Powder Versus Seating depth?

Which do you adjust first?


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Monkey Spanker

Well-Known Member
Just curious as to which is generally tackled first when developing a load. Do you adjust the powder weight first then the seating depth, or vice-versa? Is there any reliable information as to which is the preferred method?:confused:
MS
 

Brithunter

Well-Known Member
I always try to seat the bullet so that it's base as at the neck/shoulder juncture and work the powder charge out from there. I do not subscribe to this must be close to the lands stuff at all.
 

Monkey Spanker

Well-Known Member
I always try to seat the bullet so that it's base as at the neck/shoulder juncture and work the powder charge out from there. I do not subscribe to this must be close to the lands stuff at all.

So are you saying that you ONLY alter the powder weight and don't bother with seating depth at all?:confused:
 

Richard S

Well-Known Member
I'm new to reloading and am at present working on my first .243 load.
I have been going on the basis that the bullet should be seated just off the lands, which seems logical, but some people obviously disagree.
​I made an OAL guage based on the Hornady one. Have I wasted my time ?
Also, I've never heard of adjusting seating depth, after getting the powder sorted, to improve accuracy. If I try this is it trial and error, or is there some sequence I should follow.
Any advice would be appreciated.

Richard
 

Dovebob

Well-Known Member
I'm no expert, but with the 8 or so loads I've worked up I've done powder weight first and have been able to get good accuracy by varying that. I've not yet needed to adjust the seating depth.
 

Monkey Spanker

Well-Known Member
I'm new to reloading and am at present working on my first .243 load.
I have been going on the basis that the bullet should be seated just off the lands, which seems logical, but some people obviously disagree.
​I made an OAL guage based on the Hornady one. Have I wasted my time ?
Also, I've never heard of adjusting seating depth, after getting the powder sorted, to improve accuracy. If I try this is it trial and error, or is there some sequence I should follow.
Any advice would be appreciated.

Richard

I too measure the max OAL to the lands by having a bullet in a case which is just tight enough to be seated by the lands. I then set my initial loads at 20 thou back from this. I then load batches of 5 rounds at the start load powder weight and every whole grain up to the max. I test fire them at the lower weight first and upwards, carefully checking for signs of over-pressure at each stage. This normally gives me a definite weight with a better group than the others.
I then use this weight and make further batches with seating depths at every 10 thou towards and away from the lands up to 40 thou, ie, 0, 10, 30 & 40.
By this point, I have usually got my group down to sub MOA which is generally good enough. You could go every half grain of powder or every 5 thou if you wanted to perfect it I suppose, but for general stalking purposes, this method should work fine. I have friends who do it the other way around though! I'm not sure which is best or why, hence my post!
MS
 

Paul 600

Well-Known Member
You might want to see your new bullets a little deeper as per the manufactures recommendation. Think they suggest 50 thou.
 

Sharpie

Well-Known Member
Select a sensible seating depth that fits in the magazine, ensures at least one bullet diameter of neck is gripping the bullet, and IS NOT just a few thou off the lands. Base of bullet at neck junction is good.

The closer you get to the lands the more finnicky you can expect small variations to be, and your dies will have to be more precisely adjusted. Also if afterwards you want to try larger jumps then there is a risk that you will increase the pressure as the volume of the case is reduced, particularly if the powder is close to 100% of case capacity. If you start with a good jump, it is safe to try moving the bullet out, but not the otherway round.

Or copy the seating depth of a factory round that works OK in your rifle.

Choose a powder that will not be a 100% or compressed load when at max.

Work up the charge weight. You don't need to shoot 3 shots groups at each load unless you want to, you can use the ladder method which only needs one shot at each load.

Stop working up the load if you see pressure signs.

You should find that there are one or more ranges where small charge variations do not affect point of impact significantly. These are the "sweet spot(s)" you want to be using.

Choose a sweet spot, load up five rounds at the middle of the range, test for accuracy.

If it is acceptable for hunting you can stop at this point.

You could then try variations in seating depth if you want, but it is likely to have much less influence.

Then you could go back to charge variations,

​And so on ad-infinitum.

IME charge weight variation has the biggest influence, and anyway needs to be tested whilst exploring the pressure range, so should be tried first.
 

Monkey Spanker

Well-Known Member
You might want to see your new bullets a little deeper as per the manufactures recommendation. Think they suggest 50 thou.

Ahh yes, I also read that about the barnes copper ones! That could lead to higher pressures though as the copper bullets are much longer and therefore reduce the volume of the case. Need to be a bit more careful towards the max loads I suspect, especially with my Ackley cases!
MS
 

Monkey Spanker

Well-Known Member
IME charge weight variation has the biggest influence, and anyway needs to be tested whilst exploring the pressure range, so should be tried first.

Although that makes sense, seating the bullet deeper will then also increase the pressure! ;)
MS
 

Paul 600

Well-Known Member
Ahh yes, I also read that about the barnes copper ones! That could lead to higher pressures though as the copper bullets are much longer and therefore reduce the volume of the case. Need to be a bit more careful towards the max loads I suspect, especially with my Ackley cases!
MS

I think you will find you can get faster loads due to less friction. the rings mean less surface are contact. Ive measured my 120 grains at 3000 fps with 46 grains of N160. The book gets it no where near that!
 

PeterH

Well-Known Member
Powder weight first using the OCW method and then fine tune distance from the lands.
 

Muir

Well-Known Member
I'm new to reloading and am at present working on my first .243 load.
I have been going on the basis that the bullet should be seated just off the lands, which seems logical, but some people obviously disagree.
​I made an OAL guage based on the Hornady one. Have I wasted my time ?
Also, I've never heard of adjusting seating depth, after getting the powder sorted, to improve accuracy. If I try this is it trial and error, or is there some sequence I should follow.
Any advice would be appreciated.

Richard

Why is that logical??

I am like Brit. I seat the parallel sides of the bullet to the base of the shoulder and deal with powder charge. (with magazine considerations applied) I seldom need to adjust length. Loaded my new 7-08 using this method yesterday. Sub-MOA five shot groups. Now I will adjust the powder a bit and see what that does.~Muir
 

Sharpie

Well-Known Member
Although that makes sense, seating the bullet deeper will then also increase the pressure! ;)
MS

If you do as I suggest and start with a pretty good jump, then afterwards you can experiment with seating the bullet further out to get nearer to the lands without having to worry. Also best not to be working at the ragged edge of pressure, or 100% case-filling loads. If a few 1/1000" of difference in seating depth is going to cause a pressure spike then you also need to be weighing your cases, re-testing every batch of powder etc. etc. Not really applicable for hunting ammo.
 

Sharpie

Well-Known Member
I think you will find you can get faster loads due to less friction. the rings mean less surface are contact. Ive measured my 120 grains at 3000 fps with 46 grains of N160. The book gets it no where near that!

Barnes, and similar bullets, need to have a reasonable jump to the lands so that they are shifting when they engage the rifling, and their momentum helps them engrave. If you start them too close to the lands, or even touching, then it can cause dangerous pressure increases because it takes much more force to engrave into the rifling compared with a jacked lead design. Almost like a barrel obstruction.

Pressure should be allowed to build up until neck tension (and crimp, if any) release the bullet. After that the bullet should enter and engage the rifling without stopping momentarily. It needs to have a certain kinetic energy and momentum for this to work, which means it has to fly free for a short distance (jump to the lands)

The rings on a Barnes are intended to reduce this problem, but have the potential downside that the rifling may strip them more easily due to reduced contact area.
 
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