Want TDC when re-barreling??? - M14 Forum

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Want TDC when re-barreling???

This is a discussion on Want TDC when re-barreling??? within the The M14 forums, part of the M14 M1A Forum category; Everybody does, but few ever obtain TDC because it is difficult to do even with the best equipment. Having a barrel that is at TDC ...


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Old March 20th, 2017, 01:59 PM   #1
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Want TDC when re-barreling???

Everybody does, but few ever obtain TDC because it is difficult to do even with the best equipment. Having a barrel that is at TDC dosen't mean the windage is going to at mechinical zero or the front sight is going to be center on the sight mount, .052'+/ - .002" from the rt. side with muzzle facing you

What it does mean is, you have very good chance of having a Post the is vrtical, and that is the most important aspect..

Where and when people started using the chamber end and the center of the two feed rams to establish TDC is a mystery, a pooly written one....Or to determine how many degrees short of TDC at hand tight is another Mystery written by the same Author.

All the variables involved can be greatly reduced by using the flash suppressor with the F sight on, and firmly attached to the barrel, along with the rear sight at Mechinical Zero, just using the eye ball, looking for a vertical Post is better than many choices.

If using a level in both the rear sight platform and change it to the top of the sight post is at best a guess.

The only way I know of to get a TDC barrel, or very close, is to have the proper tools and an excellent level, one that reads in Mins.. Most of the time I can get to within two clicks with a centered F sight using the best tools made..

A barrel too far from TDC will ruin all the correct mods done, send your rifle to Ted Brown or Jay Wolf and have it mounted correctly.. Art

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Old March 20th, 2017, 02:18 PM   #2
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Not. A person of average intelligence is capable of performing an M14 barrel install with Badger Ordnance fittings and a Starrett machinist level. Why insult others competency for something so trivial?

http://www.starrett.com/metrology/pr...ts-levels/98-6

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Old March 20th, 2017, 02:55 PM   #3
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One of these is a good tool for this job. You can level it out the rear sight platform, then check the front sight base. This will ensure the top of the front sight is parallel to the rear sight platform.



But, if you use the FH, it is important to use the lower part of the front sight base, as it is supposed the be within 0.003" of being perpendicular to top dead center of the top spline. (The top of the dovetail itself is uncontrolled.)


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Last edited by lysander; March 20th, 2017 at 03:33 PM.
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Old March 20th, 2017, 03:07 PM   #4
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Quote:
Originally Posted by hammonje View Post
Not. A person of average intelligence is capable of performing an M14 barrel install with Badger Ordnance fittings and a Starrett machinist level.

http://www.starrett.com/metrology/pr...ts-levels/98-6
Exactly.....I use two of these when I do it. One at each end held on the gages with rubber bands so they don't have to be moved.

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Old March 20th, 2017, 03:08 PM   #5
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Quote:
Originally Posted by hammonje View Post
Not. A person of average intelligence is capable of performing an M14 barrel install with Badger Ordnance fittings and a Starrett machinist level. Why insult others competency for something so trivial?

http://www.starrett.com/metrology/pr...ts-levels/98-6
Most can not properly use the Starrett machinist level set I have.

Or the level of other surfaces...

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Old March 20th, 2017, 03:20 PM   #6
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I have a flash suppressor that has a cracked spline that I milled off the sight dovetail, works great with a machinist's level. Add one on the receiver and make them read the same, works every time.

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Old March 20th, 2017, 04:06 PM   #7
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Quote:
Originally Posted by art luppino View Post
...
Where and when people started using the chamber end and the center of the two feed rams to establish TDC is a mystery, a pooly written one....Or to determine how many degrees short of TDC at hand tight is another Mystery written by the same Author.
...
----------
Yes, using the chamber feed ramps to 'time the barrel' for final position is not ideal. My guess (I'm not familiar with 'the book') is that the 'hand tight x degrees short of final position' is a rough guide about the barrel being able to be properly tight when it IS in final position.

The ideal 'final position' of the barrel is for the sides of the front post to be parallel to the up/down movement of the rear aperture ramp, and for the barrel to be properly tight in the receiver. Also the top edge of the front post should be perpendicular to the sides of the post.

Even if all that is done correctly, it is still likely that the front sight will need to be adjusted slightly L/R so the no-wind-zero happens with the rear sight windage at mechanical zero.

Jay Kosta
Endwell NY USA

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Old March 20th, 2017, 05:38 PM   #8
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Unfortunately I used a SAI Cali Brake to "level off of" on my LRB rebarrel-didn't notice til later the dovetail was slightly angled in relation to the spline inside the brake...oh well, close enough.

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Old March 20th, 2017, 08:18 PM   #9
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Originally Posted by JayKosta View Post
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Yes, using the chamber feed ramps to 'time the barrel' for final position is not ideal. My guess (I'm not familiar with 'the book') is that the 'hand tight x degrees short of final position' is a rough guide about the barrel being able to be properly tight when it IS in final position.
If 'the book' is the one I'm referencing, then yes, that is what I think I understood when I read it, that the feed ramp divider is only an easy reference for having the right amount of rotation to be tight enough, but not too tight, when in final position. I don't recall, but I don't think that method is referenced for final barrel timing.

