Function test foul up?

[218bee]

Just was function testing a freshly assembled rifle with some USGI dummy rounds in SA enblocs....Pushed the full enbloc in, bottomed out nicely, then a gentle shove and the bolt slammed home..as fast as I could, I stripped off all 8 rounds, but every time, the last (8th) round be nicely extracted, but would get hung up loosely in the very top of the receiver...I would then remove the last round, and carefully push the EMPTY enbloc back down and close the bolt fully...Then, I'd strip the oprod back fast and....ping!! the enbloc would nicely eject about a foot high and away...
It almost seems like the enbloc is too far up and is catching the rim of the last round, preventing it from ejecting..


Just for a control, I took out a 5.9 NM rifle that I know runs like a Swiss watch...It did the same thing....

Is this a viable way to test function or do you need the hard blow-back of the live round going off?

Scratching my head here...

218bee

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[U.S.G.I.]

You can use a timing block to test functions.

The relationship among the bullet guide fulcrum, the op rod catch, op rod hooks and clip latch is complex. If it is not correct, a loaded clip will either not release the op rod catch at all when inserted and pressed into the magazine well, release the catch only when excessive force is applied, or release the catch prematurely, causing a mess & possible injury as the bolt is propelled forward under the force of the op rod spring.

The timing gauge gives a precise measurement of the “timing,” that is, when in the process of inserting a clip the op rod catch is released. It is much more convenient than using a loaded clip of dummies (this testing should never be done with live ammo!), and gives a quantitative measure of the release point. If the release point is not within spec, you begin the corrective process by replacing the bullet guide.

I keep a timing gauge in my "gunshow kit" along with my muzzle wear gauge & etc.

Walt Kuleck

[218bee]

I don't have a timing block

[Maury Krupp]

Sometimes when I cycle a clip of dummies the same thing happens to me.

Sometimes it doesn't.

All in rifles I know function properly with live ammo.

I don't think I can always manually replicate what happens with live ammo well enough.

My main concerns in a dummy function check are timing (ie, bolt release and clip latching), chambering, and sear/trigger handoff/disconnect.

Maury

[218bee]

Thanks Maury...

I have a warm/fuzzy feeling everything's OK...All parts guaged out OK and are in excellent shape..Headspace is on the money as well...One thing I overlooked is lubrication...I assembled it and forgot to grease the proper points..I don't think this will answer my question I posed, but it needs to get done before range time...

With the full enbloc fully inserted down, the oprod needs a slight bump to get things going..I'm comfortable with this, as 3/4 of my Garands do this....The extractor/ejectors are apparently working as well.....

Can you please elaborate on the function test items you mentioned, ie. " timing (ie, bolt release and clip latching), chambering, and sear/trigger handoff/disconnect."

I'm assuming "bolt releasing & cliplatching" are OK, here, albeit a slight bump needed....chambering seems OK too....

I'm a bit unclear as to the sear/trigger handoff/disconnect, though....Is there a standard function test for this?

Many thanks

218bee

[Maury Krupp]

With the full enbloc fully inserted down, the oprod needs a slight bump to get things going..
Ops Normal. Depends on a lot of stuff like clip tension, cartridge case friction, op rod spring strength, etc.

What you're really concerned with is "Does the Clip Latch engage and the Op Rod Catch release at about the same time?" If everything's working right they should. You shouldn't have to jam the clip way down to get the clip latch to engage nor should the bolt come forward (op rod catch release) before the clip's down far enough so the bolt can strip off the top round.

It's educational to take the Receiver Group out of the Stock then load a clip of dummies. Watch how as the follower goes down the Op Rod Catch starts to pivot until it releases while the arm on it simultaneously stops pushing on the Clip Latch allowing it to engage the clip.

I'm a bit unclear as to the sear/trigger handoff/disconnect, though....Is there a standard function test for this?

1. Ensure weapon is unloaded
2. Cycle Bolt to cock Hammer
3. Engage Safety
4. Squeeze Trigger - Hammer SHOULD NOT FALL
5. Release Trigger
6. Disengage Safety
7. Squeeze Trigger and hold back - HAMMER SHOULD FALL
8. While holding Trigger to the rear cycle Bolt to cock Hammer
9. Release Trigger - HEAR "CLICK" as Hammer is handed off from Sear to Trigger
10. Squeeze Trigger - Hammer SHOULD FALL

Also educational to do this with the Trigger Group out of the weapon. Pad the inside front of the Trigger Housing so it and the Hammer don't get beaten up. Then watch how the trigger and sear work with the two sets of hooks on the hammer to ensure semi-auto operation as well as produce a two-stage trigger.

I think it's all pretty neat and gives you a better appreciation for Mr Garand's genius

Maury