Hi Guys,

Today I went to the range with the Caribou .46 and some K-8 slugs that Gary recommended to me a while ago. I bought some from Jerry and kept them waiting for the testing phase. Today was the testing day.

It was a beautiful sunny day with the temperature at 81 degrees and the breeze was blowing from left to right at aprox. 10 mph.

This K-8 is a .46 caliber, 460.5 grains slug. Previously I have used the Bishops with the Caribou achieving great accuracy. The Bishops are 305 grains and the Caribou shoots them at aprox. 860 fps when the regulator is set at 3,100 psi.

First I want to establish that my regulator is damaged and what it does is that it fills the rifle at different psi, even when the regulator is set to as specific psi. That’s why you will see the huge spread in fps in the following tests:

Caribou at 3,000 psi shooting the K-8, 460.5 grns:

1) 713.70 fps 520.98 fpe
2) 718.20 fps 527.57 fpe
3) 725.6 fps 538.49 fpe

Caribou at 3,100 psi shooting the K-8:

1) 725 fps 537 fpe
2) 746.90 fps 570.57 fpe
3) 735.10 fps 552.68 fpe

Caribou at 3,200 psi shooting the K-8s:

1) 731.40 fps 547.13 fpe
2) 717 fps 525.80 fpe
3) 721.90 fps 533.01 fpe

Caribou at 3,300 psi shooting the K-8s:

1) 721.10 fps 531.83 fpe
2) 697.30 fps 497.31 fpe
3) 708.50 fps 513.41 fpe


I did test it up to 3,400 psi and the fps continued to drop compared to the previous test. After examining the test results, I decided to set the regulator at 3,100 psi.

The following is the only group shot at 50 yds.





I was running out of slugs and moved the target to 100 yds to shoot the last K-8 slugs. This was the only group shot at 100 yds. I was aiming using the fourth mil dot at the target over the group. The slugs were hitting 10 to 12 inches below the aim point. I didn’t want to change the scope settings because it is set to shoot the Bishops.



With some more time and K-8s, it would be easy to set this scope for the K-8s.

Here is a picture of the Caribou's butt stock for any of you that aren’t familiar with this rifle.



It was a blast and I had a bunch of fun!

Julio



Edited 1 time(s). Last edit at 02/20/2011 05:33PM by Julio.

Hi Julio,

Wow ... that's a nasty flier at 3 o'clock on that 50 yard group! Great shooting ... that's a beast. It likes those slugs too. Better get some more.

Man ... that's pushing some horsepower too.

Glad you had fun!

Gary

Nice shooting Julio. Looks like a great day at the range. Those K8s sure deliver the numbers, you'll have to shoot something that blows up!

BTW, the velocity spreads look pretty good to me for a huge power gun. The regulater seems to step up the pressure pretty consistently also.



Edited 1 time(s). Last edit at 02/20/2011 11:13PM by Jerry.

Julio,

Jerry and I were talking ... looking at those numbers ... it doesn't seem clear that there would be any problem with your regulator.

It would be more clear if you had numbers for .... say ... 2,700 psi .... and then 3,000 psi .... and then 3,300 psi. bit wider gap. But - even though these are fairly close in fill numbers .... any powerful big bore is going to have some variation in velocity numbers. This will be caused simply by the given micro-second when the slug slips from the breech into the bore. The gun builds back pressure, behind the slug. The slug is kept from moving ... by the rifling against the front of the slug. At a certain point ... the pressure against the slug, will cause the lead to fatigue, and shear over the edge of the start of the rifling. To expect each slug to do so at exactly the same number, isn't going to happen.

For the readers ... we've been tracking down some issues with the performance Julio is getting from the Prairie Hawk. Though I can't determine anything that sounds incorrect ... from what Julio has described ... there's something there we can't lay our finger on.

Julio ... before you send off your regulator for rebuild, you need to make it possible to hook up the Prairie Hawk directly. I know you don't have a regular fill whip. Perhaps Gerald can spot you one. You can fill, per shot, to a number ... and then just turn off the tank valve. If the whip is long enough ... you can even let it hooked up and pressurized. You'd only have to open the tank valve, and bleed to a given psi, then turn it off, each time.

Gary

Julio,

I can't even shoot my near recoilless .22 rimfire that good at 50 yards unless I'm on the Internet.

Try starting with a tank filled to 3300 psi and just direct connect without the regulator. You'll get in a lot of shooting with only a very gradual drop in POI as the tank empties.

Nice shooting!

Lon

Yeah ... that's the old "Lonster Regulator" from Standing Stone One ... IIRC. Works great.

Man ... 570+ foot pounds ... in 46 caliber!

That thing is operating waaay over spec. You better return that to the factory ... for ... ah .... evaluation ... ... we'll get an old white haired engineer right on it ....

Gary

You might need help...I know where the K8 mold is! No making new molds allowed.

Why .... I'm pretty sure that mold is in the third drawer .... see ... right ther..... ....

Maybe in the secon.....

Well, tarnation ... something's 'round here ... ... can't seem to find nothin' anymore ...

hummmm ....

Gary,

It works so well I keep my 80 cf aluminum just for that purpose instead of selling it after purchasing a CF setup.

Lon

Good diggity dawg...thats some fine shooting and some good number for ANY KIND of gun let alone a big bore.

Its official....GB knows what he's doing...lol