Load DataTitan ReloadingReloading EverythingRotoMetals2
MidSouth Shooters SupplyRepackboxInline FabricationWideners
Lee Precision
Results 1 to 20 of 20

Thread: headspeace for a nr1 mk 3

  1. #1
    Boolit Master
    Mr Peabody's Avatar
    Join Date
    Dec 2005
    Location
    Idaho
    Posts
    923

    headspeace for a nr1 mk 3

    I had a man change out a barrel for me. I had bought what Numrich parts calls a "good condition" barrel to replace my shot out one. The gentleman called me this afternoon and said the barrel was junk; it has .20 thousands on the headspace. Is this indeed too loose for a British rifle? Where can I find out the tolerances for this cartridge? Thanks

  2. #2
    Moderator Emeritus/Boolit Master in Heavens Range
    Molly's Avatar
    Join Date
    Mar 2006
    Location
    South Charleston, WV
    Posts
    1,127
    Headspace on ANY rifle is exactly what the gunsmith makes it. You may need a different gunsmith. He should know that there are LOTS of ways to deal with your situation without throwing the barrel away. Here are a few for you to consider:

    Fire the cases with squib loads to form them, and the cases will then fit your rifle perfectly, no matter what the headspace may be. They will be headspacing on the expanded shoulder instead of the rim. Just don't set the shoulder back when you size the cases for reloading and you'll be fine. This will be the simple and easy fix.

    Yet another option is to examine the bolt head and see which one it is. Brits made the 303's to headspace with replaceable bolt heads, not by changing barrels. If a rifle had excessive headspace (and the Brits were pretty casual about that too), they simply changed the bolt head to a slightly longer one for quick and easy headspace adjustment. Unless your rifle bolt is already using the longest bolt head, you can 'adjust' headspace with a different bolt head from Gun Parts Corp (Numrich). This is the easiest and the formally correct method of dealing with it.

    Another option: I have also heard of adjusting headspace by cutting a washer out of shim stock and using it to between the bolt body and the bolt head to push the bolt head out an appropriate distance. This was for a rifle that couldn't be corrected to specs by changing the bolt head. For your rifle, something like 15 or 20 thousandths should get you in the ball park, if that's what you elect to do. This is the 'shade tree mechanic' fix, but it IS technically workable.

    There are plenty of 303 fans on this forum who can tell you exactly what to look for on the bolt head, but I'm not one. I'm sure one will chime in.
    Regards,

    Molly

    "The remedy for evil men is not the abrogation of the rights of law abiding citizens. The remedy for evil men is the gallows." Thomas Jefferson

  3. #3
    Boolit Master
    Mr Peabody's Avatar
    Join Date
    Dec 2005
    Location
    Idaho
    Posts
    923
    Thanks for the reply. I do beleive I can do as your saying without much trouble.

  4. #4
    Boolit Master
    Join Date
    Dec 2009
    Posts
    4,635
    By 20 thousandth of an inch he likely meant "headgap" rather than headspace, headspace being between .064 and .074 , the cartridge rims being .064 or thinner.
    Even with the thinest cartridge rim a .020 headgap is atrocious and indicates severe wear to the bolt or action body, though with luck a badly ground down bolt face may be the real problem.

    If a bolt head ground to fit another rifle is switched out by someone unaware with the difference in length you could have bad headspace but the major parts would still be within limits and only the bolt head in need of replacement.

    The rim rests on the breech of the barrel, so if the barrel is screwed down tight and the breech end not mutilated then the barrel isn't the problem.
    If a replacement barrel was cranked on without the breech bottoming out then the barrel did not fit the action properly.
    Some gunsmiths who should know better use a C shim to get a under sized shank to clock in and torque down, however thick the shim is will be how far further out of whack the headspace will be.


    Don't try putting a shim between the shoulders of bolt head and body. It might work for awhile but isn't likely to hold up and would greatly reduce the safety margin and ruin resale value.

    Some will tell you that in wartime they allowed a headspace of up to .080 or .084, but so far no one has produced a headspace gauge thicker than the standard limit of .074 to prove that claim.

    If these rifles are properly put together, and most I've seen were well put together, I have no worries about safety, but theres a lot of sloppy workmanship on some of them, and some were sloppy when they left the factory.
    Those mountains of DP rifles are mostly those with sloppy work and badly out of spec parts that weren't worth trying to repair.
    During WW2 they had to correct bad workmanship and out of spec parts of new manufactured rifles at arms depots before they could trust them to good enough for the troops.

