Long range advice

[kmahow2]

Just so I understood correctly, a vertical spread of 18”, with a 2.5” horizontal. If that is correct then it’s called vertical stringing, usually related to variable velocity of shots or aim.

You need to run your chosen pellets out of your gun over a chrono. The extreme spread (ES) & thus standard deviation (SD) need to be small like <10fps ES, then the vertical string will be small. The smaller the ES/SD number the better. Weighing pellets should help get the best numbers here.

The other critical thing is the repeatability of the aiming mark & your ability to hold steady & repeat it. A springer requires a complete break of hold & movement of the gun to cock & load, so repeatability is difficult. That’s one reason a PCP off a bench with bags etc is more repeatable, no movement of the gun &in hold reloading.

Start with the chrono, if good numbers, then make sure you have an aiming point that can be centred on your scope.

[Dagwood]

At 100yds with the results you achieved I'd be assuming there was little or no variation in cross winds. However a variation in fore and aft wind would quite possibly have had an effect on the vertical disposition.
The weight variaition in the pellets may also have had an effect as you have suggested. How much variation is there in the fpe your rifle produces between shots and is it a springer or pcp?
So many factors; if it was me I'd just enjoy the results achieved and have another bash.
Jim
ps Which biscuits come in an 18" tin?

[Sonny200]

I agree that we probably need to be realistic with our expectations. Hard to expect a half inch group out at 50m+ unless you have some beast of a gun!

Just out of interest, have you tried 177 and 22 out at that range? I’d be interested to see if there’s a significant difference.

[NickJ]

I'd be very happy to consistently hit the tin!

For the grouping then surely weight matching the pellets would help as even the slightest of weight difference would have a significant altering of the arc over that distance?

[Born Again]

Back in the day when I was a complete air rifle anorak, I did some testing with using pellet lube and found it improved velocity consistency shot-to-shot, but only when an absolutely tiny amount of oil was applied.

The best method I found was to put two drops of lube into a ziploc bag, spread it all around the inside, then add a tin of pellets and gently move them around for a few minutes. Most of the two drops was left in the bag.

[Retnuhtibbar]

Thanks for all the replies, haven't got back at this since. Hope conditions are calm over the Xmas holidays and I'll be back at it. I've fitted a V-mach kit since, but also I have developed a cataract in my right eye .....not bad enough to be removed yet under the public system but annoying when pushing the limits target shooting. I wear glasses for reading but don't need them for anything else. I could get driving glasses but I don't need them....for driving but am wondering if they would help when looking through the scope. I was trying empty .22 rimfire cases last weekend but couldn't focus on them. I used to love the sound they made spinning away.

[MikB]

...
I was trying empty .22 rimfire cases last weekend but couldn't focus on them. I used to love the sound they made spinning away.

I used to enjoy shredding an empty fag packet offhand at 100 yards with ten rounds of 303, but I really think .22 empties are a bit challenging at that range.

Try to find something of a size between those and the biscuit tin...