I had not done chronies for my 460 in quite a while. have not shot it too much either since last winter when I bought it.
Today I decided to see how velocities were doing in most of my guns after cleaning, doing a little lube job and placing a drop of RWS cylinder oil inside the piston hole as recomended.
My 460 had dropped about 60 fps since last winter going from an average of about 820 to about 760.
Another one of my guns, a 52 did about the same thing.
I am not sure what to attribute this to: Break in? (they were practically brand new when I wrote the first set of Chronies) Do guns tipically drop that percentage of speed after a break in time?
Detonation damage to the seal? (they always detonate a time or two after lubrication). If the second I would suspect an even greater drop than that.
Another possibility. How much does temperature affect air pressure. The first time I tested it was winter and I must have done it in about 46 degree weather. Today it is almot 100!
Springers actually work better when it's warm. 46deg. is not bad, but they don't like the cold or I should say freezing temps like below 40.
Your breach seal probably just needs to be shimmed or replaced. There have been a few 460 owners here in the past that reported the same velocity drop as yours and all their gun needed was to have the breach seal shimmed.
You can dust a little talcum powder (baby powder, or maybe corn starch etc) around the top and sided of the gap where your barrel closed tight to the receiver. Do this after the gun is loaded/cocked.
When you shoot it, look for a white 'puff' that will announce any blow-by.
Aside from that, maybe the spring has taken a set or broken. Elsewise it's likely a bad piston seal.
Remove your breech seal and look to see if it's pitted or deformed. You can get a new one from Umerex. Drop me your address and I'll send you a shim.
Rob
No, not the chrony. I did all my other guns and they are doing fine, just those two.
I imagine that in order to remove the seal you have to dismantle the entire action right? So far I have done work on break barrells tuning and changing springs and so on, but never on a side lever or under lever. Any articles on these specific guns?
Rob, very kind of you! My address is:
Rick Carbajal
2898 West. Center St.
Provo, Utah, 84601
Called Umarex and they seemed to cofer with everyone that it is a breech seal problem. They insisted however that I return the gun so they can put a shim on it. I would rather do it myself, so I will take you up on the offer of sending me a shim. In fact i will pay for it if you can send me a couple.
But I can tell you this. There is a defect in the 460. I cooked another breech seal after less than a dozen shots. Return the gun and get your money back if you can.
Rob
Im beginning to think that the 460 has some design flaws. I had mine about a month when it blew up. (kinda) I was at the range for the first time with it .
It popped after about 15 shots . the sliding thumb lever gouged out some wood in the stock, and the pin on the cocking arm sheared off broke in two.
and there was a big indentation in the stock underneath, Im puzzled as to what happened or why. I got it back the other day from repair and haven't had the time to shoot it . Although it seems bone dry of lubricant.
Im thinking of trading it in to PA . I dont know how much they'd
give me for it . Its brand new with a new stock. I might opt for a webley patriot.or a Evanix for a few bucks more.
After breaking down my 34 cleaning sanding and lubing she works and fires like a champ.
Im debating whether to bother with that , As Im not hearing many good things about the 460
Rob, I don't know how to thank you! How did you get a hold of those shims and breech seals? Umarex sure didn't seem very eager to sell them to me, but it may have been just the way the conversation went. Did you get them from Umarex?
Thanks again and I will wait for those in the mail before I do anything with the gun.
I truly love my 460. Even with about 100 fps less than normal I can still see some nice groups even at a distance of over 70 yards.
My greatest thrill is to do benchrest shooting at long distances pushing the envelope of what these guns can do. The 460 shines in that department so I don't really want to loose it, sell it or return it.
Rick,
I bought the breech seal from Umerex. The shim is a metric washer I got from work. It fits perfect. It's 0.040' thick which is just right for a shim.
If you find pitting and burning on the old seal, it means you have a problem that can't be fixed except by a professional. Here's a pic of my old seal, shim and new seal...
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