JSB Knock Outs 10gr .177

Nice shooting Pete.

I tried lubeing some of these slugs, to see if some lubrication would make any difference to their velocity and more importantly if it would tighten up their groups. I used an old bottle of Napier Pellet Power lube that I have had for a long time. 1 drop per 100 slugs.

Well the long and the short of it is, the velocity went up, from an average of 993fps to an average of 999fps.
No noticeable difference in group size. So not really worth the effort of lubing them.


I've been using the 10grainers for a while now and been very happy with their terminal ballistic performance (expansion and stopping power), but the groups are not as tight as I'd like.
At 35 yards I'd get 3 touching, and two out the group. Not very far out, but far enough to know its not me, and far enough for it to bug me.

So what could be causing this...?
1 - it could be me, but its not. I know when I've pulled a shot.
2 - it could be the slugs? Inconsistencies with weight, damaged skirts, damaged pellets...? maybe, but when visually inspected they all look perfect, in fact I cant see any damage to any of them. Could be weight and head size, but Ive been shooting JSB for years and have faith in their quality.
3 - it could be the rifle. Barrel, or tuneing/pressure. Do I try go faster, or maybe slower? Try fine tunning the hammer spring pre tensioner screw? Is the twist rate just not fast enough for slugs? Maybe it just needs a clean?

Well I dont think its me and I dont think its the slugs, so time to look at the rifle.

Some barrels shoot beautifully their entire lives and never ask to be cleaned once.
Some barrels like a clean once in a while, and some demand to be cleaned after every use.
I was hoping Little Emma would be the first kind. I've put over 1000 projectiles through her barrel since I got her a few months ago, and never cleaned her, so maybe its time?

They say when you are trying to perfect something you should never change more than one variable at a time...
Well I got overly excited and changed two.
The results are good, but now I dont know if it was one or both changes that gave the better results.
I cleaned the barrel, AND I tried the 13.43gr slugs before fully testing the groupings of the 10grainers


Well I'm happy with the results either way. At 40yards I'm getting one hole groups.
I kept the power wheel on no.7, and the velocity has dropped from 999fps with the lubed 10grainers, to 892fps with the unlubed 13.4grainers. The power has gone up from 22.3FPE to 23.7FPE
I'm happy with all of that.
I prefer the idea of sending a projectile down range (on someone elses property) at 892fps in stead of 999fps.
I also fine tuned them with one eighth turn adjustments on the hammer spring pre tensioner screw. The extreme spread of velocities in a group went from 19 feet difference at the worst, to 3 feet difference at its best where it now is, so thats pretty consistent.

The next question is what will the bigger slugs terminal performance be like?
Are they going to expand as beautifully as the faster 10gr's or are they going to start passing through a rabbit?
Will they have the same devastating stopping/knock down power?

More testing and necropsys needed...

Far out - and I really do mean far out with still heaps of hitting power...

I'm going to sell my LRs and buy a PCP.

RangerPete wrote: 9 out of 10 recovered so far. The ones that are mushroomed nicely are usually found in the skin on the far side. The ones that look chewed up have hit heavy bones i.e. more than just ribs.

What sort of range were these kills, Pete?

The expansion from these 10.03gr Knockout slugs is nothing short of amazing.
No pellet I have ever tested has ever performed like this.

One of the recovered slugs I have was from a head shot at 25yards. Entered left side of the rabbits head next to the eye.
Expanded and dumped all of its 21FPE, and I recovered it under the skin on the right side of the head!!!
A rabbits head is only 5cm wide!

It seems totally counterintuitive to increase projectile speed and energy in order to stop projectiles over penetrating and exiting, but here is the proof…