The barrels I've had shortened have been BSA's and HW's, I was told by Tony Wall at SFS that HW barrels are unchocked and I can confirm that an HW95 I sent to Tony to be "Banshee'd" lost no accuracy after being shortened, I once had a choked BSA Airsporter RB2 barrel shortened and it was worse after shortening, I currently have a .22 Supersport barrel that has no felt choke (it hasn't been shortened either) which is unusual for BSA barrels as they are normally choked, I've not tried it on a rifle yet (it was a E gay purchase) but I may well put it on my Challenger as I think the .25 barrel I currently have on it will go on my new (too me) Supersport when it turns up.
Pete