Hornet - shot to shot velocity variation

[gravity sucks]

My Hornet 0.22 is doing curious things...

I must say I've been a bit suspicious for a while and having just got a PC interface for my CB625 chrono (curtosy of Robin - "Thanks again Robin") I've run it from full (230bar) to empty (when it starts to hiss) four times and logged the data.

On each run it seemed to need to warm up, taking between 5 and 7 shots to get up to full velocity.

Then it stayed there or there abouts with a degree of variation sometimes 10fps between shots until it got to Shot-75 where it started dying off, then a Shot-85 it started to build again until Shot-93 where it started going terminally down hill...

Typcally it would do a high power shot followed directly by a low or visa versa, in fact in later shots a real saw-tooth pattern emerged climbing shot after shot and then dropping suddenly.

If I could attach the graph I've created you'd see what I mean (any advice gratefully received- it says the files too big and it won't let me attach and excel file don't seem to be allowed)

Is my reg knacked or is this normal for Hornets ??? Any techie' help appreciated...

ATB Toby...

[Gary C]

Phone John Bowkett
01217 454287

[tpe]

If you can post me a jpg i can host and post it, i on't have excell at work so cant handle that file type, unless you have an open office exporter?

I would also like to see your results as i have had similar results as described by my chrono (despite still getting very good groups at 35m).

tim

[ora8i]

Email me the excel file and I post it for you. I also have a lager number of PCP traces you could compare with yours.


Regards Ora

[gravity sucks]

Is tha PM or "genuine" email if so could you let me know your address...

Ta...

[ora8i]

Email please, PM's are only good for notes, I didn't think they took atachments.
Do they?

My email is in my profile, were I hope the webspiders cant get it.


Regards Ora

[gravity sucks]

Alan...

It's coming your way...

Thanks Toby

[Gary C]

Toby

Did you call John Bowkett ?

Bit puzzled why all the mails when he designed the thing..

[gravity sucks]

Toby

Did you call John Bowkett ?

Bit puzzled why all the mails when he designed the thing..

So far all I've got is an ansafone, I've left a message and i hope for a response...

In the meantime someone oot there may look at the data and the graph and say "there nothing wrong with that" or "that's how they all work" so I was hoping for some feedback from a knowledgable 'ornet owner who may have been here before...

All the best...

[Gary C]

ah Ok matey
Good luck with both
All I ever get his John's answer phone but he does call back

[ora8i]

Hear you go

http://members.lycos.co.uk/ora8i/hor...une05%20v2.xls

anybody with excel should be able to see the graph.


The strange blip is an imbalance between the hammer/spring/valve spring/regulator.

As it comes off reg the pressure starts to fall normally then as the resistance from the valve drops a bit too low for a few shots the hammer opens the valve to far letting out more air that previously and the FPS rises for a few more shots. When some boundary level is passed FPS drops normally again, it just needs the reg re-balencing against the hammer assembly.

Regards Ora

[freewind]

Great way to display performance, why don`t the mags do this. That consistancy looks pretty good to me, I think I could live with a few blips near the end of a fill.

Andy

[gravity sucks]

Great way to display performance, why don`t the mags do this. That consistancy looks pretty good to me, I think I could live with a few blips near the end of a fill.

Andy

Andy...

The devils in the detail - if you reduce the scale and look at the area between 580 and 600 fps you'll see it's up and down like a wh@re's drawers between shot 10 and 75...

If I could do the math and work out standard deviations etc I could probably reassure myself but in layman speak...

1. the output can varies by 5-8fps between shots, not a steady decline more a "now you see it - now you don't".

2. it takes about 10 shots to wake up and work at full power.

Accuracy-wise with AA Field I can achieve a 10mm group at 27m (my optimun zero range (acc. Chairgun) but I get a vertical flyer every 10 shots or so and that what I'm tryin to cure (or learn to ignore).

Thanks for your input...
Toby

[gravity sucks]

Hear you go

http://members.lycos.co.uk/ora8i/hor...une05%20v2.xls

anybody with excel should be able to see the graph.


The strange blip is an imbalance between the hammer/spring/valve spring/regulator.

As it comes off reg the pressure starts to fall normally then as the resistance from the valve drops a bit too low for a few shots the hammer opens the valve to far letting out more air that previously and the FPS rises for a few more shots. When some boundary level is passed FPS drops normally again, it just needs the reg re-balencing against teh hammer assembly adjusting.

Regards Ora

Thanks for that M8, probably not worth bothering about because I seldom run as far as 70 shots in a session.

However any idea why it takes the first 7 or 8 shots to wake up ???

Most of my shooting is rats as they pop up at the bottom of the garden 27-yards away so I don't have the opportunity to cycle the rifle a handful of time before I have a go at the little blighter and at that range I need consistency if I'm going to finish it off...

Rgds Toby

[Darren Petts]

7-8 shots? I see two shots needed to settle the reg. This is quite normal in regged guns. I see nothing wrong with those figures at all. If you're getting flyers it isn't because the power is a problem. I know many FT shooters who'd be quite happy shooting to 55 yds with consistency like that. The difference between your highest and lowest is a pellet width at 45 yds - not sure how much better you want it