Poi shift on fx impact MK2

[spyde82]

I am userly adjusting from 930 and down to 870.

880-910 look like the sweet spot, i get great groups in that range but still poi shift.



i will try shooting some papir today so you guys can se what iam talking about

 

[spyde82]

Okay so Got some kind of a resault today. It Can absolutly not shot the jsb 18.1g pellets not with the pellet liner or my slug liner,, but it shots slugs and jsb monsters pretty good. this is out of mig 600mm slug liner.

So is it the liner or the pellets that is the problem? Remember that i have shot over 3000 shots and different batches

 

[spyde82]

So tryed some jsb hades but had trouble getting em down under 900fps so i shot them at 930fps with pretty good results, tryed the jsb heavy diablo just to be sure that it was the same, and they still did not work.

so for some reson it will not shot the jsb 18.1g pellets



i will try to order a new batch of jsb 18.1g and if it is the same, then it has to be the liner..

 

[Souhaib]

Could be 

keep us posted 

ur huma gen 3 ? 

 

[spyde82]

Yes it is 

 

[Souhaib]

I have the MK2 with amp still new breaking it in my spread is around 20-25 fps but it should sattle down when the reg and valve take there place (told from a pro impact tunner) i have the 700 mm A liner shooting the 18 at around 950 to1030 accurately at 50 m 

but did not work well at all with the RD 25.4

did you try any RD ?

 

[spyde82]

Yes but shooting Them with the slug liner and that works.



mine is a mk2 aswell. It had a defect AMP regulator, put in a HUMA, it works much better and it feels line it has more power, having trouble shooting the jsb 18.1g under 900fps

 

[guinnster1]

I'm running into the same POI shift issue with my FX impact. It was driving pellet on pellet for dozens of 18.1 pellets, then all the sudden the POI shifted left nearly 2''. No velocity change. After another 20 rounds or so, it shifted back approximately to the original POI. Scope is very securely mounted. Any ideas would be appreciated?

 

[tor47]

I'm running into the same POI shift issue with my FX impact. It was driving pellet on pellet for dozens of 18.1 pellets, then all the sudden the POI shifted left nearly 2''. No velocity change. After another 20 rounds or so, it shifted back approximately to the original POI. Scope is very securely mounted. Any ideas would be appreciated?

Try to clean the barrel first. Make sure there is no lead smearing left in it. If it then shoot fine for a while, and it starts happen again, clean again, and try with some lube on the pellets. 

 

[Khornet]

Hard to see how a fouled bore keeps giving tight groups, just different POI, with no velocity change. Not likely regulator since no velocity change. Not likely technique since this appears to be an experienced shooter. Not wind. Bad scope I would expect POI change AND worse groups, which is not what's happening here.

One astute commenter noted that the groups are proceeding clockwise, just like when you are indexing a liner.

Now anyone who's fired a 1911 one-handed can tell you the gun twists vigorously in the hand because strong torque is generated by the rifling spinning the bullet. So could the liner be rotating just a bit as you shoot, indexing itself? Or could the whole liner/barrel assembly/shroud be rotating?

 

[Gibbs]

Are you shooting with the chrono hanging on the barrel?

 

[qball]

Try Ernest rowe’s carbon tension spacer or sleeve. With the barrel tensioner you should have very little or zero POI shift. 


edit: sounds like something is loose. 

 

[Arash]

I had same problem.

Never figure it out.

Don't waste your time, shoot some thing else.

 

[qball]

I had same problem.

Never figure it out.

Don't waste your time, shoot some thing else.

I agree!!! 


OP, I’ll sacrifice and take that POS gun off of your hand.