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-   -   Barreled Receiver will not pass tilt test (http://forums.thecmp.org/showthread.php?t=275637)

krdomingue 01-24-2021 10:42 PM

Barreled Receiver will not pass tilt test
 
Looking for advice before I give up and part it out.

I purchased an HRA barrel receiver in Feb 2016 from somebody on this form who had purchased it from the CMP years prior. It sat around for a while before I collected all the parts to put it together. After I finally got around to it, it will not pass the tilt test with the lower band installed. I have tried with a couple different lower bands including a brand new one off a CMP stock set. I have tried several different op-rods to include a couple off perfectly functioning rifles. I have also tried it will three different gas cylinders.

No lower band, it passes the tilt test. With lower band it fails.

I am hoping I am missing something obvious, but I am beginning to believe the barrel might be slightly bent.

Suggestions?

Jakeroub 01-24-2021 10:45 PM

Have you checked that the barrel is not over or under indexed?

krdomingue 01-24-2021 10:48 PM

Quote:

Originally Posted by Jakeroub (Post 2008126)
Have you checked that the barrel is not over or under indexed?

No, (and I will now) but it is rubbing against the bottom of band no the side.

lapriester 01-25-2021 12:50 AM

Bent barrel is really the only thing it could be. Find a wooden dowel that freely but barely fits into the bore. It should slide without resistance from the muzzle to the breech. If it binds along the way the barrel is bent. Or and much less likely, the barrel is cross threaded into the receiver somehow.

ceresco 01-25-2021 12:05 PM

Interesting situation.... a wooden dowel isn't exactly a precision gauge. I would be more comfortable with a selected rod from a Harbor Freight set of alignment rods if I didn't have the proper ordinance straightness gauge . Good Shooting. ...

milprileb 01-25-2021 12:32 PM

Well...try all your remedies but if nothing sorts out ...Chuck In Denver is who I'd contact and have him sort it out.

No offense but here you are and it could be something you are not trained to sort out. No shame in that

krdomingue 01-25-2021 12:46 PM

Quote:

Originally Posted by milprileb (Post 2008267)
Well...try all your remedies but if nothing sorts out ...Chuck In Denver is who I'd contact and have him sort it out.

No offense but here you are and it could be something you are not trained to sort out. No shame in that


I have been through the Advance Maintenance Course and don't consider myself a complete novice, but I wouldn't be asking for advise if I thought I knew it all, so no offense taken.

Vos Parate 01-25-2021 01:45 PM

Have you tried a different operating rod?

krdomingue 01-25-2021 02:00 PM

Quote:

Originally Posted by Vos Parate (Post 2008289)
Have you tried a different operating rod?

Several.

glindes 01-25-2021 02:49 PM

Is the rear handguard installed, that is, is the lower band on backwards for this test by any chance?

krdomingue 01-25-2021 03:17 PM

I have done it both ways, but no the lower band is not backwards. The pin will only if it is in the right direction. A good thought though.

LavaTech 01-25-2021 05:21 PM

If you had radius or V-blocks, a dial indicator and hydraulic press it'd take all of 2-3 minutes to check and/or straighten the barrel by indicator alone. It is really simple to do. It's just a tool shortage problem!:cry:

krdomingue 01-25-2021 05:30 PM

Quote:

Originally Posted by LavaTech (Post 2008374)
If you had radius or V-blocks, a dial indicator and hydraulic press it'd take all of 2-3 minutes to check and/or straighten the barrel by indicator alone. It is really simple to do. It's just a tool shortage problem!:cry:

Sounds simple enough, but not one I would try on my own. Tools or no tools.

rekkert 01-25-2021 06:47 PM

you can check barrel alignment with 2 3/8th rods like the CMP does,
remove front and rear sights then balance the rods like at 19:43 in the vid
check the alingnment from front to rear
https://www.youtube.com/watch?v=5pxH...ature=youtu.be

lapriester 01-25-2021 09:43 PM

Quote:

Originally Posted by rekkert (Post 2008406)
you can check barrel alignment with 2 3/8th rods like the CMP does,
remove front and rear sights then balance the rods like at 19:43 in the vid
check the alingnment from front to rear
https://www.youtube.com/watch?v=5pxH...ature=youtu.be

It would drag on the side of the band if incorrectly indexed. The OP indicated that's not the case.

ceresco 01-26-2021 12:07 PM

I would not straighten a barrel using the exterior dimension. The bore does not necessarily line up with the exterior. The standard is to optically check straightness and go from there. Anyone can use the optical method. It is actually pretty easy. You simply view a lattice through the bore and look for curvature. I use the siding on a building--and it works! Unfortunately, you need a straight shot through the receiver which leaves out the M1 unless the barrel is removed or some complicated mirror system is used. Let us know how this ends. Good Shooting. ..

LavaTech 01-26-2021 01:21 PM

I realize that straightening barrels based on exterior measurement only is likely to produce "minute of ballpark" unless the bore is concentric (doubtful) but it does handle gross deformity and can be done without dismounting. Finalizing optically would still be best practice without doubt and the only way to assure best results.

la Fiere 01-26-2021 01:40 PM

OP - Can you clarify that the oprod is hitting the barrel band with the BR out of the stock, and not the tab of the stock ferrule?


