Hi Guys,

Today I took a break from the office and went to the range to find some me-time and try to reorganize my thoughts. Good excuse, I just really wanted to do some quick shooting and enjoy the beautiful weather.

A few weeks ago Gary presented some performance numbers from the new Nitro Express Magnum and somehow the discussion went for a while between light and fast vs. heavy and not so fast.

Jerry posted a comment that summarizes this never ending debate; “mass rule” and I wanted to try a quick test regarding this topic.
I found a bunch of phonebooks and the idea came to me. Let’s shoot the phonebooks at 50 yards with different slugs and evaluate and compare the results for each slug.




For the test I had three different .46 caliber slugs: first the Raptors weighting 230.9 grains, second the Bishops weighting 298.6 grains and third the K-8s weighting 450.3 grains.

I decided to use the Raptor as the lighter one vs. the K-8 as the heavy weight. Here is the data: The Caribou shoots the Raptors at aprox. 950 fps for 462 fpe and it shoots the K-8s at aprox. 750 fps for 562 fpe.

Right from the start the Rators are flying at 200 fps more but they produce 100 fpe less than the K-8s. Let’s see the effect of those numbers when the slugs hit the phonebooks.

The Bishops were the control group. On this first picture I shot two Bishops and to my surprise both of them paper punched the phonebook. The total width of these phonebooks is 2 ½ “ and aprox. 450 pages each.


For the test I had to place a second phonebook behind in order for me to find the slugs if they are going to pass thru the first phonebook like the Bishops did.



This picture shows the smashed Raptor slug after punching a hole on the phonebook and it stopped on the back cover. It didn’t went thru the whole phonebook.



This next picture shows the K-8 slug after paper punching thru the first phonebook and going up to 245 pages of the second phonebook. If you see, this slug didn’t deformed as much as the Raptor did.



I know that the phonebooks aren’t the best media to test the slugs penetration, but I had them available and sometimes it’s better to test and document the facts rather than stay in the theory.

Hope that you enjoy,

Julio

Great Job Julio!

Those phone books won't hurt anyone, ever again!

Those big slugs really punch holes!

Thanks

Gary

Excellent post Julio! So, I guess it's confirmed, mass rules! At least when it comes to delivering energy on target and penetration. Of course, when you are already at the point where a 200gr slug will penetrate or destroy what you are shooting at, you might trade mass for flatter shooting and the allowance for range mistakes but if you have to do the most damage down range...Mass Rules!

So Julio ...

Tell the truth now ..... you robbed those new phone books from all your neighbor's porches ... right after the phone book truck left your block ... right? hahaha.

Good post again.

Gary

Gary:

You got me there. I waited for two days and after that every phonebook that I found left on a porch was mine. People in general have lost their interest in using them.

By collecting all of the phonebooks I felt like I was providing a service to the community. I still got a few left left.

Julio

Funny how the slug weights end up virtually matching the more common bullet weights for the old 45-70 Govt. round, isn't it?

I just bought a Marlin lever action in that chambering from my brother, so I've been perusing the ammo catalogs a bit more than usual. As I recall you can get bullets in that caliber from 300 grains to 500, with stops in the middle at 340, 405, and 450-ish.

For an old blackpowder round that's over a hundred years old, the 45-70 has picked up a pretty amazing following these days, so there must be something to the "heavy bullet moving at moderate velocity" theory after all.

It would be interesting to see how your airgun and something like an old Trapdoor Springfield compare, as far as telephone books go.

Hi Julio, the amount of energy obtainable from diferent slug weights depends greatly on how the airgun is configured. I build my own airguns for my own use just as a hobbie. What I prefer to do is build and tune my guns to perform at there best with a given slug weight. I achieve this with light to medium weight slugs as I find they shoot flatter and stop more readly in the animal as opposed to a heavier slug which tends to pass through on most of the game we have here in New Zealand. Now if I were to fire a some what heavyer slug than what the gun is configured for I will actualy get less energy as the slug weight has killed the FPS to that point. The advantage is that my guns tend to ballance out quite nice( they will give a number of fairly equal powered shots off a single fill ) and are very efficient on air. The down side is that I am pretty much stuck with a given weight range of slug, as I always include power adjusters on my guns in case I want to change the slug I'm useing or simply for tuneing there is some leeway. Regards to all, Danny

Danny,

I'm still pretty stuck on the one you reported that gave three shots at 1,200 fpe off a single fill. An amazing accomplishment. Wish you had not taken it apart afterwards. Wish you'd put it back together and share it.

The degree of sophistication you report building into your guns, truely deserves proper documentation. Any rebounding hammer PCP (90% of all PCP guns) will build higher breech pressure with a heavier slug, and increase it's power curve upon firing. What you describe can only be a pulsed valve delivering a brief duration of open valve, and not depending upon breech pressure as a component of valve closing. In every pulsed valve I've built, and documented, the gun delivered far higher energy with heavier slugs. Yours is quite unique. We'd love to see the numbers of fill pressure, shot string, remaining pressure ... with the lighter and heavier slugs. We're all ready to learn something new.

Gary

Julio,

Great post! I enjoy the visual experience of blowing stuff up so regardless of how scientific telephone books are as a medium it's just cool to safely wreck stuff with these guns.

Lon

H i Rotorhead, Danny and Lon,

Yes, it’s amazing how close are the .46 air gun slug’s weights to the weight of similar bullets for the fire arms.

I will include some performance numbers for the Caribou using the three .465 slugs that I have:
1) Raptors- 230.9 grains 950 fps 462 fpe

2) Bishops- 298.6 grains 865 fps 496 fpe

3) K-8- 450.3 grains 750 fps 562 fpe

If I were a speed maniac, for sure the Raptor was the way to go. If I were an FPE maniac then the K-8 is the way to go.

But if you ask me which one of these slugs have the best overall performance with the Caribou, the Bishop is the way to go. The rifle will give you two very similar and balanced shots out of one fill.

Following Danny’s post, it’s like this rifle was balanced for the Bishop slug. Also the Bishop slug shares the same deformation at impact characteristic as the Raptor. This picture will show you how a Bishop slug ends after hitting two phonebooks. Compare it with the Raptor’s picture posted above and you will see.



Lon, I totally agree with you in how satisfying it’s to blast things away with a big bore air gun. It’s even better if you have others watching when you do it. I do enjoy doing it and as part of the process convincing others about the power and accuracy these air rifles have.

Julio



Edited 1 time(s). Last edit at 04/09/2011 06:52PM by Julio.