TargetTalk

Pistol Pellets: 7.0 gr vs. 8.2 grain ?

A wise sage recently told me: "No one uses the 7.0-grain pellets, unless your pistol is 40+ years old!"
I had informed him: "Gee, I've been using the RWS R10Match 7.0's for the last seven years . . . Olympic Trials next week!"
Sage: "Why the hell have you been doing that? You're gonna totally suck as usual!!!"
Me: "Because the 7.0 tin has a pretty picture of a pistol, and the 8.2grain can shows a dude with an air rifle!?!"
The wise sage then threw his coffee in my face & walked off in utter disgust.

Hence, 7.0gr vs 8.2grain? Sage vs. Grasshopper . . . Who's right?

Data: I had previously chrony'd my Steyr EVO10 at 568ft/sec with the 7.0gr "Pistol" pellet. Didn't think much of it - 568 being a bit fast.
( I had no data on my Morini 162, as I had thrown it in the trash after last spring's CMP match . . . )
510 ft/sec or something close being "Optimal."
Calculating thru the kinetic energy formula; solving for velocity of a 8.2grain "Rifle" pellet, keeping KE constant. We derive 522 ft/sec.
(I intentionally left a small transcription error in there, for you physics nerds to find.)
So, who's right? What's "BEST?"

As always, comments invited and your opinions criticized . . . .

Depends on your pistol. If you have access to a bench with a vise, test different pellets and see what works best for your pistol.

Less barrel time, less recoil variation, one hole groups.
Why Not use 7.0?

Well, you can tell the guy had a BIT of good sense, since he threw coffee instead of precious beer on you.

I once had a guy tell me he used light pellets because if he used heavy ones, his gun would "rear like a stallion" in recoil. (True!)

Personally, I use light pellets because I played around a lot with SSPs. They may also make slightly cleaner holes.

So, if you like a clean hole, use cheap RWS Basics.

Some of my pistols have prefered heavier pellets, but l have always seemed to make higher points with the lighter anyway.
The man at RWS just shook his head when l bought the pellets he had just proved grouped slightly bigger.

Buy two cartons of each pellet and when you finish shooting them you will know the answer.

The only caveat is that if you are using a pump or spring gun, stay with the light pellet.
Many years ago a lot of testing was done for high level comps with a Morini pistol, a machine
vice and a chronograph with interesting results.
Best group was a 3 shot one hole group that a unfired pellet could be suspended in the hole.
Main thing was that the groups were nodal as you increased velocity.
Group would open-close-open-close etc.
For my gun the pet velocity was 485 fps or 518 fps,
The next thing was to hand shoot both velocities and the lower felt better, gave good number of shot
and was better over the entire tank range, so i shot that and ended the testing.
Best pellet, well the heavy for pre-compressed and what ever brand I could get in match grade (2-3 cartons per year).

David M wrote: ↑Fri Sep 22, 2023 1:54 pm Buy two cartons of each pellet and when you finish shooting them you will know the answer.

Absolutely. This is the only correct answer.

I'd limit the variation of 7.0gr vs 8.2grain - as simply: How would the trajectory change, i.e. how many clicks on the elevation sight, if any?

brent375hh wrote: ↑Fri Sep 22, 2023 10:04 am Less barrel time, less recoil variation, one hole groups.

As for "Time in Barrel," my hypothesis would be "mathematically negligible."

Given: 7gr v. 8.2gr; 233mm barrel; physics formula: d = .5 x α x (time)^2

7.0 grain; 568 ft/sec muzzle velocity:
Time in 233mm barrel: .00269 seconds

8.2 grain; 522 ft/sec muzzle velocity:
Time in 233 mm barrel: .00292 seconds

Conclusion: An "increased time in barrel" of only 0.0023 would only give me an extra 2.3 milli-seconds to totally suck on my follow-thru & "flinch the shot."

Post-script: I possess MANY other methods to suck than the above "flinch."

In Pistol shooting pellet deviation/dispersion has a lesser effect than in Rifle shooting.
If for example pellet group causes 3 or 4 shots 9.8/9.9's in a match your may have lost those points
but it does not account for the half a dozen 8's or heaven forbid the 7 or 6 which you shot.
Improve your score by getting rid of the error's and don't worry about the pellet performance
until you can shoot a full match of just 9's and 10's.
When you can shoot a 580+ then worry about the 9.9's. till then just shoot.

Nicely put. We had a student on our college team that out shot one member of the US Olympic squad and finished right behind two other members in the 2022 Collegiate National Championships. She was shooting 7 gram RWS Basics in an ancient Hammerli 480K pistol.

"Its the Indian, not the arrow."

i tested a few different brands, both heavy and light, in my pistol (P8X): https://youtu.be/RhoGraByA9o
and than i tested different weights from the same brand (JSB): https://youtu.be/D0vfqFaWa0w

my pistol seems to like the 7.0gr RWS Club.
the different weights (and sizes) do not seem to make any difference.

atomicgale wrote: ↑Sat Sep 23, 2023 5:27 am

David M wrote: ↑Fri Sep 22, 2023 1:54 pm Buy two cartons of each pellet and when you finish shooting them you will know the answer.

Absolutely. This is the only correct answer.

I'd limit the variation of 7.0gr vs 8.2grain - as simply: How would the trajectory change, i.e. how many clicks on the elevation sight, if any?

brent375hh wrote: ↑Fri Sep 22, 2023 10:04 am Less barrel time, less recoil variation, one hole groups.

