Playing with the Extreme .308

[Fur-n-dirt]

Just for the record, Extreme airguns recommends "liquid wrench chain lube" for hammer and orings.

[Fur-n-dirt]

100 yard accuracy testing results...  3800 psi w 16x Vortex

I do not have a regulator yet, so I am at the mercy of the bell curve. 

I did some testing at 100 yards using the .309 lee 115 grain FP mold.  This was the same mold that was used to make my hollow point version discussed above.

I shot five strings (3 total shots for each string). I would have shot more, but my 8 year old was getting tired.

The chrono was measuring velocities at 975 , 987, 974 , for the first three shots respectively.  Note , the high velocity for the 2nd shot.

Anyway, I will report the best 4 out of 5 strings.  If the Olympics can throw out scores, we can't I? 

The bottom line, the gun shot consistently .  The second shot was always higher.

Center to center for all three shots
1 2.05"
2 2.4"
3 2.0"
4 threw out
5 3"

Ctc for the 1st and third shot
1 .53"
2 .59
3 .56"
4 threw out
5 .59

For a added bonus, I shot one string with the HP's.  The group for all three was 1.19"

This is not sugar coating anything, just reporting raw data from today"s shoot.

Pretty happy so far, the gun has a lot of potential and shooting consistently.

I'm going to be working on the bell curve.

This is really a hunting gun for me.  If I wanted to plink a lot , I should really get a regulator for exact pressure every time.

Maybe I'll tune the gun for consistent shots for the first and second.  A back up shot with slightly lower psi?

[rsterne]

A 13 fps spread (~1.5%) should be virtually unnoticeable at 100 yards.... certainly not 1.5" higher than the other two.... Your 2" groups at 100 yards are pretty decent for cast bullets, IMO.... Using a BC of 0.17, Chairgun give a vertical POI change of only 0.50" between 974 fps and 987 at 100 yards....

Bob

[Fur-n-dirt]

A 13 fps spread (~1.5%) should be virtually unnoticeable at 100 yards.... certainly not 1.5" higher than the other two.... Your 2" groups at 100 yards are pretty decent for cast bullets, IMO.... Using a BC of 0.17, Chairgun give a vertical POI change of only 0.50" between 974 fps and 987 at 100 yards....

Bob

Hi Bob,

Thanks for keeping me honest!  The velocities reported was done before shooting these strings, so I actually don't know the exact velocities for these groups...

The bullet locations seemed to be consistent .  One was higher and slightly right, while the others were tightly grouped.

Anyway, much more shooting necessary to define averages.  I plan to post more data..

Also, I haven't done any experimentation on any sizing, and lubes yet.

This gun is a blast to shoot!

[rsterne]

My guess would be barrel harmonics.... If the barrel is travelling lower left to upper right as it oscillates, and the bullet is exiting more to the upper right of the swing at 987 fps than it is at 974-5 fps you would get exactly what you describe.... An inch of oscillation at 100 yards is only maybe 0.007" at the muzzle.... A small muzzle weight, or slightly different barrel band tension or bedding might be all it takes to change the timing of the arc.... The ideal situation is for the bullet to be exiting when the barrel pauses and reverses direction at the end of a vibration.... That way, even rather large differences in velocity won't print to different POI....

When reloading for a .222 Remington CF many years ago, as I increased the velocity I could watch the group string out from 8 o'clock to 2 o'clock at middle velocities, and then shrink at the 8 o'clock position at around 3000 fps and at the 2 o'clock position at around 3400 fps.... Trying to get a load to shoot at 3200 fps was useless.... 2800 fps was also useless, and at 3500 you could see the groups starting to track down and left again.... The groups at 8 o'clock (3000 fps) and 2 o'clock (3400 fps) were nearly 3 inches apart, but easily covered with a dime.....

Bob

[grumpy]

The problem I have with shooting very tight groups with my Extreme is the trigger. Timney are just not 'target' triggers. Now if I could get mine down to a pound or less even my groups would tighten up big time !!

[shamu25]

Any thoughts on lock time with respect to accuracy on the big bores?  I can consistently shoot one ragged hole at 50 yards with my Extreme 45 but wonder how much better that would become if there wasn't a long interval between trigger sear disengagement and the valve opening.  I struggled a long time with consistent hold and grip with this gun especially after shooting my CZ 204 with a set trigger.   I have to believe that if the lock time on the Extreme was the same as the CZ that most of the bullets would print one clean hole.   Just curious.

[Fur-n-dirt]

Any thoughts on lock time with respect to accuracy on the big bores?  I can consistently shoot one ragged hole at 50 yards with my Extreme 45 but wonder how much better that would become if there wasn't a long interval between trigger sear disengagement and the valve opening.  I struggled a long time with consistent hold and grip with this gun especially after shooting my CZ 204 with a set trigger.   I have to believe that if the lock time on the Extreme was the same as the CZ that most of the bullets would print one clean hole.   Just curious.

