New AV 46M Velocity Adjustment

[Dale O]

As mentioned in my previous thread I ordered a AV 46M to help get me back into the sport. It arrived yesterday and I took the first 10 shots from it. I'm at 415 fps with 7.0 gr Meisterkugeln. I've read & seen photos on how to adjust the piston TDC. I'll do this myself vs sending the pistol back. My question is, is it to early to make this adjustment or will the seal break in and add fps after a few hundred shots or so?

Thanks,

[subscriber]

Dale,

I suggest you also try some other pellets to evaluate the state of your pistol.  It could be a particular batch of 7 grain Meisterkugeln, but the one I shot through my 46M and everything else shot slower than their 8.2 grain cousins.  So, use JSB or H&N or a different RWS pellet to see if your pistol is in fact shooting as slow as your current pellet suggests.

If you have 50 to 100 shots through the pistol and the piston seal is properly lubed, I do not expect the velocity to increase more after that. 

If you over oil the piston seal, the gun will actually shoot slower for 20 to 50 shots; until the excess is blow out.  Over oiled means that it sneezes an oil mist when dry fired less than an inch away from carboard; leaving a dark ring on the cardboard.

[Dale O]

Well, while drinking my coffee I decided to go ahead and raise the TDC of the piston. The process only took 15 minutes or so and I'm now at 445 fps with my first 10 shots after. I increased TDC by 2 clicks = 1/2 turn on the piston. I'm going to leave it here since there is no binding at the end of the compression stroke and I don't want to push it by adding one more click at this time. Maybe after 1000 shots I'll add that extra click and perhaps even the rubber band in the seal groove and see if I can get to 500 fps.

So far very pleased with this pistol!

[Dale O]

Just one last update. I decided to go ahead and make one more adjustment to the piston. I advanced TDC another 2 clicks, this makes one full turn in total. I'm now at a fairly consistent 485 FPS with a random 488 or 490. There is still no binding at the end of the charging stroke but I do feel the bit more effort it takes. I will leave the pistol as is now and focus on shooting.

[subscriber]

That sounds more like it, Dale.

A random 5 FPS shift does not sound too bad.  I think the more you shoot it, the more it will settle.  This assumes undamaged pellets.

[Dale O]

Might as well add a photo.

[Ronfiveo]

Might as well add a photo.

Sweet.

Ron

[dan_house]

does that mean the Baikal version of the 46 has that adjustment too?

edit:
Reading thru the threads from over the week end. the 46 - new or old- has a few threads... and one older thread being about this very thing....

 

[Frank in Fairfield]

Dale,
This speed test was from awhile ago.
My IZZY has 15,000 shots since I have owned it.
Even though the manual says not to do it, I store it with a pump of air.
My C9A is stored with two.😂

[Dale O]

Thanks Frank, looks like I'm right in line with where it should be. I had a IZH 46M back in 2000, I sold it to get a PCP. I really like the new AV version but I'm surprised my charging lever is showing signs of wear already, the bluing is wearing off and less than 100 rounds fire so far. I don't remember my IZH wearing like this.

[subscriber]

Dale,

Any "gun" mechanism that rubs blued surfaces together will go bright in the first day of use.  That shiny set of surfaces then serves to point out spots that need to be lubed.

It would concern me if rubbing surfaces galled; as in went rough via adhesive wear; rather than became smoother with use.  Either way, a little molybdenum disulphide grease on the cam surfaces will smooth the movement of the lever and help prevent strange wear.  The oily carrier will also prevent rusting.  If you don't like black grease, then you should at least oil those surfaces.

Galling, or adhesive wear occurs with soft metal friction pairs.  To avoid it, harder material conditions (heat treatment) are used, typically with one part 10 points Rockwell C harder than the other.  Two equally soft similar metals tend to "cold weld" and rip bits off each other.  As you cannot change the hardness of the parts already in an airgun, you can lubricate them to help them live a long happy life.

Galling, or adhesive wear:
https://www.sciencedirect.com/topics/materials-science/adhesive-wear#:~:text=Adhesive%20wear%20occurs%20when%20two,and%20attachment%20to%20the%20other.


I am not seeing any galling in your image, Dale.  But, unless you wiped the part dry for the picture, the fact that it is dry seems to indicate that it needs a bit of lube.  The primary cocking cam surfaces are elsewhere.  They work much harder and certainly need deliberate lubrication.

[Frank in Fairfield]

Thanks Frank, looks like I'm right in line with where it should be. I had a IZH 46M back in 2000, I sold it to get a PCP. I really like the new AV version but I'm surprised my charging lever is showing signs of wear already, the bluing is wearing off and less than 100 rounds fire so far. I don't remember my IZH wearing like this.

My cocking arm wears underneath..
I keep grease on it.
I do not know if that type of metal rusts..

[Dale O]

Well, if anyone is interested I've decide to sell my AV 46M. It's a great pistol but I can only shot outdoors, In WI that doesn't leave much time. I will post it for sale in the classifieds section soon but I can not do so until I reach 20 posts. Selling for $550, includes hardshell case, pellets, targets all tools & seals that came with pistol and a Acetech AC5000 chronograph.

[Dale O]

For some reason I can't attach all photos. If you send me a PM maybe I can send that way.

[Dale O]

Trying again.

[Dale O]

Another.

[Dale O]

One more.