Pellet weight inconsistencies

Sorting out the extreme weight differences has gotten rid if most of the head scratchers. The rest, as long ad they're reasonably close, seem to maintain a fairly close POI out to 50yds. That being said I do sort them into lots by the 1/10gr just to play it safe. Most of the time I still just shoot straight from tin with a quick glance at the skirt. That does well enough for normal shooting. My shooting is like 99% springer though so my goals are usually 1.5 moa average and not what some high end PCP shooters may be going for.

I did some weight sorting out to the .1 or .2 grain I don’t remember exactly but it was not significant to accuracy.

That said, I think there is always some gain by weighing all of them and culling the very heavy and very light pieces.

But feel free to test the very heaviest and lightest together and see if they shoot worse than the others.

For Benchrest there are so many variables that seem to be significant, so if you measure/sort/cull for every imaginable variance, you’ll end up rejecting most all of them. I think the lack of really good pellets is holding back airgun Benchrest on a very fundamental level.

i think fine tuning the valve and hammer into a jeweled work of art is about 100x more pertinent to consistecy than .1 grain weight or a scratched pellet skirt

i have weighted , head size / skirt size sorted , roll tested even to exact measurements ,( for instance) every pellet was 10.24 G for all shots in a given event .

My opinion is This : if you did this exactly the same you would need to do enough for 30 days shooting 100 pellets a day to form any meaningful data.
Your asking about weight differences of .10, .15. , . 20 or maybe larger separations ? i would say 50 pellets per weight ,size etc. would give results .
I mostly shoot bench rested and targets @ <1/4 inch / 5 shot groups does this help your thoughts ? I would only sort for shots in a competition.

I usually refer to Bob Sterne research (rule of thumb) when looking at variables affecting accuracy.

He says that at 100 yards using a pellet with a BC of .030 and a velocity of 900 fps, a shooter should keep things within 1% error rate for accuracy to be unaffected/unseen.

Hence, what I try to do is keep ES and Pellet Weight Variance at or under 1%.

At 900 FPS:
- 1% ES = 9
- 1% pellet variance (JSB - 25.39) can vary 25.39 grains.

Of course wind variance isn't in the equation and can't be controlled. It's likely the most difficult thing to conquer - out of everything.

I knowMike N. shoots pellets right from the tin, but he's a "wind-whisperer" and otherwise a "Shooting God" and not to be compared to mere mortals. .

I mostly shoot at home and am limited to no more than 35 yards. I shoot more 30 yard challenge targets than anything else. I shot a 192 with my Prod on one fill so it had at least 40 fps difference during the target. I did hold slightly higher at the end and that is not as good as several of my other guns but it shows that you don't have to have a 10 fps ES to shoot fairly well at 30 yards.

I've also weight and head size sorted pellets. I only have a head size gauge in 177 so that is the only caliber I have sorted for head size. I think head size makes more difference than weight. But my one 200 at the 30 yard challenge and my 3 199s were all shot with pellets straight from the tin and through a magazine (H&N Baracuda Match 22 caliber pellets and Carm magazine).

I sorted a tin of FX 34 grain pellets in 25 caliber and a partial tin of JSB 33.95 grain pellets recently. I know JSB made both. But the FX were much closer to 34 grains and much more consistent than the JSBs. But my P35-25 shoots the JSBs better (current best is a 194).

Others have commented pellet variation makes a lot more difference at 100 yards. They are probably right. The few targets I've shot with pellets at 100 had 5 shot groups 2 inches or bigger. I just used pellets straight from the tin and through a magazine. I will probably try again with sorted pellets some day.

The Hard Air graphical report shows specs down to very short distances.
Follow the graph lines to 40 yards, extrapolate to 30 yards.

The magnitude of error is very forgiving at short distances ............ at those ranges, shooting technique is most important.

From my experience weight sorting definitely makes a difference @ 100 yds and closer all you have to see is sort a tin shoot 10-20 over the crono then take the 1’s you sorted out and shoot the same number over the crono and compare sd’s. The thing you have to remember for the target is the path is like a cone from the end of barrel to target. Put a target at the end of the barrel they all go thru the same hole put it at 50 now you have a 1/2” group and then at 100 you have a 1” or more group not even considering that a 2 mph breeze pushes pellets 1 1/2” or more !

Solo1 said:

From my experience weight sorting definitely makes a difference @ 100 yds and closer all you have to see is sort a tin shoot 10-20 over the crono then take the 1’s you sorted out and shoot the same number over the crono and compare sd’s. The thing you have to remember for the target is the path is like a cone from the end of barrel to target. Put a target at the end of the barrel they all go thru the same hole put it at 50 now you have a 1/2” group and then at 100 you have a 1” or more group not even considering that a 2 mph breeze pushes pellets 1 1/2” or more !

