600MM STX Superior .25----heaviest/longest projectiles used?

[mackeral5]

I have one of these that I am setting up for a regulated/bottled Marauder. The lower is setup for .300 with .281 porting so it should be more than capable of pushing the STX Superior's limits.

What is the heaviest ammo (and velocity) you have shot accurately in the 600mm .25 STX Superior liner (the standard, not the heavy.)

 

[steve-l]

The weight limit for the FX barrels is usually the width of the magazine opening in the breech. In the mag, it would be about 40 grain. If single loading a bit more for a .25 cal. As far as velocity with the 600 mm barrel, it is possible to get around a 1000 ft/sec max with the 25 grain pellet and best accuracy at about 940 ft/sec. For the 40 grain max is about 940 and best is about 890 in my experience. All of that is without a moderator. Good Mods will attenuate the velocity a bit.

 

[Vetmx]

I have a 600mm superior on my RTI .25 for one reason. The 33.95 pellet going right around 900fps. That gun could make a man question why anyone would ever try to shoot a slug. Out to 125 yards or so its on the money every day all the time. No good days no bad days. Always the same. You can’t take advice about speed from FX guys or even possibly me. FX guns deliver air to the back of the pellet differently than your gun will. Either way, if you do it right, you’ll find happiness. I tensioned mine using my mod.

 

[mackeral5]

Great feedback. I have other guns that shoot the 33.95's very well, it is indeed a great projectile that seems to do well running fast or relatively slow. Even out of cheap barrels such as the old Crosman xl725 barrels, the 33.95's are hard to beat.

My desire for slugs is mostly due to having molds and the ease of casting slugs vs pellets. One mold in particular, the MP 6.35 airgun bullet, I really like this bullet and am hoping to be able to shoot it well out of one of my barrels. I have a GM .25 barrel with the choke removed, it shoots them decently enough, and likely could be improved upon, but it is only 19". Takes a bit more air than I prefer to get those bullets up to speed.

I have had this STX Superior since right after they came out but never did anything with it.... I recently assembled a Brod with a .281 ported bottom half and will have barrels/probes for .300, .25, and .22. The .22 is setup for Prod mags so it will accept the MP 5.55 airgun bullet, the 34gr .22 version.

I am hopeful, that maybe I will get lucky and the Superior's slow twist can stabilize such a long bullet. Hopeful but not very confident since we are talking about a 48gr bullet that is about as long as will fit in a .25 Mrod mag, call it .438-.440"

I do appreciate the feedback.

 

[Vetmx]

For that 48 you’ll need a superior heavy.

 

[mackeral5]

For that 48 you’ll need a superior heavy.

I was worried that would be the case. The STX Superior is already set up with a thimble for the Brod, it just needs one more layer of CF sleeve. At some point I'll finish it and test. Worst case it is a low reg setting 33.95 pellet shooter...

 

[qball]

Any .25 pellets and slugs up to about 30 grain.

 

[bigHUN]

ZAN 41 gr and 44gr. The 46 single load only.

 

[Healthservices]

I'm going to single load some 60 grs when they come in. See if they can make it out of the end of the barrel. They are 12.9 mm long. And actually I just realized that I just stole the parts off the 600 barrel to make a 700 barrel so this does not apply! Sorry


Allen

 

[PBuffa]

I have one of these that I am setting up for a regulated/bottled Marauder. The lower is setup for .300 with .281 porting so it should be more than capable of pushing the STX Superior's limits.

What is the heaviest ammo (and velocity) you have shot accurately in the 600mm .25 STX Superior liner (the standard, not the heavy.)

I bought a “lot”of NSA 43 grainers. The battleship slug of the .25 world. I just hope they are accurate. Yes, they fit the mag and will be running down a slug barrel

 

[Centercut]

I bought a “lot”of NSA 43 grainers. The battleship slug of the .25 world. I just hope they are accurate. Yes, they fit the mag and will be running down a slug barrel

Yes, they will shoot out of the standard STX Superior, probably in a "Meh" accuracy. They shoot better in the Superior Heavy (Slug), and best in the older Slug A liners... I've shot them from 880 to 950 fps... Same accuracy at the speed range. I'd recommend 900 fps.

 

[PBuffa]

Yes, they will shoot out of the standard STX Superior, probably in a "Meh" accuracy. They shoot better in the Superior Heavy (Slug), and best in the older Slug A liners... I've shot them from 880 to 950 fps... Same accuracy at the speed range. I'd recommend 900 fps.

Awesome
Thank you

 

[mackeral5]

I ended up ordering 700mm Superior Heavy in both 22 and 25. My application is a DIY project, based on the Marauder platform. the intent (hope!) is to accurately shoot the MP molds 6.35 Airgun bullet at ranges beyond 100 yards. Then have a separate probe/barrel kit to change calibers and shoot JSB Beasts and the MP Molds 5.52/5.55 airgun bullet at similar ranges.

Thanks to all for your input.