.25 impact initial testing

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greenanchor

greenanchor

Member
Oct 4, 2015
33
0
Surrey
Been playing around with the impact. 25
-cleaned polished barrel
-polished the long valve rod and hammer.
-made sure the ports lined up.

Now I've set my reg at 125 as any higher doesn't increase velocity (maybe 5/10 fps)

valve is on 3 lines showing (2.5 gaps)
And further out only increases fps by 5fps
slight turn in and it starts to drop fps.

power wheel is on 4 any higher, again not much increase in speed.

So as far as I understand I'm almost as efficient as I can get it while being at the near max output/power.

I'm getting the following results using a little combro chronograph:
mk1 heavies 34gr 720/725 fps
grizzlies 31gr. 810/815 fps
Baracuda 31gr 840/845 fps
kings 25.4s always read 'Error' on my chrono???

looking very consistent (was 10-15 fps spread before the clean/polish)

looking at most people's results the Kings run about 100fps faster than heavies so I'm guessing I'm about 820 fps with them (it never reads this pellet for some reason)

Kings so far are super accurate, at ranged 50 meters touching cloverleaf grps (single loaded) not so keen out of the magazine!

im scratching my head now how to to get the heavies up to 820/830 fps!!

no leaks/puffs detected at all that I can find???



 
I hope not as I tightened up the slop in my .25 impact power wheel. I was getting about 780 fps out of the box. I'm now getting 820 fps with 34gn mk1 heavies which I'm happy with. So far it's very accurate. I've not tried to adjust the reg pressure which seems to be about 125 Bar if the gauge is correct.

Greenanchor, your opening post said you were getting 725 fps with mk1 34gn and 845 fps with Baracuda 31gn. Doesn't seem right to me (40ft/lbs vs 50 ft/lbs).
 
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"ClearedHot"Guys, you might want to re-check with Ernest on his video adjusting for the play(slop) in the power wheel assembly. I think I recall him correcting us on a subsequent post that this was advisable for the .30 Cal only.
I'd love to be proven wrong since it would be nice to have this consistent across different calibers. 

Rock
Click to expand...
No this is for any caliber.
 
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I think I found the problem. The probe was not in the right place. I took a thin strip of electrical tape and taped the probe to mark exactly where it was seating in the barrel.

then took the barrel and probe off and checked the probe/transfer port fit according to the mark.. There was just over 1mm of probe Showing in the barrel port and 1mm of gap between the probe tip and the start of the barrel proper. So the pellet skirts were sitting in the brass portion and the barrel port was restricted.

I took the tape off and pushed the probe right in. Up to the barrel. Now transfer port even more restricted but I'd prefer the pellets to be seated in the barrel...
with the probe in situ I used a fine metal burr tool on the dremel and took the excess off the probe until the brass port and probe port were exact match.
nice path for airflow, took apart and polished all burrs out.

now the probe needed to be brought forward, took the cocking block/probe unit off and gave it to turns (left hand thread)
so the probe now sits just over 1mm further in than before. Perfect. Slight pressure as you close the sidelever now but good to know the pellets will be seated just right.
Testing tonight!
 
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"GQ"
"ClearedHot"Guys, you might want to re-check with Ernest on his video adjusting for the play(slop) in the power wheel assembly. I think I recall him correcting us on a subsequent post that this was advisable for the .30 Cal only.
I'd love to be proven wrong since it would be nice to have this consistent across different calibers. 

Rock
Click to expand...
No this is for any caliber.
Click to expand...
This video is not for any caliber it is for 30 cal only....

See this thread 
http://www.airgunnation.com/topic/fx-impact-25-cal-grub-screw-how-many-threads-should-it-show-past-the-hammer/#post-147593

 
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Hi Ginuwine,
I take the barrel and probe off the gun. Align probe in barrel and measure from the barrel (outer part not inside lip)to the back of the probe. 
When you put it all back in the gun you can't take that measurement directly because the pellet prob block is in the way. So then measure from the back of the gun (move rubber butt plate down fully)through under prob block to flush with the back of the barrel. You won't be able to put veniers actually on the barrel but the breach block and barrel are flush so just go to the block. 
With the gun cocked measure again from the back of the gun to the back of the prob this time. 
The difference between the measurement should equal your original measurement. Move the prob in or out to make the numbers match and align prob. 

https://drive.google.com/file/d/0B0Ph4Q8M-S89dkNXSFI2VG8xYTA/view
On the trouble shooting guide there is a recommend distance from the back of gun to the pellet prob. 
It has a picture of how to measure it. If you want to make certain you might want to take the measurements as I did. 
Cheers Michael
 
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