I heard there are a few versions of the smooth twist from the early ones to the current production barrels.
Some said they were designed for JSBs and I'm seeing a lot of guys report the 18 grain work great.

I don't have any 18 grains yet, they're on order. The 14 grain JSB express work ok good but it's not
a 1 hole deal like others have reported.

Anyone notice accuracy differences between the 18, 16, and 14 grain JSB in smooth twist barrels?

The 18 gr JSBs work great in my Royale at 33 fpe, better than the 16s never tried the 14s. So I guess they are fussy but you should get one hole groups with no fliers at 40 yards with JSB 18s.

RogerV

still shoots the 18gr JSBs resonably well. Non Lead are 1/4" @40yds, JSBs run 3/8". It does prefer non-lubed pellets, which is kinda nice...

Mine shoots best with JSB exact jumbo 18grains at 25fpe.

at least the two different .22 I tested with pellets other than JSBs. Mine shoots JSB 18.1 & AA 16gr 5.51( seems to barely edge out JSB 16gr ) and is pretty accurate with the 14.3gr. Accuracy is best if kept under 900fps.

No matter what speed I tried it just didn't shoot well with JSB pellets. But with Barracuda Match pellets it goes into one hole all the time. I like the barracudas as well cuz they have stronger skirt and give more energy.

spectrum, 890 FPS to 940FPS.

It was what AOA tested it with, I never tried or needed to try another pellet in it.

I bought 6000 of them the day the gun came in, and never looked back.

For me it is always 18.1 grain Exacts, so I guess I am the pellet fussy one.

With a label change on the JSB tins, I thnk they also did a re-tool of the dies whether advertised or not. The samples I have on hand of the old label 18.1's and the new label 18.1 seeem to be a little different than just the color of the label on the tin. The pellets have some slight differences that may be retooling, or replacement of a die, or something...whatever the case, I find they don't neccessarliy work the same out of the guns that I have been using them in. I have actually had the broadest amount of success in ST barrels using the 15.8's in .22.

Regards,
DaveG
See more picts @http://davegcustomstocks.com

Although my ST Whisper shoots JSB's great, both 15.9 and the 18.1's, it also shoots other pellets really good.

I have been able to get at least 3/4 inch groups at 40 yards with CPHP, H&N FTT and Baracudas.

So far this rifle has been the least fussy for me. But I must say it does prefer non-lubed pellets.

Jim in MN