Click to expand...

Don't forget temperature and humidity, it all plays a role.

And don't forget the friction in between two materials inside rifling

Bob,

I'm so glad you have all that time on your hands to go shooting...!
I'm a bit short on my supply of time — it seems like forever that I haven't had a range day. Maybe this Wednesday I get to hit it hard!


With time on hand, I recommend to dig into a ballistic calculator.
For me this has been nothing short of "revelation" — to try different scenarios of power, weight, caliber, range, etc. etc. and make comparisons.
▪ One conclusion I drew was that at shorter ranges, out to say 30y, most sophisticated equipment and most nifty techniques don't make that much of a difference: Aim, shoot, done.
▪ Another conclusion was the ideal caliber for a PCP pistol for my particular application.
▪ Etc. etc.



About your question how projectile weight variations influence precision:

Many ballistic calculators have a function that calculates "vertical stringing."
I'll run your weights and ranges:

▪Projectile: .22cal MRD "25.39gr"
▪Muzzle energy: 45.66FPE
▪Ranges: 50y and 100y
▪Muzzle energy: 46.0FPE (assumed)
▪BC: 0.040
▪Scope height: 2.50" (assumed)


▪Weight variation: 24.90—25.94gr
= An extreme spread of 1.04gr

➠ Resulting in muzzle velocity variation: 912.2fps—893.7fps
= An extreme spread of 18.5fps

▪Average MV: 903fps

RESULTS:
50y: The weight variation of 1.04gr
will cause a velocity variation of 18.5fps,
that will cause an impact variation of 0.22" (0.56cm) at 50y
(0.11" below and above your POA).





100y: These same weight and velocity variations will cause an impact variation of 0.94" (2.39cm) at 100y
(0.48" below and 0.46" above your POA).





Matthias



PS: The app I used is the GPC Ballistics app — free — no advertising — no spying.

▪ for cellphones: Android, iPhone
▪ for computers: Windows, MacOS, Linux

Link: https://gpc.fotosoft.co.uk/

Calculating theoretical accuracy is useful....in theory.

It's possible to have large velocity spreads that don't show on the target. There are far more things going on to create or diminish vertical at the target than spread alone. Just because a ballistic app says you get x amount of vertical with a certain of velocity change...doesn't make it so. If a super tight velocity spread was the only thing (or even the most important thing) responsible for vertical at the target...life would be very easy for a BR shooter. It is, however, very popular... theoretically.

Mike

thomasair said:

Calculating theoretical accuracy is useful....in theory.

It's possible to have large velocity spreads that don't show on the target. There are far more things going on to create or diminish vertical at the target than spread alone. Just because a ballistic app says you get x amount of vertical with a certain of velocity change...doesn't make it so. If a super tight velocity spread was the only thing (or even the most important thing) responsible for vertical at the target...life would be very easy for a BR shooter. It is, however, very popular... theoretically.

Mike

Click to expand...

Lots of fanatics of ridiculously tight extreme spreads. In actual shooting (including field target competitions, both AAFTA and high power) I've always found it doesn't matter nearly as much as most make it out to seem like it does.

thomasair said:

Calculating theoretical accuracy is useful....in theory.

It's possible to have large velocity spreads that don't show on the target. There are far more things going on to create or diminish vertical at the target than spread alone. Just because a ballistic app says you get x amount of vertical with a certain of velocity change...doesn't make it so. If a super tight velocity spread was the only thing (or even the most important thing) responsible for vertical at the target...life would be very easy for a BR shooter. It is, however, very popular... theoretically.

Mike

Click to expand...

Hey Mike,
Other than wind/atmosphere differences, which other variables would you rather tell shooters focus on?

Unfortunately, there aren't many things that don't contribute to vertical.

Hammer weight, return spring weights, ssgs, plenum size, barrel stiffness, tuners, lube, etc...can all give you vertical when you have no velocity spread.

I can't tell you what is right and wrong...only that changing any one of these variables can add or detract from vertical.

There are lots of other variables outside the gun involving how the gun is supported that have a massive effect too.

Velocity spread is the easiest to master of all the variables.

Mike

I was using today -.25 - 34gr MK2 at 40y and even that close a group will open to a inch with a spread of 18 fps between shoots so at 100y it will certainly be unusable for me.. I changed pellets to the new aea 34gr and my spread whent down to 3 so jsb is definitely taking us by the hair with such a bad product.. how aea managed to have a consistent product and jsb don't....