I use the ones that are tapered.
That way, they will work on calibers from
.22lr to .45colt and then some.
I have never used the 'caliber specific'
guide. It may stay in place better, or it
may be in my way......don't know.
I use the ones like this
The only criteria is still simple.....
there are a couple of different sizes 'inside diameter'
for your cleaning rod.
I use them in the .22 size
.22 Muzzle Guard
That way they are more universal to me
for my use.
Some cleaning rods start at .27caliber.....
so the .22caliber wouldn't fit over it.
If your cleaning rod that you now have
will go into your Henry or Single-Six...
it's a .22 rod.