seating depth 2

[jtl]

Jumping on the back of the other seating depth. Howa 07/08, coal of eld-x to lands is 2.94, but the nearest I can reload because of receiver length is 2.88. This means Ive a huge jump to lands. This the norm? or just stick to other bullets?

 

[NP435]

Jumping on the back of the other seating depth. Howa 07/08, coal of eld-x to lands is 2.94, but the nearest I can reload because of receiver length is 2.88. This means Ive a huge jump to lands. This the norm? or just stick to other

 

[Leupsak]

If they shoot - use them.
If they don't - measure the OAL and adjust along with powder weight.
If nothing works get come Vihtavuori powder and use their load data and if needed change the bullet link

 

[Alantoo]

60 thou a huge jump?

Hornady recommend 2.800" COAL have you tried that?

Alan

 

[weejohn]

It's doesn't matter on the jump as long as they shoot well and your not crushing the powder too much .

 

[HandB]

I find that small bore bullets like .222 and .243 prefer a small jump to the lands such as 15 thou but larger bullets like 7mm and 7.62mm work fine with large jumps, such as 75 or 100 thou. But your mileage may vary so I suggest test out what size jump gives you the tightest groups.

 

[Gm81]

I use Viht data and powder in my 308. I had this made 100 thou longer to take copper. I was obsessed with finding the lands and 20 thou off etc. Then try loads then seating.
After advice from the man that made my rifle and needing a place to start. I just look at Viht Coal and load that with different charge wights. So far I haven't had to play with seating depth. But the jump will be huge in loading terms.
As I learnt you just need a number to start from. Where you end up is part of the reloading journey.
Obviously I load to shoot deer. So touching is good enough. One hole is dream worthy and probably beyond how I shoot.

 

[sikadog]

I use the age old idea of seating the base of the bullet to the base of the neck of the case, its a good place to start and a good place to end.

 

[jtl]

I loaded 5 rounds to 2thou off the lands , had to load separately because of the coal and 1/4 inch at 200yds 3 rounds, now same loading that fit the action and I only got 2 1/2 . I know its usable but the difference is crazy

 

[Terrydeer]

Can you get a magazine to accommodate longer bullets, with the T3x you can put a 270 mag in and happy days

 

[jtl]

No its floor plate so thats as long as it will take.

 

[Foxyboy43]

Hmm.
When I started on my reloading odyssey the rule of thumb was to seat the bullet to the depth of the calibre, check for any pressure signs then if you are that way inclined start to chase the lands then back off whatever length floats your boat…….. Other advice was to load to the length of the magazine except I soon found out that for some rifles some lighter bullets simply fell out of the case!
My goto with a new shape/weight bullet is to seat it in a fire-formed case with a squeezed neck (just tight enough to hold the bullet) then gently chamber the dummy round 5 times measuring the COAL each time as the chamber seats the bullet to length. This gives you your chamber length for that bullet as a starting point and now you can back off to the same floating boat scenario……

 

[Alantoo]

I loaded 5 rounds to 2thou off the lands , had to load separately because of the coal and 1/4 inch at 200yds 3 rounds, now same loading that fit the action and I only got 2 1/2 . I know its usable but the difference is crazy

Have you repeated that to confirm the figures, or are you happy that you can repeat that based on your past experience?

There are too many variables in my shooting to draw conclusions from 3 rounds.

Alan

 

[ChesterP]

Most tangent ogive bullets irrespective of calibre are said to be more jump tolerant than some (but not all) secant ogive designs. It's not unusually to see .308 for example, with mag length being 2.800 and the bullet jumping 60 to 80 thou. My own conclusions on secant ogive bullets, which I'll admit isn't that scientific, are that unless the seater used seats them concentrically (not all will) will exhibit sufficient runout to ruin accuracy. Perhaps loading close and personal to the lands gives less scope for the bullet to become as misaligned. As long as the correct seater is used (which grips around the bullet nose rather than pushing on the tip) I've found that many secant ogives can be quite jump tolerant too. I use a 30 thou jump on some and have no accuracy issues. People tend to get worked up about seating depth and in particular, chasing the lands, which is a rather pointless exercise as why find a seating depth that gives the optimum barrel time only to change it to remain the same distance from the lands? I've stuck to the exact same seating depth for all my loads irrespective of throat erosion and they seem to shoot as accurately now as when the barrels were new. Eric Cortina has published a few videos on Youtube where he shares his findings and concludes the same thing.

I guess there's many analogies you can use to better understand load development variables, but the basics of barrel harmonics depend on pressure rise time (and for those who subscribe to pressure wave theory, that as well) and barrel time. Imagining the barrel sinusoidal harmonics, altering seating time and charge alter the time the bullet takes to reach the muzzle and the optimum is said to be when the bullet arrives coincident with the barrel being on axis for consistent shot to shot accuracy.

Whatever this time is, is a function of pressure (charge applied) and distance travelled, although this is an over-simplification of what actually happens from detonation.

It's a bit like saying that correct camera exposure is a combination of shutter speed and lens aperture where you may have many multiples of either which coincide to give correct exposure, so it is with seating distance and powder charge to meet the optimum barrel time.

 

[jtl]

Yes Allan , Im fairly confident on the results. Im about to try the reloading depths with N540 that they suggest. This will be miles from the lands but well see!

 

[plumber01]

From my experience, ( so worth jack) after playing around with seating depths,( for years) and mainly using long heavy target bullets, it seems the correct SAMI /loading manual length gets better results. If using shorter hunting type bullets, it seems slightly better about 10thou off lands, however as I dont shoot these type of bullets in competitions, it doesnt really matter as I dont need sub 1MOA , and probably cant get it out of a 270 or generally with hunting ammo anyway.
Although weirdly my Sauer 308 is better with a slightly smaller jump than my AI with the exact same bullets, and they both have the same chamber length.

 

[User00044]

60 thou a huge jump?

Hornady recommend 2.800" COAL have you tried that?

Alan

^^^^^^^^^^^^this^^^^^^^^^^^^^

Why are you obsessing about being close to the lands ?
SAAMI spec dictates an o.a.l of 2.800 , your rifle magazine is designed to accept rounds of that length.



Use Hornadys' recommended o.a.l to start , you may be pleasantly surprised .

 

[jtl]

Ive used the recommended depths and achieved a little over moa, where the different bullets allowing Ive been 20 thou off the lands and achieved 1/2 min with the same loads, Ive also single loaded rounds set at this jump to the same ends,wont fit action in multiples so Im interested to see if others have achieved with different settings

 

[dropmdead]

I would suggest to start with Hornady's load data and have a play around with seating depth, going in or out (your choice, no wrong answer either...).
Most of the manufacturers have potentially greater insights to suggesting what works and what doesnt, and when they do its usually not far off....
There's no point in trying to load a hunting rifle with competition methodology, if your rifle chamber has been cut to not allow you to do so.

 

[User00044]

Agh! I see your dilemma.
I personally , start long . It helps if you've something like a Lee hand press , Load all long and work shorter , it'll save you some ammo . Don't forget to take notes