I've seen barrels that were back-bored and wondered if that area that was not rifled at the muzzle end would cause a problem with the powder gas causing turbulence and mess up the bullet's accuracy? I've only seen this on heavy barrel 10/22's and wondered if there was a reason?

OTOH,
There seems to be some call for the idea for shorter barrels,
especially for 22s , but also for centerfire match rifles.
This is manifested in the use of bloop tubes added to(clamped on) short barrels.
Idea is to have shorter barrel time for the bullet, but still
a long iron sight radius. I would think this would be especially helpful for Off hand shooting.
beltfed/arnie

A friend of mine uses back bored barrels quite a bit (22rf) with no problems. All I can say, no personal experience.

I can speak from personal experience that the back bored barrel has not caused any loss or gain of accuracy. I've had several, and have one in .22LR presently. The other two came to me already done, and I believe it was done to repair a damaged crown, and not change the length of the barrel, or outward appearance. I was hesitant to buy the first one, but the price was cheap enough I figured I'd reline, or replace the barrel if it shot poorly. It shot great, so never changed anything.
  The gun I have now is a full sized #1 Rolling Block chambered in .22LR. It had a 22" half octagon barrel on it when I bought it, and shot extremely well. A beautiful trigger job, and really nice custom extractor. I loved everything about it, except that stupid stubby barrel.
I took it to John Taylor and we discussed the possibility of welding on 8" of barrel and relining it. But seemed a shame to hurt a good bore. So instead John turned the round part of the barrel down smaller, and made up @19" section of .45 caliber barrel to slip over the turned down section. He made it a snug enough fit to press on with Loctite, and butt to the octagon portion. So it now is a 30" barrel, externally, but 8" of it is .45 cal. and 22" is .22LR.
The proof was in the shooting afterwards, and it shoots exactly as it did before. But now it looks correct, and not too stubby for the overall appearance.

I have had to backbore a few old barrels that were muzzle wore for 2-5" with the rest of the bore being good. It turned the barrels into good shooting barrels where before some of them would even keyhole. 
Lee Gibbs Pres.ASSRA

I had also thought about drilling out the bore and lining it but the liners for a barrel this length cost more than a replacement used barrel in good shape. So I'm back to the back-boring but what is the standard diameter for back-boring a 22 rimfire?

By the way, Thanks for all the replies. I was not sure if the question I posted was crazy or not.