Slow moving pellet trajectories

[Dornfelderliebe]

Due to an impending project (code name Bertha) I am trying to understand pellet fight paths with slow moving ammo. I know they are loopy.
I've just put a nice external condition auction buy Meteor together and what ever I did wrong has resulted in an M.V of 220 fps with .22 Superdomes.

Rather than Mither about it, this has given me the chance to explore low speed guns.
I've already got a nice .177 cadet and a disappointing Mk6 Meteor which both shoot well in their own way, so slow is not necessarily bad.

What I want to find out is whether heavy pellets starting out a slow muzzle velocity, loose less energy, hence velocity further out. Say a maximum of 25 yards, and pellets up to 44 grains. This difference is likely to have been observed by FAC shooters at long range.

My question is do heavier pellets retain velocity better and therefore not drop off as much as say standard weight .22s and in theory would this lessen drop?

Assuming this Meteors open sights were set up previously for 20 yards, today it dropped 17 inches and my 10 yard zero'd Webley premier drooped 4.
Interestingly you can almost count the gap between firing and impact. It's like a large clock between ticks and is very audible.
Out came the 1/4 bore Meteor with the usual immediate impact (508 fps with Marksmans) so I'm hearing it properly.

[Shed tuner]

drag is proportional to the square of velocity, so yes, slow moving projectiles (all things being equalish) will also ways lose velocity slower that faster moving ones... which of course means they lose erergy more slowly, as the mass is fixed.

Here's your trajectory with 11.3 FP / 340 fps at the muzzle, 44 grain pellet, and a high BC of 0.05 (educated guess, but it won;t make that much difference): 3/4" of holdunder at 10-15 yards, bob on at 20, 1.5" holdover at 25, and 4" at 30. But it is still doing 315 fps at 30 yards, and retains 9.7 FP energy, having lost almost nothing. A 12 FP .177, by comparision, would have lost around 100 fps at that range.



If I had this gun, I'd actually zero it at 18 yards, for a nice PBR of 5-21 yards (with a 1" KZ).

[angrybear]

My question is do heavier pellets retain velocity better and therefore not drop off as much as say standard weight .22s and in theory would this lessen drop?

That depends What if any constants are being used ?

If both start with the same velocity then the heavier pellet should retain more energy & therefore more velocity causing less drop rate. (the pro FAC argument)

if both start with the same energy, the heavier pellet will not have as much velocity, which will result in a greater comparative drop rate. (the pro .177 at sub 12 argument)

Then again are they zero'd at the same range ? (because the zero range controls the trajectory) or to give the best PBR +/- 0.5"

It's the same old argument dressed up in a new set of clothes.

[Dornfelderliebe]

That depends What if any constants are being used ?

If both start with the same velocity then the heavier pellet should retain more energy & therefore more velocity causing less drop rate. (the pro FAC argument)

if both start with the same energy, the heavier pellet will not have as much velocity, which will result in a greater comparative drop rate. (the pro .177 at sub 12 argument)

Then again are they zero'd at the same range ? (because the zero range controls the trajectory) or to give the best PBR +/- 0.5"

It's the same old argument dressed up in a new set of clothes.

Hello AB
I did not realise I would be reprising the 177/22 argument. As we are talking about sub 12 then the 44 grain pellet will start at a lower velocity and it's characteristics there after are my query.
In other words I was asking how loopy it would be and according to Jon's answer less than I originally thought.
May I clarify things a little. I am thinking of a 30 cal. pellet.
What might ruin this exercise is whether it would work in view of how much air would be required in the wider bore, something that I suspect will need real life testing unless some one knows the applied physics.

BTW two tins of Hades make excellent weights for the lateral raise exercise for some one with dodgy shoulders.

[angrybear]

What I meant is the basis of the same argument.
What I can tell you from my testing over the years is that once you go over 25-26gn in a sub 12, the muzzle energy falls off a cliff so to get 11ftlb with a 44gn pellet would take a LOT of power.

