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Pellet sorting / inspection / batching - my present ultimate strategies for long ranging .

September 10 2007 at 9:23 AM

Yrrah  (Login Yrrah)
YFOT

There is one strategy I have hinted on a number of occasions but from memory not explained ... Scott in Colorado may have some curiosity satisfied.

I will not claim that anyone following this procedure will or will not benefit above what they may currently undertake in their own treatments. Nor do I think you will necessarily notice any difference out to normal air gun ranges of 50 metres or so. I think I notice about 0.20" to 0.25" at 100 yards in best conditions in groups that average around 1.15" to 1.35" or so. My very best groups have come when using the full Monty.......

Here goes: - on serious pellet batching with inclusion of a couple of discriminatory procedures that I have developed these last four or five years. I have PCPs in mind and in particular the JSB Exact .22 pellet.

I emphasize that the current pellet that stands above all others for my purpose ( from my two PCPs ) of long range group shooting is the JSB .22 cal Exact 15.9 gr round nose with a BC of 0.036 / 7 / 8 depending which altitude range I am shooting ( corrects to 0.032 / 3 at sea level ) from my BSA Hornet and RWS Excalibre, both FAC 27 to 28 fpe.

After washing and rinsing if you think that to be necessary .....: Take 1 to 5 in the order indicated.

# 1. Inspect inside skirt lips with a magnifier for excess lead flashing and other fixed debris that could contribute to unbalancing the pellet in flight. Look for gaps in the edge of the skirt lip. Put any rejects aside for future specific research tests or plinking.

Normal clean skirt:

[IMG][/IMG]

One with flashing in a batch that slipped by the excellent quality control of JSB some years ago.

[IMG][/IMG]

# 2. Weigh and batch sort the clean pellets into three or more weights. I find good powder balance scales to be sensitive to perhaps 1/20 th gr by interpolation .....
The assumption is that the heaviest are the normal pellets that have properly filled the die in the stamping process and do not have an excess of air bubbles / air pockets. ( Note the reject pellets with additional flashing may have also weighed at the heavier end of the scale ).

# 3. The Yrrah Roll: I developed this to discriminate the ratio of pellet head size to pellet skirt size. I tried measuring the heads and skirts with calipers and a micrometer but was not satisfied that the measurements did not in fact introduce a ding into the soft lead; and it is almost impossible to measure the lips of head and also skirts in a way that does not have some angle. So the Yrrah Roll goes like this.

See picture worth a thousand words . .. .

[IMG][/IMG]

The skirt of each pellet is placed against a unit mark on a ruler that is stuck upside down to a glass top table. It is upside down so that the edge touching the pellet is at half pellet height above the glass surface. This facilitates pellet alignment. Much care to be taken here in aligning the pellet so that both head and skirt touch the ruler. If it feels wrong it probably is wrong. Some skill will develop with practice.

Now the table should have the tiniest tilt. Stack a leg with paper to get the required tilt that will allow the pellet to roll when given the tiniest encouragement, either by gently blowing through a straw or touching with the softest feather...... The pellet now rolls in an arc according to its head to skirt diameters ratio. The second ruler is placed such that after the pellet has rolled a reasonable distance the second ruler is located tangentially to the incoming pellet.

OK so we roll the pellets and as each one arrives at the second ruler we transfer it across to the other side of the ruler standing on its skirt to be batched with similarly indexed pellets. See pic...... You will notice that there will be a somewhat normal bell curve discriminating the different arcs taken by the pellets.

Now the ones that describe the tightest arcs have the biggest difference between their head size and their skirt size......... OK, that is established but that does not mean that those which have been batched together all have the same head size and skirt size as one another. The RATIO however is the same.

# 4. In order to now discriminate head size and re-batch the Yrrah Rolled pellets into further sub units we need to group them according to head diameter. That will sort them into those that not only have the same ratio of head to skirt diameter but also the heads and skirts must logically be sorted according to size. .... I have already indicated that I do not like using calipers or micrometers but if you have a three point micrometer of suitable dimensions ( if such exists ) and the necessary skills you may try it!... I use a simple method that seems to work..... Others have done this ( Anthony and probably others ) so it is not my innovation.

[IMG][/IMG]

It requires patience and trial and error but it works. ... Adjust a caliper to an approximate head size and lay a pellet on the gap. With some manipulation the caliper gap can be so adjusted as to allow some pellet heads to drop through while their skirts, being larger, get hung up. With trial and error you can batch the pellets into say three different head sizes. ( Take little notice of what is written on the tin, it may or may not be close, and in any case I have yet to find that I cannot re batch into about three different sizes. Head size differences may mean slight differences in the dynamics of chambering into the bore.

# 5. The HFI test:

We now have numerous batches of pellets sitting in all those spare empty tins you thought you would never use ... Mark each tin according to some category you have dreamed up. Numbers and letters in combinations may be better than worded descriptions ( Think binomials ) ...............
We are finished or almost finished batching depending upon whether or not all the pellets came from the same die lot. We will now establish that and at the same time prepare each pellet for index loading into our rifle... Requirements are a magnifying glass and a waterproof permanent felt pen with a fine point.

HFI Test : Using the magnifying glass and in good light, peer up the shirts of the pellets into the hollow recess. What you will see is a "fingerprint" from the die stamper. It will probably look like a pattern of criss crossed lines. (I am still talking of JSB Exact .22s remember as they are the best small bore long range pellet and if you don't have a rifle that loves them then start saving ) ..

After some practice you will get to recognize the "fingerprint" pattern. JSBs never seem to have pellets from different dies in the one tin but from tin to tin over the years I have come to recognize a number of different stampings. .... OK, with your fine tipped permanent marker felt pen you now place an indexing dot on the outside of the pellet skirt to identify one and the same particular aspect of the fingerprint you see inside the pellet. Put each back into its own batched tin. ...... If you find different stampings from different dies then of course they must be batched separately........ If you use other types of pellets, you will have to find " fingerprints" perhaps of a different kind.

When long range serious shooting time arrives, I draw pellets for each five or ten shot group from the same batches. The ones that weighed the heaviest ( the pellets should have batched into at least three different weights ) are saved for the most serious attempts when conditions are near perfect..

Now if you have a single shot rifle like my BSA Hornet, then you will index the felt pen spot such that each pellet is loaded into the chamber in precisely the same orientation. The reason for this is to account for any fractional imperfections of the particular die, be they real or imagined. If real then you are accounting to some extent for their geometric qualities such that any imbalance will be similarly dealt with by the rifle and barrel such that the pellets will emerge from the crown with the same orientation and therefore have a chance of setting off in the same direction and trajectory.... If you have a repeater then you orientate the index mark such that as the magazine rotates into position, the pellets will be similarly indexed into the chamber.

Well there you have my most fastidious batching strategies and they should be done in the order of 1 to 5 as above.......... You may or may not find this of interest, I hope you get something from it........... Kind regards, Harry in OZ.


    
This message has been edited by Yrrah on Sep 11, 2007 6:38 PM


 
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