milsurpcollector Posted May 19, 2007 Report Share Posted May 19, 2007 I have 1940 98k receiver with an 8mm mauser barrel. Bolt is matching but bent further down. I have trouble lifting the bolt more than 3/4 of the way after shooting. Headspace is perfect with the stripped bolt. I disassembled the rifle and found no set back in lug area. I used some kasenit heat treating compound on bolt handle camming area results are the same bolt is still hard to lift more than 3/4. I stripped bolt and tried one of the fired cases and the rifle does the same thing. The chamber is polished with scotchbrite. what is going on???? Link to comment Share on other sites More sharing options...
riceone Posted May 20, 2007 Report Share Posted May 20, 2007 Where the bolt was re-bent could there be some metal galding on the receiver? riceone. Link to comment Share on other sites More sharing options...
milsurpcollector Posted May 20, 2007 Author Report Share Posted May 20, 2007 Where the bolt was re-bent could there be some metal galding on the receiver? riceone. The finish is worn off in that area but I dont know if its galling. I tried another bolt and it does the same thing only to a lesser extent. I also checked my brass, thinking it might be pinching due to brass growth. not the case. The reamer I used is new purchased from brownells and on its first chambering job. Im not sure if I have this problem with surplus ammo. I cant remember. Link to comment Share on other sites More sharing options...
Doble Troble Posted May 20, 2007 Report Share Posted May 20, 2007 If the chamber is good (and I'd carefully inspect/measure fired cases) its got to have something to do with the bolt. Since the bolt handle was modified that would be the first place I'd look. The root of the handle is important for opening the action. If its soft it can make opening difficult, if its the wrong dimension or lacks the camming relief it can create problems. Take it one step at a time and you'll get it figured out. Link to comment Share on other sites More sharing options...
Jimro Posted May 22, 2007 Report Share Posted May 22, 2007 a quick check is to lubricate the camming surface on the rear of the bolt body, if it fixes your problem then it's "galling". Jimro Link to comment Share on other sites More sharing options...
milsurpcollector Posted May 27, 2007 Author Report Share Posted May 27, 2007 In my quest to fix or find out why its so hard to open the bolt on my rifle I have discovered some interesting stuff. I thought the cam at the root of the bolt was worn so I welded a liitle to it and reshaped the camming area. The result----No change the bolt is still hard to open with a spent round. I should mention that it is also hard to close with the spent round or a resized round. I tried some yugo surplus which chambered easily, so I decided to measure my chamber which is 8mm mauser At the breech my barrel measures .4673 The correct spec is .4757 At the shoulder my barrel measures .430 The correct spec is .4361 to .4381 The specs are from Kuhnhausen's book. It appears I have an under size chamber. I used a finish reamer for the whole chamber, no rougher. The reamer was purchased new from brownells made by Dave mason So what do I do now? as i said the gun headspaces perfectly Is it possible to get an undersize reamer? Link to comment Share on other sites More sharing options...
Jimro Posted May 27, 2007 Report Share Posted May 27, 2007 Polish the chamber with some fine grit wet sandpaper and progressively work finer and see if that fixes the problem. A dowel with a vertical cut through it makes a handy tool to hold the sandpaper, and an electric drill will spin it just fine It's what I would do. Jimro Link to comment Share on other sites More sharing options...
cold shot Posted May 27, 2007 Report Share Posted May 27, 2007 Just a though, what if the reciever is warped or bent? I read where you used another bolt and it done the same. Just a thought. Dave Link to comment Share on other sites More sharing options...
milsurpcollector Posted May 27, 2007 Author Report Share Posted May 27, 2007 I guess I will try the sandpaper, after calling brownells and Dave Mason. I have used other reamers and have not had this kind of problem. I really think the reamer is under sized, or maybe I am missing something? As far as the receiver being warped, I dont think thats the problem. I have tried the barrel in 3 different receivers. I always checked the headspace and corrected when nessisary. Link to comment Share on other sites More sharing options...
sonic1 Posted May 27, 2007 Report Share Posted May 27, 2007 ...have you tried this action with another bolt? Link to comment Share on other sites More sharing options...
fritz Posted May 28, 2007 Report Share Posted May 28, 2007 I would doubt that reamers are undersize, but it has happened to me more than once that I have a tight chamber when I have reamed it so that it closes on a go, and does not close on a no-go. You can polish the chamber out to a smoother fit (recommended) or just ream a wee bit more when it closes on a go. fritz Link to comment Share on other sites More sharing options...
BobVZ Posted May 28, 2007 Report Share Posted May 28, 2007 An outside chance may be the safety lug is contacting the receiver after the gun is fired and the case is fire formed. Mark the safety lug with magic marker and cycle with a fired round. Another cause might be a chamber that is reamed out of plumb with the bolt face. Again, when the round is fire formed it binds when the bolt is rotated. Link to comment Share on other sites More sharing options...
milsurpcollector Posted May 28, 2007 Author Report Share Posted May 28, 2007 Thanks for the replies guys, I polished the chamber out with some 320 grit sandpaper followed by 400 followed by scotchbrite. I have the breach end at .471 which is still undersize by .004. I broke my cheap chinese gauge so I can no longer measure the shoulder. I dont think the chamber is off plumb from the bolt face because new ammo work fine. I did check the safety lug its not touching anything. I have decided to do the following: Buy a new set of dies ( the Lee sizer die has an off center mandrel) Get some new brass to be used only in this gun ( my other brass has all been fired in large military chambers) New brass chambers and extracts easily. Thanks for everyone's comments, posting my thoughts here kept me from throwing my $130 douglas barrel into woods when I got frustrated. Link to comment Share on other sites More sharing options...
z1r Posted May 28, 2007 Report Share Posted May 28, 2007 Thanks for the replies guys, I polished the chamber out with some 320 grit sandpaper followed by 400 followed by scotchbrite. I have the breach end at .471 which is still undersize by .004. I broke my cheap chinese gauge so I can no longer measure the shoulder. I dont think the chamber is off plumb from the bolt face because new ammo work fine. I did check the safety lug its not touching anything. I have decided to do the following: Buy a new set of dies ( the Lee sizer die has an off center mandrel) Get some new brass to be used only in this gun ( my other brass has all been fired in large military chambers) New brass chambers and extracts easily. Thanks for everyone's comments, posting my thoughts here kept me from throwing my $130 douglas barrel into woods when I got frustrated. I'd suspect that your problem has more to do with using brass that has been fired in another chamber. Just yesterday I was resizing some .223 brass and tried some range pick ups from a friends rifle. Even using a small base die I wasn't able to resize his brass enough to chamber in mine (either of them). Yet, when I neck size brass fired in these guns it chambers without effort. I have never run into a situation where a minimum chamber (lengthwise) has caused hard extraction. It can cause hard insertion especially if your brass is long but once the bolt has closed the shoulder is repositioned and the brass comes out easily enough. Link to comment Share on other sites More sharing options...
Racepres Posted May 28, 2007 Report Share Posted May 28, 2007 Absolutely agree w/ Z1r!!! Some [nearly all that I have] "custom" [that means non military as well ] chambers simply will not accept a round which has been fired in "another" chamber!! Even w/ small base dies!! Means the 1f brass from my 1917 will never go into my Turkington!!! Can't even be turned into 6mm'06s!! Heck I even ended up w/ a K98 that seems normal but for numerous reasons I suspect that it was rechambered.. and yep .. you guessed it.. gotta segregate brass!!! Drives me crazy ... but, such is life!! MV Oh! and It is definitely Not a Headspace thing!!! More about Diameter! Link to comment Share on other sites More sharing options...
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