The "Tilt Test". What it is and why we do it... - M14 Forum

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The "Tilt Test". What it is and why we do it...

This is a discussion on The "Tilt Test". What it is and why we do it... within the Reference forums, part of the M14 M1A Forum category; Many times M14/M1A owners come here with a range of cycling, extracting and feeding issues. Symptoms can include: -Short stroking/no stroking of the action -Failure ...


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Old April 20th, 2009, 06:24 PM   #1
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Lightbulb The "Tilt Test". What it is and why we do it...

Many times M14/M1A owners come here with a range of cycling, extracting and feeding issues.

Symptoms can include:
-Short stroking/no stroking of the action
-Failure to feed a new round from the magazine
-Failure to extract the old round from the chamber
-Failure to eject the old round from the chamber

For the rifle to cycle, extract, eject and feed the gas system must be in a working order and the action must be smooth throughout its range of travel. One of the first tests that we suggest when one of these problems occurs is called the "Tilt Test". There are two types of tilt tests. One checks the movement of the op-rod and bolt through their ranges of travel and the other tilt test verifies the freedom of movement of the gas piston.

The action tilt test:
To test the op-rod and bolt for their freedom of movement, you first need to remove the barrelled action from the stock. Next, remove the op-rod spring and op-rod spring guide. From here, you can either perform the tilt test with the action out of the stock or in the stock, being held in by hand or by locking the trigger group in without the spring and guide (Note: if you leave the trigger group in the rifle, then engage the safety. This will pull the hammer out of the way of the bolt path so that it may travel all the way back without resistance). I prefer to perform the tilt test in and out of the stock to see if there is a difference. If the stock is causing binding, you will be able to spot it if the action is in the stock.

There should now be nothing to keep the op-rod from sliding back and forth under its own weight. Now, tilt the muzzle up at about a 30 degree angle. A good action should allow the op-rod's own weight to slide back, unlock the bolt and slide all the way to the rear, taking the bolt with it.


Notice the trigger group and op-rod spring/guie is out and on the table. This is the maximum angle my rifle needs to induce full movement

Next, tilt the rifle muzzle down about 30 degrees. The weight of the op-rod should bring the bolt forward and fully lock the lugs into the receiver. The op-rod should contact the gas piston tail.



If there is binding, note the beginning or trouble spot where the binding occurs and inspect your op-rod channel, bolt tracks, op-rod alignment to the receiver and the op-rod fit through the op-rod guide.


The piston tilt test:
This test can be performed without ever removing the action from the stock or the op-rod spring and spring guide. All you need to do is lock the bolt to the rear and tilt the muzzle up at about a 60 degree angle. You should be able to hear the gas piston slide back and bottom out in the gas cylinder with the tail of the piston fully protruding.



Now tilt the muzzle down at about a 60 degree angle and you should hear the piston fall forward and bottom out against the gas plug.


The total time it should take for each movement is about a second and a half or less. Some times the rifle simply needs a slight tap on the butt of the stock to break the piston loose. From there, it should slide free. If you still have no movement, cycle the action by hand a few times (don't let the action slam home though) and see of the piston loosens.

If it still won't move, then you may want to consider cleaning your gas system and testing your rifle out at the range to see if the problem persists.

If your rifle passes all these tests, then we can move on to diagnose other things like gas port alignments, bad extractors and such. These tests help us eliminate variables that cause troublesome errors.


Last edited by Lash; April 9th, 2011 at 10:46 PM. Reason: updated per tonyben's request
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Old April 20th, 2009, 08:08 PM   #2
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Excellent post, great info for the fng's and reminder for us older folks

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Old April 20th, 2009, 10:57 PM   #3
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Good post, thanks !!

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Old April 21st, 2009, 04:45 PM   #4
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Well done, tonyben. Thanks for another good one.

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Old April 23rd, 2009, 09:36 AM   #5
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Excellent how to, very clear, concise, and well written!

