JSB Knock Outs 10gr .177

I was out on another race course two nights ago and took Little Elly and her 8.44gr exacts, and Little Emma and her 13gr slugs with me.
Was a good night, I finished very late (I hate daylight savings!) and finished on 17 rabbits, 5 hares and a rat.
I thought the hares, being 3 or 4 times the size of a rabbit, would be a good test medium to see how the slugs perform, so I collected 4 hares and one smallish rabbit for dissection.

The rabbit was a double shoulder shot, through both shoulder blades, at around 40 ish yards, and the hares were various angles through the chest, shoulders, spine and neck, with one head shot. Hares shots ranged from 40yards out to 113yards.

Well, after about half an hour of careful skinning and dissecting, do you know what I have to show for my efforts...?
Nothing.
Not one slug recovered.

So what does this tell us?
Well I've had a few days to think it over and here are my conclusions.
I dont believe that these slugs are expanding. If they were I would have surely found at least one in a hare, or at the very least under the skin on the far side!

If I had been shooting the 10grainers at 996fps for 22FPE, I know they would have mushroomed beautifully and stopped with in the targets, I know this from experiance.
If I had been shooting 8.44 exacts at 813fps for 12.4FPE, the rabbit would have probably not been a pass through (.177 round nose pellets do tent to icepick through things and it wasn't a big rabbit), but most of those pellets at those distances would have definitely still been in those hares.

So why were the 13grain slugs not in the hares? Because I believe at 892fps, they are not expanding, they are acting like a heavy solid, or a heavy round nosed diabolo pellet and are simply over penetrating.

So why are they not expanding? There are two reasons I can think of.
1- They are not traveling fast enough.
2 -Their hollow point design/shape is not big enough.
Maybe be a combination of both.

The faster a projectile hits "something", the harder that "something" behaves.
Like shooting directly into water, at slow impact speeds there will be a small splash and the water will just engulf the projectile and the pellet retains its shape. The same pellet having a high velocity impact will cause the water to act very hard there will he a big splash and will the pellet will deform (or mushroom).

It is actually quite difficult to get a diabolo shaped pellet to "mushroom" in a rabbit, unless you hit heavy bone, which will chew up the pellet, not really mushroom it. To get an 8.44 grain to "mushroom" in soft tissue is almost impossible.
I know this because I have recovered many pellets from many rabbits.
If fact with my sub16 FPE test, I found that an 8.44gr exact at 921FPS, (15.9 FPE) will pass diagonally through all the soft tissue and stop under the far side skin of a rabbit, and be recovered looking perfect and almost re-usable.
And yet you can shoot the same 8.44gr exact at 400fps into a solid steel plate and it will turn into an M&M?
So how fast do you need to hit a rabbit to make that rabbit act "hard enough" to deform and mushroom a projectile.

I dont know the exact answer to that question, but I'm sure there is a direct correlation between the answer to that question and the design shape of the pellet or slug.
A hollow point is definatly going to help the projectile expand, there by reducing the required velocity.

When I compare the 10gr KnockOut Mk3 (third design shape) side by side to the 13.43gr Knockout (which is still at Mk1, first design), there is a very big difference between the shape, size and diameter of the two hollow points
I have no way of quantifying the differences, my vernia can't measure a cavity that small, but the 10grainers holow point looks at least 50% wider in diameter, it is also slightly deeper (measured very unscientifically with a tooth pick).
Because the hollow point diameter is wider, the walls of the slug are visibly thinner, which will certainly aid in their opening up.

The 13grainer definatly has a more robust and solid construction, smaller hollow point, thicker side walls and is a bit longer than the 10grainer (of course it needs to be to get those 3 extra grains of lead in there).
I believe the 13grainer will expand and mushroom, IF it is traveling fast enough, but at 892fps I dont think I'm pushing them fast enough to get them to mushroom in soft tissue and give the terminal ballistic performance that I'm looking for.

Does that mean they are no good? Of course not!
They were giving tiny one hole groups at 40yards, velocity's with an extreme spread of 3!
I took a hare at 113 yards with a 13.4gr .177 projectile, thats nothing to turn your nose up at.
If you wanted to use them for close range or long range hunting, I have no doubt they will and do kill just as dead as any pellet or other slug. Even if you wanted to use them for extreme bench rest shooting, they would be perfectly suitable and fit for purpose, no problem at all.

But I am looking for a very particular type of performance, I am looking for devastating terminal ballistic performance.
I want a projectile that dumps all of its energy into the target, mushrooms and comes to a complete stop with in the target, NO exiting.
I am also trying to get that performance from the smallest, lightest, lowest energy projectile possible, and still be accurate at distances out to 100yards.

The 10grainers at 999fps were giving that type of performance but the groups were not as tight as I would have liked.
So I'm going to go back to the 10grainers and spend some time trying to fine tune Little Emma with 1/16th turns of the hammer spring pre tensioner screw, till I can get their extreme spread as close to 1 as possible, and we'll take it from there



Edited by RangerPete - 18 Oct 2024 at 11:46pm

Was working on a big property tonight so I thought I'd give the 13grainers one last try, and took Little Emma and the 13.4grain KnockOut slugs out to work tonight.
They sure do shoot straight and hit hard!
Only 3 rabbits and a possum, but they literally knock the rabbits over.
I have noticed quite a hight occurrence of ricochets when using these 13.4grainers. Only a few but still way too high for my liking.
But I guess thats a product of the high passthrough rate and the high retained energy slugs carry down range, especially if they havent dumped much of that energy into the target.

Tomorrow I'll be changing back to the 10grain slugs, retuning the rifle and rezeroing scopes at 40yards.

Edited by RangerPete - 21 Oct 2024 at 12:00am

Well, that is one helluva list of defns Kruzaroad!
The M no. meaning is a secret huh? Just gummint codes probably with no logical meaning assigned by the Head Gummint Bean Counter...

God I miss working for the gummint, driving around in the 4WD all day, (Kruzing da road) easily keeping the boss happy by every now and then pinging a poacher. But with my big mouth there's no way i was never going to get promoted...and it took dumb me 11 years to figure out that you must tell the boss what he wants to hear rather than the reality of the situation.   No regerts though - I'd likely be useless half dead and rotting wood by now if i was still working for the gummint.  

Edited by JasonEdward - 21 Oct 2024 at 2:30pm

Ja it has to do with regulations from the Czech government.
Because JSB pellets are manufactured in Czech republic, I believe it is a code to indicate which caliber and class of ammunition it is.
I guess rim fire would probably have a different code? And military ammo another code...???

Edited by RangerPete - 21 Oct 2024 at 5:25pm