Yup, if the cross hairs change from the time the sear disingages and puffs air, accuracy will suffer.  The hammer is a big mass too!  This suggests a nice firm set into the shoulder so the inertia of the hammer minimizes twist...

Ray, is that what you do?  Currently, I'm setting the gun on bean bags front and back.   Manny once said that he got better accuracy w/ the Evanix by not using a bag in the back since the bullet was moving slower..

Cheers.. 

[Fur-n-dirt]

The problem I have with shooting very tight groups with my Extreme is the trigger. Timney are just not 'target' triggers. Now if I could get mine down to a pound or less even my groups would tighten up big time !!

Yup, lighter trigger will definitely help.  I built a custom 1022 with a nice 1.5 lb trigger recently.  Makes a difference.

By the way, I think the timney trigger is adjustable; however, I'm not messing with it!

[Fur-n-dirt]

My guess would be barrel harmonics.... If the barrel is travelling lower left to upper right as it oscillates, and the bullet is exiting more to the upper right of the swing at 987 fps than it is at 974-5 fps you would get exactly what you describe.... An inch of oscillation at 100 yards is only maybe 0.007" at the muzzle.... A small muzzle weight, or slightly different barrel band tension or bedding might be all it takes to change the timing of the arc.... The ideal situation is for the bullet to be exiting when the barrel pauses and reverses direction at the end of a vibration.... That way, even rather large differences in velocity won't print to different POI....

When reloading for a .222 Remington CF many years ago, as I increased the velocity I could watch the group string out from 8 o'clock to 2 o'clock at middle velocities, and then shrink at the 8 o'clock position at around 3000 fps and at the 2 o'clock position at around 3400 fps.... Trying to get a load to shoot at 3200 fps was useless.... 2800 fps was also useless, and at 3500 you could see the groups starting to track down and left again.... The groups at 8 o'clock (3000 fps) and 2 o'clock (3400 fps) were nearly 3 inches apart, but easily covered with a dime.....

Bob

I agree..   maybe one adjustment could be bolt preload attaching stock to receiver.   Maybe the tank compressing in the stock would preload the barrel band ?

By the way, does anyone know if the barrel band allows the barrel to slide?  Looks like the band is firm on the barrel.   

[rsterne]

I'm not a fan of having both the barrel and air reservoir locked solidly into the same barrel band.... I've seen too many cases of the reservoir changing length with pressure and bending the barrel up or down as it does so.... I usually use an O-ring to mount the barrel inside the band....

Bob

[shamu25]

A loose barrel band reminds me of the night mares that I had with my Marauder.   It was designed to float but needed constant adjustment as it seemed to touch at some point after a few days of use.  I believe that the Extreme is dead tight.  My AA S510 is also tight and unbelievably accurate.
Love the Timney trigger on the Extreme.  Never messed with it as it was so crisp and just about right for me.  Do not have a trigger pull gage so not sure where it is set.
I have tried both a firm and loose shoulder hold as well as with the fore piece.  I seem to get just as good of groups with my caldwell rear bag and front Rock rest  with just a casual hold on the gun both front and rear allowing it to float a bit.   Other guys like it tight.

[grumpy]

They come set at about 4 poundish according to Brent. Most of my target guns run from 4 oz to 13 oz at the heaviest. Allan told me once he would not advise taking the timney under 2 pounds for safety reasons.

[Fur-n-dirt]

Dad came up for a visit; pictured here shooting the extreme .   I switched vortex scopes with a better reticle.

After sighting in , he shot a .57" ctc 3 shot group at 50 yards.  Not tethered/115 g FP/7.7 spring/3850 psi

Shooting great.   At 100 yards, the 3rd hold over is almost perfect.

[Rescue35]

Looks like great fun. I always enjoy the chance to do something fun with Dad.

[Fur-n-dirt]

Shot a coyote with the extreme!

video , click here..

[Rescue35]

Nice Yote! Good shooting.

[nappyman]

One down and how many more to go ? Nice shooting would have love to see the kill on vid yet I know I have missed or lost many shots farting around with a cam

[Fur-n-dirt]

One down and how many more to go ? Nice shooting would have love to see the kill on vid yet I know I have missed or lost many shots farting around with a cam

I have a Contour cam that's mounted to the shotgun and it works pretty well ..  just flip a switch and forget about it..

[Fur-n-dirt]

I am planning to go to the range later this week..  I'll be trying bullets that are sized and lubed.   Oh yeah, going to try a bullet of my own design from an accurate mold.  Its a FP.   

Should be fun.