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Old April 23rd, 2009, 09:48 AM   #6
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Thanks gentlemen.

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Old April 24th, 2009, 05:59 PM   #7
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Nice job there, sir.

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Old April 26th, 2009, 10:15 AM   #8
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This should be a sticky!

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Old April 26th, 2009, 05:22 PM   #9
 
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I have a used, but unfired, SA Loaded, the piston will only slide back and forth a couple times then it always sticks back. I take it out wipe it off and it will be okay for a couple slides then it will stick. There is no carbon, but a some oil in the piston sleeve, I cleaned it out as much as possible. I need to shoot it tomorrow to test it out since it's used. Minor sticking like this won't damage the rifle will it? I cleaned it up and lubed it already, (not the piston), my plan was to break in the barrel tomorrow then tear it down and clean it up good.
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Old April 26th, 2009, 05:29 PM   #10
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Nope, no damage will result. It should be okay. I prefer to run the system completely dry as the oil can collect carbon and form a paste. While on the range, if you encounter a sticky piston, you can add a drop or 2 of hoppe's oil to the vent hole at the bottom of the gas cylinder to loosen it up for the day and clean it all out when you are done.

Just to be clear, during routine maintenance, the inside of the gas cylinder should be kept dry

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Old April 27th, 2009, 08:25 PM   #11
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Tony - thank you very much!

I've got a brand new Springfield with a synthetic stock. It passes the "action tilt test" fine detached from the stock. However, it fails with the action in the stock - friction starts with the bolt about 1/2 way back and there's another increase in friction about 1" before the bolt is all the way back. The operating rod is rubbing on the inside edge of the stock. The contact point is on the curved portion of the operating rod where it drops down toward the cylindrical portion (hope that makes sense). I can see traces of the friction points both on the op rod and on the stock.

I haven't fired this rifle yet - still learning as much as I can until I can get to the range. Should I fire the rifle first or work on the inside edge of the stock opening until we pass the "action tilt test"?

BTW when I say "it fails", I mean I can hold the rifle fully vertical and still have to pull back on the operating rod to get the bolt all the way back.

Any advice will be greatly appreciated.

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Old April 28th, 2009, 04:30 AM   #12
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Take some sand paper to the stock where the friction point is. The rifle is safe to shoot, but you may have cycling errors of some type. What would be interesting to see is if you went to the range, fired a mag and noted accuracy/cycling status with a friction point and then sand the contact area until you have relief and note any change in accuracy or cycling.

I am happy to see that this has helped you identify a potential problem before you even hit the range.

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Old April 28th, 2009, 04:48 AM   #13
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Forgot to mention, if you left your trigger group in the rifle, then make sure the safety is on. This will lower the hammer enough to let the bolt slide all the way back without friction just before the bolt reaches it's end of travel.

I will edit the first post to note this.

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Old April 28th, 2009, 07:15 AM   #14
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Quote:
Originally Posted by tonyben View Post
Forgot to mention, if you left your trigger group in the rifle, then make sure the safety is on. This will lower the hammer enough to let the bolt slide all the way back without friction just before the bolt reaches it's end of travel.

I will edit the first post to note this.
What if there still is substantial friction between the bottom of the bolt and the top of the hammer even with the safety on? With the trigger group installed and the safety on, the bolt stops when it hits the forward edge of the hammer. Pulling the op rod backward, I can see the hammer being pushed downward (toward the trigger pivot) by the bolt. The hammer is cocked at this point, so is this supposed to happen?

Thanks for any and all advice.

P.S. I already took care of the friction with the stock. Sorry for not going to the range first and then fixing it - it just wasn't right.

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Old April 28th, 2009, 07:26 AM   #15
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On mine (keep in mind, I have only had one), the hammer moves out of the way when the safety is on. Maybe someone else can chime in and tell us if their hammer still contacts the bolt with the safety on.

I wouldn't be concerned about it though. As long as it is functioning okay, then I would consider it a non-issue.


Now hit the range!!

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