fx impact 177 groups

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Hi guys,

I just purchased a 0.177 Impact and I do OK (could be better) at 45m (see the 2 inch disk picture below) but when I try at longer ranges like 70m the 
groups open up too much.

The 45m group was shot at an average of 918 fps with the power wheel at MAX (the regulator pressure is around 110-115) and the valve at 4 lines showing.
The 70m group I shot by ONLY changing the wheel. I tried all settings and Power D seems to give the best group (as bad as it is). At this power I am getting around 889 fps

My goal is MOA at 100m but I do not see that happening any time soon if the gun is shooting as it is.
I am shooting the JSB 10,34 at the 4,52 diameter

Any thoughts as to what I should do to get the Impact to shoot better?

AirRanger,
How did you tune yours to get good groups at 100 yds? 
What speed are you shooting at? 

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Shooting jsb 10.34 at around 912 FPS, reg pressure is at 106 bar, valve 3.5 lines out, power wheel set for default.25 distance but using setting C, or if set to default.177 distance then power setting A, 174 shots from 250 bar, grouping below is 19 shots with two sighters, at 100 yards, 38,2 is the amount of centimetres drop from a 29 meter zero.

I like to wash and lube my pellets but this particular barrel doesn’t like them, this barrel has been polished with 3m abrasive medium, emphasis on the crown and pre twist area and transfer port/ lead in, my mags have been tuned to not damage or clip my pellets
while loading or advancing.


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Thank you riazp,

That is an excellent group.
I guess I need to do some more fine tuning.
I followed Matt Dubbers advice in his excellent video on how to tune your impact and after getting the reg pressure close to 900 or so only adjusted the power.

I will do some fine tuning using the valve spring adjustment.
I guess if I can get the 45m group tighter I will be better off at the further ranges.

Just to compare, what does a 50m group of yours look like?

Many thanks.
 
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@Mariosh

I don’t usually photograph my groups at 50 as the range is 100 and I need to put up a tripod with target, or move my shooting position, give me a few days, I shoot everyday so I will break out the tripod...

I can say that at 30 m it will shoot about 12 mm/.5inch or so clover patterns, with the cursory 1 or two flyers per mag, so 50 m will be a bit larger.

Of all the tuning I did to this barrel I think that the mag work and lead polish resulted in the best gains for the effort. If pellets load poorly then maybe they are getting damaged, my mags were very tight, and were scraping the pellets when indexed.

My Impact is a gen1, I have no warranty anymore so I regularly take it apart to service/lube/inspect. After around 25k .22 shots I decided to change my reg piston and washers. I found that the new washers had gouged out parts of the piston, resulting in a jumpy reg!

I had to deburr the washers, polish contacts, clean their surface and then had to very carefully polish out the gouges on the piston. This was the final piece in the puzzle, my reg is very consistent now, great for long range...
 
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Hi riazp,

Thank you very much for the info.
No need to go out of your way for pictures.

I am not a very mechanicaly inclined person to take the gun apart so I rely on my gunsmith for any work done. So far it’s been OK.

From what you say it seems you also have the 0.22 caliber. I am also thinking of shooting a 0.22

Is there a reg pressure that works for both .177 and .22 so that you just change the barrel and probe and then just change the power setting and re-zero the gun?

Best of luck.
Keep on shooting straight.

MariosH
 
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Here are the groups. I included some at 30, 50 and 91 meters. All groups are 7 shots, except the one at 91 meters of 21 shots. 30 meter target has some single shots and groups. lower left quadrant was used to sight in and verify strelok at the various ranges. I was getting a little stressed during the 91 meter groups and it shows in the dispersion, the last group of the day was the 21 shot cluster with the 4 fliers.

I haven't ever done a three range test at the same time before, what was surprising to me was that you could get the same group size at all three ranges, but you have to concentrate to pull them off at 91 m
.
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I wish I could say that practice makes perfect, but I think that the gun needs to be capable before range time can lead to improving. This Impact of mine has driven me crazy.

The .22 barrel I have shoots at 20 like the .177 at 100! I have done everything known to man to try and make it shoot half decently.

I very nearly turfed my gun, after replacing, tuning, polishing, chrony work, reg tuning, multiple silencers, multiple manometers, cocking blocks and pellet probes I broke down and just bought a Vulcan.

Having the Vulcan was like a whole new world in .22. but I couldn’t compete with it due to it being too powerful for HFT or FT, hence the .177 barrel.

The importer had brought two .177 into the country and I bought one to try and sweeten the deal for the next potential owner. But all the work that I had done to the Impact really paid dividends when I inserted a good barrel into it!

The Vulcan has lived in its bag for a few weeks now, and the Impact is proving to be everything that I always dreamed it would be, but it was a labour of love to get it to work properly.

The sucker for punishment that I am went and ordered a second Impact in silver .22 twist x, some idiots like me never learn...
 
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Hey riazp.,

What you are saying is the Impact has to be tuned first. I hear you...
I've reached the same conclusion.

I watched plenty videos on you-tube and have been trying to emulate (accuracy wise) guys like Matt Dubber from AirGunsSA and Ted from Ted's Holdover, but I keep on forgetting that those guys are shooting .22 and higher calibers.

That is why I turned to this forum. I am looking for others who are also using a 0.177 because I need to judge if I am close to the limit of the gun in the 0.177 caliber.
I bought my Impact used from a friend who hardly used it and I am just starting to tune ir, whenever I get some free time on the weekends.

I appreciate all the information you gave me.
Have fun with the new Impact with the twist X barrel.
Post back when you get and use it.
I hear it is/will be very accurate.

Cheers
 
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