dog229 here.
I am wanting to open up my mod barrel on my 1956 ap 870 12g. to i.c. to do more dove or quail
hunting. My barrel is 1956 plain barrel and looking on how to do this seems simple to do with a oversize bore bit but cost is the factor so will look for a smith to do it. Also, barrels of this era are said to be really made better so if anyone has done this with success let me know.
Dog229 gone

I have an 1100 with a 28" mod barrel and I want to open the bore for skeet. I had a SKB (Itacha) o/u that I bought cheap but is was 28" with fixed chokes of full and modified, not good for skeet. I took a telescoping gage (T shaped) and set it for skeet size. I then dropped down the barrel to see how much of the t-handle stuck out the end of the barrel. I removed the gage and put to the outside with the same amount of t-handle extending beyond the end of the barrel. Luckly, it came to a support for the ventilted rib. I then cut the barrel down, cleaned up the end, remounted the bead and I had a 26" barrel that was skeet/imp cyl.

I now have a modified barrel that I'm doing the same thing. I measured it out and if I cut about 1 3/4" - 2" off, it will be a 26" skeet choke. I will remount a bead and also put one in the middle which it didn't have before. I'll cut the barrel with a cut-off wheel or my electric hacksaw and then clean it up on a milling machine. I bought the beads, drill and tap at williams firesights--total cost under $50. I looked for a replacement skeet barrel and they're around $200. The tools to install rem chokes is over $200 (reamer and tap). This seemed to be an economical alternative and in the future I can look for a rem choke barrel at the gun shows.

Another alternative that I am still contemplating is to take a brake cylinder hone and hone down the barrel until it gets to the proper size (mod=.709, skeet=.724--only .015 needs to be removed [mod -> imp cyl is only .010). The hones are available at car part stores for under $20. The advantage is the cost and there is no need to remount a bead.

All the gunsmiths in my area have an 8-10 week wait.

Just my 2 cents, probably all it's worth.

I'm not sure about changing the fixed choke but you can get the gun drilled for choke tubes. This can usually be done for under $100. You will have to check with the machinist to see if it is possible with your gun.


Many places can do it:

Rose Action Sports This guy is a member of ARFCOM and comes highly recommended. A friend used this one with good results.

R & D CUSTOM BARREL SERVICE

Williams Gun Site will do it as well but the only install tru-choke tubes

Other local shops may do it as well.