New .457 Extreme.

[bluethunder]

Here's another important tip for Extreme owners. When my bolt sheared off I had to take the rifle apart to send the bolt back to Extreme for the repair. When I removed the action from the air tube I noticed that Extreme had locktighted the 2 bolts that hold the action to the air tube. These 2 - 3mm bolts can be seen at the bottom of the loading port.
     When the repaired bolt was returned I put the rifle back together. When I reinstalled these 2- 3mm bolts I just torqued them tight-- I didn't lock tight them.
      Once the rifle was back together I resumed group shooting. After about 75 shots I started to have to add some elevation to maintain my point of aim. Then the groups started unexpectedly opening up. Then I started skipping bullets off of the ground into the target. Then I couldn't hit the board at all. So I moved up to 50 yds. and still couldn't even hit the target board. I moved up to 20 yds. and still couldn't even hit the board. Mind you, this was a rifle consistently shooting soft ball sized groups at 100 yards. One bullet skipped off of the ground and wizzed off into the distance clipping leaves out of a tree as it achieved orbit. I had lost all control. I checked the barrel but I had been routinely cleaning it. It was shiny with no lead build up. So I quit. Took the rifle to the basement and started pulling it apart. I took it out of the stock, removed the scope and I remembered something that Allen had told me. Allen is the other co-owner of Extreme Big Bore rifles. He told me that if accuracy is an issue with the rifle make sure that the bolts at the bottom of the loading port are tight. So I put the 3mm wrench to the bolts and much to my relief they had shot loose. So this time I put blue lock tight on the 3mm bolts. Torqued them up tight and put the rifle back together. Took it back outdoors and resumed testing where much to my relief the rifle's former accuracy returned.

[Jeremy1982]

Blue,You were talking about the slop in the thin barrel effecting accuracy,I too have ran into that with my extreme.I only noticed it at 80 yards + but I was shooting groups with just the 4500 psi in the tube,1st shot was dead on then 2nd was a little high.Due to the 2nd round exiting the barrel a little later in the recoil.Anyhow I tryed to lay my hand across the barrel to tame the recoil on the send shot but if I pressed down too hard it would throw the shot way off.I finally decided to take some black silicone and ran a good thick bead in between the air tube and barrel..took the back of a pen and smoothed the joint like a concave.Looks great and helped a lot!

[bluethunder]

Thanks for the idea Jeremy. It would be nice if Brent and Allen would either build the rifle with a thicker walled barrel or at least build a spacer that fills the gap between the air tube and the thin walled barrel. Then a few nice barrel bands to keep every thing stable would give the rifle a nice finished look and probably greatly enhance the accuracy of our flex-o-rifles.

[rsterne]

By the looks of the photo in the first post, the barrel may be a candidate for an epoxied on carbon fibre sleeve.... Even adding 1/16" of CF all the way around will do a lot if the strands are running lengthwise.... CF is stiffer than steel for the same OD, and a LOT lighter.... If the barrel is a 5/8" OD you could use a 3/4" OD CF tube with a 1/16" wall....

Bob

[bluethunder]

Bob,

   Who is capable of doing such an epoxy job?

[rsterne]

Sean Pero did the one I have, but several guys on the forum have done them on their own guns, there was a thread in the PCP gate on it just recently.... You have to sand the barrel to give it some "tooth", degrease it perfectly, have the tube so that it is a nice slide fit and use a thin viscosity epoxy (eg. Acraglas).... Plugging the muzzle goes without saying, and hanging the barrel during curing to prevent any curve is likely a good idea....

I have a 1/2" OD liner on my .224 cal Hayabusa with a 5/8" sleeve on it and I'm sure it more than doubled the stiffness and certainly helped the accuracy....

Bob

[Nutcracker]

I finally got a chance to get the Extreme out of the safe yesterday. I could not get it to fill. It was working fine when I put it away. When I put it away, it  probably had less than 2000 psi in it, that was about two weeks ago. It was empty when I got it out and no matter what I tried I could not get it to take air. The valve was moving back when I would put the nitrogen to it, but for some reason air kept going through the barrel. ?? I am going to send it back to get it fixed, but was wondering is this common, or just my bad luck.

How much psi should I store it with?

[rsterne]

Try cocking it before you fill, the hammer is likely holding the valve open.... I store my PCPs with whatever was in it when I stop shooting, or full pressure if I want it be able to grab it and go....

Bob

[Fur-n-dirt]

Try cocking it before you fill, the hammer is likely holding the valve open.... I store my PCPs with whatever was in it when I stop shooting, or full pressure if I want it be able to grab it and go....

Bob

Good advice..

[Nutcracker]

Try cocking it before you fill, the hammer is likely holding the valve open.... I store my PCPs with whatever was in it when I stop shooting, or full pressure if I want it be able to grab it and go....

Bob

Good advice..

