8mm Mauser marked 7.86

jdc606 · July 12, 2016, 11:45 AM

Have a G 24(t) Mauser DOU 41, stamped 7.86 where the barrel meets the receiver. Am assuming this is actual bore diameter and why my 8mm reloads (using .323 bullets) are showing signs of excessive pressure even though powder charges have been mid to low.
No collector value in the rifle as it was re-blued, lumber "cleaned up", top forearm piece trimmed off, back in the day (60's) when folks didn't appreciate history and never thought an unmolested WWII rifle would be worth more than $20-$40.
Should I quit shooting this rifle even using minimum recommended powder charges? I have a couple hundred old Remington 170 gr. marked .322 on the box or am I just asking for trouble? I am not into casting lead bullets and would prefer using up the old components.

mapsjanhere · July 12, 2016, 12:19 PM

No, that's in the normal range for 8mm Mauser. They used a test plug to get the land-to-land diameter, not the groove-to-groove diameter as typically described in the English literature.

TimSr · July 12, 2016, 12:31 PM

Early 8mm Mausers had a .318" bore instead of the .323". I'm not familiar with the markings you mention, but I'm pretty sure .323" is 7.92mm which would make 7.86mm pretty close to .318" off the top of my head, without doing any real math.

jdc606 · July 12, 2016, 03:20 PM

So much to learn about K98's. Found a Mauser 98 Tech page where a member measured the bores of 8 or so different 98's. The Czech manufactured as is my G24 had measured bore diameters like mine 7.86mm = .309. The author recommends using max loads 4.5-5 grs. less than published maximum data for German made K98's.
The Czechs are tighter land to land with wider rifling lands than typical 98's used for reloading development.

Link to article: http://www.mausershooters.org/display/tech_articles.htm

mapsjanhere · July 12, 2016, 05:15 PM

The Germans made 255,000 of them, and used them with their standard load all through the war. I don't think you'd have to worry too much.

July 12, 2016, 11:45 AM	#1
jdc606 Senior Member Join Date: October 24, 2015 Posts: 129	8mm Mauser marked 7.86 Have a G 24(t) Mauser DOU 41, stamped 7.86 where the barrel meets the receiver. Am assuming this is actual bore diameter and why my 8mm reloads (using .323 bullets) are showing signs of excessive pressure even though powder charges have been mid to low. No collector value in the rifle as it was re-blued, lumber "cleaned up", top forearm piece trimmed off, back in the day (60's) when folks didn't appreciate history and never thought an unmolested WWII rifle would be worth more than $20-$40. Should I quit shooting this rifle even using minimum recommended powder charges? I have a couple hundred old Remington 170 gr. marked .322 on the box or am I just asking for trouble? I am not into casting lead bullets and would prefer using up the old components.

July 12, 2016, 12:19 PM	#2
mapsjanhere Senior Member Join Date: August 6, 2009 Location: Albuquerque Posts: 2,832	No, that's in the normal range for 8mm Mauser. They used a test plug to get the land-to-land diameter, not the groove-to-groove diameter as typically described in the English literature. __________________ I used to love being able to hit hard at 1000 yards. As I get older I find hitting a mini ram at 200 yards with the 22 oddly more satisfying.

July 12, 2016, 05:15 PM	#5
mapsjanhere Senior Member Join Date: August 6, 2009 Location: Albuquerque Posts: 2,832	The Germans made 255,000 of them, and used them with their standard load all through the war. I don't think you'd have to worry too much. __________________ I used to love being able to hit hard at 1000 yards. As I get older I find hitting a mini ram at 200 yards with the 22 oddly more satisfying.

July 12, 2016, 12:31 PM	#3
TimSr Senior Member Join Date: March 8, 2013 Location: Rittman, Ohio Posts: 2,074	Early 8mm Mausers had a .318" bore instead of the .323". I'm not familiar with the markings you mention, but I'm pretty sure .323" is 7.92mm which would make 7.86mm pretty close to .318" off the top of my head, without doing any real math.

July 12, 2016, 03:20 PM	#4
jdc606 Senior Member Join Date: October 24, 2015 Posts: 129	So much to learn about K98's. Found a Mauser 98 Tech page where a member measured the bores of 8 or so different 98's. The Czech manufactured as is my G24 had measured bore diameters like mine 7.86mm = .309. The author recommends using max loads 4.5-5 grs. less than published maximum data for German made K98's. The Czechs are tighter land to land with wider rifling lands than typical 98's used for reloading development. Link to article: http://www.mausershooters.org/display/tech_articles.htm