Try as hard as you can to get your state to follow the 4-H National Rules.
Get the Event Synopsis at:
http://www.4-hshootingsports.org/
I really feel bad for kids that show up to Nationals with 1) no idea of the rules they will be shooting under and 2) wrong equipment ... while both are in the end their responsbility to know ... the project leaders and state leaders are somewhat responsible as well.
1) The .22 rifle 3-Position event is an NRA "any rifle" event with iron sights. That means your kids will be competing against olympic style rifles. Other rifles will do well too. I start my shooters out with Izhmash CM-2's for right handers and have Marlin-2000's for leftys. My daughter shoots an Anschutz 1912 in her precision gear as the rules allow this.
2) The .22 rifle silhouette event is what you would think of as an NRA "heavy" (not hunting) rifle event .... rifles up to 10 lbs-2oz. We use Remington-813's and Kimber 82-G's. Many kids also use CZ-452s ...
10lb-2oz means you can do almost any .22. As an example again, my oldest daughter uses a Kimber 52-G with a 36X scope
3) The CMP Rimfire Sporter event limits the weight of the rifle with sights to 7-1/2 lbs and is a 3-position slow/rapid fire event. I tend to like the 10-22 for this event, but there are many rifles which you can mount a light scope on and make this weight. If your kids practice with it a 10-22 is fine, but if they don't practice a lot, a bolt action, clip fed may be better. Scopes here are not as critical ..... a nice 3-9X taped at 6X is fine.
I also like to have spotting scopes to sight in with (on #1 & 3) that they can see the holes in the targets at 50m. We've found that the Celestron 50mm zoom with 45' eyepiece is VERY good for this (P/N:52232). You should be able to find these for less than $100
If your rifle is light enough you could easily use the same one in #2 & 3 above, but you do not have a lot of range time (at nationals) to resight-in the rifles between the events.
My personal preference is that the kids have 3 guns, one of each event.
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I should comment on PaulB's response as well. In NM we have shooters that basically group into the rifle categories as does VA, but we use National rules so all compete against each other .... just by looking at our state match scores you can tell the differences.
I know it's hard, in terms of dollars, to equip correctly. I, as a coach feel
terrible if I have to send a kid up against a better equipped kid when I know their potential is limited by the equipment. (If they only come to one practice per year, then any old rifle will do)
We are VERY fortunate here in NM with our NRA Foundation dollars going to primarily YOUTH programs .... JROTC, 4-H, Scouts, & Summer Camps are big receivers.
The funding and equipment don't come overnight ... I've been at this 5 years now, and finally have what I consider I need to run decent programs. Maybe I'm lucky (???) in that I have 3 kids that will spread my time out in this to about 10 years, so I thought, and continue to think long term
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One more suggestion: Incorporate an Air Rifle program as well ... the training is the same and carries over. You can shoot Air 90% of the time all year round indoors for a LOT less money than .22.
I hold 3 practices per week ... Air on Tues & Thurs and then alternate Sundays of Air & 22. Right now most of the kids make 1-2 per week ... I don't really expect them to make all three, but certain times of the year, the really serious ones will