

>Make a miniature ramp with a piece of glass, just steep enough for gravity to do its thing. Waiting at the bottom of the ramp is one of those giant pill-boxes us old people use to organize our meds. You know the one: MTWTFSS! Release the pellets as repeatable and robotic as you can, from the exact same place, and you’ll find that most of them drop into Wednesday for example. And a few in Tues and Thurs. The others can go to hell, because there’s your flyers!

I find (in my opinion) that disparity in head size has a more profound effect on accuracy than disparity in weight. When you want to get even more OCD, start sorting the various “Days” by weight, and dig deeper to see what head size your gun likes best - and hope its Wednesday (in this example)!

HTH

Brian / @airgunner.usa 

The JSBs have been so consistent in head size that I just check a few from each tin early on in the sorting process. After weighing I roll them and the gun does seem to shoot some of the rolled groups a bit better than others. So, I just sort them into weighed rolled groups. Using the ones that I know don't shoot quite as well when I don't care about the accuracy as much.

There's a geometric proof floating around on this form that shows the only way that two pellets can roll to the same spot is if the head diameter and the skirt diameter and the distance between the two bearing surfaces are identical.

A lot of people think that rolling measures the ratio of those two diameters it does not. Rather than redo that proof here I just recommend you look for it and it will explain what rolling tests.

I personally think that a slope of 1 in 25 is just about perfect for your rolling table. I also think that weighing after rolling or vice versa is probably a good idea because a pellet could have a thicker skirt and still roll to the same place as one with a thinner skirt even if the dimensions that are tested are identical between the two pellets.

I have had good luck with sizing pellets but after I size them they don't roll in a curve anymore. I think what I'm doing there is sizing the head and the skirt to the same diameter. Those pellets sized that way still shoot good for me in a couple of my Diana rifles.

OldCrow - how do you head size? Pellet Gauge or something similar?

Angle of the table - I did notice a shorter curve at higher angles on the table. I think mine is about 1 in 20 as well. I use an 11 x 14 glass with a 3/4 (really 5/8 inch) block under the end. Seems to give very consistent results. Looks like weather might be bad this weekend, so shooting might not happen.

Every gun is a bit different, so will to experiment with mine. I have JSB's and Corsman's washed, lubed, weighed, and sorted for bad pellets. So far, while not sizing the head, I've rolled the pellets from a height of 6 inches and it's amazing the difference in arc. Arc is anywhere from 4 to 9 inches on the JSB's. I have them ready to go by weight and arc, and even have a couple pellets identified as bad via rolling to see how badly they shoot. With the weather I might be limited to chronograph work, but we'll see if it all makes a difference someday.

I haven't worried much about sizing as the FX barrels basically mash the pellets into the same shape / size before they exit the barrel. I'll pass along any info I get, but sounds like I just need to find the combination that works for this gun.

Many thanks,

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I head size with a pellet sizer. 

With a new rifle I first find out what pellet it shoots best. Then I sort a tin of those by head size and shoot them for groups. Once I know what pellet and head size I M going to shoot in that rifle. I buy a sleeve of them at two thousandths larger. I size those for the rifle. Works for me. When I use that process I don't roll the pellets because I size the skirt along with the head. I think this process is just fine for pellets with thin skirts. It may not work on hard alloys or thick skirts.

My opinion on this and probably incorrect-

It seems that anything that "rolls" to the shorter end of the scale (assuming that means the skirt is relatively wider than head) should shoot relatively consistently with the ideal head size becasue the leade is going to seal well and the barrel will compress the skirt/head to the ideal level. Might have a bit more resistance but doesn't seem like it would be a lot. Those that "roll" to the longer end of the scale (assuming that means that skirt is relatively smaller than head) might have some blowby and might need a bit of energy to expand the skirt and seal. Maybe a shooting test to compare the "ideal" (Wednesday) and all those with relatively larger skirts to all those below that point in skirt size might be informative?

My opinion on this and probably incorrect-

It seems that anything that "rolls" to the shorter end of the scale (assuming that means the skirt is relatively wider than head) should shoot relatively consistently with the ideal head size becasue the leade is going to seal well and the barrel will compress the skirt/head to the ideal level. Might have a bit more resistance but doesn't seem like it would be a lot. Those that "roll" to the longer end of the scale (assuming that means that skirt is relatively smaller than head) might have some blowby and might need a bit of energy to expand the skirt and seal. Maybe a shooting test to compare the "ideal" (Wednesday) and all those with relatively larger skirts to all those below that point in skirt size might be informative?

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Interesting thoughts. I have no clue what the answer might be to that one. A test is a good idea I hope someone does it. Another thing similar to your point is the idea that rolling may or may not distinguish pellets with a "bent" head relative to the skirt or one which was not symetric around its axis.. It might not take much in that characteristic to throw off the pellet and still not show up in the sort. Lastly is the idea that you can have one which is shorter/longer between the bearing surfaces. A shorter distance in that dimension would roll "high" and a longer one would roll "low".

It is a complicated test.

I've been using an air gauge to size my pellet heads. It's pretty accurate but a little pricey. I shoot the same during a tournament so I can dial in by FPS. I weigh, gauge, wash & lube my .177 for my RAW rifle. I'm going to try your suggestion and roll them. I heard that that most difficult part of rolling is trying to roll them identically/consistently. I've got a local tournament this Sunday so I'll see if they make make an improvement rolled. 

I think finding a good regulator may be key also. I open to suggestion on the best regulator for consistency. I don't need power for a .177 at 25m but If I can get the air moving the same with each trigger pull that would be awesome.

Thanks for the tip. Bob

To those of you that roll pellets, I started an experiment tonight.

I've washed, lubed, inspected, and weighed batches of pellets, but still get a flyer once in a while. So, thought pellet rolling might help.

However, as I understand the accepted procedure, you need to do head sizing first, then roll to ensure the relationship between the head and skirt are consistent.

But, at this point, I'm not willing to spend the $50 for a pellet gauge.

So, other than finding damaged pellets (which to me makes it worth the effort), is there any advantage to rolling without head sizing first?

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Salt Lake 58

Look around for the Yarrah Pellet roll method, he is the one that posted about it, and has all the information for that method.

Here is a starting place, Google = "Yarrah pellet roll method", go to images page and all the info is there, for you to read.

HTH's,

Don

Salt Lake 58

I just found this info here,

https://www.airgunnation.com/topic/d430l-177-hn-ftt-25meters-yrrah-roll-anecdotal-1/?referrer=1

HTH's

Don