New to me CMP special that a buddy of mine bought in 2016.
He locked it in safe and never shot it.
Sold it to me a few months back.

Tore it apart and greased everything with Lubriplate grease.
Go it to the range this weekend and ran 8 en blocs through it.
6 of the 8 en blocs it would fire and eject first round but not pick up next round out of clip.
Everytime it did this the bolt went far enough to the rear that it re-cocked the rifle.
When I pulled op rod to the rear it appeared that the follower popped up a little higher and pushed the rounds up a bit further.

I'm not new to the Garand, have another CMP Special and a 45 SA that function just fine with the same handloads.

Any ideas as to what may be causing this ?

I would say, first and easiest, lube the op rod spring and channel and try it. I know...It doesn' t make sense. The rifle is short stroking.
Edit....use grease, not oil. GAA was spec'd, it is a light low viscosity grease.

I had the same issue and traced it back to the clips I was using. They were cheap aftermarket clips that had significantly egregious Parkerizing on them. I polished them up, inside and out, with gray 3M pads and lightly oiled them. Now the gun feeds lickity split. Of course no such issue ever occurred when using honest-to-god GI clips.

What kinda ammunition?

Handloads Viking

Have no issues with them feeding in either of my other 2 rifles

I've also got a bunch of HXP and PVRI M2 ball I guess i need to try as well

I would take it apart again and make sure everything is assembled correct. I would replace the recoil spring since it provides the power to raise the cartridge follower.

Yeah, I can swap one out of one of my other rifles easy enough.
Good idea, thanks.

Might start by changing the operating spring. Then ammunition.

Interesting so far. Does enlightenment follow?

Did not get to the range this weekend, will keep you posted.

Although greasing op spring and channel was met here with crickets...that's ok, it's not explained fully in FM 23-5 either. But there is one other remote possibility, and that is the gas plug relief valve could be leaking. National Match conditioned rifles replace the valved plug with a solid plug, just for that reason. This, of course assumes you are not firing rifle grenades.

I've fed my thumb to a few Garands.

What is your handload?

If HXP ammo functions ok your load may be just slightly too light for that rifle and its tolerances. The rifle may loosen up with more use and work with your load. My Special is really tight.

I would be sure to grease the grooves on the receiver legs that guide the follower. The way I look at is, if there are wear marks at any point on a part, it gets a dab of grease, at least to start with.

Do you always load the enblocs with the top round on the left or right. If so, try the other way.

46.5 grs H4895
GI Brass
CCI 34
168 Hornady BTSP

Top round on the right

That load should work.
I too prefer to load the enblocs with the top round on the right. Seems to be easier on the thumb.

That always works for my Garand.

I repair a lot of Garands for ceremonial use. If it did this for different clips then do this. First, make sure the gas cylinder screw is tight, Then (even though this should not be a problem with an in spec gas cylinder lock) make sure the gas cylinder is on correctly. If you cannot move the front handguard the cylinder may be set too far back and partially blocking the gas port. Then Try a new op rod spring. If that fails measure the tip of the op rod. Needs to be at least .525 in all directions. If that's ok, try one of the gas cylinders from one of your other rifles. If that does not work, replace the follower arm. Next the bullet guide. Next follower rod. Process of elimination. Believe it or not the CMP does send out rifles occasionally with bad parts and rifles assembled incorrectly..

We have a winner.
Swapped it w another rifle yesterday and it ran like a singer sowing machine.

Glad you have it fixed.

CMP refinished guns are known for having a parkerizing similar to 220 grit sanding paper. I have had to single load a bunch of rounds before they will load from a clip. I wonder if polishing the contact surfaces with steel wool might not work.

Cool thing about Garands they are pretty easy to fix function issues. Most of the time it is just a spring.

Glad you figured it out. First steps in repairing a Garand issue: check correct assembly, grease/oil, springs. Most issues will be resolved with these steps.