Cadet rifles are usually converted to rounds like .22 Hornet, .218 Bee, .256 Win Mag, or .357 Mag. Larger, more powerful, rounds seem to work but are
limited by the size of the barrel shank and most are hard to load because the lever has to be held down to get the large round into the chamber.
I wanted a larger round that would load easily and not stress the small shank of the cadet barrel. My choice was what I call a 5.6X50R improved.
In the above picture the round on the left is a .357 magnum. Next to it is a .223. Both have the same diameter case. The third round is the European 5.6X50R
Magnum. This is a .223 on steroids, 5mm longer and with a rim. The last round is the one I chose for a conversion. It is a 5.6X50R opened up to 6.5mm and
fireformed to slightly straighten the case and add a sharper shoulder. Also this is the same as a 6.5 TCU only 5mm longer and with a rim. I use 6.5TCU
reloading dies.
My rifle was made using a 6.5 TCU reamer. I plan to make another rifle but will order a custom reamer. The rifle was originally a BSA Take-down .300 Extra
Long. When I originally purchased the rifle I got the receiver, stock, and forearm with a horn tip, no barrel. My first barrel was a .357 Mag. The second
barrel the 5.6X50R. Both use the same extractor. The breech block of the .300XL came from the factory with a small firing pin and the trough in the top to load
a long round.
I have a large supply of 6.5mm 140gr bullets. So far these are the only ones I have tried. A good load seems to be a 140gr bullet at 2350fps.
I think the best hunting load would be the 120gr Barnes TSX at about 2600 fps.
This case could be used as .22 or opened up to 6mm, .257 , .270, 7mm, or even .30 cal. Or used to make a rimmed .221, or .223.
