Starting Seating Depth ?'s

B

boatbum101

Beginner
Feb 7, 2018
10
0
Generally speaking it's been my experience that cup & core like to be seated out if possible . Monometals like more of a jump IIRC Barnes states start with .050 off . Where in this scheme of things do the NAB & NPT fall ? I've read that some treat them as a cup & core & that some have found they like a jump of more generous dimension . My endeavour this time is hunting loads for a 6.5X55 Tikka T3 & a recently rebarreled Rem 700 30-06 . Bullets on hand for 6.5 include 120 NBT , 140 NBT , 140 NAB , 140 NPT , Horn 129 SP , Horn 140 SP & SST , Horn 160 RN , Norma 156 Vulkan , 156 Oryx , 156 Alaska & Lapua 155 Mega . I belive with the possible exceptions of the Oryx , NAB & NPT these are all cup & core & should be treated as such . In my rifle the closest I canget with the 120 NBT is .032 off & still keep a caliber's worth of shank in the neck so the only place I have to go is further off if this doesn't work . The Horn 129 will leave me only .006 off & everything else will have to be seated deeper to give .010 - .020 off . I know this is subjective & the rifle will tell me what it wants .
For the 30-06 it'll feed 3.400 oal thru the mag with no problem & I only have a few types on hand 150 & 165 Speer HC SPtz , 165 NPT & 180 Horn SP . These are all cup & core so no unknown there . The 150 again keeping enough shank in the neck will only allow an oal of 3.197 which leaves me .178 off , 165 HC will leave me .151 off & 165 NPT will leave me .098 off . No great loss if they don't shoot I'll just go heavier or with longer bullets .
 
When I start load development, I check magazine length, and I check distance to lands, and seat .020" to .030" off as long as it fits my magazine. I adjust seating depth in or out to tighten up groups, but I don't like to jam bullets into the lands. I will go as close as a light kiss to the lands if need be, or seat further out to adjust for accuracy.
 
For me and for most hunting rifles I have owned. I always start at maximum magazine length and shorten, .10 at a time. On most of mine the magazine is the limiter. I have found the LRAB challenging for accurate loading but the AB not so hard. In the 7 calibers the 162 gr, BTSP Hornady has always been very accurate but not a good performer on elk. In the .308 the Nosler 168 gr CC, is a stellar performer on targets, and the 180 Partitin is a stellar performer on big game. I shot some very good groups last fall in my 300 WM with th 180 Speer FB, sub MOA at 300 yards
 
As a rule of thumb, providing that magazine depth allows the application of the rule of thumb, I seat all cup-and-core bullets as close to the lands as practical for the initial testing. Most cup-and-core bullets have shot best for me at between 0.005 and 0.020 inches off the lands. Monolithic and bonded-core bullets have always performed best (with very few exceptions) with a sizable jump to the lands. Most monolithic and bonded-core bullets have wound up being at close to 0.100 inches off the lands. Partitions and A-Frames have acted much as cup-and-core bullets; I have loaded them somewhat close to the lands. This has held across a broad spectrum of calibres (from 0.204 to 0.458) and cartridges for many years.
 
Thanks Gentlemen this gives me something to work with . It too has been my experience that the Hornady bullets are too soft for larger game & sometimes iffy on large hogs & bear at less than ideal angles . OK for boiler room or neck shot but not for a shoulder shot . Generally do OK on deer .
 
5shot":2fa6hynw said:
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
Click to expand...

+1 for Berger’s method. Works for many bullets, not just VLDs.


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joelkdouglas":2dxhq3un said:
5shot":2dxhq3un said:
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
Click to expand...

+1 for Berger’s method. Works for many bullets, not just VLDs.
Click to expand...

That's the method I use as well.
 
taylorce1":2qvpynn3 said:
joelkdouglas":2qvpynn3 said:
5shot":2qvpynn3 said:
http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/
Click to expand...

+1 for Berger’s method. Works for many bullets, not just VLDs.
Click to expand...

That's the method I use as well.
Click to expand...

Same here, but I skip the up close intervals with Bonded Bullets.
 
Interesting isn't it?

There may be an optimal length for accuracy, but with a lot of rifles, it's not possible to use that length, and still have the cartridge feed through the magazine.

Examples of mine include:

Most traditional lever actions, like my 30-30 Glenfield. For smooth functioning ammo, I really need to load to factory lengths. It's easy with the lever-actions, basically just seat to the cannelure and crimp.

