Mk3 Sports Power Curve

[Pod]

Following on from the Air Wolf power curve thread...

I ran my Mk3 Sport over a Combro chrono today:

Full power from 200 BAR fill:
764, 773, 778, 776, 778, 780, 780, 779, 781, 781
778, 781, 783, 782, 784, 785, 786, 784, 786, 782
785, 716 , 789, 788, 791, 791, 793, 793, 791...

At this point I decided that the power was getting a little high so I backed off the power one level, refilled and started again:

752, 750, 753, 745, 756, 748, 752, 757, 759, 755
755, 756, 760, 759, 760, 757, 762, 760, 762, 758
765, 760, 766, 764, 764, 766, 760, 757, 770, 768
765, 699, 767, 769, 772, 774, 775, 706, 775, 775
776, 775, 775, 776, 778, 777, 772, 779, 706, 778
781, 779, 781, 707, 782, 782, 781, 785, 778, 785
781, 784, 713, 783, 784, 779, 783, 712, 785, 782
783, 784, 784, 708, 781, 715, 782, 785, 705, 786
785, 782, 709, 709, 713, 711, 710, 710, 782, 775,
719
I gave up at this point as the bizzarre way out readings were coming too regularly.

I was in two minds with regard to posting this - there is obviously something wrong with either the rifle or the chrono. The chrono has just been looked at (a Combro) and the rifle has been great for a good few months - I just had cause to chrono it as it was shooting a little low a few weeks ago on a freezing cold and damp day.

So has anyone else noticed a power curve like this on a Mk3 Sport? Is it just one of those things and as long as it holds a 'good enough' zero (I can't be sure that it does at the moment) over a full charge then I should just live with it? Should I send it to Daystate or buy an expensive chrono and check it thoroughly before bothering the busy Daystate folks?

[sparky]

What fill you putting in the Sport mate, looks like a bit too much, i put 200bar in the one and 190bar in the other

Pete

[verminhunter]

[QUOTE=Pod]Following on from the Air Wolf power curve thread...


At this point I decided that the power was getting a little high so I backed off the power one level, refilled and started again:

752, 750, 753, 745, 756, 748, 752, 757, 759, 755
755, 756, 760, 759, 760, 757, 762, 760, 762, 758
765, 760, 766, 764, 764, 766, 760, 757, 770, 768
765, 699, 767, 769, 772, 774, 775, 706, 775, 775
776, 775, 775, 776, 778, 777, 772, 779, 706, 778
781, 779, 781, 707, 782, 782, 781, 785, 778, 785
781, 784, 713, 783, 784, 779, 783, 712, 785, 782
783, 784, 784, 708, 781, 715, 782, 785, 705, 786
785, 782, 709, 709, 713, 711, 710, 710, 782, 775,
719
I gave up at this point as the bizzarre way out readings were coming too regularly.

First ten shots in their mid 40's and high 50's.
Then after 50 60 and 70 shots they were higher?
At one stage say shot num 4 your 745 and shot num 80
your 786 wow thats alot of diffrence,41 fps,have it checked out.

[Rich]

Cold weather and the firing valve sticking, that's my guess.

We've had a S400 at the club today that is usually so regular it must be on Ex-lax, but it's been throwing out about a quarter of the shots at 10fpe or thereabouts compared to its normal 11.4 to 11.5. We noticed it because these shots were dropping an inch and a half low at 55 yards and spoiling otherwise good groups.

I hope you get to the bottom of this and let us all know the outcome because a Mk3 Sport is probably going to be my next rifle.

Rich

[sparky]

Do the test again with a 200bar fill, check all pellets and also try and keep the gun in the same position.

Pete

[Pod]

Fill pressure is 200 BAR. I did think maybe the effective pressure had lowered over time (?) but the strange readings I was getting when I got 80+ shots means that if I fill to a lower level to get into the 770s straight away, I'll only get between 30 and 40 consistent shots.

Rich: Would the cold cause the firing valve to stick?

[Sam Vimes]

Before you get really upset what was the weather doing in your neck of the woods? It wasn't generally cloudy with the odd ray of sunshine poking through? I've seen my combro do some strange things in direct sunlight.

Chris

[Pod]

It has been dull and overcast. But this isn't the first time I've had wierd results. It put out similar stuff a couple of weeks ago (probably grey and over cast as well - but can't remember) which is why I had the chrono looked at. I also took the liberty of cleaning the 'don't know what it is called but it might be the firing valve' (big shiney metal thing with a spring on that lives in the centre of the solenoid ) as well as I suspected some lube had got in there. Very small amount of oil was found in the housing but I don't think it was enough to upset

[Sam Vimes]

Pod,
good luck with it mate. It's got to be worth trying another chrono before you get to despondant.

Chris

[sparky]

Pod if you have had it apart take it all out again and make sure its all dry etc and in the cap did you notice the black rubber with a hole in there, if so make sure that is dead level when you put it back together.

Pete

[Pod]

Thanks chaps. I've decided to e-mail Daystate but as they've been so great with me over previous issues I had with another rifle, I feel so guilty .

[Pod]

Pete YHPM.

[sniper22]

funny this because pete and i were chatting this morning. my mk3 sport fills to 220 bar officially but i fill to 200bar.
it shoots 4.53 daystates between 790fps and 795fps and thats it. has the back end been off it? i run my armature dry and polished. lube tends to make it inconsistant. i stopped chronoitis ages ago because its hitting the spot every time with boring regularity.

[P1Fanatic]

Paul - dont Turners have a chrono you could use to double check?

Simon.