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Author Topic: Have Chronograph. Will Measure!  (Read 320 times)

Offline Akzle

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Have Chronograph. Will Measure!
« on: January 20, 2019, 07:29:20 PM »
So I have finally stumbled into a chrony, which obviously means I need to measure everything.

Some points: I can karate chop at about 60fps (about 150fpe);
My .177 "1000 fps" gun is only doing 690 (10.something grain pellets) for about 11fpe - this has given me some kind of comprehension of the british 12 ftlb restriction,  I'd be rather suprised if you could wring more out of a springer.

But the point of this post was: The 2245 (That's a Crosman 2250 without the butt stock)
No Mods yet. 14.2gn Crosman Premiere pellets, 10 shot groups.
The data:
2240 Barrel
Av 336 fps,
Sd 11,
3.58 fpe

2250 barrel
Av 358 fps,
Sd 4,
4.07 fpe

The min/max/avg velocities averaged out to 14 fps higher in the long barrel (as expected with CO2) but the biggest win for me was the Sd - halved the spread.

I will try with different pellets, and I'll swap out for the modded internals and post up again. I also have a stupid-long (20") .17 barrel I may try just for shits'n'giggles.
« Last Edit: January 21, 2019, 08:55:02 AM by Akzle »

Offline Akzle

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Crosman for Crosman, and, The Law of Diminishing Returns
« Reply #1 on: January 21, 2019, 08:53:32 AM »
Temperature is 20degrees and i'm in the shade. Didn't do any warming of the gun, took my time between shots but could have taken more.

H+N Baracuda Match 21.14gn (Irrelevant, because they group poorly)
average 220fps;
Sd 12;
2.7 fpe

Gamo Promag 15.43gn (Actually worked out the best, all touching at 12m)
average 294;
Sd 11;
3.208 fpe

So, i deduce...
The FPE decreased for increase in pellet weight (and subsequent lower velocities).
That's pretty much my pellet selection in .22, but i would be interested to see if the trend continues that way with lighter pellets...

Offline Mintie

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Re: Have Chronograph. Will Measure!
« Reply #2 on: January 21, 2019, 09:33:35 AM »
Something is wrong with your Crosman, off the shelf a 2240 is about 6fpe and the 2250 barrel gets it up to about 8-9fpe. Generally you will get higher FPE from heavier pellets which leads me to think that your transfer port seal is probably leaky, heavier pellets are producing less energy as they are putting more back pressure on the TP seal which is leaking it out.   Just a guess anyway!
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Offline JS

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Re: Have Chronograph. Will Measure!
« Reply #3 on: January 21, 2019, 12:44:15 PM »
Something is wrong with your Crosman, off the shelf a 2240 is about 6fpe and the 2250 barrel gets it up to about 8-9fpe. Generally you will get higher FPE from heavier pellets which leads me to think that your transfer port seal is probably leaky, heavier pellets are producing less energy as they are putting more back pressure on the TP seal which is leaking it out.   Just a guess anyway!

Seems low for the '1000fps .177' too.. may need to check the chrony too??
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Offline Akzle

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Re: Have Chronograph. Will Measure!
« Reply #4 on: January 22, 2019, 10:59:49 AM »
Something is wrong with your Crosman, off the shelf a 2240 is about 6fpe and the 2250 barrel gets it up to about 8-9fpe. Generally you will get higher FPE from heavier pellets which leads me to think that your transfer port seal is probably leaky, heavier pellets are producing less energy as they are putting more back pressure on the TP seal which is leaking it out.   Just a guess anyway!

Didn't notice any gas escaping... pretty sure i put a nice soft one in. Stock bolt probe. I will check though, cheers

Offline Akzle

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Re: Have Chronograph. Will Measure!
« Reply #5 on: January 22, 2019, 11:02:09 AM »
Something is wrong with your Crosman, off the shelf a 2240 is about 6fpe and the 2250 barrel gets it up to about 8-9fpe. Generally you will get higher FPE from heavier pellets which leads me to think that your transfer port seal is probably leaky, heavier pellets are producing less energy as they are putting more back pressure on the TP seal which is leaking it out.   Just a guess anyway!

Seems low for the '1000fps .177' too.. may need to check the chrony too??

the gun is ages old. I wouldn't be surprised if it was down, and 1000fps is marketing hype anyway, i could try some 4gn pellets... if i had any.

 chrony reads good on powder burners measuring sub/supersonic. plus it's brand new.

