I want to get a rifled cantilever barrel for my Remington 870 express 20 ga. and I found one for $200 on the cabela's website but it's 18 inches and I was wondering if that will effect the speed and accuracy alot? any other input on slug guns will help because im new to gun hunting for deer I am usually a bowhunter only.

Howdy waterfowler, I am in just the opposite situation as you. I have been slug gun hunting for quite some time (whitetails mainly), and am now tryingbowhunting. Here is my opinion on slug guns. I have tried smooth bore shotguns and full bore slugs, a bolt action Mossbergrifle barreled gun, and now have an H & R Ultra slug hunter. The ultra slughunter is by far the best rifle I have used for these types of hunts. The last whitetail I took (on a "short range" hunt) was at an honest 150 yards, as per Leica 1200 rangefinder, and a good rest. I shoot the Winchester 12 gauge Platinums and they group great. I have not found a single pump or auto shotgun that combined with any replacement rifle barrel, shoots as well as my H & R Ultra slughunter. The good news is that you can get one of these complete rifles for just a little more than you are going to spend on that barrel upgrade, and you have a whole other rifle. I would recommend one thing though, consider the 20 guage over the 12 guage. The 12 guage is pretty stout to shoot, and unless you are hunting dinosaurs, the 20 gauge version will be plenty of rifle. Good Luck!

To answer your original question, the 18.5" barrel is quite sufficient to get the full velocity and spin out of the sabot, so extra length will not help much with a cantilever and scope/red dot. If it has iron sights, extra length will help some with with the extra sight distance. 'Follower' has a good point in that the H&R is a great gun, and I have never used more than one shot anyway.

My 14yo son uses the 870 20ga with a deer barrel and bird barrel, and it works great for switching between deer and bird season while maintaining full familiarity with the gun. I do the same thing with a Benelli Nova with a bird barrel and cantilever slug barrel. That said, just today I was coveting an H&R Ultra Slughunter in thumbhole laminate on Gunbroker for $300....

12 ga.
http://www.gunbroker.com/Auction/Vie...?Item=77331915
20 ga.
http://www.gunbroker.com/Auction/Vie...?Item=77331869

These are great guns and much lighter to carry.
I have an H&R topper in 20ga that I used for pheasant hunting 28 years ago in college here in Iowa (paid $54.99 at KMart). It's still a fun shooter.

Both of my slug guns have the shorter barrells on them. With a rifled barrell, don't worry about at thing. I have an 1100 and 1187.

http://www.midsouthshooterssupply.com/item.asp?sku=000631365H30

20" Hastings barrelwith scope mount for $145.

is this an reliable sight? how can they sell gor so much cheaper there?

Hastings has been making aftermarket barrels for most shotguns since the late 80's. I have not heard of any problems with the Hastings barrels, or the Mossberg rifled barrels for the 870 either. My son has a Remington barrel because it came with the combo. I'm not sure that a true Remington barrel is worth the added $100.

Anyone out there using a Hastings?

I have a Hastings cantilever for my Browning BPS. Had it for about 15 years and it still is a serious tack driving barrel....as far as slug guns go.

I buy from Midsouth all the time, and save a lot because they list their prices so low. I think they sell so cheaply because they don't waste their money on advertising and such, like other companies that sell good things for discount prices. They also have a minimum purchase amount, $20, or you'll get an additional fee. Purchasing in larger quantities allows them to keep prices low as well.You'll have to register there, which will only take a few minutes to complete, and then you can start saving money

I've had a hastings cantilever barrel for 10 years. Once I FINALLY took the time and shelled out the money to see what it liked....and took the time to REALLY get that sucker clean it'll shoot cloverleafs at 50yards all day long. If you consider a deer a 4" target that means it's a 300 yard gun. Nah, my point is that it's more than enough and that's about as good as I ever hear of non-fixed barrels doing.

I have a 870 in 12g

18" is no problem...actually may help with accuracy

You WILL need to buy sabot slugs to reap the benefits of a rifled barrel

You DON't need to pay the extra for 3" slugs...It's highway robbery as it is.

If you've still got good eyes and don't need the magnification look at a "reddot" scope instead of a normal scope. Bought one for my pistol and slapped here on my slug barrel for kicks...I just may buy another!!!! Low-light becomes a non issue and gun fit becomes a non issue. Find the little glowing red dot, when its in the right spot...pull the trigger! Eye doesn't have to be lined up at all.

I'd also suggest putting some swivel studs on your shotgun to attach a real sling to. Those "shotgun slings" are just a pain.