Confusing Ithaca 51 gas port question.

[greer]

 I wish I could answer more questions than I ask but it seems to not work out that way. I have two Ithaca 51 semi auto 20 ga shotguns in the shop. One says Magnum on the reciever and has a 3" chamber the other one is 2 3/4" chamber. The magnum has started catching hulls and jamming according to the owner and when I checked the gas ports one was not drilled all the way through and the other seemed either partially blocked or was a smaller hole to begin with. By comparision, the non magnum 51 had both holes drilled through and both were bigger than the one open hole in the magnum. My question is are the model 51 magnum versions suppose to have just one port? It's odd that this gun ever functioned at all, but it seems like the customer said it had worked. When I put the non magnum barrel on the magnum it worked  fine and threw the hulls out about 5 ft. using 2 3/4 heavy game loads. That one port is not just clogged, it's not drilled all the way through the barrel wall. Just curious if this was a characteristic of the magnum version. If anyone can understand this rambling question and is familiar with the Ithaca 51 I would love to hear from you. Thanks. greer

[jedman]

 I bought my first M 51 in 1974 and still own it, I have also owned several others but they have all been 23/4 chambered models.
I have always used a small diameter drill bit and cleaned the 2 gas ports on the ones I have owned and they have been the most reliable semi autos I have evr used.
I think if the 3" chambered barrel was drilled for 2 gas ports you would at least see a sign of the second port.
The one I still own has over 30 K rounds thru it and I use to load light 12 ga. dove loads with only 7/8 OZ of shot and they fed and functioned perfectly, It is as reliable as a chisle.
Don't know if I have helped you with the problem your having but get a #55 drill or a piece of stiff wire and poke it thru the ports and that you can see it while looking into the bore.
Also check the ejector on the bolt if you need to you can sharpen the angle with a file if it's worn.
The gas ports on my barrel measure about .050 dia. Hope this helps.   Jed

[greer]

Thanks Jed. The magnum does has two holes that look identical. One of them just stops short of going all the way through. I did think the shotguns looked well made. The little piston that kicks the action back is interesting. Not much to wear out. Maybe someone out there owns a magnum.   Thanks again. greer

[gunnut69]

I've not seen a lot of the M51's but the system you're observing is also common to the 1100 Remington. I've not seen any indication of a second hole being started but not completed on an 1100 mag barrel but carbon/plastic wad fouling can indeed become a problem. Use a pipe cleaner (used on pipes to clean the hole in the stem) along with acetone to remove this fouling. I would avoid using a drill as accidental alteration of the demensions can be detrimental to the life expectancy of the shotgun. If the mag works OK with the short chambered barrel and is clean then it's likely just a fouled gas port. This systwm has made the 1100 a staple in the shotgun market.

[greer]

Thanks for the reply. I know it's probably uncommon but this port simply wasn't drilled all the way through. No wire of any kind would even start. I did use a .050 drill ,which is what I think the ports are suppose to be, and cut out metal only. The shotgun is working fine now with 2 3/4 heavy game loads. I need to put some low brass through it and see how it does. Thanks again.   greer

[gunnut69]

Greer--If the 51 operates as the 1100 does the magnum barrel should only have a single port. Drilling the other port out will allow too much pressure into the action for too long. This will likely cause damage to the gun at some point. sooner--later?? These guns were not self adjustiong as far as gas regulation was concerned. The mod you made to the 51 may be extremely dangerous. Not when fired with 2 3/4 inch round but when fired with the 3 inch rounds it is designed to handle. Other than chamber length the difference bnetween 1100 3 inch and 2 3/4 inch barrels is the 2 holes in the shorter chambered barrels.  If the second holes had been needed the gun would never have been functional not that it just started not working..

[greer]

That's the info I was trying to find. I didnt know the magnum version 1100 had a single port. I guess I'll block up the port I just opened up and get an assortment of shells to test fire. Thanks for the heads up.

[jedman]

 greer,  When I recomended using a drill bit to clean the gas ports I explained that poorly, what I needed to say is I use a drill bit between my thumb and finger as a " pick " and also turn it with my fingers to clean out the ports. I dont use a power tool to turn it or actually drill with it.
I wonder if when they made the gas piston housing if they were pre drilled partially and after being soldered to the barrel were finished drilled into the bore ?
                                                                                           Jed

[greer]

 Jed. I think thats excactly what they did. They used the same gasblock on all of them and only drilled through the barrel on one side on the magnum barrels. It was just my ignorance, no ones bad advice for sure. Most of the time I use a pipe cleaner dipped in carbon solvent. I just got in my head that the factory forgot to drill one side. I'm not sure that the gun ever functioned well with standard loads. I think thats common on shotguns designed for magnum shells. I guess I learned a few things, the hard way as usual. It would be interesting to "reblock" the port with a small screw that could be removed when you wanted to shoot standard loads but I guess that might be risky if someone down the road left it out with 3" shells or sold the gun without the screw. Thanks.       greer

[gunnut69]

I wouldn't use a screw as an adjustment. Someones sure to leave it out and any resulting damage would be your fault.. I have seen 1100's that would function light loads ell but not all. Also have seen some lightly open the existing single hole, just a very few thousandths to facilitate function with light loads. Usually if the gun is clean and properly lubed they will function albeit a bit sluggishly.

[greer]

Thanks. That's what I was thinking. I'll probably clean it good and epoxy it shut.   greer