Offline Dvlnme

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Re: Have Chronograph. Will Measure!
« Reply #6 on: January 24, 2019, 06:16:22 PM »
have owned chronos since mid 1980s learnt long time ago that very few things chrono as advertised most
 airguns advertised as 1000 fps dont make it with normal pellet weights any way,bit surprised bout the
 2240 tho most are as mintie said if seals etc are good when new,but you older one prob got some issuses
 like all us older guys eh!!funny tho as i got older my gas system got better lol.
 cheers mike

Offline Pauly5

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Re: Have Chronograph. Will Measure!
« Reply #7 on: January 24, 2019, 10:19:31 PM »
I thought that as you get older you become a crossman.    ::)
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Offline Dvlnme

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Re: Have Chronograph. Will Measure!
« Reply #8 on: January 25, 2019, 08:41:56 AM »
yep its all bout gas control mate and like old co2 crosmans i have trouble at times keeping that gas under
 control lol
 cheers mike

Offline Dvlnme

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Re: Have Chronograph. Will Measure!
« Reply #9 on: January 25, 2019, 08:56:22 AM »
now you got chrono you in trouble coz now you test every gun you own constantly just coz you can,had that
 desease for over 30 years now and its incurable,the good side is it removes all the guess work about how
 guns are actually performing,but down side is your ammo costs go up significantly coz you just got to
 know now,i got first chrono in 1986 when was commerically making bullets and very serious action pistol
 shooter,never been without one since,any one who reloads ammo or is serious bout their shooting should
 have a chrono,as they cheap today,they cost allmost $2000 back in 1986 mate as the ones available then
 were full statistical ballistic lab types so were expensive,today the equivelent chrono cost bout $200 or less
 as i tend to postion them out 100yds at times these days i destroy my share of them with badly placed
 bullets every now n again so buy them 3/4 at time from US cheap,havnt buggered one for while tho.
 cheers mike

Offline Akzle

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Re: Have Chronograph. Will Measure!
« Reply #10 on: January 25, 2019, 12:44:50 PM »
have owned chronos since mid 1980s learnt long time ago that very few things chrono as advertised most
 airguns advertised as 1000 fps dont make it with normal pellet weights any way,bit surprised bout the
 2240 tho most are as mintie said if seals etc are good when new,but you older one prob got some issuses
 like all us older guys eh!!funny tho as i got older my gas system got better lol.
 cheers mike

It's not so much the gas production... as the leaks!

Offline Akzle

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Re: Have Chronograph. Will Measure!
« Reply #11 on: January 25, 2019, 12:47:32 PM »
but down side is your ammo costs go up significantly

Yeah well.. have gone from shooting $3.50 factory loads to 94 loads so.... now I can shoot 3 times as much!  ;D

Offline Dvlnme

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Re: Have Chronograph. Will Measure!
« Reply #12 on: January 25, 2019, 02:30:12 PM »
got a gas  leak to and promised my mother when was a kid would get it fixed when got older,but just never happened eh,
 cheers mike

Offline Dvlnme

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Re: Have Chronograph. Will Measure!
« Reply #13 on: January 25, 2019, 02:48:07 PM »
your gas leak must be contagus coz been chronoing a co2 rifle today was doing 720fps couple weeks age
 today doing only 670 fps and that was after refilled it,so some thing not right my gues would be needs a
 new probe seal but without a chrono i wouldnt have known or even noticed proberly for some time too.
 chronos one the handiest tools for any shooter to have,as they ellinate all the guess work eh!!,we all know
 some one whos allways bragging on the velocity etc their guns doing,but really only qouteing the makers
 claims,a chrono owner actually knows exactly the velocity of their guns,allways amuses me listening to
 some one bragging when i really know what his gun is more likely to be doing having chronoed one or more
 of same gun he has,just smile and say nothing as dont want burst his bubble eh.
 Its lot easier to calculate trajectorys when you know the exact velocity,i like to check actual velocitys at
 25/50/75 yds as well so know the real power level at these distances with my hunting rifles and can decide if got enuf power to do job cleanly.
 cheers mike
 

Offline Novagun

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Re: Have Chronograph. Will Measure!
« Reply #14 on: January 26, 2019, 11:48:19 AM »
Nice one Pauly5.