I've used see-thu's before, from the ridiculously high Holden Ironsighters, to some that I still have on a couple .22's that are very reasonably low.
The ones on the .22's just barely allow me to use the irons below the scope, and the scope is not lifted much off the usual line of sight. Seems like a great use of see-thrus on these 2 .22's. And I've found them to be very useful for squirrels in the woods using the scope, and then pests around the house up close and personal using the irons.
However, I've solved the problem of being able to use my irons AND my scopes for center fire on a couple rifles that are relegated to my fairly close-up swamp hunting, crowded timber hunting, and other brushy areas.
My solution is the old system by Weaver known as the Pivot-Mount system. Some don't like them b/c they don't return to the exact POI every time, but in my practice in use I find that the POI shift is almost legible. This could be b/c the 2 rifles I use that employ the Weaver Pivot-Mount system are both quite low recoiling cartridges (.243 and 6.5 X 55) but I'd be surprised if properly installed that POI would shift more and .5" @ 100 yrds, and I certainly will never get a shot beyond 150 yrds in the places I use these 2 rifles.
The Weaver Pivot-Mount system uses a special base and ring that snaps over to one side if wishing to use the irons, then snaps back down in place held by a tough spring steel retaining clip. I don't believe they are made anymore, but I got into collecting them a while back and have a crap load. I plan to sell them off on eBay soon, but I'll keep a few for the rifles I own.
You can still find them available on eBay, and also in very limited amounts in some very well stocked gun accessory shops. I'd also think you might do well to check with older generation gun shops that have been in the same location for generations.
Again, I wouldn't use this set-up on anything where I needed to use a heavy recoiling round AND needed to ever make shots beyond 175 yards, but it works great for me in the applications I mention above.
Last edited by 8mm/06; 02-21-2013 at 06:35 AM.