disco accuracy and power issues,any advise/ideas.

[one_shot]

last year i hunted rabbits with my trail npxl .22,my particular xl pushed cp domed pellets @ 940-950 fps.
i dropped large rabbits out to 80 yards,1 shot...instant death.
but that gun is long gone.

tonight i pulled out the disco,dusted her off,installed the open sights.
fired 50 rounds from 25 yards.
my max psi was 2400,but my powerband is from 1800 down to 1400 the last time i shot her (mths ago)
the gun is stock,except for the stock and fake suppressor,extra barrel band.
ive never grouped the gun with open sights.
today at 20 yards from a rest,the best group i pulled was 1.25.
at 10 yards i was able to pull in 3/4.
im a target shooter,im used to 1 hole groups at 10 with a 4x scope.

eversince i got the disco,my groups arent consistent.sometimes a nice 1 hole at 10 scoped,next group 1 inch,next 1 hole...ect.
i even tried to keep the gun filled in the power band.

after all that i took her on the hunt today.
first 2 mins on the hunt,i dropped a nice rabbit at 25 yards with a headshot.i was impressed...my first big game with the disco.10 mins later a fat bunny poped out 30 yards infront of me.i missed,bunny ran back to the brush.i reloaded,2 mins later he returned.i fired from 30 yards hitting him in the head.rabbit back flipped and ran off.

i know i hit his head,i saw the impact.
i instantly checked accuracy at 30 yards,i was dead on.
25 mins later i closed in 15 yards out on a 2 nice bunnies,took aim 1 inch behind the eye.....and fired,this time the pellet strayed off to the right hitting the bunny towards the rear of the head and upper neck.
he jumped up about 6 ft in the air,layed on his side doing the death roll,while i reloaded to try the 2nd buuny.
but i wasnt fast enough in running down the 2nd bunny....that one got away.
so i turned to the down bunny,as i walked up the bunny rose to its feet and bolted for the brush in a zig zag path.was clearly stunned.
bunny ran about 2 feet into the brush,i was 10 yards behind him.he stoped...i fired round #2 into the back of his skull.
to my supprise....he just flopped around and ran 5 yards deeper into the woods.
now im stunned....first thing i do is reload...then check my pressure on the disco.
in disbelief....i was in the powerband,just above 3/4 green on the gauge.
2 shots to the head...bunny still alive and now suffering because of me.
so i had to finish him off.
3rd shot from 8-9 yards right between the front legs,a vital shot....but the bunny darted after impact.i searched for 30 mins....no bunny.

my point is.....what could be wrong with my disco,giving me inconsistent power and accuracy!
every shot sounds powerful in the powerband.
if i cant humanely drop rabbits with 14.3 grains at 840 fps.....

this is a 22 ftlb gun.

[MustangMike]

have you checked the crown, the break on the end of the barrel might be clipping, and if you are using cphp's id suggest a better pellet..

cphp's have a very inconsistant skirt/head size. thus some pellets fit loose and others fit tight cauisng a larger group then expected..

[one_shot]

ive tried jsb's,h&n ftts & cuda's,a few others,the cps gave me the best results...ill look closer at the crowning,but when i checked it a few mths ago....she was good.
my stock is secured tight,my barrel has 2 bands that fit nice to prevent flex.
my muzzle brake actually increased the accuracy.
i cant figure this disco out.

[one_shot]

just removed the brake,crown is good,barrel is clean,so is the brake.
ill keep digging around.

[amb5500c]

That's a beautiful hunk of wood.
Richard

[gene_sc]

Could it be your pellets are clipping the muzzle brake inside?

[geewhiz380]

try another scope ,another would be a nice barrel cleaning ,check front side screws that holds action and stock ....good luck and keep us updated ..jorge

[one_shot]

That's a beautiful hunk of wood.
Richard

thanx richard.....its one of my many unfinished projects.
its a highly modded titan stock,carved out to fit my hand exactly.filled in the gap for the break barrel,started covering with spanish ceder accents.one day ill finish it.

Could it be your pellets are clipping the muzzle brake inside?

the brake is centered and bored to .30 caliber,theres no lead marks or scuffs on the inside.i even coated the inside with marker and fired shot through it.
one thing ive noticed is the breach itself...if i squeeze the barrel to the air tube,oil squishes out indicating movement.the breach screw is very tight already,id hate to strip it.
but this may be may problem.

try another scope ,another would be a nice barrel cleaning ,check front side screws that holds action and stock ....good luck and keep us updated ..jorge

barrel is clean,ill try to clean it again and install one of my newer scope tomorrow.

[MustangMike]

maybe try moving the rear barrel band up the barrel slowly.. like shoot a 5 shot group and then move the barrel band up the barrel one band width at a time..each time you move it, refill to the pressure you shot the previous group at and shoot another 5 shot group.. if accuracy improves shoot another 5 shot group and keep going.. if the groups start opening up again try moving the band up again..

thats what my plan of attack would be with a ghost issue... checking the muzzle break for clipping would be the very first place i would suspect the issue would be..



*****the above post was post as i typed this post... considering you get movement at the breech id bet thats ur issue and maybe the only thing to do is a complete tear down for inspecting.. unless ur like me and since its already apart go ahead and replace some orings.

[one_shot]

ill empty the gun and tear down....maybe my breach to comp tube oring shrunk over time.....ill just tear into it,but any other suggestions would be appriciated.

thanx nick

[gene_sc]

If you feel no air leaks then that aint it

Just try removing muffler and check crown. Shoot wiff out muffler and see if there is any change.

