Bit of a Minor Panic

[gdavison]

Was doing a regular test of my ultimate sporter with my Combro Mk4 using the normal AA Field pellets I normally use (all good averaging 11.5) and then thought let's just do a quick string of 10 with some JSB Heavies to see what FPS I would get with them

Changed the pellet weight on the Combro and sent the first Heavy thru looks at the display 11.97 eek thats a bit close thinks I, try again 12.01 starting to be a bit concerned now, next few 11.89, 12.01, 11.99, 12.08 etc .. now I am wondering how I go about getting it back to AA or perhaps the dealer I got it from etc

Start to pack things up and go to reset the Combro back to 8.4 grains, in doing so I look at the set pellet weight I had been using 11.4 on the Combro .. check JSB Heavy tin lid.. pellet weight is 10.34

MUPPET Moment

I had set the pellet weight too heavy, try a few more with the correct setting and see 10.9 - 11.1 's

Pheow

[Blackbaronfish]

At least you checked before sending it off.

BBF

[Mark112]

Hi,

mmmmm interesting. All of my .177 rifles have been .5 ft.lb higher with heavies than with AA Diabolo Fields. In fact I set my power levels to 11.7 ish with heavies knowing that others will be lower. I also used to check power at 130 bar as this is the point at which my rifles produced he highest power levels.

When comparing pellets output I used to alternate with 5 of each in the magazine. That way it eliminates the effect of a power curve. I used a spreadsheet to calculate actual power values.

Glad you're sorted though.

Mark

[gdavison]

Hi,

mmmmm interesting. All of my .177 rifles have been .5 ft.lb higher with heavies than with AA Diabolo Fields. In fact I set my power levels to 11.7 ish with heavies knowing that others will be lower. I also used to check power at 130 bar as this is the point at which my rifles produced he highest power levels.

When comparing pellets output I used to alternate with 5 of each in the magazine. That way it eliminates the effect of a power curve. I used a spreadsheet to calculate actual power values.

Glad you're sorted though.

Mark

I plan on redoing the check again within next few days without the panic moment, also will use another chronograph to double check the Combro calibration

[Archer50]

Been there, know what you mean about the panic

It depends from gun to gun. For example, when my Steyr was shooting Exacts at 11.4 fpe (775 fps) it only managed about 11.0 with Heavies (693 fps) while with my Bobcat, there was hardly any difference. However, with my S400, HFT 500 and HW 100, I agree, about 0.5 fpe higher for a Heavy, about 0.3 fpe for a Bisley Magnum. My springers, on the other hand go the other way, giving higher power output with lighter pellets, JSB Express being the highest I've found in both my TX200 and my HW99 (lovely little gun!).

I'm always a bit surprised (and worried) how many people don't realise just how big a difference in power there can be between pellets. 777 fps with an Exact, which seems to be what a lot of HFT shooters set their guns to, could put them dangerously close to running hot with a Heavy (or whatever pellet gives greatest power output on their particular gun). In fact, allowing for the tolerances of chrono's and the inevitable velocity spread of even the best tuned gun I suspect many would fail a police test - if only we knew exactly what that is!

Alan