I am having issues fitting a USGI wood stock to my rifle. I have a USGI Fiberglass on it now and that fits tight. I tried two different GI birch stocks and cannot get the receiver to fit in at all. It appears that the legs of the receiver are a bit too wide. I know Fed Ord  Receivers are not to gi spec but the fiberglass stocks fit great. Anybody ever deal with this issue? Any help would be welcome. Thanks.

That's strange.

One would think that if the barreled receiver fit into a synthetic USGI stock, then the same barreled receiver would fit into a USGI wood stock as well.

Now, is it possible that the wood stocks you tried absorbed moisture at some point and swelled up, thus causing the receiver legs to bind?  Have you tried a couple of different wood stocks?

You may need to measure the dimension of the receiver legs to see how out of spec they are and make a decision as to whether it's worth having them ground down evenly to spec, or just finding a good receiver and replacing the one you have.  I just consulted The U.S. .30 Caliber Service Rifles (A Shop Manual Volumes I & II) by Jerry Kuhnhausen, and I don't see those dimensions mentioned in the text or illustrations.  Maybe I'm overlooking them.

Maybe just keep it in the USGI synthetic stock you have and call it good.  How does it shoot?  Does it pass a full function check?

Is the rifle made up of USGI parts, or are the parts Chinese?  If the parts are USGI, it may be worthwhile to replace the receiver with one that's forged and within specifications for geometry, materials, and hardness.  I have three LRB receivers and they are awesome.   I've heard very good things about JRA and Bula Defense too (next build will be with a Bula Defense).

Polytech M14 receivers are forged and USGI spec dimensions, something Springfield hasn’t been able to say for a very long time.

My rifle was built in the 1980's from a USGI parts kit and early 4000 serial range Fed Ordnance receiver so no chinese parts. USGI fiberglass stocks fit fine but I had one GI birch stock partially fit and this current stock a walnut will not even allow the receiver legs to go in. I was thinking of sanding the inside of the stock a little at a time until I get a snug fit. I don't want to mess with the receiver as the rifle runs fine and USGI Fiberglass stocks fit fine.

Sounds like a nice rifle. If it were me, (I prefer wood) I'd use the stock relieve it where it needs relieved or go through the trouble and bed it.

For what it's worth, I have one of the Federal Ordnance rifles like yours, as in all GI, and it runs fine as well.  Bought it new directly from Fed Ord about 1989.  It came in a fiberglass M14 stock, and I've had it in a couple of different wooden M14 stocks, birch and walnut.  The wood stocks fit quite a bit more snugly, as in rubber mallet tight.  Anyways, I always hated the selector cutout, and all the fake replica doodads looked even worse.  Fulton Armory offers good quality current production walnut stocks without the cutout.  I suppose Boyd makes them, not sure.  I bought one several months ago, put my own metal on it and with just a little bit of work and some Tung oil it turned out great.

Someday, I'll find a heal-marked Chinese M14 clone and buy it;  I've wanted one for a long time.  I do want to install USGI parts.

My bank account / wallet hates me.

Freds M14 stocks are available in differant grades .

Yes. You should definitely start cutting on the cheapest part.