forend ?

[Franklin7x57]

I bought my first rifle barrel for my encore a used 24" 45-70 "heavy". Not sure what the heavy means in forend choices and how you can be sure it is a heavy. The barrel I have on it now is a prohunter 20ga. slug barrel and the screws attach like my contender, but on the 45-70 the barrel is just tapped for the bolts. Do I need something else beside the forend and bolts?
What is the difference between T/C's 207-7708 and 207-7660?
Thanks.
Frank

[DEACONLLB]

All the encore rifle barrels as well as pistol barrels take an 8-40 screw that goes right into barrel and they should come with the forend as they are very hard to find in hardware stores. I have found that all the forends interchange from factory taper to heavy or no conture, you might have to sand a little in the inside on some of them but not much. The only forend that I have came across that I had to sand very lightely was on a Boyds custom forend never had to do any on TC forends.
 
Deaconllb