Don't know, but price 22LR birdshot before investing.
Since this is the fire I'll go off topic;
I have a 10-22 and had a volquartsen 22 short bolt. I tuned it to shoot CCI Quiets. Playing with springs I got it to run Quiets 100%.
I had about a dozen CCI shot cartridges, gave these a try and it ran them 100%.
Of course ideally you would use a smoothbore barrel.
There is an outfit (urban rifle supply) that used to sell smoothbore barrels, but now I see they will 'smoothbore' your barrel for a fee.
And now Volqurtsen offers a bolt for CCI Quiets (which is probably just the 22 short bolt without the short magazine).
Jerry
http://www.urbanriflesupply.com/ind...mp;view=article&id=97&Itemid=555