Tuning I need help tuning my Matt Dubber Special Edition!!!

[Mike_Knipp]

Ok, so I just got in my FX Impact MK II .22 slugger Matt Dubber Special Edition from Utah Airguns. I got 2 tins of the Javelin 26gr. slugs and I’ve been having one heck of a time getting any accuracy out of this combo! I was getting 960 fps at 100bar reg pressure with the hammer spring on Max (no adjustment to the screw). Couldn’t get any accuracy on any hammer spring setting or by turning the valve adjuster. I bumped the reg up to 125bar and then backed the hammer spring down so I’m now sitting at 975fps.

Still cannot get any acceptable accuracy. I’ll shoot one group stacking slug on top of slug and then the very next group will be 1.5”. I have put nearly 400 slugs through the gun at this point and I just don’t know what to do. I don’t want to shoot them really any faster than 975fps to avoid transonic range.

Does anyone have any suggestions as to what I can try before switching to a different slug? I’d really like to get these 26ers shooting like I know they can.

 

[Odoyle]

Have you cleaned the barrel and used Lemon Pledge (TOM HOLLAND STYLE?)

Perhaps if even cleaning and doing the Lemon Pledge routine maybe use a different slug liner? Or maybe Try D-Rig Varmint Knockers or NSAs or FX Hybrids or H&N Slugs?

Matt Dubber makes his own slugs BTW.

 

[Pysiths]

What tuning option did you get when you ordered it?

 

[Odoyle]

I would try shooting at 930-940fps just to see.

My 22 (no power plenum) Impact MK2 700mm STX liner at 130bar does 930-940fps average with my own home made 22gr Corbin slugs (NSA but not available commercially in between weight) it's MOA or better at 200 yards with no wind and half inch or less at 200 yards consistently that NO OTHER commercially made and sold slugs can duplicate that can at best do sub one inch with once in a great while half inch. I have not considered hot rodding this one since its a laser at 200 yards even with light weight home made slugs. (Like Air Hunters SA for real and not typical YouTube Hollywood in this case) Almost as good with 28gr home made slugs same dies just adjusted for length no power adjustments definitely slower shooting but didn't wanna screw up the perfect setting for the 22gr just have to lob them more.

 

[qball]

Shocked that it didn’t come well tuned. Have you tried a little slower at around 880? Have you retighten the liner and barrel? Something doesn’t seem right because FX superior liners have been consistently extremely accurate. 

 

[Mike_Knipp]

@Pysiths I got the standard tune which was 100 bar getting 960 fps straight out of the box.

 

[Smok3y]

I assume you asked for the standard power tune, as that is the exact speed (960) they say they set it for with 26gr javelins. So oddly enough, it sounds like it is set up exactly as they planned.

Is it possible you expected better than you should have expected?

What distance have you been shooting? If at 100 yards, having some 1-1.5” groups is not off.

 

[Mike_Knipp]

@Odoyle I have shot it at every power setting from 880fps to 975fps and I haven’t gotten any consistency. Groups are all over the place. I did clean it but only with hoppe’s no. 9, rem oil, and dry patches. I might try the lemon pledge trick but I would assume that after 400 slugs whatever was in the barrel is out by now. Not to mention the gun comes fps tuned from Utah Airguns so they would have shot it previously. And the slugs I’m shooting ARE Matt Dubber’s slugs. They are the Javelin 26 gr.

 

[Mike_Knipp]

@Smok3y I am shooting at 30 yards. 1.5” groups are unacceptable to me at that distance. I agree, should I be shooting at 100 yards, 1.5” wouldn’t be terrible but I would still expect sub MOA in good shooting conditions.

 

[Mike_Knipp]

@qball I have not retightened the liner. Maybe that is the issue. I’ll check that and get back to you.

 

[Smok3y]

@Smok3y I am shooting at 30 yards. 1.5” groups are unacceptable to me at that distance. I agree, should I be shooting at 100 yards, 1.5” wouldn’t be terrible but I would still expect sub MOA in good shooting conditions.

Dang! I was truly hoping you weren’t going to say that. Yeah, at 30, I completely agree. I would be pretty pissed too if I paid that premium. 

Are the speeds inconsistent as well?

 

[Mike_Knipp]

@Smok3y I am shooting at 30 yards. 1.5” groups are unacceptable to me at that distance. I agree, should I be shooting at 100 yards, 1.5” wouldn’t be terrible but I would still expect sub MOA in good shooting conditions.

Dang! I was truly hoping you weren’t going to say that. Yeah, at 30, I completely agree. I would be pretty pissed too if I paid that premium. 

Are the speeds inconsistent as well?

No, the speeds are pretty consistent. After each adjustment I’ll take a few shots to let the gun settle in, and once it’s settled the velocity is steady within about 10fps extreme spread. I had a buddy recommend I check to make sure I have the right size moderator on it. The gun came with the DonnyFL Koi, and maybe they accidentally put on a .177/.22 model instead of a .22/.25 model. Maybe I’m getting baffle strikes.

 

[Al_Miller]

Just throwing this out there... have you cleaned and lubed the slugs? I've had some EXTREMELY dirty slugs come my way. Turned water black instantly and there was some sizeable lead pieces in there as well. Just a thought.

 

[Smok3y]

It could be possible, that would explain the erratic behavior. That actually sounds like what happened with another manufacturer’s moderator I had on a previous Impact. Great and then very random shots. That being said, I thought I remember Donny saying to me once that sizing up wasn’t as important in 22. He recommended the 177/22 in each of the 22 mods I purchased. I know I have read where he mentions to size up sometimes, but can’t remember when.

That being said, try testing without the mod and see if it continues.

 

[Eddy1840]

If I We’re you I contact Utah Airguns that is almost 3k gun should be perfect right out of the box 

 

[Smok3y]

Another thought, which size 26gr javelins did you buy (217 or 218)? I would hope that they didn’t sell you the wrong size since you purchased the rifle with them.

 

[Odoyle]

Interesting... Is it the correct liner?

Barrel nut YUP! and either removing all the liner o-rings or adding more may help.

If all fails I think you need 28grain.

Based on swaging my own different weight NSA style (Probably Matt's using the same Corbin adjustable set up I use) and experimenting with different weights that's all 22gr and 28gr seem to outshine the rest.

 

[qball]

@Smok3y I am shooting at 30 yards. 1.5” groups are unacceptable to me at that distance. I agree, should I be shooting at 100 yards, 1.5” wouldn’t be terrible but I would still expect sub MOA in good shooting conditions.

at 30 you should be looking at 1/2 inch groups if not one hole. This definitely isn’t a tuning problem, most likely something loose. 

 

[cahil_2]

My impact 700 mm with slug A liner and Donny KOI likes .217 knockouts the best both javelin and NSA don’t shoot as well. I’m shooting them at 940. 

 

[Ghostranger169]

You might try .217 H&N 27g or .217 JSB Knockout slugs. My 700mm Superior Heavy barrel likes them better than NSAs(of any size/weight combo) and MUUUCH better than any Javelin slug.