It's common to have interference at the ferrule, but if the oprod is contacting the barrel band without the ferrule tab present, that's not normal.


Also, you mentioned the contact is occurring at the bottom of the barrel band. By "bottom" do you mean at both the 4:00 and 8:00 positions? There is no 6:00 position (band is open at the bottom) and I'm just trying to get a mental picture of what's happening.

krdomingue 01-26-2021 04:52 PM

Quote:

Originally Posted by AJsun (Post 2008711)
All of the posts sound really logical and I would agree with the bent barrel theory. I assume we are dealing with a :M-1 Garand? A simple solution, buy a new Barrel. A standard Military Barrel is not that expensive.AJ?

That may be the end result, once I decide it is a bent barrel problem. but I hate the idea of losing the original barrel.

Quote:

Originally Posted by la Fiere (Post 2008649)
OP - Can you clarify that the oprod is hitting the barrel band with the BR out of the stock, and not the tab of the stock ferrule?


It's common to have interference at the ferrule, but if the oprod is contacting the barrel band without the ferrule tab present, that's not normal.


Also, you mentioned the contact is occurring at the bottom of the barrel band. By "bottom" do you mean at both the 4:00 and 8:00 positions? There is no 6:00 position (band is open at the bottom) and I'm just trying to get a mental picture of what's happening.

Not the stock ferrule. By bottom, I mean when you looking at it with the barrel assembly upside down on my desk. It rubs/binds against the bottom of the arc made by the opening for the op-rod to run through. 12 o'clock or top, if I was holding the rifle upright.

https://imgur.com/EE0cLBs

dnmccoy 01-26-2021 05:38 PM

Have you tried other barrel bands?

RichieRich3902 01-26-2021 06:35 PM

How hard is it rubbing? Can you relieve the ferrell to allow it to pass?

krdomingue 01-26-2021 07:39 PM

Quote:

Originally Posted by dnmccoy (Post 2008749)
Have you tried other barrel bands?

Yes

Quote:

Originally Posted by RichieRich3902 (Post 2008769)
How hard is it rubbing? Can you relieve the ferrell to allow it to pass?

It would have to be what I feel is a significant amount. Not so much that it would invalidate the integrity of the band, but enough that I feel it shouldn't be done. The band is the symptom, no the problem. I would rather be sure of the cause and fix that.

Rock 01-26-2021 11:36 PM

Have you checked op rod function with the rifle fully assembled? If you have, does it bind or drag at a particular point along its travel?

Mark1 01-27-2021 10:53 AM

As Rock stated, assembly the rifle, but put chalk on the op rod. This will transfer to any area rubbing.

sparx 01-27-2021 11:03 AM

Was proper barrel indexing ever established?


Sparx

krdomingue 01-27-2021 11:54 AM

Quote:

Originally Posted by sparx (Post 2008963)
Was proper barrel indexing ever established?


Sparx

It is properly indexed.

TSimonetti 01-28-2021 07:53 AM

Please continue to define what you mean by "failing". Does it move part way and then stop? Does it fail to move at all? Is it just sluggish rather than smooth and easy as you expect?

Did you apply grease everywhere necessary?

In my few conversations with CMP armorers, they didn't seem to place a lot of finality to failing a tilt test. Their response to me usually was along the lines of "See how it shoots". Perhaps you should consider doing this?

Is it possible that you can simply file away the area that is rubbing? I know this subject was addressed already, and I know you feel that it should not be done, but it doesn't seem like chasing this rabbit further down the hole to solve the mystery will be beneficial short of replacing the barrel, which you don't want to do.

Relieving the rub area of the band is what I would do at this point. I've seen several lower bands and ferrules worked over in this manner.

sparx 01-28-2021 10:06 AM

If barrel is properly indexed then has to be a problematic barrel, as Larry pointed out early in this thread.


What are the barrel markings?



Also, I do tilt test without grease.


As Tsimonetti, asked I am curious as to how much resistance there is? Not very easy to explain this I understand.


I would fire the rifle if not already been done, be interesting to know if it shoots to (or close) the point of aim since the barrel may be bent. Also curious to know if excessive sight adjustment is required to get it on paper at 50- 100 yards.



sparx

johnpick 01-31-2021 10:40 AM

When you are dealing with mil spec parts you can get a rifle with a barrel at one end of the spectrum and a op rod and ferule at different ends and it just doesn't quite meet up. That is what you are probably dealing with and I would work over the ferule and see how it shoots and operates.

krdomingue 01-31-2021 12:26 PM

Quote:

Originally Posted by Mark1 (Post 2008960)
As Rock stated, assembly the rifle, but put chalk on the op rod. This will transfer to any area rubbing.

I don't need chalk, I already know where it is rubbing. It starts to rub when the oprod is halfway back and continues to get worse as the bolt is pulled back.

