Simple tune for Gen 2 .25 cal. Marauder Rifle

[Crusher75060]

Sounds like pellet corkscrew to me.

[KyPop]

Whenever my accuracy goes berserk I have learned that it is usually time for a good cleaning. I use a nylon brush and a solvent for air rifles then dry patches until no trace of lead comes out. I shoot 2 magazines to season the barrel then I am back on track with decent grouping.

[Bob La Londe]

correct= i mean, pellets al over the place, to high and left and right from the target... ones i get to 3000 psi i can shoot nice groups...

It would be interesting to know what velocity that is happening at. It would be nice to know what pellet you were shooting as well.

Sounds like pellet corkscrew to me.

I recently had an experience where I ran out of the CPD domes in .177s that shoot fairly in my .177 Marauder and .177 B50. I had the urge to keep shooting, and I had a tin of H&N pointed pellets. I thought my guns were broken. Both shoot poorly at short range. My standard test target is 23 yards from my bench. I decided to shoot the BAM and see if there was a speed they shot well at. I shot it until the pressure was low enough I could see the pellets corkscrew through the air to the target. They didn't stabilize until the pressure was so low I was having to raise the gun on every single shot to stay on target. This was with pellet after pellet. Not just a flier or two. Once the pellets dropped down to archery or CO2 pistol speed they were quite accurate. LOL. At normal velocities 10 pellets looked like a blast pattern from a shotgun.

I have (I admit it. I bought into the hype) a Hatsan 155 in .22 and I tried pointed pellets in it as well. While it shoots way to fast to see it I think the pointed pellets corkscrew in it as well. At my test target they were impossible to group, although the spray pattern was not quite as bad as the .177 pointed pellet described above. I do not have any domed pellets in .22 (I need to get some I suppose) but I do have some Crosman hollow points the same weight (according to my scale - not the markings on the tins). Except for the divot in the nose they are very close to the same shape as a domed pellet. Bearing in mind the difficulties of shooting a heavy magnum springer they shot acceptably well at 23 yards. I would note there was a difference in speed. The pointed pellets shoot at a very consistent 950-951, and the hollow points shot at a pretty consistent 929-932.

It seems in general a domed pellet is the most accurate in just about any airgun, and from there its a matter of finding the one that is the best fit for a particular gun. They came to a similar consensus on the TV show American Airgunner at the "Round Table"this last season. They did not specifically say it that way, but very close.

[jfm30204]

Specifications:
Fill pressure 3000 psi ( use an accurate gauge )
Velocity Screw ( 5/64” wrench ) = turn CW until stops, then 5.5 turns CCW ( don’t forget to remove the set screw first )
Hammer Throw ( 1/8” wrench ) = turn CCW until stops
Hammer Spring ( 1/4” wrench ) = turn CCW until stops, then 3.5 turns CW

Thanks for the info! I'm going to try this one and then Ray's variation to see which works best for me. A few quick questions:

1. When I open the velocity screw 5.5 turns, there is no more room for a set screw. Does that sound correct?

2. If no set screw, then might the VS work its way out and be lost?

3. The set screw itself is already lost. In case I may need to replace it, can you tell me the size?

Thanks again.

Jere

[pbgunsmithing]

I'm getting around 855-860fps w/JSBs... Very nice!
Only other pellets I have on hand are Barracudas (high 770s-780fps) & the Eun Jin's 43.2's (670-675fps).

Modded stripper (thinking may have gained a couple fps here but not much). Non of my other mods would have contributed to higer FPS...its good tune to start with and tinker from there.


I'm happy

Thank you.

[jhm757]

Specifications:
Fill pressure 3000 psi ( use an accurate gauge )
Velocity Screw ( 5/64” wrench ) = turn CW until stops, then 5.5 turns CCW ( don’t forget to remove the set screw first )
Hammer Throw ( 1/8” wrench ) = turn CCW until stops
Hammer Spring ( 1/4” wrench ) = turn CCW until stops, then 3.5 turns CW

Thanks for the info! I'm going to try this one and then Ray's variation to see which works best for me. A few quick questions:

1. When I open the velocity screw 5.5 turns, there is no more room for a set screw. Does that sound correct?

2. If no set screw, then might the VS work its way out and be lost?

3. The set screw itself is already lost. In case I may need to replace it, can you tell me the size?

Thanks again.

Jere

No! This does not seem correct! You must turn the velocity screw all the way in first, til it won't go further, then turn it out 5.5 turns. And yes you should have the set screw to keep the velocity screw adjustment from moving and possibly coming completely out. I would at least locktite it until you can get a set screw, sorry don't know the set screw size.

Jim - jhm757

[lagger]

Specifications:
Fill pressure 3000 psi ( use an accurate gauge )
Velocity Screw ( 5/64” wrench ) = turn CW until stops, then 5.5 turns CCW ( don’t forget to remove the set screw first )
Hammer Throw ( 1/8” wrench ) = turn CCW until stops
Hammer Spring ( 1/4” wrench ) = turn CCW until stops, then 3.5 turns CW

Thanks for the info! I'm going to try this one and then Ray's variation to see which works best for me. A few quick questions:

1. When I open the velocity screw 5.5 turns, there is no more room for a set screw. Does that sound correct?

2. If no set screw, then might the VS work its way out and be lost?

3. The set screw itself is already lost. In case I may need to replace it, can you tell me the size?

Thanks again.

Jere

afaik from the manual from the gen 1 it is the part number 1763-019 Screw, 10-32 X .25, SHCS item 25 on the schematic

http://tinyurl.com/k5q8gs7

[lagger]

Specifications:
Fill pressure 3000 psi ( use an accurate gauge )
Velocity Screw ( 5/64” wrench ) = turn CW until stops, then 5.5 turns CCW ( don’t forget to remove the set screw first )
Hammer Throw ( 1/8” wrench ) = turn CCW until stops
Hammer Spring ( 1/4” wrench ) = turn CCW until stops, then 3.5 turns CW

Thanks for the info! I'm going to try this one and then Ray's variation to see which works best for me. A few quick questions:

1. When I open the velocity screw 5.5 turns, there is no more room for a set screw. Does that sound correct?

2. If no set screw, then might the VS work its way out and be lost?

3. The set screw itself is already lost. In case I may need to replace it, can you tell me the size?

Thanks again.

Jere

in another schematic (for the 177 but I assume the same, ) Isee item 44 is part number 88-089 Set Screw 6-32x.125 CUP HEX HD

and on the first I posted,(if approved) the two screws are listed as 2E 1763A028 SCREW, VELOCITY ADJUSTMENT
2F 1763-059 SET SCREW, 8-32 x 125, BRASS