Yes, I know, the only real Garand is in 30/06, thanks.

I bought a .308 model from CMP, and at the range last week, it was occasionally short cycling with some .308 ammo.

It would fire, get rid of the fired case, but apparently the bolt was not coming back far enough to pick up a loaded round, as the chamber would be empty.

This was with ZQI 147 grain ammo, and one type of German 147 grain ammo.  Another German brand worked fine (147 grain also).

I had been trying to fine tune an adjustable gas cylinder, gave up fiddling with that, put in the fixed one, and while slightly better, still had failures to load - not all the time, but in batches - once clip would be OK, another boom - click -boom -click.

So a couple of questions.  Feel free to answer any or all:

Am I correct in saying that this problem is most likely a result of not the bolt not going back far enought to pick up a fresh round (no other issues or damage to parts was noticed).
If so, is the ammo just not powerful enought to reliably cycle the action?
Does the factory gas cylinder direct more gas than an adjustable one, even with the adustable one screwed down all the way?
Is this a common issue with .308 Garands?  As the rest of the rifle is set up for 30/06 (besides the barrel), are .308 Garands hungry for gas, and thus need more powerful ammo than NATO style 147 grain loads?
Am I correct in saying that commerical .308 round generally are more powerful than NATO 7.62 rounds, and thus would be more likely to cycle the action 100%?

I'll take it out next time and fire some .308 rounds from Federal from it - just wanted some insight as to what may be happening so I can focus in on what needs to change.

As usual, the M1 gets plenty of looks and complements from admirers at the range, more so than even when I'm blasting away with 3000 bucks of LWRC/Leupold/Surefire supressor AR combos.  

Thanks,

Several things to check:

1. Is the rifle properly greased?
2. Is the op rod binding anywhere on the stock? If it won't pass the tilt test, that's the likely cause.  Then you will have to relieve a little wood where it binds.
3. You should always start with a new operating rod spring. They cost a few bucks, so get a new one.
4. Do you have a tight gas plug?
5. If the gas plug, (poppet valve) is tight, is your gas cylinder in spec?  Take it to a machine shop and get it properly measured.  The bore should measure between .528" and .532".
6. Check the piston on your op-rod.  It should measure around .526" and it should be round.  Again take it to a machine shop.
7. Get the op rod tab measured.  If the tab is oversized it can bind and short stroking can result. The width of the tab is a maximum of 0.320". But you can tell by feel.  If it feels tight, you will know.
8. If everything else is good, you may have a problem with the gas port on your barrel. And right now, I can't remember the correct gas port diameter.

I'd just call CMP and they should fix it.

Among my many M1s, three are 7.62/.308s: two "full size" Garands and one 18" "Tanker."  All run like scalded dogs. Never had a functional problem, and that's with all manner of factory .308  and old surplus 7.62 ammo from the '80s. Now, on the Tanker, I do swap-in a new op rod spring every 600-800 rds (a Wolff XP Tanker op rod sprg).

I found that, for some reason, the full size .308 M1s prefer the current-production IMI .308 ball ammo to anything else. Not sure why that is, but I've zero-ed both rifles at 300yds with it.

.308 Garand barrels have a larger gas port than those of the 30-06.  .308 gas port size is .089"(#43 drill bit size).  If a #43 drill bit won't go into the hole, then the gas port is too small.  That is the first and easiest thing to check.  Someone may have accidently grabbed a barrel that was to be chambered for 30-06 and chambered it for .308.
I agree with a previous poster.  I have 3 .308 Garands(2 Tankers and one Navy) and they all run just fine.

FWIW, the gas port size on a 30-06 barrel is .079"( a hair larger than a #47 drill bit).

This x87

It could be a gas system issue or a weak recoil spring. If the spring is weak it will not push the follower up fast enough for the bolt to pick up the next round.

I would look at the ammo first zqi isn't that great.

Had same problem with mine( not a cmp)Would only function  with winchester white box 100 percent.  I feel for you.  I ditched it and got something else after 6 months

Then it was likely a gas port issue....my 7.62 guns runs flawlessly once they are "in spec".

Thanks for the respones.

I'll take a look at the gas ports.  I assume to get to them, I'll have to take off the gas cyclinder, is that correct?  

I've not done that before - the CMP manual says to tap the bayonnet lug with a dowel rod and hammer - is that the best method?

I though about getting another op spring as well - though if it's worn, wouldn't that make the bolt more likely to go back far enought to pick up a round, as there's less resistance to it going back.  I know the same spring also pushes up the rounds, so does a worn spring make the follower unable to keep up with the bolt cycle?

Also, what's a good place to pick up a spring - Browells or Numeric?  And what's the factory spring power, for a .308 if that's any different.

Go to Orion 7 and get an op rod spring.  That's to "Go To" place for op rod springs that many recommend.  Op rod spring should not be shorter than 19 1/2".  But a new one is always good.
You can use a 1/4" drive ratchet to remove the gas plug, then unscrew the gas cylinder lock, and the gas cylinder should just slide off.  It may be tight, and if so, it can be tapped off.  One thing I didn't mention earlier.  Once the plug(gas cylinder lock screw) and gas cylinder is off, look inside the gas cylinder.  There will be a cut out in the top.  You should be able to see the gas port, all of the gas port, in the cut out.  If you can't see all of it, then move the gas cylinder forwards or backwards until the port is completely visible. Having a block gas port can also cause short stroking.
When you replace the gas cylinder and lock, the optimal position is for the lock to stop at the "6 o'clock" position.  However, that rarely happens.  If it comes up short by more than 1/8 - 1/4 turn, don't force it.  If it goes past a bit, just back it up to 6 o'clock.  The hand guard can be a bit loose with no problems.