Fps readings with .25's?

[Lt. Macka]

Hi guys,

I chrono'd my rifle the other day but I only have .25's - I didn't really think about it until afterwards.

So my question - if my rifle is shooting 310fps with .25's, what would it be doing with .2's?

I'm sure this is simple maths for some on here?

Cheers
Andy

[REMSoft]

Re: Fps readings with .25's?

347FPS, by my calculation.

[Strebor_7]

Re: Fps readings with .25's?

Approx 345 fps on .20. There's a couple good apps for your phone's that can convert fps for you. Hope this helps.

[Ells]

Re: Fps readings with .25's?

around 340 - 350, as long as you're using electric/spring

[Abbadon101]

Re: Fps readings with .25's?

You can never be 100% sure. You should crono on .2's

[Caldymoose]

Re: Fps readings with .25's?

IMO, with M4 length barrels, it's around a 40 FPS difference between 0.2's and 0.25s. Some guns it will be more, others less. But generally, if its doing 300 FPS on 0.25's, it will be circa 340 FPS. You should be under the 350 mark though

[PureSilver]

Re: Fps readings with .25's?

You can never be 100% sure. You should crono on .2's

This is the truth. When you're this close to the 350fps limit imposed by most sites, you should chrono on 0.20g BBs just to be sure. That said, the problem (energy creep) is 'the other way' (heavier BBs gain, lighter BBs lose), so the FPS with .20s is likely to be lower than projected rather than higher.

[jonny lovegrove]

Re: Fps readings with .25's?

Actually closer to 30 on AEGs.
On compressed gas rifs, throw that out the window however. Long story short. Chrono on .2

[FireKnife]

Re: Fps readings with .25's?

It really is a 'chrono on the right weight' issue.

Even those chronos that supposedly convert the readings from a .25 to what they would be if a .2 are not that accurate.

'FireKnife'

[Lt3033]

Re: Fps readings with .25's?

Yeah like what has already been said, just grab yourself a bottle/bag of .2's just for chrono, I never skirmish with .2's but I make sure I have some at home with my chrono so after upgrading/downgrading I can always check before the game.

[seansamurai1]

Re: Fps readings with .25's?

Get a cheap mid or low cap, load it with .2s, label it 'for crono use'.
Some sites have mags with 20s pre loaded, others give you a handful, more just trust you use .20s.
I always have a mag on standby for crono.

[ScoobySnacks]

Re: Fps readings with .25's?

You'd think it would be a simple conversion. A 0.25gram BB, travelling at a given speed has a given amount of energy (calculated using the trusty KE=1/2.M.V^2 formula). So you can work it back form that to work out what velocity a 0.2 gram BB would need to reach the same energy. Whilst this is true, it doesn't necessarily follow that any particular gun will propel different weight BB's with the same amount of energy (in fact it's fairly certain that they won't) so chronoing with a 0.25 won't give you a reliable indication of the velocity that will be achieved with a 0.2!

The only way to know what it will chrono with a 0.20 is to chrono it with a 0.20!