New Sheridan 2260MB: Here's my groups. What do you recommend next?

[Ribbonstone]

True that little interlock of the transfer port is an important part of the design,but the barrel set screw probably does most of the holding in place.

Quite possible the flat for that sight was not made quite right....considering the the two choices....prot lined up or sight flat level and true....would prefer the transfer port to be right.


Thinking about that Crosman barrel and that rear sight flat....it's something they only do on tht one model,but the barrel is common to several rifles...suspecting that that is a later step done to already existing barrels.

[HYspd]

well therez yer problem(picks teeth)

i would believe that much barrel rotation in the breech would prevent the fitting of the transfer port in any functional fashion, so i'm voting for bad machine work...when you assemble the barrel into the breech you use the transfer port as an alignment gauge...the tport has a tapered end with i think it's a 3/16" od that snug fits into a counter bored counter sink (a shallow cylinder with a tapered bottom) that has to match to work...the tport's main body is i think 1/4" od and that snug fits into a hole in the underside of the breech that is also a match ...it's a jig saw puzzle, it only goes together one way, all the parts match and fit or they don't fit at all...

crosman would likely replace that barrel, but if it shoots well, i would keep it....so far that 10 yards group looks good but with airguns the proof is in the distance and good means it shoots well at the longest range you plan on shooting it at and then maybe a bit farther just be sure...

[WilsonLR]

Thanks for the idea HYSpd. I think I'll contact Crosman. PA is swamped and exchanging emails is a 48 hour thing. They haven't posted my review yet either. 

Per chance there were others with this problem, I read the user reviews of the Sheridan 2260MB on PA and found others that also experienced the CO2 leakage on the second or third canister and some others that mention iron sights out of kilter. Pretty much everyone put a scope or red dot on and never hit the barrel problem. Everyone says the gun is accurate and that's true shot to shot but not as a whole. That barrel alignment is a problem I'd think would hit either every unit or some percentage that came from a bad machine/person/batch.

I did a proper zeroing yesterday with the gun locked down and windage is less than 2 turns from its extreme leftward compensation. That's against the spring correct?

[Ribbonstone]

If it shoots well (and that last target was 4 out of 5 goodness) with the scope, I might let the matter rest rather than start over....and maybe end up with a nice level sight slot, but one of the poor barrels (it's pretty much a lottery ticket).


Yes...the spring that runs the internal adjustments is on the left lower side (to be able to tension both up and down with one spring).....so the turret adjustements "in" increase that spring tesnsion.

[WilsonLR]

Thanks Robert. I think I’ll stick with what’s working.

So, I had to adjust the reticle to the right which means it’s nearing the end of its tension. Will keep an eye on that. Pardon the pun. 

[WilsonLR]

Since Crosman's iron sights are useless, the nice wooden stock which was the driving reason to get the Sheridan 2260MB is too low for anything else. It's now a Frankenstein gun with a neoprene riser but I can pick it up and shoot at 10 - 20yds with crosshairs on the bull. A little heavy but at least it works.

The trigger is over 4lbs so I picked up the Baker kit that lowers that and makes it a little adjustable. Is there a hammer bounce MOD to eek out more shots per fill? I already have a power adjuster.

[WilsonLR]

I felt the report of the Sheridan 2260MB was too loud. Its crack reminded me of slapping two pieces of lumber together. Anyway, I felt it was going to be annoying so I set out to reduce it.

Having a background in audio/video production, here's the scoop:

• Sound is measured in terms of distance from the source not unlike FPS (at muzzle vs POI).
• City/Neighborhood regulations, if there are any, are usually defined in terms of a maximum sound reading at the property line.
  
• At a given moment, there is sound that is the background noise plus the sound you are adding with your airgun.
  
• The sound level of a report is the total sound minus the background level. That is, the additional sound added by the report is the loudness measurement of the gun.
  
• When you measure the effectiveness of a muzzle brake or whatever, you want to first remove the background noise at the time of the shot and then compare the two resulting measurements.
  

Sheridan 2260MB (power adjuster at max, OEM valve body with Pro-Top, OEM TP):

• WITHOUT TKO 5.5" MUZZLE BRAKE AT 4 feet: Background 55db, Report 110db. Net sound level = 55db
  
• WITH TKO 5.5 AT 4 feet: Background 53.5db, Report 91.1db.  Net sound level = 37.6
  
• Sound reduction of TKO 5.5: 55 - 37.6 = 17.4db
  

It's much improved. Being useless, the fixed front sight has to be removed. The TKO instructions provide various techniques for the various barrels it fits. For the Sheridan 2260MB plastic sight, a tap on the ramp with hammer and screw driver pops it off. A solid piece of wood will save a scrape of the barrel. The TKO slides on but requires a little elbow grease and twisting back and forth. The instructions provide guidance for how far to slide it on for different guns. For some, the PCP tube is the determining factor. For the 2260, you slide it to the specification in the instructions (1.185"). I suggest marking the barrel so you know when you've hit that point. Tightening two grub screws with the provided allen wrench finishes the job (the instructions are so complete they specify the opposing screws be positioned at 9 and 3 o'clock).

I have some work to do on the trigger so I will test for any changes in accuracy after doing the Baker trigger upgrade. That's going to be great.

In the "for what it's worth" category, I checked the level of the seat in the barrel for the front sight. With the breech level, both front and rear seats are out of level wrt the breech. With Scope, rings, magazine, moderator and comb riser, the formerly featherweight backyard plinker clocks in at 6lbs even.

Still looking for a hammer bounce mod.

[Bentong]

Try This > https://www.gatewaytoairguns.org/GTA/index.php?topic=110145.0

[WilsonLR]

Thank you Betong. Interesting. Looks like it had 3 seals by the end of it. Anyway, I forgot to include this photo in my TKO installation post and can't add it now. I am not seeing any accuracy problems but I ran out of pellets before doing a legit string.

[WilsonLR]

Today was Stainless Steel Breech Screw and Baker Trigger Kit day. I'm glad I got the new breech screw. In pulling the Crosman OEM screw out, I could tell the soft metal of allen screw was starting to give way. I picked up a stainless steel TORX #8 replacement at Magnum Power and installed it. I hope the shorter length is OK.

The Baker Airgun Trigger is wonderful. The instructions are good but there's a fantastic YOUTUBE video for it from Baker Airguns. I used a syringe of Mil-Comm TW25B which made the lube of all the small bits easy. The hardest part of the whole thing is the spring. Really tricky and stressful as one slip and that spring is going to go flying to who knows where. In the end, I had 10 pellets left to try it out and I love it.

However, after reassembly, I noticed the front scope ring was not fully seated on the breech. It had a .5mm gap caused by a lock down screw in the ring. After fixing that, I noticed I no longer had a gap between scope and GRAVmag. Fortunately, a little filing down of the GRAVmag left a paper thin gap and the scope seated nicely. The .59mm shim in the rear ring is still needed.

The gun shot so far left it missed my trap and about 3 inches low. Three turns worth of windage plus a dozen clicks of elevation and I was back on target at 20yrds. No surprise the scope is no longer zero'd but the Florida rains came and that will have to wait for another day.