Did that. I already sent it back & they found the valve bent. They said I probably dry fired it and damaged the valve. The only time I  remember dry firing  it, was when It did not fill, then I did, thinking that might help. I did shoot it down kind of low, which may have damaged it. Brent told me to not fire more than 3 shots on a 4200-4500 psi fill. I think I fired 5 shots the last time I filled it to 3500. So we will see how it does when I get it back. I have actually shot my Bandit to empty a few times and never had this problem. I guess you have to be more careful with these higher pressure big bores.

[Nutcracker]

Well got my .457 back today. Tethered it to my Great White @ 3900 psi. After sighting in, shot 3 shots @ 50 yards ,touching each other. If I get some time this weekend, will chrony it some.

[shamu25]

Was shooting mine yesterday and was getting 5 shot groups at 50 yds touching each other using 3800 fill and 260 gr bullets.  I have noticed that my gun will not group well if you simply sit it on my caldwell rock  rest.  You must grip the forearm firmly to get the groups. 

[grumpy]

The barrels can flex a little cause they are TJ Barrel liners. Normally not an issue on a shorter barrel guns. I would guess your problem has more to do with the 1 in 20 twist. My extreme .308 will shoot 1" all day long if I do my part.

[koomassa]

I love the extreme 308 what i got couple weeks ago! Someone asked why gun dont fill? answer is that gun has to be cocked when you fill it.

[koomassa]

What height of scope rings do you use in extreme and what scopes?

[Nutcracker]

Here are some tests that I have done in the past.  The first set was done with the 2 different springs provided by Extreme:

EXTREME HUNTER BIG BORE AIR RIFLE TEST .45 CAL
All shots with 280 gr Mr HollowPoint hollowpoint bullets
All shots at 40’ with chrony at 38’
 
Test 1  Light Spring
1.864 fps 4100 psi fill
2. 814 fps 3400 psi
3. 758 fps 2700 psi
 
Test 2 Heavy Spring
1.858 fps 4050 psi fill
2. 800 fps 3300
3. 756 fps 2700
 
Test 3 Light Spring
1.820fps 3500 psi fill
2. 766fps 2700
3. 720fps 2250
 
Test 4 Heavy Spring
1.826fps 3500 psi fill
2.768fps 2800 psi fill
3.717fps 2300 psi fill


The following test was done with a Century Spring which is a lighter spring than both of the above that I received with my gun.  With this spring you can get a nice bell curve at a much lower pressure. Notice the peak of the bell is at 3100 psi fill.


Here are some new numbers that I shot this am with a new spring. Brent has the .45 cal set up for 4200 psi and he said the bell curve is found with a 4500psi fill. She's a total powerhouse with fills above 4000psi. I am aiming to tune this thing down a bit for plinking and yotes etc. I received a box of springs from Century Spring in LA yesterday (thanks Marvin for the lead on Century Spring) and ran the following numbers with their Spring #2894 which is 4.5"long, .718" O.D., .072 wire dia, 20.5 coils, 7.7 #/in. spring rate, spring steel zinc plated. This spring is much lighter than the stock Extreme spring and is very easy to cock. The numbers are still quite impressive. I have not shot for accuracy yet with this lighter spring. These strings were shot in my basement. May be a few days before I can get to the range. Cold here in MI.

166 gr
3500 psi 882 fps 286 fpe
3300 psi 926 fps 316 fpe
3100 psi 928 fps 317 fpe
2800 psi 911 fps 305 fpe
2500 psi 878 fps 284 fpe

350 gr
3500 psi 667 fps 345 fpe
3300 psi 724 fps 407 fpe
3100 psi 750 fps 437 fpe
2800 psi 728 fps 411 fpe
2400 psi 699 fps 379 fpe

With the stock spring the pressure drops about 600 psi per shot. With this spring the pressure drops only 200 to 300 psi per shot. She's performing way beyond a stock 909s and similar to a tuned 909 with air to spare. I could only get 2 shots from my tuned 909s with one follow up.

Ok this has been awhile, but I just sold my Extreme to my Son N Law. He wants to detune it some. I have to order 40 dollars worth of springs from Century, so what spring number besides 2894 is usable in the extreme.457. I would like to get a couple others to play with , since I have to order that much. Thanks.

[shamu25]

https://photos.app.goo.gl/UlCOmUWSqveN00VY2
My favorite is the 72056S which produces a bell curve that Peaks around 3800 PSI

[Nutcracker]

https://photos.app.goo.gl/UlCOmUWSqveN00VY2
My favorite is the 72056S which produces a bell curve that Peaks around 3800 PSI

Thanks, I will order some of those.  Which one will make it easiest to cock?   I don't think he is going to need much power to take foxes & maybe a  coyote?  He can always put another in for deer & hogs. The factory one is almost to hard to cock, in my old age. What # is the factory one?

[shamu25]

Good news I can save you a lot of money. I just found an extra 2894 spring in my tool kit. I can send this to you if you wish. shamu25revenge@yahoo.com
 just let me know where to send. Blessings Ray

[Nutcracker]

Wonderful, sent you pm and email. Thanks