The Good, the Bad, and the Ugly

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ptthere

ptthere

Member
Dec 27, 2018
384
14
Iowa, United States
I'm scratching my head on this. I have multiple questions at the end of this so please bear with me. The quick backstory is, I recently disassembled and re-assembled a new-ish Crosman NP break-barrel (added a mod, carbon-fiber shroud, different scope mount, stock re-finish, etc). Today I took it for a spin to get it re-zero'd and dispatch some pigeons.

I got it zero'd quickly at 27 yards. I then took a dozen pigeons out in short order. Then I came in and tried taking some more target shots. Things got interesting. I was shooting three different pellets (.177) all at 27 yards under the exact same conditions. Here is the sorta-GOOD:

H&N FTT's:

1556524547_12232037495cc6ae03eab8d7.22849026_IMG_20190429_022913308.jpg


H&N Baracuda Hunter Extreme:

1556524730_18932853805cc6aebacf41b2.32933540_IMG_20190429_022544478.jpg


Gamo Rockets:

1556524876_12111374065cc6af4c3c1707.84146846_IMG_20190429_022507389.jpg


I had similar groupings before these. Now, I may not be the best shot in the world, so in each photo we could call that one stray a flyer, or user error. But I had just started to get it broken-in so I was happy with the groups tightening up (the gun was 6" groups out of the box with Crosman Premiers for the first 150 shots).

Question #1: I zeroed my rifle in at 27 yards with the 8.64 gr FTT's. The Baracuda's and Gamo Rockets weigh in at 9.6-ish gr but hit slightly higher at POI. Why? I measured a lot of the pellets. The FTT's had a head diameter around 4.50 mm average, with 4.66 mm skirts. The Baracuda's averaged 4.51 head diameter with 4.68 mm skirts, and the Gamo Rockets measured around 4.51 mm with 4.66 mm skirts. Interestingly, the Rockets beat the H&N's in accuracy, which I did not previously expect. I did expect the Baracuda's to fail to the FTT's, although I still find the result acceptable.

Before these shots were taken, I cleaned the barrel. After I took the shots that you see above, accuracy went to crap, BAD. The square-foot back-stop I was using was completely missed on the next 6 shots, about 14" off center, slightly to the right but mostly low. Out of 6 shots, 3 of them were FTT's, and 2 were a Baracuda and 1 was a Rocket. Same result.

I did not touch anything on my scope, although I feared the worst. It is a Discovery VT-R 4-16x42 AOE. Mechanically, I couldn't see anything that changed. I changed my hold a bit, and fired the next 5 shots with Gamo Rockets only... All 5 hit in the squares you see in the photos. Then I ran 5 FTT's through... Flyers everywhere, a foot right and low. Ran Baracuda's through, a foot right and low. Ran Gamos through, a foot right and low. I walked away for about 10 minutes shaking my head.

I came back, never changed a thing, I shot 10 more FTT's through and hit all 10 within a dime of my aim.

I can't seem to notice any mechanical change in my setup. I have hesitated to clean the barrel again because most consider that a curse... So what am I doing wrong? Should I attempt cleaning the barrel? The only thing I changed to the mechanics inside was adding a mod, but I see no signs of pellet clipping. The only other thing I noticed was that the Baracuda's seemed to load in the breach somewhat tight... Not "I need a hammer" tight, but tight enough to be worthy to notice the extra effort. Is it possible I loaded up the rifling with lead and it's screwing with me?

Any advice is welcome. This is a different beast than the powder-burners I am used to.
 
Well at least you stuck with the 1st 6” 150 shots. Most would have sold or stuck in a corner.

I would check the crown with a Q-tip for burrs. I’d shoot some of those pellets into a non deforming water trap or box of old rags/clothing, look for any tell tale marks. 

It is confusing when a spring gun or PCP does this. I would ask if you cleaned your rail with alcohol & cleanly roughed it up for bite with folded 600 grit or valve seating compound. But your results seem to go good, bad, good again. Besides clipping I can only think of variance in seating depth & hold. 

I’d wake up & try it fresh on a new day before I start tearing into it. 
 
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Well, I found the problem. It's the lock-up on the barrel. Horizontally everything seems fine, but there is some play in it up/down that I can literally feel. This would explain why half my shots were missing so low. It will now be a new doorstop. Considering that I took time to tinker with this over the winter, I am bummed out. I guess I need to buy a better air rifle.
 
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Why don't you try to improve the barrel lockup? See if you can remove the beveled barrel lockup pin and shim the spring or possibly find a stronger spring. Might be able to reshape the pin retention area to get more extension. I've done that (shimmed spring and reshaped the retention area to allow a few thousandths more extension) on a Hatsan 125 that had the same issue and improved it dramatically.
 
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Why don't you try to improve the barrel lockup? See if you can remove the beveled barrel lockup pin and shim the spring or possibly find a stronger spring. Might be able to reshape the pin retention area to get more extension. I've done that (shimmed spring and reshaped the retention area to allow a few thousandths more extension) on a Hatsan 125 that had the same issue and improved it dramatically.
Click to expand...

If it were a Hatsan 95 with a nicer walnut stock or 125 (I've been shopping), I'd put more time into it. But the fact is I thought this rifle was a great shooter when I first bought it. The photos speak for themselves. Sure, it wasn't spooky-accurate, but easily covering a dime at almost 30 yds was acceptable for my needs. But I spent a lot of time tweaking this $80 Crosman for months, and there are a few things I have not been happy with, the barrel lock-up/POI shifting being the biggest issue. Heck, I spent FAR more just on the scope, mod, and accessories than on the rifle itself.

Just for the sake of stress I am cutting my losses. I will probably re-sell the mod here (it works very well), pull my Discovery scope off it and mount it to my next rifle (I will be upgrading for sure) throw the stock on the bonfire and use the rest of the NP assembly as spare parts.
 
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I replaced that spring on my two Titans several times. I sent the spring to the local spring works and they made me a very long version that I just cut when I need a new one. Also I think Crosman sells them as well. Look up their parts list for the rifle you have. I live in Australia and the Australian distributor sent me a new one.

Very easy to replace. It’s all part of maintaining your airrifles. The spring is called a Jam spring and this is the parts list that I used.

Good luck

Gary

https://support.crosman.com/hc/en-us/article_attachments/201593750/BW1K77NP_EVP.pdf
 
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It isn't major work to do. A small shim under the spring and a little dremel work on the detent section of the lockup pin to allow a little more protrusion along with some good brass side washers might make it shoot fine. But your method will certainly resolve the issue for you.
Click to expand...

The work doesn't bother me. I've worked in maintenance and engineering for two decades. I'm simply stepping away from this air rifle for now. I'll come back to it at some point, but I've spent too much time with it and I would rather take a breather from it and concentrate on a new one that I have showing up. 
 
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i had an NP Trail in 22 while back and could never get it to have repeatable accuracy.

i made brass shims for receiver to breech pivot contact, redrilled and tapped front mounting screws to 1/4"x20, experimented with a multitude of pellets and scopes.

in the end, i believe that the advertised speed of 900 fps was way overstated (i chronoed multiple 22 caliber, weighed and sorted pellets, at less than 700 fps) 

in exasperation, i sold it...😕
 
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