Are you surprised? I am.

I'm certainly curious. The "why" such is the case seems to be the question since I would think the pellets have an almost identical overall shape. Does velocity vary more with the smaller diameter? Maybe not sealing as fully in the barrel and causing varying blowby? Certainly an interesting observation.

Since finding the NSA .250 33.5, 36, 36.2, VK34gr slugs and JSB 33.95 pellets all shoot mostly .5 inch groups at 100 yards in my .25 Impact 700mm slug A liner I have not tried another slug/pellet. But yes .001 can really make a huge difference in accuracy in many guns for sure.

I tried the lighter .249 slugs and while they did OK they did not do nearly as well as the ridiculously accurate .250s in my Impact.

One sighter in yellow, on right, three in one hole red, bottom and top, with the 36gr dimple nose. I couldn't see the three hole shot in the black so I dialed up in elevation and shot three more. ;^) Oh, and these were shot at 740fps as well.

I tried some knockouts in my impact and they grouped better than my Nielsen’s. That’s all I plan to shoot, but will hang on to my Nielsen’s. 

My .22 is a choked LW barrel ( Taipan Veteran Long ) as as such I've assumed that it would be better with the .216's. I also shot the JSB KO's out of it for a bit and they were reasonably accurate ( "woodchuck moa" ) but then just for the heck of it I decided to try the H&N 23g slugs. My Taipan is a laser with those - it's ridiculously accurate with them. As I type this (literally) I *just* discovered - for real - that in fact the KO's are .216 and the H&N's are .217's. Looking at strelok just now for that gun and ammo combination - 945fps is what works for me with the H&N's.

Scratching head . . . . how did I not notice / miss the two different sizes @purchase time? {sigh} Whatever - my Taipan is in a "state" where I ain't touching it - that thing shoots wicked good. ( lol! ) I just feed it air and ammo and it's really lethal to critters out too 100+ yards.

Same experience with the JSB KO .217 in my Impact and 700 sstx. Need to do more "Ernest Tweaking" but found a few "sweet spots" @ 931,941,965 and 983 that get me MOA @100.

bubblerboy64, I will take your advice and get it closer to 1000 and see what they do.

I have the NSA sample pack in both .217 and .218 and it shoots the 23gr@940 and the 27.5gr@881 in .217 quite well, not so much in the .218. When testing the NSA 24.8gr in .217 and .218 there was a 35fps difference with that .001

I will "ET" more with the NSA's, but the KO's shoot so well I might just call it a day and have a good time.

 I cast and design sluts and shoot up 500 a day. It is not blow by that effect accuracy. And yew .001 can make a difference. But that is a very crude measurememt. 

those of us whou have been at this a long time reconize that .0001 ( 1 thn Thou) can make a huge difference. Never mind 1 thou.



Many of us have found that the best results besides twist rate, is anywhere from .0001 under groove dia, to no more than .0003 over. One would think that under sized by .0001 would cause blow by. May very well so so. However, the greatly diminished friction more than makes up for it and gives almost always higher velocities and better accuracy.


and remember, 
Twist rate is NOT dependent on size or weight. It is strictly length. HP's being lighter will make no difference what so ever. And it is rare that a choked bbl will shoot as well as a non choked bbl. If shooting a choked barrel, the projectile must be sized to the choke. Not the barrel. 



Even when I do purchase aftermarket slugs, I always size them to my barrel. 



I will post a few pics of groups with my super expanding slugs. I do not sell them. 



KnifeMaker

 I hp my own molds now and the pic of the range is my personal range. My Home. ;<)

" I cast and design sluts and shoot up 500 a day." Knife - you are a lucky man. 

Sorry for the OT - couldn't resist - please continue.......

In my Impact MkII, .22, PP, 700 mm using slug A liner I couldn't get slugs to perform....216, .217, .218, cup base, dish base, flat base, 750 fps to 950. The .218 H&N 23 gr showed some promise, but not good enough. Went beck to the stock pellet liner. Last week for grins I tried the H&Ns in it, and at 885 fps or so it gives 0.4-0.5" 5 shot groups repeatedly. So I tried the other slugs, no dice, but those H&Ns sure do it for me.

Those were groups at 70 yd measured with a laser rangefinder. At 100 I've gotten 0.8" to 1.1" Promising.

In my Impact MkII, .22, PP, 700 mm using slug A liner I couldn't get slugs to perform....216, .217, .218, cup base, dish base, flat base, 750 fps to 950. The .218 H&N 23 gr showed some promise, but not good enough. Went beck to the stock pellet liner. Last week for grins I tried the H&Ns in it, and at 885 fps or so it gives 0.4-0.5" 5 shot groups repeatedly. So I tried the other slugs, no dice, but those H&Ns sure do it for me.

Click to expand...

In my .22 impact with 600mm superior liner I got NSA .217 size in 23 and 25 grain to shoot very accurately, might be worth a try.