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View Full Version : Installing Barrel: Can't Get Past 11:00


.30calfanatic
July 14, 2007, 19:20
I am installing a used G1 barrel on a new DSA receiver, and using a cheater bar won't get me to 12:00. What are the possible remedies when a barrel under-clocks?

FAL freek
July 14, 2007, 20:32
Before you start removing metal check and see if when you hand tighten it that it stops at the 11:00 position (or somewhere close to that).

Be careful you don't get too liberal with the torque also the slide where the cocking handle goes in has been known to get mashed when overtorqed. Sorry if you've done a build before but just tryin' to keep ya from mashin' your receiver.

I've heard of guys using a marker and coloring the edge of the barrel (shiny part that screws into the receiver) with the same problem you have to see if the barrels contacting the receiver so it can't be tightened anymore. If you get a smudge you might have to remove some metal. I've never tried that method cause the three DSAs I've built all went together like a dream.

.30calfanatic
July 14, 2007, 22:20
First build for me, so all suggestions/cautions are welcome.

There is still a little room between the breech face and the receiver, enough to stick a fingernail into, so it appears the barrel shoulder is making contact first. My instinct is to shave down the face of the receiver, so anyone with more experience STOP me before I screw something up.

kennaquhair
July 14, 2007, 22:23
Stop.

.30calfanatic
July 14, 2007, 22:45
kennaquhair, can you be more specific and tell me why?

ostrobothnian
July 14, 2007, 22:49
Real quick!

I think he meant that you will want to remove metal from the cheapest part (i.e. the barrel). Best way to do that is in a lathe. A search on this site will show how to do that either way.

FAL freek
July 14, 2007, 23:59
What Ostro said. Ya can get 3+ barrels for the price of a DSA receiver. Plus alot less hassle. Taking off metal from the receiver usually leaves a nice visible shiny spot after you've put the barrel on the gun. You only want to start taking metal off after you've used up all other options. How long's your cheater bar? Don't get in a big hurry to put the gun together. Sure you've waited how long for that nice reciever? Won't hurt to wait a little longer.

.30calfanatic
July 15, 2007, 09:24
Thanks everybody. This is the kind of information and wisdom I need. Slowing down is hard for me under normal circumstances; this project has had it's share of Murphy's events, from a seller on GunBroker who took my money then sold the receiver to someone else (money refunded, but from start to finish it added 5 weeks to the schedule) to ordering the receiver from DSA (12 weeks). Patience is a virtue, and one I'm lacking . . .

I'm in California, San Jose area. Anybody on this forum close by with a lathe, or is this a matter of sending the barrel and receiver to a professional? If so, recommendations are appreciated.

ostrobothnian
July 15, 2007, 09:32
OK! Have a look at this link.

http://www.falfiles.com/forums/showthread.php?s=&threadid=92877&highlight=barrel+shoulder

Glad you took a breath there! The patience will pay off.

bookertbab
July 15, 2007, 13:03
Originally posted by .30calfanatic
I'm in California, San Jose area. Anybody on this forum close by with a lathe, or is this a matter of sending the barrel and receiver to a professional? If so, recommendations are appreciated.

You don't need a lathe. Any metal removal will be very minor and a file will do just fine.

First how does the barrel time when hand tightening. If it gets to 10:30 by hand you can probably torque it on. If not remove some metal from the barrel shoulder until it does time to around 10:30 - 11:00. Don't take off too much, you only need to remove a very little.

If you screw up and remove too much metal and it overtimes you can use a breaching washer. But take your time, go slow, and you will be rewarded in the end.

thanatos56
July 15, 2007, 17:23
Originally posted by bookertbab


You don't need a lathe. Any metal removal will be very minor and a file will do just fine..

I used a 3-corner file, slowly rotating the barrel as I filed on the mating surface of the barrel... and it came out perfect.

One of those instances when a little investment in patience pays HUGE dividends. ;)

.30calfanatic
July 15, 2007, 19:47
Hand tight at 10:00, using a 4' cheater gets me to 11:00. I have a three corner file, now if I could just remember where I left my patience . . .

tigerfans2
July 15, 2007, 20:32
Originally posted by .30calfanatic
kennaquhair, can you be more specific and tell me why?


Bite my smartass tongue..........

bykerhd
July 15, 2007, 20:36
You can do it with a triangular file if you are patient and careful.
Use a Sharpie or other black magic marker on the mating surface of the barrel shoulder. Screw it in hand tight and unscrew it. The high spots will be shiny metal. File a little bit, mark it up and repeat the process. It'll take a few repeats at least. The object is to end up with even contact all the way around, all bright metal, while having the barrel hand tighten to about 11:00 or just past.

.30calfanatic
July 16, 2007, 09:06
I tried installing another barrel I have, and while it got closer to 12:00, it still isn't close enough. It stopped at about 11:30. Bright, shiny wear marks on the receiver, so both barrels are making solid contact. Each is stopping just short of making contact on the breech.

ostrobothnian
July 16, 2007, 09:12
YOU CAN DO EEEET! Use the files Luke.