  5. #5
    Boolit Grand Master

    MBTcustom's Avatar
    Join Date
    Feb 2011
    Location
    Arkansas
    Posts
    6,994
    The bolt heads are getting harder and harder to find, especially the long ones. If he just screwed your new barrel in place until the sights landed in a vertical position, and then slapped a headspace gauge in there, I could see there being .020. Some of those pieces were pretty rough. The rifle I have was about the worst. The groove diameter was .007 oversize, the chamber was sloppy and way oversize, the barrel had been hammered to upset the shoulder so that it would clock right, etc etc etc. Yeah the barrel you gave him could be used, but he might have been thinking that it wouldn't be worth it to you to make it right? Very strange.
    Do you know if this gunsmith has a lathe? If not, then that explains a lot.
    Precision in the wrong place is only a placebo.

  6. #6
    Boolit Master at heavens range
    smokemjoe's Avatar
    Join Date
    Jun 2006
    Location
    Iowa
    Posts
    1,140
    I had one that was.032 over, I soldered a piece to the bolt face and refitted it to .003 headspacing in the lathe, It really shot great then. Joe

  7. #7
    Boolit Buddy MaxJon's Avatar
    Join Date
    Aug 2009
    Location
    AUSTRALIA
    Posts
    407
    I have a No1 that I have just pulled the 60+yo barrel from and it had a .004" brass C shim between the barrel and action. It's headspace was about .065" but the barrel was pitted bad. I have a new lothar walther barrel to go in, which I will C shim once again to clock action, and hopefully the bolt face needs a couple of thou ground off to be about .062" headspace!
    THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!

  8. #8
    Moderator


    Join Date
    Apr 2014
    Location
    Way up in the Cascades
    Posts
    8,082
    Is your rifle a sporter, or are you trying to keep it "as-issued"?

  9. #9
    Boolit Grand Master

    Join Date
    Mar 2005
    Location
    Bloomfield, Nebraska
    Posts
    6,073
    Wartime standards were quite loose IIRR .062 to ,074. I turned my Gauge to .063 go and .069 no go as the ammo varies too and I prefer to use 30-40 Krag brass trimmed and reformed.

  10. #10
    Boolit Buddy MaxJon's Avatar
    Join Date
    Aug 2009
    Location
    AUSTRALIA
    Posts
    407
    Its an old target rifle it has a central sight, mismatched bolt etc.. not worth much
    THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!

  11. #11
    Boolit Master

    leebuilder's Avatar
    Join Date
    Dec 2014
    Location
    Nova Scotia
    Posts
    1,029
    I have seen this many times. If replacing the barrel the shoulder can be set back and properly head spaced and timed to the action. No1 bolt heads are usually malleable iron so building up with weld may or may not happen, soldering is a better option, this involves firing pin reseting. A old armourer told me they would headspace and time to .064 and with proof testing they usually finished at .067, which is the limit for no go Sammi specs. I have rechambered many not at all hard just need a lathe and dial. Shims work but is only a quick fix and will get you out of a pinch, I doubt the is .020 thou slop in the threads to make it safe. Replacement bolt heads can be found but they must time so order a few to ensure proper timing.
    Be safe
    When you read the fine print you get an education
    when you ignore the fine print you get experience

  12. #12
    Boolit Master
    Join Date
    Apr 2005
    Posts
    4,900
    Quote Originally Posted by Mr Peabody View Post
    I had a man change out a barrel for me. I hado bought what Numrich parts calls a "good condition" barrel to replace my shot out one. The gentleman called me this afternoon and said the barrel was junk; it has .20 thousands on the headspace. Is this indeed too loose for a British rifle? Where can I find out the tolerances for this cartridge? Thanks
    I too would take this as meaning the headspace was .020in. over the rim thickness, i.e. the cartridge has that much longitudinal free movement. I would call that borderline for safety, and almost certain to harm accuracy and case life. If it was a new and totally round barrel the remedy is to lathe-turn some metal from the barrel shoulder and/or its rear surface, just enough to produce correct headspace. Then you make the cuts and pin grooves etc. for the extractor and sights.

    If the barrel already has those cuts, a Nock's form etc., you need to remove a fourteenth of an inch of metal from the barrel, and screw it an extra turn into the receiver. This will give you less than no headspace. So you need a chamber reamer to deepen the chamber and cut a new rim recess. The extractor cut will probably need to be deepened too.

  13. #13
    Boolit Master
    Join Date
    Apr 2005
    Posts
    4,900
    Quote Originally Posted by leebuilder View Post
    I have seen this many times. If replacing the barrel the shoulder can be set back and properly head spaced and timed to the action. No1 bolt heads are usually malleable iron so building up with weld may or may not happen, soldering is a better option, this involves firing pin resetting.
    I'd agree with this. The early ones were described as gun iron, and probably case-hardened. I would much rather silver solder a thin sheet of good steel onto the face of the bolt-head, preferably using Brownells 355 silver solder, which comes in a thin ribbon so that you can position it in the joint rather than expect it to flow in.

