Changing pistons in 1100 Competition Master?

[DHart]

I bought the 1100CM used and here are the piston parts on the gun. I'm a bit confused by the diagrams I've found for the 1100 as it looks like the three parts are put into the gun separately and parts on the diagrams seem like they might differ from what I've got.

Here are the three parts

And from what I can tell, the smaller metal ring should be inserted onto the larger metal ring like this:

With the rubber o-ring sitting ahead toward the muzzle end.

Is this correct?

The gun, in a clean condition, won't cycle game loads (Winchester Super X 2 3/4" 3.25 dr eq., 1 oz),

but can cycle Remington OO Buckshot 2 3/4" 3.75 dr. eq.

DO I need to open up the gas ports so the gun will cycle more reliably? Sure appreciate your help, as I'd really like this gun to be stone reliable.

Edited December 27, 2008 by DHart

[RH45]

I'd have to break down my gun to look at the piston. I'm old and forgetfull and don't remember for sure, but, yes, the rubber o-ring is the last to go on. It should fit in the little groove at the end of your magazine tube.

I've never shot 1 oz. loads, but, when I got my CM, even though it worked o.k. with AA 1 1/8 oz, 3 dram, heavy target loads, it was "iffy" with reduced recoil slugs.

I opened the ports a little, and now it runs the light, target loads (1 1/8 oz, 2 3/4 dram) and the reduced recoil slugs without any problems.

[Dan Sierpina]

The thin ring with the inside bevel goes against the cylinder with the action bars, the larger metal part goes next with the bevel mating to the first part. The O ring goes last.

[EkuJustice]

You got their new 1 piece design(actually 2 pieces that snap together). That goes on first with the flat side toward the back of the gun, then the o-ring goes on and sits it the little groove on the mag tube. Make sure the slots in the 2 that snap together are 180 across from eachother and not together. I always liked the older 2 piece design for having the gun cycle lighter loads. I am not sure if Remingon makes them but there is someone else making them and can be found at brownells

[elynch2007]

If you had the 1100 all the way apart, the recoil spring that goes down through the stock can hang in the sleeve at the top. This is the same as adding 1/4 to 1/2 inch to the spring length or changing to a heavy spring. Target loads can not push it back enough to eject the shell. To check to see if this is it, remove the stock and the pin from the rear to let the spring tenision off and rotate and wigle the spring and see if it will move forward a little.

[GentlemanJim]

Thats the newer 1187 style piston assm

I prefer the old two piece design

But it may just be an ammo issue

The cheaper stuff Wallmart...dont work too well

I shoot the remington gun club stuff.

Jim

[Nik Habicht]

I'll add this --- once you've checked the recoil spring, before you reassemble the gun totally, coat the mag tube where the piston rides with some Mobil 1 oil. Remmy's seem to run better wet (really wet) and it makes cleaning a breeze, because you can wipe the gunk off with a shop rag.....

[DHart]

Thank you everyone for the replies... I'm going to look into finding the older style rings to try them out before I open the gas ports any. I will be wanting to run some lighter stuff along with 3 3/4 dr. 00 Buckshot.

And I'll definitely check that the recoil spring is in good shape and lubed.

Is it better to have one 1100 set up for the light stuff at the range, clays and such and a different 1100 dedicated for the buckshot for home defense? Or can I do it all with the same gun by switching out the piston rings and, possibly, opening a gas port just a smidge?

[Jaxshooter]

I don't usually lube the recoil spring in the stock because it picks up dirt etc. If you do lube it use something that will not dry out or get hard. Something like Break Free or Kroil.

[elynch2007]

unless this a 3 1/2 inch gun it should run light to extra heavy loads without opening up the gas port or doing anything else to it. Did the gun run ok when you purchased it and does it still have the factory barrel still on it? Can you lock the bolt back with one finger or does it take alot of pull to get it to lock back?

There used to be a troubleshooting guide on the Remington website, call or e-mail their techs on their support line. They used to be good at answering these type of questions. I would do this before drilling.

[b2alphaplease]

A friend had a CM 1100 that would not run anything less than 3.25 Dram loads when new. It was oiled liberally and shot several hundred rounds to break it in. Still it would not shoot anything less than a 3 Dram load reliably. Then one day at a 3-G match this friend stepped up on a stage and commenced to firing some VERY LOUD loads.

The squad started to closely watch the shooter (who is left handed) and noticed that every time a shot was fired we could see a flame from the ejection port fly out past the right ear of the shooter.

Someone asked what was going on and I guessed that the shooter was using 3" shells.

ShooterSteve then stated that could not be the case since the CM1100 only has a 2.75 chamber.

About this time the shooter finished the stage and we verified that he was using 3" shells in the 2.75" CM1100.

We then examined the gun closely to see if anything came loose. It appeared to be okay. After that the gun would run any load, even the lightest load. DON'T TRY THIS AT HOME KIDS !!!

Today the gun runs fine except for the occasional broken pin. I'm sure that is not related to any previous use.

But seriously, make sure the gun is oiled well, put the splits in the rings 180 degrees apart and spray the gas ports out with disk brake cleaner when you have it apart.

[jobob]

I've always thought that Remmys should be run wet too. A friend of mine recently told me that Remmys should be fairly dry. He said that heavy oil attracts and holds fouling. His recommendation is to just run an oily rag over the tube before reassembly. This friend is very knowledgeable about shotguns. He use to be a top shooter on the trap circuit and was sponsored by Browning. So, when he tells me something about shotguns, I listen. I haven't tried his recommendation yet, but when I clean my shotguns, sometime this winter, I may try it. Shoot a couple of matches and see what happens. I just checked the 1100 manual at the Remington website and they recommentd only light lube too. may have to change my ways.

[Les Snyder]

for heavy loads (slugs) there is a heavy duty action bar (the part the piston moves) that is full diameter rather than stepped down in the middle. There used to be two different bolt buffers (one white, and one black) for the magnum ... i think only the black one available now... for reliable 3gun if the barrel is 21 inches or about you probably want to open up the gas port a couple of number drill sizes if not close .125 inch. if you have an 1187 and a cut down 21 inch barrel with the "C" clip gas relief gizmo, have someone weld those ports closed and make it into an 1100 barrel. The 1187 slug barrel doesn't have the clip giz.

regards

Les

ps i bought the bullet several years ago and bought an M1S90 field