Help with FX Impact .30 slug liner accuracy issue.

[DanielL]

Installed the new slug liner and got atrocious accuracy. No issues with pellet liner. Installed with same 3 o-rings that from pellet liner and nothing loose.

P.S. I confirmed it was an actual slug liner by the twist rate which is easy to see and measure on FX liners.

Here is a typical group.

Here is best group.

Lest you think it's me here is AEA Varmint group shot on same day with same rest setup. $450 gun vs. $2000 gun.

Pushed pellet and slug through. They slide through with a moderate amount of force until they hit the last 1/2 inch where there must be a serious choke because it takes a much harder push to get them through that last bit.

Here is what they look like.

One other piece of evidence. There was a surprising amount of lead build up for having only run 60-70 pellets and slugs through it.

What do you think?

 

[cmatera]

Matt Duber says there should hardly be a mark on the pellet. I’d try try a sampler of different diameter slugs.

https://youtu.be/TLK5j2urOJ0

 

[DanielL]

Matt Duber says there should hardly be a mark on the pellet. I’d try try a sampler of different diameter slugs.

Might be a plan if it weren't also terrible with pellets...the most popular JSB 44.75 gr. This should not be the case inside of 50 yards.

 

[TNT19]

Imo that's a lot of groove scoring. I don't see half that kind of scoring in my $500 puncher with a steel barrel shooting pellets or slugs now. May want to get that checked maybe use a caliper to check diameter against other people and fx specs.

 

[DanielL]

Interesting phenomenon. Pushed a pellet through the pellet liner. Much more resistance through the choke but almost no lead on patch despite more pellets going through it.

 

[DanielL]

 

CORRECTION!!! HAD THEM REVERSED. LOOKS LIKE I MIGHT HAVE FOUND PROBLEM.

More info. Here is comparison between slug liner crown on RIGHT and pellet liner crown on LEFT.

In this last pic it looks like someone hit the end of the SLUG liner with a hard object! 

 

[Loren]

Try a different slug. The one you are showing has a very short bearing length, which can cause accuracy problems.

 

[cmatera]

Maybe Cerrosafe the barrel to get the ID

 

[DanielL]

Try a different slug. The one you are showing has a very short bearing length, which can cause accuracy problems.

I thought that too when I first saw how short the bearing area was on NSA light slugs but that was dispelled when I used them and had no issues (in other guns.) I did shoot a heavier weight slug with it too and those weren't any more accurate. 

 

[DanielL]

Note correction above. It looks like there is a dent in end of slug liner. Like it got hit by something. Hard to see with naked eye but can see with magnifying glass. 

 

[Loren]

Every barrel and every gun is different. 

Next thing I found is sizing. Give one of the slugs a little whack with a hammer to fatten it up and then drive it through the barrel and check for diameter. Even .001 can make a big different in accuracy.

 

[DanielL]

Every barrel and every gun is different. 

Next thing I found is sizing. Give one of the slugs a little whack with a hammer to fatten it up and then drive it through the barrel and check for diameter. Even .001 can make a big different in accuracy.

It is shooting poorly with pellets too. Several people have stated their slug liners are as accurate as their pellet liners with pellets. 

 

[azuaro]

DanielL:

The crown is damaged and this part of the barrel is critical for precision...Nevertheless, re-crowning that liner is an easy task if you have access to a lathe, I re-crown ALL of my barrels as I don't trust mass produced crowning...Make sure you cut it sharp and perfectly perpendicular to the bore: Align the bore of the barrel on your lathe using indicators and good .0001 gauges and center it perfectly.

I noticed that the indentations of the liner (rifling) on the pellet are pretty deep, keep in mind that the deeper the indentations the more turbulence when the pellet is in flight and the less precision, indentations should be minimal, meaning that just enough to spin the projectile (Minimally Invasive Barrel/liner). Check that there is no damage above the crown, this may very well be constricting (choking) the pellet excessively. 

If no damage, then re-crown and polish the inside of the barrel with Flitz or similar and push several pellets and inspect them for deformations/excessive indentations...If the indentation and no precision problem persists, get another liner as there is nothing you can do to open the bore and diminish the groove/lands measurements unless you have the right equipment to do it and to measure it...

If as said, deep indentations persist and you see no precision improvements, don't waste your time lapping (opening the bore) with abrasives as this will cause more damage than good to the barrel. The last resource is to get smaller head size pellets and to re-size the skirts jut .01 mm (.0004") larger than the bore, but this will be tedious and time consuming and in my opinion not worth it given the low cost of a new liner...NEVER re-size the heads of your pellets, you will change the aerodynamic design of that particular pellet and will never achieve the most precision.

Best regards,

AZ

 

[TNT19]

Imo best to see if they will replace the barrel that's a lot of work for a 2k plus gun. I see very minimal scoring when I pushed an 18 gr jsb and the 17.5 gr nsa through. Additionally when I had my priest 2 in 25 I didn't notice alot of scoring there either. I am an avid powder burner hunter and check my bullet grains and rifling to ensure optimal accuracy. The damage you show will absolutely cause the pellet/slugs to flip or exit the barrel at an odd angle causing accuracy issues. 

 

[Enkey]

+1 Azuaro

It cannot be explained better than Azuaro.

I see the slug excessively marked by the striae

 

[JRR]

I had same experience with my 30 slug liner! After much searching found liner needs to be

set. At 20-25 inch pounds Tork on front of liner Nut. Now getting pellet on pellet, but slugs

still not real tight.

 

[DanielL]

Thanks for all the help guys. I'll try torquing the liner nut a little more. Before I start mucking too much with the barrel finish and crown I'll just return it if there isn't a simple answer.

Rain moved in and tomorrow not looking better so this project might get pushed out a few more days. 

 

[FX-USA]

Hi DanielL, 

Sorry to hear to are having some difficulties with your FX Impact .30 slug liner, If you would like, you can DM us your Email, name, and number we can have a tech reach out to you to further assist in looking for solutions that will best fit your situation. 

Thank you, 

FX Customer Service Support

 

[DanielL]

Got a chance to shoot the .30 slug liner again today. I think I might have been contributing to the accuracy issues with my hold which is more important on a higher recoiled like the .30. Maybe that and I had everything tightened down a little better the second time and backed the velocity of the pellets down a notch (to 955 fps). I got quite acceptable groups with the 44.75 JSB’s, but terrible groups with the .300 NSA slugs in 3 different weights. I even went to hand loading them to take the magazine out of the equation. I’d get one or two that weren’t horrific than a crazy flier or two.. Now I’m suspecting it is over-choked.

Here's the targets from the 43 yard range. Pellets on right. Slugs on left. Wind picked up in gusts as I shot the second round of pellets and especially when shooting the two cards to the right hand side with pellets. This wind drift is exactly why I want to get the slugs working.