As for "Time in Barrel," my hypothesis would be "mathematically negligible."

Given: 7gr v. 8.2gr; 233mm barrel; physics formula: d = .5 x α x (time)^2

7.0 grain; 568 ft/sec muzzle velocity:
Time in 233mm barrel: .00269 seconds

8.2 grain; 522 ft/sec muzzle velocity:
Time in 233 mm barrel: .00292 seconds

Conclusion: An "increased time in barrel" of only 0.0023 would only give me an extra 2.3 milli-seconds to totally suck on my follow-thru & "flinch the shot."

Post-script: I possess MANY other methods to suck than the above "flinch."

Your math looks to be assuming that the pellet is at muzzle velocity the entire time that it is in the barrel. You know it starts at zero. It also negates the greater acceleration to MV of the lighter pellet.

If the lighter pellet shoots as good a group, why Not use it?

brent375hh wrote: ↑Sun Sep 24, 2023 7:36 am Your math looks to be assuming that the pellet is at muzzle velocity the entire time that it is in the barrel. You know it starts at zero.

Brent, please review your criticism: Run the numbers again, I actually used AVERAGE velocity - yes, it starts at zero.

For secondary proof, use: Dist. = velocity x time (in this case, average velocity.)(Also use conversion 1 meter = 3.28086 ft.)

Regardless . . .

The test I intended here was NOT how one "groups" vs the other. The "Grouping" is materially pointless; human variation swamps-out mechanical variation. I simply wanted to know if one would have significantly different trajectory than the other, hence a need to adjust sight.

Math on this: Use the difference in "Hang Time" on each vs. gravity. I got something like 1.5mm difference, i.e. one-single "Click" on any modern sight. (Steyr clicks at 1.2mm both elevation and windage; Morini is 1.0mm and 1.5mm - I forget which is windage or elevation.)

THE SWAMP:

Nice "7" on that middle target!

atomicgale wrote: ↑Sat Sep 23, 2023 5:27 am 7.0 grain; 568 ft/sec muzzle velocity:
Time in 233mm barrel: .00269 seconds

8.2 grain; 522 ft/sec muzzle velocity:
Time in 233 mm barrel: .00292 seconds

Conclusion: An "increased time in barrel" of only 0.0023 would only give me an extra 2.3 milli-seconds to totally suck on my follow-thru & "flinch the shot."

.00292 - .00269 is 0.23 milliseconds, not 2.3 milliseconds

PirateJohn wrote: ↑Sun Sep 24, 2023 8:12 pm.00292 - .00269 is 0.23 milliseconds, not 2.3 milliseconds

Proving my point! Now there's 1/10th less "time-in-barrel."

Regardless, back to topic, not enough additional "time-in-barrel," for even me to mess it up! Human error vs. mechanical error: See center pic above, nice group, except for that quite-conspicuous "7" - turd in the punch bowl.

The main theory on this post, IS THERE A SIGHT ADJUSTMENT JUMPING FROM 7.0gr to 8.2gr, if so HOW FAR?

Any time I change pellets, there's always a sight adjustment even if the new pellets are the same weight. Sometimes I even have to make adjustments if I order the same pellets but have a different lot number.

atomicgale wrote: ↑Mon Sep 25, 2023 4:19 am Proving my point! Now there's 1/10th less "time-in-barrel."

I repeated your calculations using a more convenient formula for the relation between distance, final velocity and time in an uniformly accelerated motion starting from rest:

d = ½vt => t = 2d/v

and got about the same results. But the change of the barrel time from 2.69 ms to 2.93 ms means some 9% increase. If we suppose the length of barrel time to have an effect for accuracy in the first place, in my book such a relative increase can't be considered insignificant.

PirateJohn wrote: ↑Mon Sep 25, 2023 9:19 am Any time I change pellets, there's always a sight adjustment even if the new pellets are the same weight. Sometimes I even have to make adjustments if I order the same pellets but have a different lot number.

I concur. Even though my groups are huge, the TargetScan overlay of all individual targets usually show that different pellets - certainly different weights - have a different 'epicentre' and would therefore require sight adjustment.

mus wrote: ↑Tue Sep 26, 2023 3:41 am . . . overlay of all individual targets usually show that different pellets - certainly different weights - have a different 'epicentre' and would therefore require sight adjustment.

Sure thing. However, adjust high or low, and how many clicks?

ojh wrote: ↑Tue Sep 26, 2023 3:04 am . . . the change of the barrel time from 2.69 ms to 2.93 ms means some 9% increase. If we suppose the length of barrel time to have an effect for accuracy in the first place, in my book such a relative increase can't be considered insignificant.

PirateJohn wrote: ↑Sun Sep 24, 2023 8:12 pm .00292 - .00269 is 0.23 milliseconds, not 2.3 milliseconds

Okay, so we’re talking “.23 milliseconds,” aka 2.3x10^-4 rephrased as 25,000 nano-seconds!!! Just not enough extra "barrel time" for me to totally suck the shot – I have MANY other methods to totally suck!

mus wrote: ↑Tue Sep 26, 2023 3:41 am I concur. Even though my groups are huge . . .

If you are trying to convince yourself that heavier is better, maybe try some 10 grain pellets and turn your velocity down to 400 fps for good measure. I'm sure a very consistent hold would play a factor in repeatable results, especially over 7.0 grain pellets at 525fps.