I have a bunch of H&N Sport 8.18 grn pellets, as well as some 11.57 grn Silverpoints. Anyone here know roughly how much of a velocity drop (~%) out of a PCP target air rifle that is supposed to be at 495fps? Do not have my chrony with me right now and just trying to see if anyone has tested this out here before.
Velocity difference between mid weight and heavy weight pellets
- Thread starter COREY
- Start date
It may not be linear...
But for the OP- with a 495 airgun it really need to have the lighter pellets. The silverpoints are too heavy for that power plant imho- how do they shoot?
If the 8.18 grain pellets did in fact achieve a muzzle velocity (MV) of 495 fps, the rifle would be producing about 4.5 foot pounds of energy (fpe).
A 4.5 fpe rifle shooting a 11.57 grain pellet can be expected to achieve an MV of about 420 fps, which is about 85% of the velocity of the lighter pellet.
But as been pointed out, the MV - energy relationship isn't necessarily linear. The 11.57 grain pellet is about 40% heavier, while the velocity decrease is about 15%.
And there are some unknowns involved. For example, unless it's chronographed, no one can know exactly what energy or MV the rifle in question actually produces.
A 4.5 fpe rifle shooting a 11.57 grain pellet can be expected to achieve an MV of about 420 fps, which is about 85% of the velocity of the lighter pellet.
But as been pointed out, the MV - energy relationship isn't necessarily linear. The 11.57 grain pellet is about 40% heavier, while the velocity decrease is about 15%.
And there are some unknowns involved. For example, unless it's chronographed, no one can know exactly what energy or MV the rifle in question actually produces.
question
FWB 10 m rifle at under 495 FPS
field target rifles for international competition are 12 foot pounds at under 800 FPS with a 8.4 weight .177 pellet
Can the 10 m rifle at 25 and 50 yards for benchrest be competitive against the field target rifles?
sure the drop will be greater but how would this affect grouping
looking at a rifle but not sure I wish to change the internals to achieve what is needed for FT or BR
thanks mr guru
FWB 10 m rifle at under 495 FPS
field target rifles for international competition are 12 foot pounds at under 800 FPS with a 8.4 weight .177 pellet
Can the 10 m rifle at 25 and 50 yards for benchrest be competitive against the field target rifles?
sure the drop will be greater but how would this affect grouping
looking at a rifle but not sure I wish to change the internals to achieve what is needed for FT or BR
thanks mr guru
If your FWB 10 meter rifle is relatively new, that is no more than 10-15 years old, it is likely a PCP. A PCP with little to no recoil is an advantage over a springer, which, depending on the design, can recoil quite a bit.
I had a FWB 300S that when refurbished delivered about about 7.3 fpe, which meant an 8.4 grain pellet had an MV of about 625 fps. With its anti-recoil system, it was good for bench shooting in very calm conditions out to about 30 meters, near the maximum distance of the range I used at that time.
A less powerful 10 meter air rifle such as the one to which you refer, would be ideally performing well at 10m with flat nose pellets that are typically a little lighter in weight. Flat nose pellets would not be as good aerodynamically as round nose pellets for long distance shooting.
The 12 fpe limit for field target is derived from the limit on air rifles in the U.K., where FT is a big sport. In FT the longer the distance, the larger the target. In benchrest shooting, the goal requires being able to shoot as small a target, as it were, as possible. At 25 yards/meters, whether indoors or out, an 8 fpe rifle shouldn't be at a tremendous disadvantage. Outdoors at 50, where wind can play an increasingly difficult role, a little more energy or MV might be a good idea, especially with lighter .177 pellets, but not necessarily decisive.
If I was going to pursue 50 air rifle benchrest shooting, I would prefer a .22 caliber air rifle because heavier pellets are available. Furthermore, I would prefer to use a PCP rather than a springer, even if both produced the same level of energy. The reason for heavier pellets being an advantage, is that even 40 grain .22LR bullets are at the whim of even slight changes in wind, and relatively light .177 pellets would be that much more challenging to use outdoors.
