Brand new Fx impact .30 shot string horribly inconsistent

Whats the reg set at? are you saying that on paper the gun is terrible? 30FPS? not that big a deal IMO if the groups are good.

Do you mean the two O rings on the brass part of the barrel where the TP is?

Don't think the outer barrel O rings are the problem. Incorrect or mismatched rings might be an accuracy issue, but velocity comes from within.

Just something to check. Measure the muzzle end of the shroud. See if a 30cal pellet will actually fit.

Shoot it more and then recheck. Mine in .22, settled in at very consistent 20fps higher after about 800 shots.

I bought it from pyramid air, and Im starting to suspect it was a return.
Clues ive found are a spring in the valve stop instead of the nitrile ball

Click to expand...

The spring is a new feature and has replaced the rubber ball.

My erratic accuracy was caused by the cheap FX moderator.

Just picked up my new impact .30 m2 last week. I didnt get to shoot it more then a few shots, here and there and all seemed ok... a little inconsistent but i chalked it up to the barrel needing to lead up.. i then picked up a chronograph and couldnt believe how inconsistent the shot strings are...



Example

867

869

867

888

892

867

866

869

886

etc.



I bought it from pyramid air, and Im starting to suspect it was a return.

Clues ive found are a spring in the valve stop instead of the nitrile ball, and the two outer barrel orings are different... one is thinner then the other. Im thinking, or i should say hoping the barrel oring is the issue, and not something more serious inside...



Can anyone confirm that an outer barrel oring would create the erratic velocity issue?

Click to expand...

An Impact is all about getting it tuned right.

When there is a spring instead of the rubber ball, you will likely have the latest version with the power plenum installed.

The new setup does not have the rubber ball anymore, and the valve return spring has moved from inside the plenum tube to the valve adjuster.

Try turning it in to increase the valve spring tension, or try a lower power setting, and see if things improve.

Clean the new barrel yet? It sound like the inconsistency is there, not in a bad fitting external o-ring. To get better consistency try silicone lube on the pellets, and if you have a grain scale, weight sort them as well.

Just picked up my new impact .30 m2 last week. I didnt get to shoot it more then a few shots, here and there and all seemed ok... a little inconsistent but i chalked it up to the barrel needing to lead up.. i then picked up a chronograph and couldnt believe how inconsistent the shot strings are...



Example

867

869

867

888

892

867

866

869

886

etc.



I bought it from pyramid air, and Im starting to suspect it was a return.

Clues ive found are a spring in the valve stop instead of the nitrile ball, and the two outer barrel orings are different... one is thinner then the other. Im thinking, or i should say hoping the barrel oring is the issue, and not something more serious inside...



Can anyone confirm that an outer barrel oring would create the erratic velocity issue?

Click to expand...

Hi, yes the orings on the brass TP have two different size the larger one is at the end, the wall thickness between TP and liner adapter is thinner so Can’t support a deep oring groove.

the impact are set at a standard speed to a specific caliber ——> reg pressure, HS preload and valve return spring. They are not custom tuned for the lowest ES. Dealers can mix and match To meet customer orders, and owner have different needs or requirements to get best performance.

Don’t make to many adjustment at one time each adjustment need to settle to get a true measurements, if to many adjustments are taken with give false results true reading will take longer.

the valve return spring knob has min control over speed and ES in conjunction with reg pressure, HSTA preload and power wheel setting.

you need to break-in a new impact, oring and metal need to cycle a lot to get that smooth finish on metal and rubber. I recommend filling to 250 and dry fire to 100b and refill then shoot pellets fast to 100b refill again this time take a crony string from 250 to 175b and you will see a big difference just make sure the gun is in a shooting vice so gun is pointing at the same place Unless you have a FX crony mounted on the barrel, if you still have issues still PM me will assist in your tuning.



Ernest

Here's a pic of the two outer barrel orings. I rolled them out of their slots to show different sizes better

Click to expand...

The o-rings have been those sizes for about a year and a half.

Hmm. Might be a problem with the regulator. Try shooting a bit more, if the issue persists contact Utah Airguns.

Im thinking that something must be broken inside. i will not believe that it just needs to be tuned right to correct sudden jumps, and drops in velocity. 

Its frustrating because the gun is so accurate on the consistent shots... same hole at 30 yards.

Im thinking valve issue though, not reg.

Click to expand...

I agree that I don't think it is a traditional tuning issue. I'm no expert, but I don't think that either the valve or reg are likely to cause this behavior. I would disassemble and clean it, especially the hammer assembly. I don't know what lubrication, if any, is recommended by FX, but I had similar symptoms from a RAW, and cleaning and lubing the hammer assembly cured it, still going strong after several thousand shots. 

A few post up Ernest Rowe said to shoot it more and if the problem still persist he would help you tune it. That is where I would start.