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Old March 21st, 2017, 02:51 AM   #10
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Art. Looks like you stirred a pot. Witch is a good thing. I am curious about what you are referring to when you speak of good tools or the best tools made for this application.
I have used a rod thru the rear sight and a rectangular bar stock on the front sight base. I also have used a level resting on some aluminum bars that attached to the same points. The first ones of these store bought aluminum bars were made incorrectly and required clearance added to them.
I think you are very concerned with OP rod alignment. This is also affected by the barrel timing. Yes it can be manipulated by other means.
Something else to consider is how well the rear sight base is machined with respect to the receiver legs. This is discussed in Mr. Kuuhnhausen's book. I once checked this on every build, but have stopped doing it. The reason is simple. Most are not perfect and there is very little to be done about it. Add in a factor of the front face of the receiver not being square and it is wonder we even hit paper.
Oh lets not forget people over-torquing barrels.
While we strive for perfection we must learn to accept something that is not. A well made receiver with a well made barrel assembled by someone who understands most of the issues will no doubt out perform one of lesser quality.
Thank you for continuing to create interest and conversation about our beloved rifle. Keep your flame suit on and keep up the good work.

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Old March 21st, 2017, 03:15 AM   #11
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Art, thanks for bringing up great points of interest.
I have been using the Badger tools for a few years and they have been working fine for me. I found I could be much more accurate with a digital level than I could with the 4' parallel bars I used to use. The same level is moved from rear fixture to front until they are equal. Rear fixture sets on flat of rear sight base and front fixture replaces front sight and connects to dovetail setting on flat of flash suppressor.
" There is more than one way to skin a cat".



Semper Fi
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Old March 21st, 2017, 05:31 AM   #12
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Quote:
Originally Posted by nf1e View Post
Art, thanks for bringing up great points of interest.
I have been using the Badger tools for a few years and they have been working fine for me. I found I could be much more accurate with a digital level than I could with the 4' parallel bars I used to use. The same level is moved from rear fixture to front until they are equal. Rear fixture sets on flat of rear sight base and front fixture replaces front sight and connects to dovetail setting on flat of flash suppressor.
" There is more than one way to skin a cat".



Semper Fi
ArtB
This ^^^^

I sat in Bruce Dow's shop here in Florida as he re-barreled a Garand for me, he took a little off the shoulder for it to clock & tighten properly, then, with the gas cylinder on he had a set of electronic levels on the flats and set it pretty near TDC or zero, then, used a chamber reamer to set headspace. It took him all of about 30 minutes...

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Old March 21st, 2017, 07:04 AM   #13
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I like the Husky digital level....

Quote:
Originally Posted by nf1e View Post
Art, thanks for bringing up great points of interest.
I have been using the Badger tools for a few years and they have been working fine for me. I found I could be much more accurate with a digital level than I could with the 4' parallel bars I used to use. The same level is moved from rear fixture to front until they are equal. Rear fixture sets on flat of rear sight base and front fixture replaces front sight and connects to dovetail setting on flat of flash suppressor.
" There is more than one way to skin a cat".



Semper Fi
ArtB
Hello Art,

The husky level shown is new to me, I'm going to run one down..

One of the most important aspects of using the level is: Use the same level both front and real, and never reverse it..Forgot to put that in my Thread..


Found the perfect scope, for me anyhow, to use on the M1A. A Redfield BR 6400, 16 power, the 1.4" movements are excellent. Yesterday was my second attempt using it, best five were .810". Interesting load: Fed cases CHS at 1.628" - 2,008" long, Fed LR primer with 38.7 IMR 3031.. The rifle just goes POOF when fired, no sharp bark as ususal. Give it a try at 100..

Going to 80 today, so off the the Golf course to have my Wife beat me again..

Best regards, Art L.

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Old March 21st, 2017, 07:21 AM   #14
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Quote:
Originally Posted by art luppino View Post
Hello Art,

The husky level shown is new to me, I'm going to run one down..

One of the most important aspects of using the level is: Use the same level both front and real, and never reverse it..Forgot to put that in my Thread..


Found the perfect scope, for me anyhow, to use on the M1A. A Redfield BR 6400, 16 power, the 1.4" movements are excellent. Yesterday was my second attempt using it, best five were .810". Interesting load: Fed cases CHS at 1.628" - 2,008" long, Fed LR primer with 38.7 IMR 3031.. The rifle just goes POOF when fired, no sharp bark as ususal. Give it a try at 100..

Going to 80 today, so off the the Golf course to have my Wife beat me again..

Best regards, Art L.
Fantastic on the scope. Glad it's doing the job for you.
I haven't been shooting the M-14 much lately, more the .308 bolts.
Using 38.3 of 3031 for 168s at 100. DAG berdan primed cases work the best for me. Working on the 100yd smiley face on the 1" pasters for the demo season.
Enjoy the 80 deg and the golf coarse. I will settle for 50 and a little prone workout this afternoon.

Semper Fi
ArtB

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Old March 21st, 2017, 08:08 AM   #15
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I don't build rifles but this is fascinating as I never really thought much about how you get the front post vertical when installing a new barrel .

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