A CZ varmint rifle in 204 Ruger. The rifle has a detachable magazine, which severely limits the cartridge length. If I try to seat the bullets out farther, they simply won't fit in the magazine.

My Rem 700 short action. I can get just a skosh (very scientific measurement, learned from Mom) over the factory 2.8" then ammo won't fit into the magazine. With the original factory barrel, I could seat the bullet out so danged far, the loaded cases looked silly! They could only be single-loaded. The Krieger barrel has much shorter chamber/leade.

My Model 70 Win cycles factory length 375 H&H cartridges very nicely. Loaded "long" they produce excellent accuracy, but won't fit in the magazine, or cycle through the action.

I've found that for a lot of hunting rifles, it doesn't really matter how far off the lands I might want to seat them, basically if I don't load the ammo to factory lengths, it won't fit in the magazine or cycle through the action.

A little off-topic perhaps, but it's the first thing that occurred to me with my morning coffee after reading this.

Guy
 
Guy Miner":33f64v0o said:
Interesting isn't it?

There may be an optimal length for accuracy, but with a lot of rifles, it's not possible to use that length, and still have the cartridge feed through the magazine.
Click to expand...

Guy,

I use the Berger method with max COAL that feeds from the magazine. I still find it works very well, I'm currently working with my 6X45 and 105 RDF bullets. The RDF touches the lands at 2.64" but feeds from the mag at 2.44", so I'll just start there and my next jump will be to .050" off lands. When I move to 100 grain Sierra and 95 grain NBT I'll be able to get closer to the lands at magazine length.
 
boatbum101":4x0cx8pe said:
Generally speaking it's been my experience that cup & core like to be seated out if possible . Monometals like more of a jump IIRC Barnes states start with .050 off . Where in this scheme of things do the NAB & NPT fall ? I've read that some treat them as a cup & core & that some have found they like a jump of more generous dimension . My endeavour this time is hunting loads for a 6.5X55 Tikka T3 & a recently rebarreled Rem 700 30-06 . Bullets on hand for 6.5 include 120 NBT , 140 NBT , 140 NAB , 140 NPT , Horn 129 SP , Horn 140 SP & SST , Horn 160 RN , Norma 156 Vulkan , 156 Oryx , 156 Alaska & Lapua 155 Mega . I belive with the possible exceptions of the Oryx , NAB & NPT these are all cup & core & should be treated as such . In my rifle the closest I canget with the 120 NBT is .032 off & still keep a caliber's worth of shank in the neck so the only place I have to go is further off if this doesn't work . The Horn 129 will leave me only .006 off & everything else will have to be seated deeper to give .010 - .020 off . I know this is subjective & the rifle will tell me what it wants .
For the 30-06 it'll feed 3.400 oal thru the mag with no problem & I only have a few types on hand 150 & 165 Speer HC SPtz , 165 NPT & 180 Horn SP . These are all cup & core so no unknown there . The 150 again keeping enough shank in the neck will only allow an oal of 3.197 which leaves me .178 off , 165 HC will leave me .151 off & 165 NPT will leave me .098 off . No great loss if they don't shoot I'll just go heavier or with longer bullets .
Click to expand...
Both my 700s 7mm mag and 3006 shot the tightest groups with accubonds seated out as long as possible so they were just engaging the rifling. Didn't have any issues with the magazine in either. I tried 6 or 7 different powders in each and reloader 22 gave me the best groups and velocity in both. My 3006 with 180 Accubonds max charge re 22, was about 2,750 fps from a 24 in rem 700

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I really don't play around to much and 90% of the time I'm .010 off the lands. On Big Game rifles if it shoots MOA or better I'm done.
Why because there Big Targets and in close to 40 years of hunting when I have missed it wasn't because of the load, it was Me.
 
1100 Remington Man":kkp12ej9 said:
I really don't play around to much and 90% of the time I'm .010 off the lands. On Big Game rifles if it shoots MOA or better I'm done.
Why because there Big Targets and in close to 40 years of hunting when I have missed it wasn't because of the load, it was Me.
Click to expand...

Agreed, and I go about my stuff the same way, as long as I can hold MOA'ish sorta groups out to 600 I figure anything else is probably more my fault than my load/rifle.. :mrgreen:
 
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