De-tuning

[kiwi]

Hi...I aiming at building a springer for back yard target/can shooting.
it is a .177 B11. I have alway gone the other way power wise for killing
little cute critter's.
Other than the normal stuff to smooth a springer what ealse can be
 done when power is not the goal. I can only get a 15m  "10 most lightly" range in the back yard
so as long as it will punch cardboard at 10m thats kool.
I was thinking lighten the moveing mass , ie - tophat/piston to reduce recoil  & less
preload on the spring to reduce power. I'm aiming for somewhere around 500/600fps.
Is this the right way to get the what  I'm after ????

Ps - its only ever going to be a back yard toy so I just want to use what i have to build it
no new spring etc , don't mined turning/making bits.

[70GTvert]

Mass will make some impact, but not what your looking for. Stipulation is using the factory parts? Trying heating up the bottom 2-3 inches of the spring red hot, but let it cool down naturally. that part will loose it's temper and thus reduce spring power. This MAY result in the spring shortening somewhat (taking a new set) and some additional firing noise. Some have noted that opening the transfer port up will lower the FPS once it is done beyond a certain point, but that would be like dry firing, so I would pass on that. If you have the means, the best bet would be to increase the piston length a couple of inches, that would reduce the amount of load on the spring when cocked. See if anyone you know can make a longer one for you.

[howie1a]

I just finished chronying my Bam11 it does 675.3 as an average fps that brings it to an 8 fl. lbs. rifle I was using  CHP at 7.9 gr. all I have done to it was to a lube & clean it is a nice shooter I shoot in my garage just under 10 m. so my use is like what you want to do.You will like the rifle it's very nice.If you go to the china gate you can see the stock rework I've done to the Bam 11 it's under (( Hi Mike see what I did to your rifle (PICS ) - howie1a : 2/6/2009 12:29 PM  )) howie

[kiwi]

Hi..the Bam 11 and the SPA B11 are totaly diffrent guns
B11 is made by Snowpeack airguns "SPA" China
it rated at 1000fps

[howie1a]

I have been thinking about an easy to de tune a springer some where  I read about a test that was done on springers leaving them cocked for 1 hr -- 1 day -- up to about 1 month and the power loss they developed, My thinking was to de tune a springer why not just let it cocked and stick it in a closet for a month then chrony it if you want the power back put in a new spring  I know it sown's to easy but what do you think ? howie

[kiwi]

Why not - nothing to lose

[howie1a]

Look in our library under Keeping a Springer Cocked By Ken Pangh  that is  ware i seen the write up on  keeping a springer cocked and how it affected the power of the gun. howie
   

[RedFeather]

You could drop the power level by leaving your gun cocked but I wouldn't recommend it.  For one, it will be inconsistent regarding power levels.  Probably spend half your session re-adjusting the sights each time you take it out.  And, over time, the fix will become permanent.  How about some heavy tar?  I see where they caution using too much since it drops fps.  Maybe a little extra while you're about it will slow it down a bit more plus should dampen vibrations.  You can always wipe it off if things don't turn out to your liking.

[howie1a]

error

[howie1a]

Why would the power be inconsistent what you are doing is to reduce the power of the spring once it has the power of the spring lower it should stay that way.(( read the leaving a springer cocked it the library,)) my thinking is this will be a permanent power loss not some thing that will come back, kind of like when set the spring but much  simpler  to do than tearing down the gun and put a lighter spring in if tow were to change the spring to a lighter one you would have to find a spring with the same OD and the same Length but made of a thinner wire this will give you a lower power rifle and keep everything else in tack, either way it is possible.I wouldn't try heating the spring and to try to take some temper out of the spring or cutting  it shorter this will make everything to loose . Also I don't think you could put enough tar on the spring to make the difference you are looking for. just a thought howie

[Gene_SC]

Red I think the Velocity tar would be a good idea for de tuning but you would have to experiment on how much you would apply. Although it is not the best way to de-tune a springer but better than weakening the spring. I find that since I have been tuning springers there are several ways to detune them but you have to have the machines to rework the parts and add on mods also. Spring type plays a good part in varying the fps. But that can work against you if you do not set it up correctly. There are endless ways to do it correctly.

[kiwi]

machines an't a prob....
basic stuff lathes/mills etc plus
cnc machine centres / cnc constance surface speed lathes
3000 watt laser / turret punch with 30 tool mag /
surface grinder / press brakes - should I continue ?

have thought I should draw up a air gun export the files to the cnc's
and go down a hour or so later and pick up me new air gun. lol
Ps - can't broch the rifleing in the barrel  then twist it

[Gene_SC]

Paul I am sending  you adoption papers..:) You got room for one more air gun junkie..:)