What is correlation of twist rate, weight of pellet and speed for accuracy?

[GHairgunner]

Using the Ghost 22 I have taken 1:16 and 1:24 twist barrels and shot many pellets at lots of different speeds. Results show me that the 22gr AEA pellet at 1030fps out of the 1:16 twist barrel works the best over the MRD 25gr pellet out of the 1:24 twist barrel 940fps tail wind, 960fps head wind (best settings for the 25gr).

Yes both pellets have been in both barrels at speeds ranging from 900 to 1050fps.

Why is it the lighter pellet has great accuracy with more spin stabilization?

 

[Solo1]

I e been shooting the 21.9 aea also and find it doing well even better at times than the 25 aea and i cant really say why and thats from the 22 23”ghost barrel @ 975. I would have to believe its a combination of shape and ctr of balance ?

 

[Spit-in-Lead]

At what distance are comparing accuracy?
I would think the lighter pellet may have a slightly great distance between the CG and CP, and may be more stable. Lots of factors there as you know.

 

[GHairgunner]

At what distance are comparing accuracy?
I would think the lighter pellet may have a slightly great distance between the CG and CP, and may be more stable. Lots of factors there as you know.

For me and the 22 most of the testing is done at 50 yards but even at 100 it holds true.

 

[Spit-in-Lead]

Good to know. Im getting my 25 setup and will start tune with 25 grain followed by 33 at 50yds. Are you shooting the 23 or 28 barrel in 22?

 

[Danman]

Interesting topic! I hope to get the 1:17.7 slug barrel eventually and (oddly enough) shoot mrds out of it for starters. Mine currently has the 1:30 twist barrel and that barrel does one thing really well. And that is shooting heavy pellets, very fast, at distance. RTI and FX (well before the Ghost) have been pushing Mrds fast with there slower twist barrels as well with excellent results, often pushing past 1000fps. My thoughts on what will happen is this: mrds will begin to spiral, out of the 1:17.7 barrel at high speeds and long range (past 50) vs my current barrel with the 1:30T, but remain accurate at slower speeds.

 

[Chief55]

This is one of many stabilization calculators. The G1 is not perfect for air guns, and it is mostly for slugs, but I imagine that it should work for pellets some also. It can save a lot of money and frustration avoiding most of the slugs that will not work. Length, weight, speed, caliber and barrel twist are the main factors. With the calculators you enter to values and click on calculate to see if it will be stable. It might be fun to see what it says about different weight pellets. Length would be the main factor.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

 

[Franklink]

Interesting topic! I hope to get the 1:17.7 slug barrel eventually and (oddly enough) shoot mrds out of it for starters. Mine currently has the 1:30 twist barrel and that barrel does one thing really well. And that is shooting heavy pellets, very fast, at distance. RTI and FX (well before the Ghost) have been pushing Mrds fast with there slower twist barrels as well with excellent results, often pushing past 1000fps. My thoughts on what will happen is this: mrds will begin to spiral, out of the 1:17.7 barrel at high speeds and long range (past 50) vs my current barrel with the 1:30T, but remain accurate at slower speeds.

I used a 1:17.7 non-choked LW barrel in my Vet Long and shot MRDs out of it.
Tested that barrel extensively. It shot MRDs well up to 910fps. Beyond that, they destabilized.

High point with that barrel was a tie for second @ 2022 Extreme Field Target @ EBR. They broke the tied score by first miss or offhand shots or something, so officially 3rd place. Anyway, the MRDs @ 890-900 from a plain old 12 groove 1:17.7 CAN be fairly competitive.

MRDs from a slow twist poly at 950-960 are quite a bit better at resisting the wind than MRDs from a standard barrel @ 890-900.

 

[Franklink]

Using the Ghost 22 I have taken 1:16 and 1:24 twist barrels and shot many pellets at lots of different speeds. Results show me that the 22gr AEA pellet at 1030fps out of the 1:16 twist barrel works the best over the MRD 25gr pellet out of the 1:24 twist barrel 940fps tail wind, 960fps head wind (best settings for the 25gr).

Yes both pellets have been in both barrels at speeds ranging from 900 to 1050fps.

Why is it the lighter pellet has great accuracy with more spin stabilization?

What you're seeing is something I've heard a lot of people report the same on recently. AEAs or JTS in the 21-22grain range, going REALLY fast.

I'd be interested to see someone do some downrange speed collection comparisons here, either with a LabRadar or a downrange chronograph. Reason I say that is because, traditional wasp-waisted pellets strip speed, FAST. And these AEA/JTS 21-22 grainers look more like a JSB 18.1 (wasp-waisted) then they do a fat waisted .22 pellet in the 25+ grain range, which are better at long range speed retention. From similar experiments I've run on comparable pellets, it doesnt matter whether they leave the muzzle at 910 or 1010, they're going the same speed by x yards. That may be 70, 80, 90, 130 or more yards, but at some point the starting speed simply doesn't matter. If the catch-up distance is less than 100 yards and your max distance is 100 yards, you're just wasting air and making more noise than necessary.

 

[Franklink]

Using the Ghost 22 I have taken 1:16 and 1:24 twist barrels and shot many pellets at lots of different speeds. Results show me that the 22gr AEA pellet at 1030fps out of the 1:16 twist barrel works the best over the MRD 25gr pellet out of the 1:24 twist barrel 940fps tail wind, 960fps head wind (best settings for the 25gr).

Yes both pellets have been in both barrels at speeds ranging from 900 to 1050fps.

Why is it the lighter pellet has great accuracy with more spin stabilization?

