Ruger .22 Airmagnum mystery

[Gsyme]

My Ruger .22 air magnum was shooting 800 fps with JSB 18 grain pellets. I read a few reviews from guys who got better performance with this rifle after taking it apart and cleaning it. Said they found a bunch of black gunk and metal shavings in the chamber from the factory.

So I did that. I did find some metal shavings inside the chamber. I cleaned everything with a clean rag. Got quite a few tiny bits of metal out of the chamber. Put it all back together. Now it shoots those same pellets at 775 fps. 14.3 grains at 835 fps. I guess none of this is terrible, but I am miffed with myself for making the performance worse. Also, the gun is advertised as 1000fps with lead pellets...not sure which size they used to get that speed.

What did I mess up? I put a few drops of RWS silicone chamber oil in the chamber and on the piston seal before putting back together. Was that my mistake? I also put a few drops of RWS spring cylinder oil on the spring before re-assembling. Did I simply add too much oil? Could I have bent the spring ever so slightly, thereby reducing power?

Thanks for any advice. Be severe. Tell me what I did wrong and what I should do now. My plan for the moment is to keep shooting it. If I did simply add too much oil, perhaps it will work through it and the speed will come back up?

- G. Syme

P.S. I had about 600 shots through the gun before doing all this.

 

[pdxFrank]

Perhaps less oil meant less "dieseling" or similar effects to the pellet speed? YouTube has several videos on the subject, most of which I'd object.

Now that it's clean, it might be shooting closer to proper speeds.



The xxx FPS any airgun/pellet you read is likely under ideal circumstances, perfect test gun, and non-lead pellets.

Me, I wouldn't worry so much about FPS/FPE until you get the gun to shoot accurately and consistently. Is it shooting that 775 with a tiny spread?



My 3-cents. Good luck, keep us posted!

 

[Gsyme]

Thanks, Frank. Very sensible. You're right. Accuracy has got to be more important than power. Especially since I am new to air gunning. Not sure why I am so preoccupied with that 25fps loss. I haven't shot any groups since I put it back together. I'll do that today if I get a chance. 

I also noticed that the stock is a bit loose. I thought I had tightened everything up well but apparently I missed something. I will tighten that up, perhaps use a bit of loctite and see if it makes any difference as well.

Thanks again for your help.

- G

 

[bandg]

IMO accuracy isn't necessarily more important than power, but accuracy must be present for the power to mean anything. I view both power and accuracy as important to varying degrees, especially when one considers hunting use or longer range shooting. As to the specific rifle, I would think that cleaning that chamber, while a good thing, might have reduced overall "lube level" and might be causing a bit more seal drag. As you note, if it is consistent and accurate then 25 fps shouldn't make any profound performance difference.

 

[Gsyme]

Good point, bandg. Right now, I hunt soup cans, so power is pretty important. I will have to do more testing, but that 25fps loss does seem to have made a significant difference in my clean and humane soup can kills. Before, from 35 yards my can hanging on a string would not move a whole lot - the pellet would pass straight through both sides. Now it flips all over the place in its death throes.

- G

 

[bandg]

At least those cans are going down. A little flipping around in the process is OK. In my view the power/accuracy balance really relates the most to trajectory. How flat will (or can) a particular combination shoot? It can make a noticeable difference once one gets beyond 35 yards. Inside that range, power may not matter much at all. I have a 2" aluminum plate hanging in a tree at 65 yards that my LGU will hit consistently with 1 dot holdover when zeroed 1/2" high at 35 yards. Not particularly useful as I wouldn't routinely take game shots at that range but it illustrates that flatter trajectory can be a good thing.

 

[JayJay]

Interesting. The Airgun Detectives review got 900 fps with a 14 grain pellet. https://www.youtube.com/watch?v=zIlMrJhaK8w

It's a 25+ foot pound gun for sure. You're getting about 22 foot pounds. That's a 10% drop.

I don't see how cleaning or over-oiling would lower performance. Something else must be wrong. Is your chrony accurate? Did you leave some shims out? Is there a chip in the port? (just grasping at straws here). 

Question: is the cocking effort any less? Is there less kick? 

 

[Gsyme]

I don't know if the chrony is accurate, but it is consistent and I'm using the same one before and after I took apart and cleaned the rifle. The temperature has been in the 40s here this whole time. And, as I said, I can see the difference in performance the way my cans behave when hit from the same distance.

I was getting 800+ consistently with 18 grain pellets before - so, not too far off from the 25poinds.

Don't think I left any parts out. By shims, do you mean shims under the breech seal? I've tried adding and subtracting those and it doesn't seem to make any difference.

Cocking effort feels the same. Kick - maybe slightly less but it's hard to say. 

Maybe I did inadvertently let something into the chamber when putting back together. When I reassembled I did not re gunk the piston or spring with anything than a little RWS spring oil for the spring and chamber oil for the chamber.

I am tempted to be more generous with lube on the spring and piston and see what happens. There certainly was less grease on those parts after I was done cleaning. Seems to be the only thing other than my conjecture that perhaps I somehow damaged the spring during reassembly. 

If I do try more lube - what should I use? I know this is a controversial question.

Thanks so much for your time and thoughts. I am having fun learning about this gun. It will be that much more rewarding when we figure it out.

To respond to Frank, earlier: My groups are the same before and after. Definitely not tiny- but I am a beginner. My first airgun. app. 2" groups at 25 yards depending on the day. 

 

[Gsyme]

I forgot to say: I shoot without a rest, standing up, with open sights. Just making excuses for my wide groups. 

 

[Gsyme]

I think I got this about half-solved. I noticed that the bracket which attaches to the underside of the barrel was loose. My stock screws were tight, but because of that loose bracket the whole barrel assembly was able to slide back and forth almost 1/8 of an inch inside of the stock. Bad of me to miss this. So, before tightening anything, today I measured the speed.

3 shots averaged 771 fps.

I took off the stock, really tightened down that bracket and used locktite, then replaced the stock and tightened everything. Nothing moves now. Measured the speed again: 3 shots averaged 783 fps.

I also remember that the day I did the rebuild it was warm and sunny before I started and when I first measured the speed- quite a bit colder in the evening after the rebuild when I checked the speed again. Possible that temperature difference accounted for some of the loss? I intend to do some research to see how much temperature affects springers - but if you feel like saving me the trouble I won't complain.

Thanks again for the free input you fellas have given me. This hobby is starting to push my online chess habit out of the way.

- G 

 

[JayJay]

I doubt the spring was damaged. Spring steel is heavy gauge music wire which is really tough stuff. You could pull it and check for a collapsed or cracked coil. Airgun Detectives' Air Magnum got 779 fps @ 24 foot pounds with JSB 18.13 grain pellets. So your 783 fps is actually better than they're getting! The 800 fps may be due to dieseling. I had some mild dieseling with my new HW95. It took about a tin until it settled down. It's also possible the spring broke in and compressed a little.

 

[Gsyme]

Well that's good to know. Thanks JayJay. I appreciate the note. From reviews I've now scoured online, people get a range of speeds from this gun, some much faster than mine, but now mine seems to be about normal. I admit, my first shot of this rifle sounded like a firearm - so maybe even after 500 hundred shots it was still dieseling a bit and the cleaning reduced that effect.

I intend to try and be satisfied now and focus more on tightening my groups than worrying about speed...as Frank and Bandg have suggested as well. I watched some of the Airgun detectives video but my internet is being slow and taking forever to buffer. Maybe I'll try again a bit later and learn something more about my gun.

- G