[Puccini]

In the last few range day I have had my SAI M1A fail to cycle ocationally.

I always single load at the range and last time , on the 3rd or 4th round,
the bolt stayed closed and the spent brass was left in the chamber.

This is the 2nd time this happened and I cleaned the rifle carefully after each range visit.

I especially pay attention to the gas system to be sure its cleaned and adjusted properly.

I do have the spacers in the gas system so there is no slop and I always check
the gas port for cleanliness.

 

[KurtC]

As always, the first question is:

What ammo are you using?

 

[Buelligan]

Are you sure the bolt is staying closed or is it short stroking?

After shimming the gas cylinder, did you confirm the gas port in the barrel is lined up properly with the gas cylinder?

 

[Snyper762]

Most either ammo or assembly. Pull the piston out of cylinder, use a punch to verify gas port is lined up. Put her back together properly, make sure gas plug is tight. Then quit cleaning it every range trip.

 

[Puccini]

As always, the first question is:

What ammo are you using?

_________________________________________________________________

LC match brass
41.5gr IMR4895
CCI #34 primers
Sierra 168 MK
2.800 OAL
All ammo checked with a Wilson Chamber guage

 

[Puccini]

Are you sure the bolt is staying closed or is it short stroking?

After shimming the gas cylinder, did you confirm the gas port in the barrel is lined up properly with the gas cylinder?

____________________________________________________________________

I did check the gas port and it seemed lined up

 

[Buelligan]

Does it pass the tilt tests?

Video courtesy of forum member Tonyben
[ame]https://www.youtube.com/watch?v=l8JcgLh4PI4[/ame]

 

[KurtC]

Screw your sizing die down 1/4 turn more. You have a tight chamber. You can also size the case, turn the case a bit and size again.

OR

Bump your charge up to 42 grains. While 41.5 works fine in most rifles, it is in fact a light charge meant for target shooting. You would never find factory ammo with that light a charge.

 

[rvr350]

Screw your sizing die down 1/4 turn more. You have a tight chamber. You can also size the case, turn the case a bit and size again.

OR

Bump your charge up to 42 grains. While 41.5 works fine in most rifles, it is in fact a light charge meant for target shooting. You would never find factory ammo with that light a charge.

Wow! I thought i was the only one. It seems to happen a lot to m1a owners. Either bump up the charge (if on the low side like this case), deep clean your chamber, the most obvious was to dial down the dies a quarter turn or so.

 

[DstRflMn645]

Puccini,

With the bolt open and the muzzle pointed up, you should be able to slip an empty case into the clean chamber and have it fall out from it's own weight. If it doesn't, case is not sized enough (you may need small base dies) or the chamber is very dirty.

John

 

[shooter86314]

KurtC said:

Screw your sizing die down 1/4 turn more.

Seriously? That's about .018" of additional shoulder bump. Too much, especially if the resized cases check OK in the Wilson gage.

I concur with other members above: check the integrity of the gas system. Also check for interference of the oprod. Do the tilt test without op spring. Grease properly.

 

[JayKosta]

Check how much force is needed to extract an UNFIRED round (or just a resize empty case) from the chamber. A moderate 1-finger pull on the oprod should be plenty - if it needs a really strong pull then your cases probably need to be resized a 'little' smaller.

And VERIFY by sight that the locking lugs on the bolt have rotated fully closed on the chambered case - the lugs should look the same as when bolt is closed on an empty chamber.

Jay Kosta
Endwell NY USA

 

[POLACK]

http://www.brownells.com/reloading/...adspace-tools/wilson-case-gage-prod33287.aspx

 

[Guest]

I use a RCBS small base full length resizing die. Brass sized with my Redding die sticks in the chamber.

 

[Puccini]

OK, I checked the entire rifle. Action falls open and closed by gravity as does the piston. The gas port is properly lined up. Everything is greased right.

I took one of my reloads and it slipped easily into the chamber and fell out easily.

Then I took some of my fired cases and inserted it into the chamber and it would not seat all the way in. But I assume thats not surprising. I would doubt that they would without sizing.

I cleaned the chamber carefully before I did that.

Not every round fired fails to eject but a few do. I always fire single shot with a mag in the well and the action is closed with the brass still in the chamber after firing.

I am an experienced reloader and use a recommended load for target. I noted the load in a previous post.

I'm baffled by this.

 

[Buelligan]

Is the spindle valve in the open position?

 

[KurtC]

OK, I checked the entire rifle. Action falls open and closed by gravity as does the piston. The gas port is properly lined up. Everything is greased right.

I took one of my reloads and it slipped easily into the chamber and fell out easily.

Then I took some of my fired cases and inserted it into the chamber and it would not seat all the way in. But I assume thats not surprising. I would doubt that they would without sizing.

I cleaned the chamber carefully before I did that.

Not every round fired fails to eject but a few do. I always fire single shot with a mag in the well and the action is closed with the brass still in the chamber after firing.

I am an experienced reloader and use a recommended load for target. I noted the load in a previous post.

I'm baffled by this.

See post #8

 

[Capona]

If it's still closed, you got no gas. You have a spindle closed or has a problem.
Or your reloads are really weak but I doubt they would be that weak.

OK, I checked the entire rifle. Action falls open and closed by gravity as does the piston. The gas port is properly lined up. Everything is greased right.

I took one of my reloads and it slipped easily into the chamber and fell out easily.

Then I took some of my fired cases and inserted it into the chamber and it would not seat all the way in. But I assume thats not surprising. I would doubt that they would without sizing.

I cleaned the chamber carefully before I did that.

Not every round fired fails to eject but a few do. I always fire single shot with a mag in the well and the action is closed with the brass still in the chamber after firing.

I am an experienced reloader and use a recommended load for target. I noted the load in a previous post.

I'm baffled by this.

 

[wiz1997]

I use a RCBS small base full length resizing die. Brass sized with my Redding die sticks in the chamber.

Similar results here with my 2012 Scout.

Cases re-sized with the Redding die will fit in a Wilson gauge, but will often get stuck in the chamber.

The same case will fit, but tight if given a little push, in a Sheridan Engineering gauge.

Case re-sized with a RCBS small base die will drop in and fall out of the Sheridan gauge without assistance, and has yet to get get one stuck in the chamber

The Sheridan gauge is manufactured to SAAMI chamber specs, unable to determine if the Wilson gauge is manufactured to the same specs.

Works for me.

I have the slotted Sheridan gauge just cus I like to see what is going on with the brass.

 

[Puccini]

Range test results.

I took my M1A to the range with a box of Winchester Xm80cl and every round ejected perfectly and I got a nice tight group at 100yds.

I went back to my loads and first one failed to eject. It looks like the bolt never moved.

The rifle was cleaned and checked meticulously and lubed as per the instructions. Everything ok.

I went back to my loading bench and took apart a few of my handloads.
All of then came in at 41.5 of IMR4895.

LC 68 Match Brass
41.5 IMR4895
SIE 168gr Match bullet
CCI #34 primer
Sized with an RCBS FL die
Triming and OAL OK according to the Sierra manual
All rounds checked ok using a wilson chamber guage.

The only clue I have is that when I tried to slip a fired case back into the chamber, the Winchester almost made it but the LC match brass would not.
They went all the way in except for the last 1/8 inch to 3/16 and then they got stuck.


Any ideas????