I've found some pictures but haven't found one even listed for sale online. Found a 512 (lower power) but no 513.
Guess I'll keep watching
Just out of curiosity, how much would one cost with the discount? What is you're reason for wanting one?
If it's just the velocity claim, you should be aware that it it is probably based on a very light pellet as most are overblown manufacturers' which are commonly tested with the lightest pellet they can get their hands on(and I swear some are chronying cleaning pellets to get the figures). Such a claim doesn't really tell you much about it's usefulness for hunting unless they tell you the pellet weight the claimed FPS was shot with.
http://www.airguns.net/calculators.html Also, if you are unfamiliar with spring rifles, you will be rudely surprised as to what you accuracy with it will be since it is no doubt pretty crude. In addition, you won't find any aftermarket tuning parts to improve it's firing behavior.
If you just have to have the power, a better choice might be an RWS 94 which is a Spanish gun(Cometa)which received a top rationg here:
http://www.reviewcentre.com/products9.html It's based in the UK, so some model will have different brands depending on who imports them here and most velocity figures will be for the sub 12FPE permitted without FAC in the UK.
which has gotten pretty good reviews, NOT a Gamo. Before I knew anything about adult airguns, I got suckered into buying a Gamo 890 primarily because they are the only manufacturer that advertized in American Rifleman with an inflated claim of 780fps in .22(and if you pay atttention, also the only ones that get reviewed there and always glowing one). It's a POS and nobody has parts to improve them and if you attempt to tame it youself with a tar tune, you void the lifetime waranty for your efforts. For an air rifle, mine makes a pretty good doorstop and hasn't been touched since I bought a used BSA Supersport with a Synergy tune and a 4x30 AO Sportview for less than I got the POS BSA 890 "combo" for.
I just picked up a Slavia(CZ) 631 for <$80. It's not a "100" fps gun but does ~600 with accuracy. There are two tuners who will tune this gun R.Best and marty at Silver Streak sports. I'lll be paying about $95 for a Best tune on the 631(he also does RWS 94s) which will cost more than I paid for the gun. The RWS 94 like all "magnum" speingers has a pretty harsh firing cycle that makes accurate shooting dificult. The tunes don't increase power(and in some cases may slightly decrease it) but greatly smoth out the firing cycle making it easier to hit what you're aiming at..
They also make a 630 with a smaller different stock for about $15 less. It's real accurate right out of the box(but dry) and is pretty heavy and long for kids but the 630 is the same gun except for the stock, rear sights and trigger adjustment(both can be adjusted but the 631 with a screw in the trigger guard and the 630 you have to take the stock off and move the triggger spring to different notches).
For a detailed review of the 631 go to:
http://home.hiwaay.net/~ispellan/Airguns.html For a review of the RWS 94
You will probably have much more luck posting your 513 questions at a forum where it is only airgunners, rather than here where most seem to be powder burners who also shoot airguns.
http://www.airgunforum.com/ The general airgun forum is probably where you'll have the best luck asking about a Russian gun. There's also a good link for classified on the page to find a good used airguns.
http://www.airguns.net/class_ad.html Sorry for being so long winded but I hate seeing somebody make the same costly mistakes I did if I can prevent it.
