Discussion on Rifling

sheepherder · 10-23-2011, 10:37 AM

I read this comment on another [Enfield] forum...

Well all the Lee Enfield bores I've examined had very deep rifling grooves, as would be expected since original acceptance specs call for grooves from .005 to .008 in depth. Conventional rifling of the day called for grooves .004 in depth.

http://www.surplusrifleforum.com/vie...?f=27&t=113788

To put that in perspective, a sheet of lined notebook paper is ~.003"...

'Conventional rifling' applies (I suppose) to other rifles...

Does the Luger have ~.004" deep grooves??? Let me see...

I see my Lugers barrels are marked as follows:

1 - 8.84mm [.348"]
2 - 8.81mm [.346"]
2 - unmarked commercial

Assuming a Parabellum bullet is .355", that means that the difference in diameter is .007" and .009"...which would work out to grooves .0035" and .0045" deep...

So, yes, my Lugers [as marked!] are ~.004" and would be 'conventionally rifled'...

The central point of the discussion was that a barrel can be shot/worn to the point of groove depth being only ~.002" and still be accurate, if handloaded accordingly (bullet dia selection)...

I don't have any specs here to compare...

But I would have expected a rifle barrel to have shallower grooves, due to its greater length [compared to pistols]...

Anybody like to comment???

FNorm · 10-23-2011, 11:32 AM

Interesting, Rich.

But then lets look at wear. Pistol is short, and uses around 4-5 grs, power. Usual muzzle velocity is around 1200 +. I think it is hard to wear out a pistol barrel. Rifle while longer uses more power and is going 10X the speed of a pistol bullet.

Examples. I load 30.06 in the 2650 fps range, .308 in the 2550fps range. My 6.5 -284 is in the 3300fps range, and I expect to only get about 1200 rounds outta it. M1 Garand barrels are rated in the amount of throat erosion. A 1 is pretty new, a 5 is pretty shot out. About 1000 rnds per number.

FN

nukem556 · 10-23-2011, 11:56 AM

I'm also wondering if they were referring to the Enfield 2 groove barrel for the .005-.008 figure .....I've never slugged my 1943 Long Branch No.4 barrel, but from visual inspection it's easy to see the grooves are quite deep...perhaps for more "bite" given only 2 grooves?

Norm....what do you do with that 6.5-.284 hotrod? Do any NRA long range rifle matches?

FNorm · 10-23-2011, 08:54 PM

Nukem,

That's my 1000 yd gun. 28 inch Obermeyer barrel, 25 power Leupold.

10-23-2011, 10:37 AM	#1
sheepherder Lifer Lifetime Forum Patron Join Date: Feb 2009 Location: ...on the 'ol Erie Canal... Posts: 8,183 Thanks: 1,400 Thanked 4,442 Times in 2,330 Posts	Discussion on Rifling I read this comment on another [Enfield] forum... Well all the Lee Enfield bores I've examined had very deep rifling grooves, as would be expected since original acceptance specs call for grooves from .005 to .008 in depth. Conventional rifling of the day called for grooves .004 in depth. http://www.surplusrifleforum.com/vie...?f=27&t=113788 To put that in perspective, a sheet of lined notebook paper is ~.003"... 'Conventional rifling' applies (I suppose) to other rifles... Does the Luger have ~.004" deep grooves??? Let me see... I see my Lugers barrels are marked as follows: 1 - 8.84mm [.348"] 2 - 8.81mm [.346"] 2 - unmarked commercial Assuming a Parabellum bullet is .355", that means that the difference in diameter is .007" and .009"...which would work out to grooves .0035" and .0045" deep... So, yes, my Lugers [as marked!] are ~.004" and would be 'conventionally rifled'... The central point of the discussion was that a barrel can be shot/worn to the point of groove depth being only ~.002" and still be accurate, if handloaded accordingly (bullet dia selection)... I don't have any specs here to compare... But I would have expected a rifle barrel to have shallower grooves, due to its greater length [compared to pistols]... Anybody like to comment??? __________________ I like my coffee the way I like my women... ...Cold and bitter...

10-23-2011, 08:54 PM	#4
FNorm Patron LugerForum Patron Join Date: Mar 2009 Location: Colorado Posts: 978 Thanks: 68 Thanked 127 Times in 108 Posts	Nukem, That's my 1000 yd gun. 28 inch Obermeyer barrel, 25 power Leupold. Attached Thumbnails

10-23-2011, 11:32 AM	#2
FNorm Patron LugerForum Patron Join Date: Mar 2009 Location: Colorado Posts: 978 Thanks: 68 Thanked 127 Times in 108 Posts	Interesting, Rich. But then lets look at wear. Pistol is short, and uses around 4-5 grs, power. Usual muzzle velocity is around 1200 +. I think it is hard to wear out a pistol barrel. Rifle while longer uses more power and is going 10X the speed of a pistol bullet. Examples. I load 30.06 in the 2650 fps range, .308 in the 2550fps range. My 6.5 -284 is in the 3300fps range, and I expect to only get about 1200 rounds outta it. M1 Garand barrels are rated in the amount of throat erosion. A 1 is pretty new, a 5 is pretty shot out. About 1000 rnds per number. FN

10-23-2011, 11:56 AM	#3
nukem556 User Join Date: Jul 2010 Location: Irmo, SC Posts: 625 Thanks: 35 Thanked 168 Times in 107 Posts	I'm also wondering if they were referring to the Enfield 2 groove barrel for the .005-.008 figure .....I've never slugged my 1943 Long Branch No.4 barrel, but from visual inspection it's easy to see the grooves are quite deep...perhaps for more "bite" given only 2 grooves? Norm....what do you do with that 6.5-.284 hotrod? Do any NRA long range rifle matches?