My son's turning 9 next month and since he had such a good time shooting with my smallest carbine at the last Mission HFT meeting (scoring 16 out of a possible 40 on his first effort) I decided to get him an air rifle all his own. By his age I'd already been shooting for a couple of years, and between that fact and his enthusiasm his mother couldn't very well say no, little as she likes shooting sports. So I ordered this kit:
Baikal IZH-61, or MP-61 as is printed on the side of this spring-piston 5-shot rifle, ordered direct from the distributor as no one else had one in stock - http://www.baikalcanada.com/air_rifles_izh61.htm - Had to email them and ask if they'd sell me one or point me to a distributor, but they had no problem selling direct. Cost $165 including tax and shipping to Vancouver.
Leapers Bug Buster Compact CQB 6X scope from D&L - http://www.dlairgun.com/Scopes/Leapers/ ... OIEWQ.html
Leapers offset scope base to deal with the very short dovetail and mag release button clearance issues, also from D&L - http://www.dlairgun.com/Mounts/Leapers/ ... -25H4.html
Some carbon fiber tube with an ID of 13mm and OD of 15mm, to add some stiffness to the barrel in hopes of getting rid of the front barrel stanchion. That didn't work out quite like I'd hoped... but more on that later. Bought two 500mm tubes from this shop through their eBay store - http:..www.carbonfibertubes.net
I did a lot of reading of various blogs (especially stuff by Derrick of anotherairgunblog - http://anotherairgunblog.blogspot.ca/20 ... -deux.html ) and kept notes of what to look out for with disassembly and tuning and reassembly. I won't go into all the details of that stuff as it's covered very well on the linked blog post and others related. Basically I did that stuff when the rifle got here on Monday, then got into some things I wanted to do beyond the basics of making a spring-piston air rifle happy.
My son is a little guy, growing fast lately, but still fairly small. He's doing martial arts the past couple of years so he's no weakling, but the physical size issue remained. Even at the shortest extension the stock of this rifle was about an inch too long, so I carved out a bit of plastic in the tapered portion and drilled through to make a new location to put a bolt an inch further in than the minimum factory setting. Of course the plastic cylinder cover was blocking this shrinkage, so I cut off an inch from the portion which is part of the grip/forestock. With the eye relief and LOP situation resolved through this shortening and thanks to the offset Leapers mount, I moved to the forestock which was much too long. Cut off 3" of that and glued the end cap back in, rounding the plastic over to make it somewhat decent looking. My boy isn't fussy about perfection, just wants his airgun to look decent. Actually as far as he's concerned this whole project is just too cool for words, so I can do no wrong.
The cylinder and grip/forestock casting were nowhere near a good fit. About 4mm of wobble fore/aft with even slight pressure on any part of it. This was a major source of vertical stringing in my early testing. Solved it by staring at the problem long enough, then settling on drilling a 1/8" hole through a portion of solid plastic in the buttstock portion and inserting a stainless steel rod with a rounded front end overlapping the front section of the stock. By placing and angling this hole just right I managed to have the buttstock slide the pin over the front portion very snug so it pinches everything together. Zero rocking now. Of course this won't work when he grows and wants the length of pull longer. I'll probably weld a bolt to the cylinder then and drill for a flat headed bolt to pinch it tight.
I chopped the barrel down by 3" to lighten the front end futher. This cost power, dropping tuned velocity to about 430fps with 7.5gr H&N Finale Match pellets in .177", 450fps with 7gr pellets. I carved a groove into the front end of the bolt and made a urethane O-ring of sorts to seal that against the breech, and that brought me back up to 450fps with the preferred 7.5gr. I actually tried a chopped-down used mainspring from my QB57 in this one and it went up to about 550fps, but was jumpy and too hard to cock and would probably cause undue wear on the guts so I went back to the stock spring, with a 2.75" long fitted delrin guide.
Funny thing; the stock steel guide came installed inside the piston end, which made the initial firing cycle extremely harsh and twangy. A properly fitted longer plastic guide settled it right down. There was a circlip missing from the main spring retention/cocking pivot pin, but I had one so just popped it in. Baikal's answer? " We have been selling this model for 10 years, and this model was always very satisfactory for our customers." Yeah, alright... I'm happy with the cheap Russian rifle. Just wrote to report glitches in hopes of helping out with quality control.
