EXTREME .308 "Whiteout and Alpha 30 wins 1st & 2nd at EBR 200 yd event!

[Rizen 1]

Well, here is the start of the "WHITEOUT" build... We (Brent Hoag, Chris Alls and I) started this build to test the 200 gn "WHITEOUT" bullet that Bob designed. With the help of Bob and many others, here is our progress so far....

[Rizen 1]

More pics....

[rsterne]

Everything looks great, guys.... the bullet looks awesome, can't wait to see how it shoots....

Bob

[Rizen 1]

Bob, what do you think of the adjustable bolt probe?

[rsterne]

Looks great.... I had a replaceable one in my Hayabusa .357, two different lengths, with a short one for bullets and a long one for pellets.... The face of the bolt was flush with the back of the barrel port and the probe just threaded into the nose.... Same basic idea, without the adjustment and lock nut.... On the Disco Double I used a retractable bolt with the handle running in a "J" slot.... Push the bolt forward to seat the pellet or bullet (using the base).... then swing the handle down to the lock position and then withdraw it so that the nose is flush with the back of the barrel port.... The only problem is that the O-ring needs to be in the barrel instead of on the bolt, as the bolt has to withdraw about 1/2".... It completely clears the barrel and port, so no restriction at all.... and you can tune the gun by limiting how far back the bolt pulls and have the nose cover part of the barrel port like a slide throttle in a motorcycle carb.... It's nice for dialing the power way down for pellets....

Bob

[PakProtector]

Bob, the Gen1 marauder breeches are so easy to implement this on...very good performance indeed.

I am at a bit of a loss as to why the extreme high power folks don't use it exclusively.
cheers,
Douglas

[jimreed1948]

This is interesting.  I'm in the market for a big bore and maybe this is the one.  Your details are a little sketchy.  How many shots are you trying to achieve.  The current .308 Brent builds gets 3 shots.  Do you expect more or less?  What type of distances are you expecting to shoot this to accurately?

[rsterne]

This is being built as a 200 yd. rifle, shooting a 200 gr. bullet boattail (shown) at over 1000 fps....

Bob

[jimreed1948]

This is being built as a 200 yd. rifle, shooting a 200 gr. bullet boattail (shown) at over 1000 fps....

Bob

Thank you for the information.  Will be watching this for sure.

[jimreed1948]

Anything new going on with this build?

[rsterne]

I understand the rifle is complete and ready for testing....

Bob

[Rizen 1]

Chris and I went to Brent's for a few days to finish the Whiteout build and do some testing.  Here are a few pics....  The gun is incredible!!!!

The groups were shot at 100yds after about 9 hours of testing and tuning..
Chris is a genius with tuning Brent"s guns   as you can see with our final groups WITH THE 200 GN BBT

 

[K.O.]

NICE...

[wimpanzee]

Very nice! Thank you for sharing.

[rsterne]

Looks great, Mike.... How big is the 10-ring and the red dot (or what did the group measure)?.... and how many shots in the groups?.... Certainly looks like both bullet and gun are doing the job.... What velocity did you end up using?....

Bob

[C.ALLS]

Looks great, Mike.... How big is the 10-ring and the red dot (or what did the group measure)?.... and how many shots in the groups?.... Certainly looks like both bullet and gun are doing the job.... What velocity did you end up using?....

Bob

The red center dot measures .6" and there are 5 shots in each group. The bullet/gun combo looks to prefer a muzzle velocity of 970fps. The gun likes to be held and shouldered firmly as we found out after Mike shot those two groups.

[Mr.bullet]

ohhh my gooddddddd   



YO QUIERO UNO  ( I want one  )


it would be possible to know what kind of valve has been used in this incredible PCP? design measures etc ....

I'm looking for good design to make my PCP valve ....

A greeting

Pau

[C.ALLS]

ohhh my gooddddddd   



YO QUIERO UNO  ( I want one  )


it would be possible to know what kind of valve has been used in this incredible PCP? design measures etc ....

I'm looking for good design to make my PCP valve ....

A greeting

Pau

Unfortunately I believe Extreme Bigbore is pretty secretive of their valve specifics.

[Airgunhunter73]

That is a awesome rifle, the boolit looks like a missile and the accuracy with it was great, how many shots do you get with it untethered.
Thanks Terry

[C.ALLS]

That is a awesome rifle, the boolit looks like a missile and the accuracy with it was great, how many shots do you get with it untethered.
Thanks Terry

Well the air tube is a shortened 20" version of Extreme's standard 24" 300cc air tube. With the shorter tube, using Helium, a 4500 psi fill and a 12 lbs/in spring running around 1/2" preload I can shoot 3 shots inside a % 3 extreme spread. The gun uses almost exactly 450 psi per shot and that's pushing the 200 grain BBT bullet at 970fps for roughly 420ft/lbs. As I've said many times the Extreme Bigbore guns respond well to different tunes.

After meeting Brent I now understand why he builds his guns and tunes them how he does. He specifically makes his guns with the big game hunter in mind. The good news is with nothing more than the proper spring and the owner being okay with a slight decrease in power the guns can easily be tuned for 3 tight shots.