Go Back   Maryland Shooters > Topics of Interest > Gunsmithing
Don't Have An Account? Register Here

Join MD Shooters

Reply
 
Thread Tools Display Modes
Old August 15th, 2018, 09:48 PM #41
Blacksmith101 Blacksmith101 is offline
Grumpy Old Man
 
Join Date: Jun 2012
Posts: 11,117
Blacksmith101 Blacksmith101 is offline
Grumpy Old Man
 
Join Date: Jun 2012
Posts: 11,117
FYI
I was reading Understanding Firearm Ballistics by Robert A. Rinker and came across this on page 56:
Quote:
"Actions and cartridges must be a suitable match for pressure as well as cartridge fit. For example, it is possible to change barrels and convert a .30-40 Krag to .30-'06. The .30-40 Krag produces a breach pressure of about 43,000 p.s.i. and the .30-'06 about 55,000 p.s.i. The Krag action and its single locking lug cannot safely handle the extra 12,000 p.s.i."
Blacksmith101 is offline   Reply With Quote
Old August 15th, 2018, 11:34 PM #42
noahhh noahhh is offline
Member
 
Join Date: Jan 2009
Location: Arnold,Md
Posts: 158
noahhh noahhh is offline
Member
 
Join Date: Jan 2009
Location: Arnold,Md
Posts: 158
During the later active duty life of the U.S. Krag, the Ordnance department jacked up velocity of 220 grain ball ammo from its original 2000 fps to 2200 fps in an effort to "modernize" the cartridge (keep up with the Jones's as it were). They immediately started getting complaints from the field about bolt lugs cracking. That put paid to that folderol and they dropped back to 2000 fps right quickly. The old standard 220 grain/2000fps load accounted for trainloads of big game and became "obsolete" only when we convinced ourselves that we had been fooling ourselves all along and migrated to ever more powerful cartridges.
noahhh is offline   Reply With Quote
Old August 15th, 2018, 11:47 PM #43
TargetGrade's Avatar
TargetGrade TargetGrade is offline
Senior Member
 
Join Date: Aug 2017
Location: Pensultucky
Posts: 2,805
TargetGrade TargetGrade is offline
Senior Member
TargetGrade's Avatar
 
Join Date: Aug 2017
Location: Pensultucky
Posts: 2,805
As I said, the Krag has only ONE locking lug. It does NOT cam on the handle but the lug itself.The bill floats very easily between the bolt and receiver. Would it act as a safety lug.... I doubt it but maybe. If the lug did break the bolt would be trash at minimum.
Attached Images
 
TargetGrade is offline   Reply With Quote
Old August 16th, 2018, 08:51 AM #44
noahhh noahhh is offline
Member
 
Join Date: Jan 2009
Location: Arnold,Md
Posts: 158
noahhh noahhh is offline
Member
 
Join Date: Jan 2009
Location: Arnold,Md
Posts: 158
The root of the bolt handle is a secondary safety lug, more so on the M1892-96 shown above than on the later M1898, but the main safety lug is the long one on the side of the bolt body. In the event of a catastrophic failure of the main single lug, the safety lug(s) will prevent the bolt from flying straight back into the shooter's head. There's a lot of redundant precautions built into the design.

Years ago the late Michael Petrov, renowned collector/expert of pre-war American custom sporters, took a .30-40 Krag and tested it to destruction (via remote control). He used ever increasing charges of Bullseye pistol powder until he got up to an ungodly charge of around 25 grains before the action came unglued. The receiver shattered and the bolt whipped out to the right but never left the gun. The kicker was that he had ground the main locking lug completely off and conducted the experiment with just the safety lugs holding the force of the discharges. Don't try that trick at home kids.
noahhh is offline   Reply With Quote
Old August 16th, 2018, 09:34 AM #45
iH8DemLibz's Avatar
iH8DemLibz iH8DemLibz is offline
When All Else Fails.
 
Join Date: Apr 2013
Location: Libtardistan
Posts: 24,177
iH8DemLibz iH8DemLibz is offline
When All Else Fails.
iH8DemLibz's Avatar
 
Join Date: Apr 2013
Location: Libtardistan
Posts: 24,177
As stated above, the rib on the bolt body, that mates with the receiver, is a substantial safety feature.

It's a bearing surface that can take oodles of rearward pressure.

Maybe in another 126 years, folks will accept this as truth and put to bed, forever, the single lug/weak action myth.