Anyway, the CF tube was too snug a fit to get onto the textured finish of the hammer-forged barrel, so I turned the barrel down very slightly on my lathe until a firm press fit could be managed with epoxy on the barrel and in the tube. Pressed that on after trimming to desired length, leaving an inch at the front for a black delrin (acetal) muzzle brake/air stripper. It's press-fit onto the barrel, and the conical insert is a harder press-fit, had to hammer that in.
The recessed sharp metal lever to release the magazine was too much for my son to manage so I made a delrin sliding button, fussy and ugly solution I know, but it works. Combined with a long bolt pinching it into place with some brass to build that up and shrink tubing to stay with the grey theme, he's got enough leverage to pull back against the return spring I put between this and the scope mount. A ball bearing embedded in the delrin acts as the push interface on the lever. Works well, but when he's a bit older I'll take that out of there, it's just too ugly.
In running pellets over the Chrony F1 and trying to zero the scope I filled a 5-shot magazine enough times to become impatient with the fiddly quality of the thing and its tendency to fly out and go to ground (on my workshop floor, which happens to be covered in ebony shavings this week), which could be painful among weeds and rocks and dirt. So I talked to my son about it and he didn't mind my modifying one magazine such that it can only fire 2 shots and stays trapped in the rifle after releasing it. I drilled for a 10-32 bolt, found one the right length and threaded for it, screwed it into the inserted magazine's far end, and presto, trapped magazine. With HFT there are two targets at each station. One shot per target allowed. So there's really no need for a 5-shot mag anyway, and it's just one more thing for a kid to forget, whether or not there's one pellet left. With this system he shoots the station and knows the mag is empty for walking to the next one. And it's easy to remove the bolt so he can swap in the 5-shot mag for plinking if he prefers. I suspect he'll stick with this system as it means no dropped mags, no dropped pellets.
Here's what the rifle looked like with this stuff done:
After doing most of the mods including gluing on the CF barrel sleeve (this stuff is REALLY amazingly stiff for 1mm walled tubing, and weighs practically nothing) the groups at 10 metres were still about 26mm centre to centre at best, with the odd one further out:
I did a fair bit of zeroing, but eventually realised I wasn't grouping well at all and tracked part of the problem to the lack of a midpoint barrel mount. The factory plastic one is just hideously ugly and more than a bit wobbly so I made one out of delrin, inset tightly into the forestock hole and firmly bolted down. It's turned out to a hair under 15mm to make a very firm slide fit onto the CF barrel sleeve.
It's too late this evening to shoot at my 10 metre trap on the porch, but at 6.5metres in the house (longest I can shoot inside, this being a complicated little place) the improvement was obvious. No more fliers unless I mess up the hold. I'm finding that a reasonably firm grip and pulling the stock with a few pounds of force into the shoulder, just moderate pressure, while 'floating' the forestock on my left hand results in the best consistency. Too loose on the shoulder and it opens up to twice the group size, with the odd flier way off the bull. Here's the 6.5m target, centre to centre about 10mm:
So my conclusion after spending a couple of days (with a moderate flu, so not mentally fit for doing real work where I can't make mistakes) tinkering on this airgun? I think it'll do to get him started with HFT. He'll take a while to adapt to shooting a springer, and the accuracy potential just isn't that of a PCP, but for targets out to maybe 20 metres he'll have a realistic shot at knocking them down. Further out will be a roll of the dice unless my boy turns out to be a magician with a springer.
The gun is worth the price to me - about $350 all told. I would not recommend it to non-tinkerers as it really is quite unstable and hence not terribly accurate, at least the more recent model with the plastic stock and scope rail. Sure it'll probably work for a while, and many may work for a good long time. But I had to add a 4mm spacer inside the left side of the forestock frame to stop the cracking already starting from the mounting screw there, which had a huge space beneath instead of a solid casting element. Bad mould design there, and elsewhere in places. For anyone somewhat keen on digging around and finding solutions to little cheapness issues I'd say go for it, it's a fun project gun. Kept me busy for two days which I'd have probably spent reading on the couch as this cough/flu isn't leaving me a lot of energy. With the stock open sights and nothing else done to it I can see it being a fun camp chair plinker for beer cans out to 50 feet. But it takes considerable modification to make a modestly respectable target shooter out of it.
