PCP's....kick?

[JohnBam]

Was wondering the thoughts on this.

Zico on Wednesday noticed that he was geting a recoil effect and a POI shift on some position and support changes while trying the long range stuff.

Is this down too muzzle flip, or is there recoil in PCP's. I was quite surprised at the results Z was experiencing as I thought PCP's would be practically immune from that type of behaviour. Obviouslly at long range any change is accentuated quite a bit.

Zico was shooting a Verminator with a Wheirauch (I know i've spelt that totally wrong ) silencer.

[Arnold]

PCP's does recoil, but at 12fpe you just do not feel the recoil. This becomes more noticeable at FAC levels. When you are shooting Heavy dai sung pellets at 60FPE you definatly feel the recoil

[bigtime]

thought it was just the muzzle flip you noticed on fac guns

[Born Again]

I noticed a definate recoil on my Rapid when long range testing. I think it was more pronounced because I used Harry method of barely holding the rifle, no cheek contact and very light hold.

I'm not sure yet whether it was recoil from the hammer, from the pellet, or just the "jet" effect of the air. More testing needed.

[theboymike]

I've been thinking about this for some time, and I'm glad someone else brought it up

I've done a bit of testing off the bench rest with the S410 recently; and it definitely jumps quite a lot when fired.

The way I see it you have two sources of recoil - an initial rearward reaction force to the forward movement of the striker, with a subsiquent forward movement as it hits the valve stem.

Secondly, you have the "true" rearward recoil in reaction to the pellet moving down the barrel, and finally the "jetting" or "rocket" effect as it leaves the muzzle.

I think the striker generated movement is by far the most significant on account of its greater mass, and can be likened to the recoil of a springer - all be it on a smaller scale. Because of this it would stand to reason that PCPs are hold sensitive.

I shot a series of groups at 55yrds with the S410 a while ago; all off a soft beanbag at the forend and a jumper under the butt. The first few groups were shot gripping the rifle "as normal", the final two attempting to allow as much free movement during the firing cycle as possible.

Avg. group sizes for the normal hold were about 1.25", while those for the light hold were fractionally over 1". Perhaps a more interesting observation is that the shots within the normally held groups were all fairly evenly dispersed, while the lightly held groups took the form of tight clusters spoiled by a couple of fliers. Removing 2 shots from each of the loosely held groups drops the avg. group size to 0.6".

I think there is scope to improve these groups further since the conditions were not ideal - the hold could have been more consistent, while the scope being used was only 6x and PX'd at 35yds - so a bit of PX error could have crept in although I did my best to keep this to a minimum.

I quite fancy knocking up a resting rig to absorb any recoil, although it's a question of time and money apart from anything else.

Also we have "Rika Trainer" kit at our club for 10m training - basically it provides an on-screen trace of the gun's muzzle on the target throughout the firing cycle. I'd like to set this up on the S410 at some point to see exectly where the POI travels during firing.

Interesting stuff

[Zico]

I'm not sure yet whether it was recoil from the hammer, from the pellet, or just the "jet" effect of the air. More testing needed.

Yep, 90-95% of the muzzle flip is when firing a pellet only, once or twice I fired fresh air .. and judging solely by the feel the muzzle flip near dissapeared. The "For every reaction there is an equal and opposite reaction" principle in action here. Was using JSB 4.52, would the theoretical reduction in friction of a 4.51 diam pellet reduce it a little.. or would pellet skirt expansion nulify this?

As John says, i was experimenting with different clamping and supports to see what was produced the best results. Interestingly, a loose clamp to act solely as the horizontal hinge and ensure totally vertical muzzle flip coupled with minimal butt support proved to have the most consistant POI... same principle as a springer but only apparent at the 94 yard range we were attempting.

I attempted resting the rubber butt pad on the table and I could feel the vibration which made the groups about 5 times worse.


My very 1st 3 shots of the day (with the loose clamping and minimal support) were within aprox 1.2 inch (iirc John?) the breeze picked up a little.. I then got a few wind affected shots that took it out to about 4 iches The highlight of this 8 shot group was 3 shots through ONE ragged hole!

How effective are these muzzle flip compensators? Anyone have any definative test results? I used to consider them OTT and a bit gimicky... but not any more.

[JohnBam]

Yep, 90-95% of the muzzle flip is when firing a pellet only, once or twice I fired fresh air .. and judging solely by the feel the muzzle flip near dissapeared. The "For every reaction there is an equal and opposite reaction" principle in action here. Was using JSB 4.52, would the theoretical reduction in friction of a 4.51 diam pellet reduce it a little.. or would pellet skirt expansion nulify this?

As John says, i was experimenting with different clamping and supports to see what was produced the best results. Interestingly, a loose clamp to act solely as the horizontal hinge and ensure totally vertical muzzle flip coupled with minimal butt support proved to have the most consistant POI... same principle as a springer but only apparent at the 94 yard range we were attempting.

I attempted resting the rubber butt pad on the table and I could feel the vibration which made the groups about 5 times worse.


My very 1st 3 shots of the day (with the loose clamping and minimal support) were within aprox 1.2 inch (iirc John?) the breeze picked up a little.. I then got a few wind affected shots that took it out to about 4 iches The highlight of this 8 shot group was 3 shots through ONE ragged hole!

Spot on mate

Enlightening stuff lads, maybe the PCP's aren't as 'dead' as I thought