On a windy day, I'd expect the lighter/faster pellet to get pushed A LOT more @ extended ranges than the heavier one.

 

[Solo1]

On a windy day, I'd expect the lighter/faster pellet to get pushed A LOT more @ extended ranges than the heavier one.

I don’t think that is necessarily true bc comes into play too. And my experience 13 gr ko slugs bears that out. Also the 21.9 aea @ 980 fps is very surprising.

 

[Franklink]

I don’t think that is necessarily true bc comes into play too. And my experience 13 gr ko slugs bears that out. Also the 21.9 aea @ 980 fps is very surprising.

BC is exactly what I was referring to.

Specifically the BC of the 21.9 AEA versus a 25.4MRD shot from a slow twist polygonal barrel at correct speeds.

I'd be interested in an actual, real world-collected BC, as the % of speed retention the typical way that we use it in airgunning, not the theoretical/rocketeering definition of BC.

(Please refrain from a lesson in theoretical external ballistics here, ballistics programs available to airgunners don't offer all the adjustment parameters to tweak drag laws and form factors, etc , so we fudge it and use the BC as a measure of speed retention, and therefore long range resistance to wind deflection. It's not a perfect method, but it's what we have, and what we use, and quantifies long range wind resistance).

 

[GHairgunner]

Good to know. Im getting my 25 setup and will start tune with 25 grain followed by 33 at 50yds. Are you shooting the 23 or 28 barrel in 22?

I'm shooting my custom designed barrels. Being a competitor I got tired of waiting for good barrels. Don't know if they are the best around still defining that. The barrels far exceed the stock versions. LW may make good sub 20ft lb barrels but that's where it stops.

 

[Grunt64]

Using the Ghost 22 I have taken 1:16 and 1:24 twist barrels and shot many pellets at lots of different speeds. Results show me that the 22gr AEA pellet at 1030fps out of the 1:16 twist barrel works the best over the MRD 25gr pellet out of the 1:24 twist barrel 940fps tail wind, 960fps head wind (best settings for the 25gr).

Yes both pellets have been in both barrels at speeds ranging from 900 to 1050fps.

Why is it the lighter pellet has great accuracy with more spin stabilization?

Short answer: the lighter pellet shoots better because it matches the twist rate.

The 22gr is shorter and easier to stabilize, and the 1:16 twist gives it more RPM, which cleans up any yaw right out of the barrel. Pellets don’t need a ton of spin, but they do need enough to stay centered.

The 25gr MRD is longer and heavier, and the 1:24 twist just doesn’t give it quite enough spin at 940–960 fps to fully settle.

So the 22gr + 1:16 + 1030 fps combo hits the stability sweet spot, while the 25gr + 1:24 is close but not ideal.

 

[GHairgunner]

Short answer: the lighter pellet shoots better because it matches the twist rate.

The 22gr is shorter and easier to stabilize, and the 1:16 twist gives it more RPM, which cleans up any yaw right out of the barrel. Pellets don’t need a ton of spin, but they do need enough to stay centered.

The 25gr MRD is longer and heavier, and the 1:24 twist just doesn’t give it quite enough spin at 940–960 fps to fully settle.

So the 22gr + 1:16 + 1030 fps combo hits the stability sweet spot, while the 25gr + 1:24 is close but not ideal.

So is the answer to spin the 25 gr more or shoot them faster to get them to stabilize?

 

[Grunt64]

So is the answer to spin the 25 gr more or shoot them faster to get them to stabilize?

“You can only stabilize the 25gr more by shooting it faster — you can’t add spin without changing the twist. But even at higher fps, the 1:24 twist is still borderline for that pellet’s length, which is why the 22gr in the 1:16 twist outshoots it.”

 

[GHairgunner]

“You can only stabilize the 25gr more by shooting it faster — you can’t add spin without changing the twist. But even at higher fps, the 1:24 twist is still borderline for that pellet’s length, which is why the 22gr in the 1:16 twist outshoots it.”

So if I shot it in the 1:16 twist barrel and made it go faster it would start to stabilize better? Or would a slower twist with the faster speed be the way to go?

 

[Franklink]

If we're talking about .22/25.4 MRD and similar....there is a long track record, going back about 7-8 years, to when it was THE long range pellet choice of anyone wanting to be competitive, of shooting them from 950-1020fps out of slow twist polygonal barrels. The two most frequent being the 6 groove 1:32 (RTIs specs for LW) and/or the 5 groove 1:30 (Daystate/BRKs specs for LW).

With a good batch of MRDs (yes, the good batch is the kicker) and the above, there is simply no better performing 100 yard/.22 pellet option.

 

[Solo1]

I think the 21.9 aea is better so loong as the wind isn’t too crazy now a days anyway

 

[Franklink]

I think the 21.9 aea is better so loong as the wind isn’t too crazy now a days anyway

That was the kicker with the MRDs in that speed with an exceptional example of one of those rifling profiles.....BCs in the 0.055-0.057 range. They are GOOD in the wind, for what they are (a .22 pellet).

I've got a 8 more tins (#350 CT) of some FX branded MRDs that only come out for serious matches to be used in the RTI LR barrel in my Vet Long. That recipe won one of the EFT Grand Prixs in 2024, and was tied for 3rd high score at the same EFT Grand Prix this most recent summer. Both years I only attended the one EFT Grand Prix.

The .30 AEA options are now boasting BCs up into the 0.07s, and have somewhat obsoleted the .22 MRDs as the long range pellet of choice for long range pellet games.