Tuning Need a .30 Maverick Expert! +/- 30FPS swings with for no apparent reason! TONS of data inside!

Suppose to be getting my 25 back from FX. I was getting a similar set of symptoms before it broke! Hammer locked up solid. Tech called and said hammer had developed a " burr" on sear connection. My gun is 1 1/2 yr old. 1000's of shots. I mean 1000's !
The difference in hammer speed ( according to tech) would cause this. Rational person would agree.
Just a thought.
I mentioned this to AirShootist on his FB page the other day. I had this happen on my .30 quite a while back. I ordered another hammer, and the pellet probe carrier(82) and the pin that goes in it(82.1). After assembly, I noticed the pin sticks out a bit farther to contact the face of the hammer better, which should reduce the chances of that burr forming. I don't know if the carrier had the hole for the pin drilled more shallow, or the pin was longer. I didn't compare before assembly. Either way, I haven't had the issue since, and that has been many thousands of high power rounds ago. Definitely a worthy suggestion Keyman ;)
 
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So... Got out to shoot a bit today. this 977, 979, 981, 953, 978, 980, 977, 956 business is getting real old. So I wasted a bunch more slugs today. But then I began to think. Hmmm, how could I be very consistent and then just have one shot always drop by like 30 FPS and then go right back up to where I was?

Maybe it is, in fact, my FX Chronograph? Well, I happened to have an old F1 Chrony in the shed, so I busted it out. Now, it does have a sub par brand (Rayovac) battery in it that sat for more than 12 months including winter (was disconnected, at least) AND I one time shot the unit (lol) with the Condor SS at like 70fpe (still works, but who knows how accurately) but it was the only thing I had to get a litmus test here. So I shot a string of 970s shots and sure enough on the FX chrony hit that dreaded 953 shot. Well, the F1 Chrony read 973 for that shot! Sooooo... that is.... interesting. Could be a total fluke due to the bad battery and having...well... been shot once. Also it was rainy/cloudy and those chronos need direct sunlight...

Could I possibly just be a victim of an FX chrony that doesn't like .30 slugs? Or maybe I got some bunk Duracells? I mean, the thing reads fine with the .22 and that gun is always shooting within a few FPS. Before, though, I was getting great readings from the thing on the .30, like this one from back in early May:

1658604929001.png

So... I am stumped. Now it's between "my gun is inconsistent" and "my chrono is inconsistent"....

I should probably have a look at the hammer like you guys recommended above. Can I easily remove from out the back? Would be good if one of you guys could give me a quick how-to.

Maybe it would also be worth messing with the chrono. Maybe change the minimum return? Buy fresh new Energizer lithium batteries and try that?

Any additional thoughts here would be helpful. Hope you guys are having a great weekend without immense airgun frustrations! 🥴
 
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If you shot thru two chronies at the same distance or very close and one says its 30 fps slower and the other reads fine my guess the slow reading is a bad reading. Buy or borrow another chrono and see what happens. I am not familiar with the fx chrono but it could be more sensitive than other types. Do you see that slow reading hitting different in the group.
 
I mentioned this to AirShootist on his FB page the other day. I had this happen on my .30 quite a while back. I ordered another hammer, and the pellet probe carrier(82) and the pin that goes in it(82.1). After assembly, I noticed the pin sticks out a bit farther to contact the face of the hammer better, which should reduce the chances of that burr forming. I don't know if the carrier had the hole for the pin drilled more shallow, or the pin was longer. I didn't compare before assembly. Either way, I haven't had the issue since, and that has been many thousands of high power rounds ago. Definitely a worthy suggestion Keyman ;)
OK so I yanked the hammer. Looks a little burred up. Tell me if you think this looks OK:

1658610295404.png
1658610320971.png
1658610619851.png


This appears to have been done by the little sprue hanging off the probe carrier (82). At least it is only on one side of the hammer

Should I just simply order those 3 parts (82, 82.1, 83) and see if that fixes this?
 