Name:  IMG_8345.jpg
Views: 40
Size:  77.2 KB
iH8DemLibz is offline   Reply With Quote
Old August 16th, 2018, 10:05 AM #46
noahhh noahhh is offline
Member
 
Join Date: Jan 2009
Location: Arnold,Md
Posts: 158
noahhh noahhh is offline
Member
 
Join Date: Jan 2009
Location: Arnold,Md
Posts: 158
Wait a minute. Is that a Norwegian Krag?
noahhh is offline   Reply With Quote
Old August 16th, 2018, 07:38 PM #47
Doco Overboard's Avatar
Doco Overboard Doco Overboard is offline
Senior Member
 
Join Date: Jul 2016
Location: The heart of the Delmarva Penninsula
Posts: 2,245
Doco Overboard Doco Overboard is offline
Senior Member
Doco Overboard's Avatar
 
Join Date: Jul 2016
Location: The heart of the Delmarva Penninsula
Posts: 2,245
No US Krag was designed to have the bolt guide rib act as a second bolt lug. A secondary feature yes as well as the m96 and earlier actions having additional vertical lugs encompass the bolt handle which was removed to save labor on all the later rifles. The locking lug mortise is also designed with an inclined ramp. Some lap the ramp to allow the guide rib to bear on the bridge when the bolt is closed in an attempt to strengthen the action which it probably does but what really happens is that HS is increased and with the ramp gone, the ability to overcome mainspring pressure and the benefit to move the bolt forward the last .150" to seal the chamber on different rim thicknesses becomes less. This is not much of an improvement if your into carefully prepared hand loads and could be considered as going backwards.

Primary extraction comes from another angled ramp at the right rear of the receiver bridge when the bolt is lifted. The bolt face is recessed enough for nominal rim thickness. It also fits nicely into the internal breeching ring even though the outer diameter is thin. At 12o is a extractor groove however that compromises the completely sealed chamber by the rim that if fit correctly allows the extractor claw to get a nice purchase. Never had it happen but maybe if a case or primer is blown the extractor groove will allow the blast to go up and away from the shooters eyes?

Norwegian and Danish Krags are made from better steels and superior heat treatment. Up into the thirties and maybe later.
The Norwegian Krag is made so that the guide rib and locking lug are closed at the same time. The Dane is the one with the box mag that rotates forward and some time has a barrel shroud. It operates the same as the US but is said to be stronger because of the enhanced heat treatment.

The Norwegian has a 1.050 breech face and is LH thread 12 TPI, the US 10TPI and .980 barrel stub....Dane 12 TPI v type threads.

Sedgley in Philadelphia screwed 06 barrels into the Krags he built to test them but never recommended or offered them.

.348 is the other cartridge for Krag conversions I think. Soon I'm going to working on a a retro sporter. Ill stick with 30/40.
Doco Overboard is offline   Reply With Quote
Old August 17th, 2018, 01:16 PM #48
Art3's Avatar
Art3 Art3 is offline
Eqinsu Ocha
 
Join Date: Jan 2015
Location: Harford County
Posts: 2,484
Art3 Art3 is offline
Eqinsu Ocha
Art3's Avatar
 
Join Date: Jan 2015
Location: Harford County
Posts: 2,484
Quote:
Originally Posted by Cruacious View Post
I might actually mill the bolt out and set a new barrel a bit further back. Changing the feed ramp angle would also be beneficial probably. It will likely need serious machining to get it right as well. This won't be a job for hand tools, this will be more of a job for a machine shop and possibly a CNC machine. Also, the extractor can be lowered with some machining.

It may also be possible to do a slight redesign on the bolt at the same time to reinforce it (as I believe the bolt is the weakest link of a Krag). I may be getting into serious gunsmith concept here though, but that's just how I am sometimes with my ideas. If it isn't broken, why can't I make it better?

Also, I'm not married to the idea of 30-30 WCF entirely. I could also go for 30-06 with a light load, etc.
If you are doing this because you will enjoy the process, by all means, have at it. For my .02, it seems like a lot of work compared to rolling your own to come up with an "economical" to feed Krag. You'll end up with something unique...but is it really that unique? A Krag in .30 NotKrag is still .30 cal. Personally, the juice vs. squeeze ratio just isn't working for me.

Now...if you want to do all of that replacing and reengineering to come up with a functional Krag in, say, .22lr or .357 mag...put me on the waiting list for one
__________________
.
.

"Dear autocorrect: I'm really getting tired of your shirt!"
Art3 is offline   Reply With Quote
Reply

  Home Page > Forum List > Topics of Interest > Gunsmithing


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 04:39 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
2018, Congregate Media, LP Privacy Policy Terms of Service