Quote:

Originally Posted by Rock (Post 2008888)
Have you checked op rod function with the rifle fully assembled? If you have, does it bind or drag at a particular point along its travel?

I have tried it in everyway possible. See above answer to where it is rubbing.

Quote:

Originally Posted by johnpick (Post 2010506)
When you are dealing with mil spec parts you can get a rifle with a barrel at one end of the spectrum and a op rod and ferule at different ends and it just doesn't quite meet up. That is what you are probably dealing with and I would work over the ferule and see how it shoots and operates.

True there is some variation from part to part. Particularly when dealing with used parts but that is why I went through a progression of parts to see if it was any particular part that was the problem. I am fairly certain that it isn't the lower band that is out of spec. I am reluctant to file medal off of it when it isn't the real problem. It might solve the immediate issue, but could leave me with a subpar barrel.

When I have the time I will attempt to check if the barrel is straight or not. If not, then I am not sure what I will do. I started this project back in 2015, because I wanted an HRA in my collection and I thought it would be fun to build out a barrel receiver. I have since acquired a better HRA example for my collection. I could replace the barrel, but I built a great shooter at the AMC course and don't need another one. It would be a good experience to replace the barrel, but then I would end up with a rifle that cost more than it is worth. Breaking back down for parts, might be the final answer.

Thanks

la Fiere 01-31-2021 12:36 PM

Just my 2 cents worth, I think the next step is to either confirm a bent barrel or take that off the table. A couple of pin gauges would not be too expensive:


https://www.mcmaster.com/pin-gauges/...z-plug-gauges/


I've found Roy Baumgardner's "Precision Shooting With The M1 Garand" a helpful reference. In his discussion of the operating rod (Part 5 which begins on P. 27) he advocates bending the oprod to fit each specific rifle. In the end, it may turn out that the peculiarities of your rifle require the middle of the oprod to be bent downward to clear the barrel band. If everything else is good (barrel indexed properly, not bent, etc.) then fitting the oprod to the rifle as it exists may be the solution.



You should also look very carefully to see if there are any other interference locations. The way the oprod comes out of the gas cylinder is a good indicator. For example, with the bolt closed there should be vertical movement of the oprod in the gas cylinder. If that's binding or tight it's an indicator of how the oprod needs to be bent (almost always a change to the oprod will affect two locations).



I don't know what others experience has been, but for me the usual interference at the barrel band / stock ferrule is with the bottom of the oprod tube rubbing against the top of the ferrule. That's pretty common and sometimes I've removed some material from the concave part of the ferrule tab just for insurance. I don't think I've never had one rub at the top like you're describing.


One last thought, are you holding the BR upside down when doing the test? I suppose that could cause the top-rubbing situation you're seeing.

BuddyBGood 01-31-2021 07:54 PM

Tilt test
 
La Fiere,your last sentence was spot on.
I had a rifle doing same not passing tilt test.I was testing legs up so I could see where the problem was.I did somethings to relieve binding to no avail.

Turned it over legs down and it worked flawlessly.

Cranky182 02-01-2021 12:00 PM

This may sound silly/ goofy, but check the op rod piston. If it is not "straight" in the op rod, it will drag. Had that issue yesterday with a buddies rifle, tried Three different op rods and gas cylinders, all worked except the one with the "offset/ uneven" op rod piston. Op rod would make a ratcheting noise, when coming out of the gas cylinder (under its own weight/ pressure), when it was tilted straight up and down (in a gas cylinder that was not on a rifle).
Most op rods will just slide straight out of a gas cylinder without any noise.
Hold the op rod piston up towards a light source and slowly turn it. If it's uneven, you will see a gap difference between the end of the op rod and the bottom of the piston.
Your op rod and or Gas Cylinder may also be slightly bent out of specs. I would check both op rod and gas cylinder in Two or Three different rifles and gas cylinders. Hope these couple ideas help in solving your head scratching issue/ problem.

Ronwall 02-01-2021 01:18 PM

Quote:

Originally Posted by krdomingue (Post 2010551)
I have since acquired a better HRA example for my collection. I could replace the barrel, but I built a great shooter at the AMC course and don't need another one. It would be a good experience to replace the barrel, but then I would end up with a rifle that cost more than it is worth. Breaking back down for parts, might be the final answer.

It sounds like you're tired of fooling with it and you don't have a use for the B/R anyways. If I were in your situation I would sell the B/R with disclosure of it not passing a tilt test and be done with it. I'm sure someone out there would enjoy the challenge of solving the issue.

sparx 02-01-2021 05:35 PM

Quote:

Originally Posted by Ronwall (Post 2010871)
It sounds like you're tired of fooling with it and you don't have a use for the B/R anyways. If I were in your situation I would sell the B/R with disclosure of it not passing a tilt test and be done with it. I'm sure someone out there would enjoy the challenge of solving the issue.


I might like this challenge!
(note: cmp notifications do NOT reach me jimlis22atgmail.com)

sparx

sparx 02-02-2021 10:34 AM

PM sent to OP Krdomingue
sparx


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