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Inspecting the hammer a little more, I see that it is out of round due to those burrs. This is making it so I get resistance when I insert it into the receiver. I am pretty well thinking this is 100% the cause of my problem. Gun is under warranty so I will hit FX up about it and see what they say. Pics of the burrs below where you can see they are raised a bit; making the circumference out of round, and causing slight binding with the receiver:
1658611396756.png

1658611435951.png
 
Sorry, I just saw this, but.... Yep, that can't be helping your ES at all, and very likely is the root of your problem. You can clean it up with a file, and get that edge back level too. I'm sure FX would send you another hammer at the very least. I would order those other two parts, just to be safe, if it were me. You may find like I did, which is the new parts combo engages the hammer better and is less likely to cause the issue again. I think you're definitely on the right track though ;)
 
Just send it back to fx usa...they have a tech there that is really friendly and he will fix your gun for free..just do that. He'll also call you and walk you through everything that he does to your gun.
Mav is back with FX along with a note describing all these items and a $10 gift card for Starbucks since he is gonna need a coffee for this one!
 
So... Got out to shoot a bit today. this 977, 979, 981, 953, 978, 980, 977, 956 business is getting real old. So I wasted a bunch more slugs today. But then I began to think. Hmmm, how could I be very consistent and then just have one shot always drop by like 30 FPS and then go right back up to where I was?

Maybe it is, in fact, my FX Chronograph? Well, I happened to have an old F1 Chrony in the shed, so I busted it out. Now, it does have a sub par brand (Rayovac) battery in it that sat for more than 12 months including winter (was disconnected, at least) AND I one time shot the unit (lol) with the Condor SS at like 70fpe (still works, but who knows how accurately) but it was the only thing I had to get a litmus test here. So I shot a string of 970s shots and sure enough on the FX chrony hit that dreaded 953 shot. Well, the F1 Chrony read 973 for that shot! Sooooo... that is.... interesting. Could be a total fluke due to the bad battery and having...well... been shot once. Also it was rainy/cloudy and those chronos need direct sunlight...

Could I possibly just be a victim of an FX chrony that doesn't like .30 slugs? Or maybe I got some bunk Duracells? I mean, the thing reads fine with the .22 and that gun is always shooting within a few FPS. Before, though, I was getting great readings from the thing on the .30, like this one from back in early May:

View attachment 277876
So... I am stumped. Now it's between "my gun is inconsistent" and "my chrono is inconsistent"....

I should probably have a look at the hammer like you guys recommended above. Can I easily remove from out the back? Would be good if one of you guys could give me a quick how-to.

Maybe it would also be worth messing with the chrono. Maybe change the minimum return? Buy fresh new Energizer lithium batteries and try that?

Any additional thoughts here would be helpful. Hope you guys are having a great weekend without immense airgun frustrations! 🥴
I have experienced similar stuff on my .22 Maverick- 1 or 2 shots out of a couple of mags. 25-35 fps. I also got a new hammer but could see nothing wrong with the “old” one. Never thought about the FX chronograph cuz I have set up with a consistent power supply of 5 volts. Maybe that’s why FXs owner had a new experimental chronograph at the recent Rocky Mountain challenge!
In Sub12 YouTube video he polishes his sear on all touching surfaces and the hammer and spring!
 
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OK quick update here, guys!

Newman at FX called and said the gun is fixed, leak tested, and on it's way back. He said the hammer was beyond salvation and just threw a new one in. He reported chrony readings of right at 1000 with the 44.5 grain pellets, with 3/5 shots being the exact same velocity. I also had the front reg slow-leaking out the vent hole, he said that is fixed, as well. Let's just hope this thing is back to consistent velocities like it was when I did the Huma transfer port video (it was shooting MONEYYYYY for that).

This season I don't intend on being laid up in the hospital... so if I were a coyote in my area.... I'd be very afraid! Missed the whole spring season this year... after buying a $2300 thermal scope that has sat in it's box since I bought it.....

Thanks to everyone who commented here and tried to help!
 
If I had a dollar for every time I had a regulator leak, pretty easy fix.
No, not an easy fix, at least in my case. I've personally replaced all the orings in there, got it to mostly shut up, but the tape test doesn't lie. I think either my reg housing or the bottle adapter is outta spec. I suspect it is leaking around the OD seal on the reg body.