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-   -   7mm-08 specs (https://www.huntingnet.com/forum/reloading/300760-7mm-08-specs.html)

zrexpilot 08-17-2009 04:26 AM

7mm-08 specs
 
I boughta H&R barrel for my rifle in 7-08 and I am having accuracy problems., using factory ammo. I am new to reloading and I am loading up some loads for it. I did some checks on the chamber to find COL and it seems this chamber might be shorter than normal. Is there a certain spec, say from back of case to the lands and what is it for a 7-08. Someone told me on another board to check that but I havent got a response back. I used a spent case and put a bullet into it leaving it long and smoked the bullet with a lighter, chambered it and pulled it to check COL and the lands leave a mark on the bullet as well, it was 2.21 to the lands and COL was 2.83 on a 139 gr.

LaneNebraska 08-17-2009 05:11 AM

The MAX COL seems to be 2.80, So I would drop it down to 2.70 and start there. Cause it seems your chamber is a little shorter....

Here are some very informative links on the 7mm-08:

http://www.realguns.com/archives/158.htm

http://www.chuckhawks.com/7mm-08.htm


http://reloadersnest.com/frontpage.asp?CaliberID=43


Hope this helps:s1:

bigcountry 08-17-2009 06:38 AM

Specs are 2.8" for max COL. I have a short chambered 7mm-08 where I can only load to 2.74" and be .005 off the lands. But I like it that way.

If you can load a bullet to 2.83 COL and bearly touch the lands then its not short chambered.

zrexpilot 08-17-2009 06:56 AM


Originally Posted by bigcountry (Post 3410177)
Specs are 2.8" for max COL. I have a short chambered 7mm-08 where I can only load to 2.74" and be .005 off the lands. But I like it that way.

If you can load a bullet to 2.83 COL and bearly touch the lands then its not short chambered.


with a 139 gr its touching lands at 2.83 . So where would you seat this bullet at to start.
with a 120 gr its touching lands at 2.88, where would you seat this bullet at to start.

Pawildman 08-17-2009 07:50 AM


Originally Posted by zrexpilot (Post 3410192)
with a 139 gr its touching lands at 2.83 . So where would you seat this bullet at to start.
with a 120 gr its touching lands at 2.88, where would you seat this bullet at to start.


.........Personally, I like to start my load development at .020" off the lands. If I find a promising load, I'll start tinkering with seating depth. I realize some folks like to start just on or just off the lands.....just the way I like to do it...

LaneNebraska 08-17-2009 08:17 AM


Originally Posted by zrexpilot (Post 3410192)
with a 139 gr its touching lands at 2.83 . So where would you seat this bullet at to start.
with a 120 gr its touching lands at 2.88, where would you seat this bullet at to start.

For the 139g I'd load at: 2.70, 2.75, 2.77, 2.78, 2.79, 2.80

For the 120g I'd load at: 2.75, 2.80, 2.81, 2.82, 2.83, 2.84, 2.85



I never seat bullets touching the lands, that's just me....

bigcountry 08-17-2009 08:29 AM


Originally Posted by zrexpilot (Post 3410192)
with a 139 gr its touching lands at 2.83 . So where would you seat this bullet at to start.
with a 120 gr its touching lands at 2.88, where would you seat this bullet at to start.

Personally. I would load at 2.8" for both to start out. find a load that is promising from different powder combos. After you find a good range of powder load, play with the COl a little. Load to 2.78, 2.8, and 2.82. See if one gets you where you want.

zrexpilot 08-17-2009 12:55 PM

seems like I could wear a barell out before I find a good load. LOL
whats acceptable cool down between shots, is a warm barrell ok or does it need to get back to air temp
I have 40 rounds loaded in sets of 5, gonna do 5 shot groups

zrexpilot 08-17-2009 03:15 PM

this barrell might have a problem.
For one my 120 gr measure .2815 and my 139s measure .282.
well when I seat the bullets .03 under, my 120's push in fine leaving no marks on a bullet I felt pened. the 139 feels tight being fed and is leaving a mark at one side of the bullet.
Like the area of the throat

I have checked and rechecked and come up with the same numbers. I did the cleaning rod method in the bore for COL and it matches up perfect with the other way.
2.83 for 139's
2.88 for 120's
even .05 off the 139,s leaves a mark on one side of the bullet
??????????

bigcountry 08-19-2009 06:51 AM


Originally Posted by zrexpilot (Post 3410652)
this barrell might have a problem.
For one my 120 gr measure .2815 and my 139s measure .282.
well when I seat the bullets .03 under, my 120's push in fine leaving no marks on a bullet I felt pened. the 139 feels tight being fed and is leaving a mark at one side of the bullet.
Like the area of the throat

I have checked and rechecked and come up with the same numbers. I did the cleaning rod method in the bore for COL and it matches up perfect with the other way.
2.83 for 139's
2.88 for 120's
even .05 off the 139,s leaves a mark on one side of the bullet
??????????

Hmm,thats not good. So your saying loading to 2.78", you see land marks on the side? Mossyoak33 was at my house one day with his 7mmmag, and I could feel some sort of imperfections in the throat using my stoney point tool.

Have you tried the split case method yet? Take a dremel and split the neck and tiny bit of the shoulders. Just enough tension to hold a bullet in place, and chamber and pull out and see?


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