You can do it with a triangular file if you are patient and careful.

W.E.G.
July 16, 2007, 09:47
Originally posted by lngnmn
First make sure that the chamber end isn't tight up against the rec. feed ramp area...

See also http://www.falfiles.com/forums/showthread.php?postid=1960113#post1960113


"Here is a kinda half-assed sketch of what could be going on here.

The arrows indicate relevant points of reference.

Notice that the ass-end of the barrel may be more-or-less "squared-off" by
comparison to the receiver into which it must mate. So, when the barrel
is "bottomed out" you end up with a gap between the breech face and the
receiver. (Top three drawings)

Sometimes you can round-off the outer edge of the barrel to make it fit deeper
into the receiver, but without altering the depth of the dimension from breech
face to the datum line on the cut for the shoulder of the chamber. (Bottom three
drawings)"

http://www.falfiles.com/forums/attachment.php?s=&postid=1960113

.30calfanatic
July 17, 2007, 01:19
bump

Hebrew Battle Rifle
July 17, 2007, 04:50
Every .005 removed from the barrel shoulder will allow the barrel to advance one "hour" or 30 degrees. So, if your barrel hand times to 10:00, removing .005 evenly will let it time to 11:00

Fred-in-PA
July 26, 2007, 14:15
This thread is really interesting to me because I have a related problem. I had finished timing and headspacing my fourth build (a refinished GPG Imbel barrel on a type II DSA receiver) The barrel timed to about 10 o'clock. I removed a little material from the barrel shoulder and torqued it on using Court's barrel timing rods and a barrel vise from ratas along with a good receiver wrench. Anyway, the barrel timed perfectly and I headspaced w/ a .260 locking shoulder. When I went to test fire and sigt in, the shots were 12" to the right at 50 yards. By the time I got the sights adjusted to hit center at 100 yards, I ran out of left windage.

I went home, pulled off the barrel, tried to see if anything is bent (I can't see anything)
I re-timed it and made sure that I did not overtime the barrel.
Went out to test-fire and got the same results, bullets strike far to right (12" when rear sight is centered)

Is the gas block off? Or is the front sight post hole drilled off-center?
Should I re-time the barrel again and this time purposely undertime it so the bullet strikes are farther left? Would that make the gas piston bind?


Any ideas?

dougjones31
July 26, 2007, 15:00
Fred,


You could have any of several problems...

1. You screwed up and timed it incorrectly both times. Probably not, but if beer was involved.......:wink:

2. The barrel is bent. You say it does not look bent but it very well could be bent and you just cant tell. Probably not, but I have to list it.

3. The bore is off center. This would cause your problem easily. You can ususally look at the muzzle and see if it looks like the wall is thinner on one side. I would put a laser bore sighter in the chamber and unscrew the barrel and watch the red dot. If it makes a big circle on the wall then the barrel is bent or the bore is off center.


You asked if the gas block was off????? If you used the timing tool then there is no way that is possible.......is it?

OH!!!!! #4. I forgot to ask if you have a muzzle brake on the gun. It is possible that the bullet is hitting it and throwing the trajectory off. lok at the inside of the muzzle thingy and see if you see copper marks.

Dunk RD
July 26, 2007, 15:20
Befor I bought a lathe I used a Makita half inch drill. Had a fine thread bolt that fit inside the flash suppressor. Cut the head off and put it in the drill. On high speed, used a small, fine mill file. Doesn't take very much so go slow and check often.
For small amount use emery paper and a thin flat peice of metal. easyier with two people to hold the drill and file.
Dunk RD

Fred-in-PA
July 26, 2007, 17:16
I checked the inside of the muzzle device, there are no copper marks in flash hider.

When I mentioned the gasblock being "off", I meant the threaded hole for the front sight, but if that was "off" the barrel would still be timed to the position of the front sight.

USMC 0341
July 26, 2007, 17:17
30calfanatic,

Not sure if you have gotten through this problem yet - so here's what I would do.

If you have the old, chopped receiver stub use this to back a piece of 60 grit sandpaper. With a hole the diameter of the barrel (threaded end) cut in the sandpaper put the barrel through this hole and screw the receiver stub on to back the sandpaper and keep the contact with the barrel shoulder square and even.

If you don't have a receiver stub use the DSA receiver with a thickness of cardboard to take up the slack.

Do this a few times until the barrel will hand tighten to about 10:45.

Also, if screwing the barrel into the receiver seems rough and uneven, take a marker and blacken the barrel's threads. Screw the barrel into the receiver once and then remove it. Look for spots on the threads where the ink has rubbed off - particularly if it seems to wear off unevenly. Lightly sand any of these areas (lightly!). Hand tighten into the receiver again. It should go smoother than before.

Try this and let me know if it still won't tighten to 12:00.