177 cal mag grouping ??????

[fgwhite]

guys i never shot a magnum i got a 125 sniper in 177 tell me some thing i have read where people useing ruger air mags get them to shoot is it commom knowlage that a 1200 fps gun wount group with 8 grain pellets i not worrking about going sub sonic i just woundering if these 1200 fps guns useing 8 grains can group

[Lambchops]

8 grains is too low. Try 10.2 and above. CPUM, Kodiaks, etc.

[Motorhead]

Yup,
Until you get enough weight and resistance of a BIG pellet in the tube, recoil / jump is just too severe for decent accuracy.  Speed another issue as address above. 
Spittin light pills at or near supersonic speeds sounds cool but about as accurate as throwing rocks.

10.5 or 13.43 JSBs, Crosman 10.5 heavies, Eugin 16's should do MUCH better for ya.


 A lot of users DE-TUNE with the Titan NP ram.

[Bullit]

If you can, run your current gun/pellet combo thru a chronograph to see what the true speed is.   I ideally want to get it shooting under 0.85mach@muzzle, and that'll be a balance of power and accuracy.  Going faster makes the pellet unstable approaching sonic velocity.  G'Luck,  Mike

[supertech77]

Being experienced with the r.a.m in 177 cal.nothing under 10.gr would work ,without going SS, 10.5 cpum's were most  accurate,16.gr eunjin's were a very close 2nd,but shooting the eunjins,cost me my 1st spring,then i completed a self tune,with the vortek kit ,thanks to a member here,[DmikeM ]and could use the 16gr all i wanted,but why ? when the 10.5gr cpum's worked just fine,and they were at 980fps,and so much cheaper ,other important accuracy point on it was the hold,mine worked best with the artillery hold,with the front hand near the front of the trigger guard,it was accurate out to 120 yards with the cpum,s and the eunjins 16gr,the 16's had a lot more energy on impact out that far. ,now' the r.a.m has a 25cal barrel on it,with a heavier spring,even better,

[SpringerMan]

8 grains is too low. Try 10.2 and above. CPUM, Kodiaks, etc.

Theoretically, if your rifle could shoot an 8 gr pellet at 1200 fps, a pellet weighing 12.76 gr would be needed to reduce it's velocity to 950 fps, with the fpe remaining constant. ( 25.58 fpe in this example ).

Another poster stated ".85 Mach" as the maximum velocity, which is approximately 950 fps. The .85 Mach is a valuable number to remember, as velocity above that enters the Transonic Region, where higher air drag and turbulence begin to destroy accuracy.

"Transonic" - http://en.wikipedia.org/wiki/Transonic

At Standard Sea Level conditions (corresponding to a temperature of 15 degrees Celsius / 59 degrees Farenheit), the speed of sound is 340.3 m/s (1225 km/h, or 761.2 mph, or 661.5 knots, or 1116 ft/sec) in the Earth's atmosphere.

http://en.wikipedia.org/wiki/Mach_number

[thekid]

My Hatsan 125 would break the sound barrier with mistergugelns 8.2gr and group like sh!t.
Used 10.5 gr crosman premeirs...it would launch them out the door at 970 fps.
Those .177 hattie mags are serious hitters and need some weight to control them.