I have a Remington Marine Magnum that I carry at work.  It shoots about a 1 1/2" group at 50 yards with Remington slugs.  It shoots about a 4" group at 50 yards with Brenneke slugs.
Unfortunately, it shoots about a 15" group at 50 yards with Federal Tactical slugs and those are the ones that I am required to carry at work.
I have lengthened the forcing cone and polished the entire barrel interior.  I'm very impressed with the Remington slug groups but I need some ideas on how to improve the accuracy with the Federal slugs.
Thanks

EDP, Well it looks like another Department with a one size answer to a complicated question. As you know all shotguns do not like the same ammo including some in the same model.

Are you shooting slugs only? If so experimenting with fully rifled barrel or maybe a rifled choke tube. Do you know anyone that you can borrow a rifled barrel or a barrel that accepts screw in chokes?

Do you want to shoot buckshot from the same gun? Again borrow a barrel with screw in chokes and try different chokes until you find one that shoots the Federal slugs and buckshot well.

Check with a gunsmith, maybe Hadaway will jump in, you could get your barrel threaded for chokes, still no guarantee that it will shoot the Federals well.

Well that all I got for you. Don't feel bad my Department gives us guns that you can't pull the trigger on, very frustrating. MIKE.

We have to carry Remington 870 shotguns.  Mine is a Marine Magnum and so it doesn't have screw-in chokes unless I have them installed.
We have to carry Federal Tactical 00 buck in the magazine but can carry Federal Tactical slugs in the sidesaddle or elsewhere if we qualify with 100% on our slugs at qualifications.
We can then transition to the slugs if we need to make a longer shot than is capable with the buckshot.   My gun shoots good with the buckshot but hates these Federal Tactical slugs.

P.S.  Mike, what do you mean that you have guns that you can't pull the trigger on?

EDP, We have Glock 19's that the department changed the trigger three times until most have a 12-14 pound trigger pull. MIKE.

I have some federal tactical slugs, but have not shot them yet.  I am wondering now if the reduced load is your problem.  That is too big a variation from the other groups you shot.

Is everybody else shooting good groups with these slugs at 50 yards?

Were any of your shots high on the target compared to your point of aim or were they all low?  As I recall, on the box for the Federal loads it does not have the dram equivalent, so I was not able to figure out how much powder is in these loads.

I have a 20" 870 cylinder bore barrel that is ported, I can't imagine that fixing your problem, but you are welcome to try my barrel if we live close enough to meet up on a Saturday. Porting is the only thing you have not tired yet.

It makes you wonder if it is the marine grade barrel coupled with lower velocity slugs?

Zoub, most of the guns seem to be shooting these slugs okay but very few guns shoot them great.  The main reason that we carry the Federal Tactical ammo is that it's the cheapest reduced-recoil ammo out there.  The Remington reduced-recoil slugs and 8-pellet buckshot seem to shoot significantly better through just about every gun that we've tried.  The problem is that Remington is very proud of their reduced-recoil ammo ($$$).  
Through the years, I've always had guns that liked certain brands of ammo better than others.  Up until now, the guns that I've carried at work have worked fine with the Federal ammo.  This particular gun just seems to really dislike the one brand of ammo that I HAVE to use and it's very disappointing.
Yes, the reduced-recoil slugs did hit slightly lower at 50 yards than the regular slugs.  It was difficult to say excatly how much lower because of the terrible grouping.

I would hazard a guess that there is some difference in the construction of the slugs themselves or the way the shell is loaded that is cousing your problem. Try miking some Remington and Federal slugs as well as checking for hardness. Disect a couple of rounds and see what you find. IIRC, Federal still uses paper wads, but I am unsure if Remington uses a plastic shot cup or not. ???

It seems like a bad idea to pay to have the barrel threaded and buy a 5" rifled slug tube just to find out it may not work either.

You have to buy another 870 OR....you could put a regular barrel on your gun, that likes the slugs but it would look uglier than you know what on that marine model.  Then again 2 tone is in and you could be ahead of your time by doing it.  Still, people would make fun of you and your 2 tone pimp mobile shotgun.

Fresh idea!  

I have never done this but have said I am going to for the last ten years.  When it comes to rifled slug barrels, the real accuracy nuts pin their barrel to the receiver.  Basically drill and tap the receiver, and a mathcing spot on the barrel so it ALWAYS lines up the same way, it becomes much more ridgid, taking play out of the barrel.  Logically this adds accuracy.

I have not done it, seen it, handled it or have any technical specifics, but it might be something you could try, that is not too expensive.

Z, I have a Remington 12 gauge 870 Wingmaster with a fully rifled barrel that I had pinned. It does not shoot that much better than before, just a pain in the ass to clean now.  But the real issue is even if the pinning did tighten up the group that does not mean it would would shoot to point of aim with the bead sight. He might still have to put on some sort of sight to move the group to the point of aim. Does that make sense or do I have to get some sleep? MIKE.

I think Mike is right, choke tubes are probably your best bet. A rifled tube will probably do the trick. I mean it can't get much worse.

I can't think of any other solution. Lengthening the forcing cone and polishing the bore will reduce velocity somewhat, but that shouldn't cause 15" groups.

Give me a call if you can't get it worked out. I'll study on this a day or two.

Good Luck,
Lee
www.thearmsroom.com

Boy, I'm getting a lot of mileage out of this link.

www.gun-tests.com/performance/dec97gggupgrade.html

I don't think choke tubes will fit in my gun because the barrel is ported right up to the Trijicon tritium front sight.  It has a Trijicon rear tritium ghost-ring sight.  A rifled tube wouldn't work anyway since the gun also has to be able to shoot 00 buck accurately.  
I might try switching the barrel if nothing else seems to work.  I just really love this gun and it shoots other slugs well, just not those Damn Federal reduced-recoil slugs that we have to carry.
If someone will post a pic for me.  I will send you a picture of the gun to show it all tricked out for work as a patrol shotgun.  I think you'll then understand why I don't want to give it up.

I have no experience with other makes, but the 5" tube on a BPS I tested with a 6x weaver rifle scope grouped 1-1/2 inches at 100 yards with the worst damn trigger for a scope one could imagine.  It seems most shotgun triggers feel like they are made from crushed beer cans compared to a crisp 2 stage on an AR.  The tubes may work. The only other thing I can think of is perhaps a Browning Boss type device.  It really does work on my A-bolt .300 wichester.