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All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Big Bore AirGun Gate => Topic started by: superchikn on May 14, 2022, 02:12:12 PM
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For those of you who sort your projectiles by weight, in my case .357 home cast 95 grain slugs, what criteria do you group your weights into? By 1/100th , by 2 or three hundredths? I dont imagine thousandths matter at this weight like with .22 or .177, but with the bigger bores is a 100th significant , or 5 100ths or only worry about 10ths?
Thank you
Mods, if I put this in the wrong place I apologize , but my thought was that this was big bore specific.
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A 1% difference in weight will only cause a 0.5% difference in velocity, and heavier slugs will carry their velocity better downrange, so at the target the velocity difference will be even less.... That means you will never see a trajectory difference within 100 yards due to that amount of weight variation....
If you sort by 10ths of a grain, with a 95 gr. slug, you are sorting by 0.1% increments.... IMO that is a waste of time.... If you discard and remelt any slugs that are more than 1/2 gr. from your average that is probably good enough, as that is just over a 1% total range of weights.... Unless your cavities are different, you should never really get any "heavy" slugs, and "light" ones may indicate a void, which can shift the CG off-center.... That can result in a "flyer"....
Here is a typical weight distribution range for premium grade pellets (from Hard Air Magazine)....
(https://hardairmagazine.com/wp-content/uploads/2022/02/HAM-Weights.jpg)
88% of the 50 pellets weighed were between 18.21 - 18.35 grains, which is a 0.75% overall spread.... It is the "outliers" that might cause fliers.... Even the total spread of 2% is low for the average pellet, and from a trajectory perspective would be unnoticeable in practical terms....
Bob
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Wow Bod, That is tremendously helpful!
This is a new mould NOE 359 93 RN, and I am still figuring out my Challenger 357 bulpup.
My barrel slugs at 356 ish so I got my sizing dies today. The slugs were dropping at .358 so I sized them down to .357.
Then I sorted the 100 or so slugs into piles by the 100th. The vast majority dropped between 94.8 and 95.2 with a pile of lighter slugs. Again this is a new mould and I am quite new to casting pellets/slugs.
So I will watch for the light ones and remelt and put the rest of them together.. I just didn't want weight to be a major factor while I am try to figure out the sweet spot with the gun and diameter for the bore.
Thank You for your help!
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Bob,
I apologize for the typo on your name.
I guess I need a little more sleep, I did not sort by 100ths, my scale only reads to 1/10 grain.
Just cast another 200 approximately and although there are some outliers 90% or better are within 8/10 grain range.
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My view on sorting projectiles into groups by weight is that unless you resight your gun for each weight group (and can actually tell the difference in point of impact).... you may as well just shoot what you have.... The exception is when most of them fall within an acceptable range of weights, and you discard the rest, or just use them for velocity testing (which is what I do)....
Bob
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I am not a sorter. i have dabbled with it with commercial pellets a few years ago but I do not shoot competitively and do not have the time for that.
Being new to casting, My first mould is the NOE 217 - 20 RF.
I have cast over 500 of those pellets and most look great. Some are a little light at the skirt, others have some flash, I have been adjusting the pin depth in an effort to eliminate the flash. While a slightly short skirt may be visible easily it is not always, and the same goes for flash, So i figured the best way to get my mould and technique dialed in was by checking weights.
i was following suit with the 357 mould as I'm trying to find something that works in my challenger.
having weighed the 200 or so I cast this afternoon and 90-95% being within the parameters you outlined I feel pretty comfortable with my results at this point. I expect to be able to shoot at my buddies house tomorrow if the rain stops and get some more data.
This would be an easier quicker process if I could shoot the Challenger in my back yard like all of my other airguns, but that would not quite fly.
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I sort the NOE 358-152-HPs down to 1.0 grain. They are very easy to handle and sort so that's just what I do.
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I sort the NOE 358-152-HPs down to 1.0 grain. They are very easy to handle and sort so that's just what I do.
Same here with the NOE 356-84-RF-CC5 pellets. The rest either go back in the pot or plink with.
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With exception of hollow points, most of what I cast is signing 1 grain extreme spread. And most of what I cast is more than 125 grains. Then I powder coat which throw the entire thing out of whack.
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Well the Noe 359-93 RNs did not shoot well at all, sized to 356 and 357 but better than the 358 they drop at. I had sorted them yesterday into bags by 1/10th, This was done before I started this thread.
Groups of 4-6 inches at 45 or so yds and a couple shots would get close but there was no pattern to it.
This slug-
https://www.amazon.com/dp/B001OPTGSW?psc=1&ref=ppx_yo2ov_dt_b_product_details, (https://www.amazon.com/dp/B001OPTGSW?psc=1&ref=ppx_yo2ov_dt_b_product_details,)
shot much better sized to 356 and unsorted. Maybe 3" or so with a flyer or two.
Of course they had to be single loaded but they might be telling me I need to go heavier.
I shot a string over the chrono two weeks ago, i think they were the JSB 81 pellets but I did not record anything, I think it is shooting hot and if i remember correctly there was a 50 -60 fps drop between shots, maybe more.
Accuracy does not improve from 25mpa - 15 mpa, about 8 shots so I am thinking just too much hammer spring , and or I need heavier ammo.
This week I will pull the barrel again and recheck the crown and the leade. I had smoothed the ports inside and had not seen any damage on the slugs I had pushed throuth the barrel.
This is frustrating!
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Heavier in a challenger might be hard, only so much room.