[one_shot]

theres no air leak,checked with soapy water while firing.
the brake is permantly attached to the original tip.i made the attachment a 0.02 ths press fit,then bored and worked while attached in place.
ill have to scope the gun,shoot 30 shots,then remove the attachment and re-shoot 30 more shots,then compare the results.
ill do this test next.

my crown looks nice and even all the way around.
both on my barrel and attachment.

i just tried some accuracy test from 10 yards,bench rested on a sandbag,open sights.
30 shots is what i got from 2000 psi down to 1000 psi.
then 40 shots from 2400 psi down to 1000 psi,i finished off last group at 850 just to complete the set.

i was very steady,used the same hold and cheek weld,0 wind shooting cphp's.
i know the rear sight on the disco is too close,its fuzy but this is the best i can get from her open sights.
my stoeger x10 currently has no sights or scope,and i can do the same groups with that gun.
maybe its the cphs as you stated,sofar i ve only found 1 pellet that groups better,but its a 21 grain round,my disco only shoots it at around 630 fps thats only 18.5 flbs.

[one_shot]

the groups arent that bad...but there not great.ill print 4 in 1 hole,then a 5th stray.
its just getting to me.
poi is constantly shifting aswell,i aimed for the center every shot.

or is this normal disco open sight groups.
will someone go shoot their disco at 10 yards,rested with open sights.
please....lol.

[gene_sc]

what pellets u using?

When you check your crown make sure you stick a q-tip in and pull out slowly. If there are fibers stuck to crown you need to polish it.

[one_shot]

running cp in the brown box of 625 count.
ive ran a few qtips,leaves behind no fibers.
ill go try the scope with and without the muzzle brake.
ill see if i have any other .22 rounds left....but i think i got rid of all my rws,h&n,jsb....ect.

[one_shot]

installed the scope,rough sightin at 10 yards shooting cp domed.
3-9x40 cp scope kwik-site 2 peice steel scope mounts.
i use these mounts because they are solid,and keep my scope close to the barrel,allowing a firm cheek hold and eye relief position.ive made alot of efforts on this gun to achieve good accuracy from cheap pellets.

from the same rest as before.
shot 5 shots with brake on,then 5 shot with brake off.

you can see without the brake the poi shifts drastically.
my groups are tighter with the brake installed.

now onto my my problem,from seeing the 2 groups....your thinking i started this thread for nothing.
but i think ive solved my problem.
ready!

only 2 explinations that i can come up with.
#1....im a horrible shot with open sights....not likely....but possible.
#2....being my breach moves with open sights,i tried to move it with the scope installed,alot less movement,infact the breach feels more solid.

i think once the scope is bolted on and secured it strengthens the breach,when i shoot the breach moves/vibrates less giving me more accuracy.
the rigid scope mounts take out that vibration.
im trying to come up with a way to test this theory....besides my scope/no-scope groups.

but by doing all this ive rulled out the pellets,my homemade brake/barrel crown....ect.

please explain your thoughts on my theroy,if you think im making any sense,or sounding like a babbeling idiot!
thanx.

10 mins ago i dropped a starling at 55-60 yards @ roughly 1400 psi.
so i know the accuracy is there with a scope,im just trying to get accuracy with open sights for use as a brush gun at close range.

[rsterne]

The wandering POI is consistent relative to your pressure.... It starts high, drops, stays there, and then rises again at the bottom of the string.... This is backwards to what you would expect, as the velocity is low at high and low pressures and higher in the middle, in the "sweet spot", which in your gun seems to be from 1800 psi down to 1400.... very typical for a stock Disco.... First of all, with a stock hammer spring there is NO point in filling above 2000 psi, the velocity drops more and more as you increase the pressure above 1800....

I had a similar problem with my Disco, and I cured it by playing with the set screw on the top of the barrel band (I only had the stock one in the original location).... I found that having the set screw JUST touching the barrel produced the best groups, and the least change in POI.... Obviously, the screw won't stay like that, it will work loose.... so once I found the best position for it I secured it with a drop of loctite.... While there was still a small residual shift in POI, it was maybe 1/4 of what it was originally with the set screw tight....

There is also the possibility that your muzzle brake has changed the barrel harmonics and with the pellets you are using, when the velocity is in the "sweet spot" the barrel is at the bottom of an oscillation.... Since it is reversing direction, the groups are tighter then.... When the velocity drops a bit (high or low pressure) the barrel is in the middle of a swing, travelling vertically quite rapidly, hence the opening of the groups, the vertical stringing, and the higher POI.... Think of the pendulum on a clock.... At the ends, it's standing still as it reverses.... In the middle, it's moving the fastest....

That would be my guess.... that the added mass of the muzzle brake is emphasizing what happens normally in any rifle.... Try the barrel band setscrew first, though.... it's easier....  

Bob

[rsterne]

Your drastic change in POI with the brake suggests my idea about the oscillations may be correct....

Bob

[MustangMike]

if the brake is causing the issue id suggest a tko 6.5, plenty of people use those with any issues with groups opening up

[one_shot]

i agree with you explained poi shift/harmonics....ect.
but it seems to be worse with the use of the scope.
i understand quite well about the pellets flight path with different pressures aswell.
my sweet spot has a nice predictable path,sightin at 10 yards,poi is dead on at 60 yards,at 30 yards i aim 2 mills below my target,80 yards 1 mill over,100 yards 2.5 mills...ect.
all that changes if im not in my sweet spot,that flight path is altered,still has the same arch,just poi is at a different yardage.
been trying to learn it for about 1 year now.

i think i need to stabilize the barrel,my rear barrel clamp is just slightly touching the barrel,i can move it by hand with lil effort.ill try what you suggested.
but the way i have it set....is the way it worked best for me in the past.

thanx bob.