7 Saum neck diameter, ordering a reamer

M

montanablackdog

Well-Known Member
Joined
Feb 8, 2011
Messages
136
Im the process of ordering a 7 Saum reamer for 180 class bullets. And looking at a .185 free bore with a .3185 neck diameter. My Smith thinks that might be a little tight on the neck diameter and to maybe go SAAMI of .3220. Any experiences or feedback?
 
C

can1010

Well-Known Member
Joined
Feb 27, 2012
Messages
1,432
with ADG brass you want .320 min. and .322 will be ok. my 7 saum has .318 with .225 free bore and i have to turn my necks to clean them up and the longer free bore works with 175-180 hornadys and bergers and most monos but is a little long for the 165-168 class those are better .180-.190 free bore
 
Mikecr

Mikecr

Well-Known Member
Joined
Aug 10, 2003
Messages
6,084
Location
NC, oceanfront
Your 'smith' wants to go 3.5thou bigger? wow
How thick are your necks. Or measure loaded neck OD.
Any thickness under 17thou is clearance.
 
C

can1010

Well-Known Member
Joined
Feb 27, 2012
Messages
1,432
Your 'smith' wants to go 3.5thou bigger? wow
How thick are your necks. Or measure loaded neck OD.
Any thickness under 17thou is clearance.
ADG brass .3165 with 180 hybrid
 
M

MagnumManiac

Well-Known Member
Joined
Feb 25, 2008
Messages
4,376
I have only one neck turn barrel left…..moved away from them some time ago now.
When I order my reamers, after measuring case neck wall thickness, I order a neck that is .003” larger than a case with a bullet loaded in it. .004” is my absolute maximum clearance.
If you go with a turn neck chamber, buy as much brass, 200-300, as you can find and turn them all the same to give you .003” clearance. Any tighter than this can cause major issues.

Cheers.
 
Mikecr

Mikecr

Well-Known Member
Joined
Aug 10, 2003
Messages
6,084
Location
NC, oceanfront
ADG brass .3165 with 180 hybrid
So with that, the OP would already have 2thou clearance.
Some may call that tight but it's not really. And another 1thou would be ok as well, but another 3.5thou is excess for sure.

All that expansion on firing has to be sized back for reloading.
Keep that in mind, as the more sizing you do, the higher the prices for it.
 
C

can1010

Well-Known Member
Joined
Feb 27, 2012
Messages
1,432
i would never go .002-.003 on a hunting gun with all the differences lot to lot and manufacture to manufacture and todays market having to settle for what is available not always what you want unless you are set up to turn necks.
.004-.006 clearance and a good bushing die will serve you well without overworking brass and a lot less headaches.
 
Mikecr

Mikecr

Well-Known Member
Joined
Aug 10, 2003
Messages
6,084
Location
NC, oceanfront
Except ~5thou does work necks more than necessary.
That reloading for a 'hunting gun' might be assumed as sloppy, is really a matter of choices (not chance).
Your choice could be to work necks more than I would -or not.

My guns are hunting guns. They don't have or need clearances that high.
 
C

can1010

Well-Known Member
Joined
Feb 27, 2012
Messages
1,432
hunting gun doesn't mean being sloppy it means putting a bullet into the killzone of your quarry effectively and accurately at your max effective range. we aren't trying to hit the same bullet hole every time for trophy/money and even then we are hearing more and more shooters are increasing clearances and not loosing accuracy, even some are saying the extra clearance gives better bullet release for more consistency.
 
Mikecr

Mikecr

Well-Known Member
Joined
Aug 10, 2003
Messages
6,084
Location
NC, oceanfront
Extra clearance DOES NOT provide better bullet release.
A bullet fully releases with ANY clearance. I've tested it.
The only time clearance affects bullet release is when there is truly zero clearance/interference fit.
And anyone with a bolt action would know they were trying to chamber a round into that condition.

If the OP wants to go ~5+thou neck clearance, then I will just suggest he anneals consistently, constantly, and load develops with that.
 
M

MagnumManiac

Well-Known Member
Joined
Feb 25, 2008
Messages
4,376
i would never go .002-.003 on a hunting gun with all the differences lot to lot and manufacture to manufacture and todays market having to settle for what is available not always what you want unless you are set up to turn necks.
.004-.006 clearance and a good bushing die will serve you well without overworking brass and a lot less headaches.
I turn my necks to give me the .003” clearance if needed. I skim turn anyway to keep my neck tension consistent.
I have rifles with anywhere up to .008” neck clearance, my new 300RUM is a good example. I will be turning them too, but I will only be doing that after they are annealed and sized, not before.
That is a lot of brass movement and will have to be managed.
I agree with people moving away from tight clearances…..I did that very thing some time ago. It makes no difference to accuracy in any way you can measure, but going too loose does effect the brass.

Cheers.
 
loonie

loonie

Well-Known Member
Joined
Dec 15, 2012
Messages
233
Location
Montana
I would go with what you listed , then skim turn your necks to exactly the clearance you want . Your freebore minimum for 180 gr bullets. I have .200 on mine and it perfect for 180 vld and 175 lrab.
 

Similar threads

T
Replies
2
Views
793
Tmccoy
T
H
Replies
0
Views
320
highdrum
H
M
Replies
7
Views
6K
L
H
Replies
12
Views
3K
gebhardt02
G
C
Replies
3
Views
2K
trueblue
trueblue

Recent Posts

Top