Chairgun lists a 43gn .25 pellet so using that with 11.4 muzzle energy at 20yds it retains 9.72 or 92.3%,
by comparison a 20gn FTT at 20yds has 9.34 or 90.5% or a .20 11.4gn retains 8.04 or 84%.
as for loopy purple is the 43gn .25, red is the 11.4gn .20.

[TonyL]

Nicely explained for you by the fine two chaps above, Tom. This should be a fun exploration.

[Dornfelderliebe]

Yes, thankyou both for your answer particularly the bit from Jon about still doing 315 fps at 30 yards. Rather like a politician, I do like headlines and pictures which I can grasp hold of, with limited understanding.

The volume of air needed to produce the power is going to be the limiting factor. I have a Mercury for a test bed which I do not intend to do any thing which cannot be reversed hence taking up Les Allam's kind offer of a Meteor barrel.
I'm sure it will need long stroking which I have already dabbled with along side a Welsh Willy kit which I shall order today and I have a spare Mercury piston.

When you look at the Hatsan Carnivore it's obvious that the cylinder is huge and the cocking effort would be too great for me in my current state. It does however produce 30 fpe.
https://www.youtube.com/watch?v=WcPK17YKS58

An earlier Heath Robinson experiment with a Marks man glued to an H&N at 39 grains worked ok but my cheap Chinese chrono would not read the velocity.

Will it even fire? As Harry Hill says. There's only one way to find out.

[TonyL]

drag is proportional to the square of velocity, so yes, slow moving projectiles (all things being equalish) will also ways lose velocity slower that faster moving ones... which of course means they lose erergy more slowly, as the mass is fixed.

Here's your trajectory with 11.3 FP / 340 fps at the muzzle, 44 grain pellet, and a high BC of 0.05 (educated guess, but it won;t make that much difference): 3/4" of holdunder at 10-15 yards, bob on at 20, 1.5" holdover at 25, and 4" at 30. But it is still doing 315 fps at 30 yards, and retains 9.7 FP energy, having lost almost nothing. A 12 FP .177, by comparision, would have lost around 100 fps at that range.



If I had this gun, I'd actually zero it at 18 yards, for a nice PBR of 5-21 yards (with a 1" KZ).

Lovely explanation and brilliant chart, Jon.

[TonyL]

This is going to be a most fun and eye-opening little project for you, Tom.

[Shed tuner]

it would probably work best if you put the big bertha barrel on the mercury, as the meteor, even long stroked, is unlikely to have the volume you need...

[angrybear]

Further to my post#5
When I previously tested heavy pellets in a .25 I was using my Hatsan striker springer & over 25-26gn muzzle energy fell off a cliff,
But I just tried some 33.95gn king heavies in my Scorpion se PCP & the ME went UP compared to the 20gn FTT I usually shoot, so it may differ between PCP & springer or it may not be a rule of thumb at all
FTT 20gn, 506 fps, 11.37fpe, King heavy 33.95gn, 396 fps, 11.82fpe.

[Dornfelderliebe]

it would probably work best if you put the big bertha barrel on the mercury, as the meteor, even long stroked, is unlikely to have the volume you need...

Yes that is what I planned and if the transfer port is less, open it to 1/8 in and no more. If it proves to need more air then I'll look for an unloved Mercury.

[Dornfelderliebe]

Further to my post#5
When I previously tested heavy pellets in a .25 I was using my Hatsan striker springer & over 25-26gn muzzle energy fell off a cliff,
But I just tried some 33.95gn king heavies in my Scorpion se PCP & the ME went UP compared to the 20gn FTT I usually shoot, so it may differ between PCP & springer or it may not be a rule of thumb at all
FTT 20gn, 506 fps, 11.37fpe, King heavy 33.95gn, 396 fps, 11.82fpe.

I believe PCPs give higher figures with heavier pellets, the opposite to springers.