  14. #14
    Boolit Master

    leebuilder's Avatar
    Join Date
    Dec 2014
    Location
    Nova Scotia
    Posts
    1,029
    Spot on BOS
    Some rear sights will set perfect in the handguards but some nose caps fall short of the muzzle crown. The forestock should be rebedded too, to ensure a good fit, the barrel taper is set back as well. .020 is alot! It is unsafe in my opinion, .074, .076 is the limit for the military, I stick with the modern .067 max just to be safe, some of these rifles are close to a hundred years old, respect and safety is paramount!
    Be well
    When you read the fine print you get an education
    when you ignore the fine print you get experience

  15. #15
    Boolit Buddy fivefang's Avatar
    Join Date
    Mar 2015
    Location
    Nye County
    Posts
    142
    molly , .303 head spaces on the rim, go to a Auto part's store & buy several strips of "Plasti-Gage" of various increments, for just a few$, put Apc. across the rim, insert casing into the Chamber CAREFULLY & close the bolt, then measure what you see, add shims, or reduce the barrel-shoulder, or file the reciver, all this works, have fun, Fivefang

  16. #16
    Boolit Buddy MaxJon's Avatar
    Join Date
    Aug 2009
    Location
    AUSTRALIA
    Posts
    407
    Feeling a bit proud using my lathe and depth micrometre etc.....I have timed my No.1 barrel to the action and as I calculated the bolt face/head would need approx. .010" ground off for a desired .062" headspace! I did however have to take the rifle to my workplace to grind the bolt face/head for final headspacing. Polished the bolt face to a mirror finish after grinding the bulk of .010" stock removal. Had a win!! Awesome!! It was pretty straight forward really.....drilling the pin hole for the rear leaf sight is a bit of a worry however......
    THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!

  17. #17
    Boolit Master

    leebuilder's Avatar
    Join Date
    Dec 2014
    Location
    Nova Scotia
    Posts
    1,029
    Quote Originally Posted by bullbarrel033 View Post
    Feeling a bit proud using my lathe and depth micrometre etc.....I have timed my No.1 barrel to the action and as I calculated the bolt face/head would need approx. .010" ground off for a desired .062" headspace! I did however have to take the rifle to my workplace to grind the bolt face/head for final headspacing. Polished the bolt face to a mirror finish after grinding the bulk of .010" stock removal. Had a win!! Awesome!! It was pretty straight forward really.....drilling the pin hole for the rear leaf sight is a bit of a worry however......
    Good for you, I remember the same feeling. I place the sight on where I want it and use a drill just to mark it's position then remove and file a notch at the mark, this give the drill bit a bit of a "start" reset the sight and clamp tight and drill carefully. If it looks off square I do it on both sides. The odd time I go a smeck over size and make a pin. Once I soldered a sight on.
    Be well
    When you read the fine print you get an education
    when you ignore the fine print you get experience

  18. #18
    Boolit Master
    Join Date
    Mar 2005
    Posts
    4,612
    Here are the SAAMI standards for the .303 British chamber and cartridge.

    One of the problems with Lee Enfield chambers is that they are significantly longer than loaded cartridges. The Brits did not seem to document these chambers either.
    If you do not need your rifle to be original you can turn the barrel in a turn and have it chambered with a SAAMI reamer and see if it cleans up. This would provide a better fit to SAAMI ammo.

    http://members.saami.org/ManualsStds/CC_Drawings/Rifle/303%20British.pdf

    EDG

  19. #19
    Boolit Buddy MaxJon's Avatar
    Join Date
    Aug 2009
    Location
    AUSTRALIA
    Posts
    407
    Leebuilder thats exactly what a mate tells me to do! Thanks!
    THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!

  20. #20
    Boolit Buddy MaxJon's Avatar
    Join Date
    Aug 2009
    Location
    AUSTRALIA
    Posts
    407
    Quote Originally Posted by EDG View Post
    Here are the SAAMI standards for the .303 British chamber and cartridge.

    One of the problems with Lee Enfield chambers is that they are significantly longer than loaded cartridges. The Brits did not seem to document these chambers either.
    If you do not need your rifle to be original you can turn the barrel in a turn and have it chambered with a SAAMI reamer and see if it cleans up. This would provide a better fit to SAAMI ammo.

    http://members.saami.org/ManualsStds/CC_Drawings/Rifle/303%20British.pdf

    The barrel i bought is a lothar walther, apparently has a match chamber, and tru .311 groove. Its certainly a lot tighter than my No4 chamber, but its getting a bit loose on the headspace, its out around 66 thou. Seperates case heads if i load it too hot!
    THE ONLY WAY YOU CAN HIT THE CENTRE OF THE TARGET IS WITH A CENTREFIRE!!!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check