I did a test on a 222 Remington seating depth, and got hardly any difference.

Now I have finished the neck tension test, I thought of running a seating depth test on the same rifle.

Any guesses??

I have only hunting rifles and have mucked around a bit testing seating depth, always to find the optimal depth contributing to best and most consistenf accuracy. In almost all cases the optimal seating depth sweet spot was a little off the lands. Sometimes I had to go a little deeper to get cartridge fit into a magazine. I experimented with progressively deeper seating just to see what happened to accuracy.
In all cases when I moved too far from the sweet spot groups opened up. The degree of group enlargement seemed relevant to the combination of components used for the particular load. Some groups opened only gradually, others dramatically.
It was not as scientific in approach as your tests Saeed so I will be interested to see your results.

Just checked the throat in this rifle.

2.980" touching the lands.

Maximum over all length for the 308 is 2.800, so this one has a long throat.

Should be interesting to see what happens.

curious how you will set up the test. what brass are you using "the same once fired from the neck tension test"?
Are you going to use different tensions or one constant
thanks

Sorry, I should have explained.

I will use a Redding FL and seating due set.

I will use the same rifle.

Same powder.

Same bullets.

I loaded a bullet way out.

Chambered it, and measure the over all length.

I did this 3 times.

Lengths varied between 2.981 - 2.984.

So I am going to use 2.980 as a starting point.

My intention is to increase the seating depth by 0.030” to start with.

Once I am down to 2.800 - which is the maximum fir the 308, I will increase it by 0.020”.

This will involve a lot of shooting, but I think I need the practice.

I am going hunting next month.

Missed my hunt last year

one of my high velocity cast bullet rifles loves 1.5 thou of neck tension.

but the key is the bullets are seated long and are allowed to be seated to the same oal by chambering the round.

if I up the tension I need to move the bullets back .005.

I also HAVE to turn the case necks to get the rounds to chamber so the bullet being centered to the barrel before being chambered like above is imperative.

your rifle probably doesn't have the problems mine does, but a low neck tension higher start pressure might be the velocity equaling out your looking for.

kind of a mashup of the two techniques you been playing with.

quote:

Originally posted by Lamar:
one of my high velocity cast bullet rifles loves 1.5 thou of neck tension.

but the key is the bullets are seated long and are allowed to be seated to the same oal by chambering the round.

if I up the tension I need to move the bullets back .005.

I also HAVE to turn the case necks to get the rounds to chamber so the bullet being centered to the barrel before being chambered like above is imperative.

your rifle probably doesn't have the problems mine does, but a low neck tension higher start pressure might be the velocity equaling out your looking for.

kind of a mashup of the two techniques you been playing with.

How can you consistently measure seating depth to 0.005”?

Seating depth

Yes

You need it.

For most hunting applications with cup and core bullets.

I never found much difference.

Can it make a difference yes.

Is it worth while playing with yes, no and maybe.

It all depends on what your trying to do with any peculiar rifle.

I got it easy.
I designed the bullet and the chamber reamer then I had the mold made.

so the ogive isn't really a normal ogive, it's a taper similar to the one Hornady uses.
that makes measuring to the same place on the bullet a breeze.

anyway. the point was about allowing the rifle to seat the bullet and find it's center, rather than doing it 100% with a size die.
the neck tension is enough to not let the bullet rattle around, but not too much to stop it from moving easily under bolt pressure.

the key is insuring you have a slightly worked neck like 2 steps in from an annealed case so the tension is equal.

an interesting article I read on the subject.

https://precisionrifleblog.com...ad-development-tips/

For my rifles depth does seem to make a significant difference in "most" cases. I am playing around with hammer bullets in a few and those seem to be a bit less bothered by seating depth, which is nice.

I was recently testing some 168gr berger vld's in a 7rem mag, and followed berger's testing protocol. load up a bunch of 1 powder charge, and play with seating depth of .010", .050", .090" and .130", and fire groups.

In my rifle the groups got smaller with each depth change, with the last 2 being pretty close, just under 1". The first 2 groups were about 2", then 1.5", then just under 1", then 0.75". kinda neat to see.

Well that's certainly interesting - if I'm reading this right, the best accuracy for this rifle was from .12 to a little more than 1/4 of an inch of bullet jump.

Over the years, my rifles, of various calibers, various bullets have always shot more accurately with the bullet touching the lands.
Another part of this, the case mouth flaring for bullet seating, is left to a very minor degree. As I chamber the round slowly I can feel a slight gritting, scraping during the last gnats eye lash of going forward into chamber.
This was not discovered through any research, it was an over sight on my part. I was loading 20 rounds od 25-06 with 100 grain Speer HPs for plinking and ground hogs. I had 20 or so rounds of the loads from a earlier batch. What loosened the seating die, I have no idea. The new batch shot a tighter group then the earlier group.
I tried the same thing on 243, 405 Win, 375 Whelen, 45-70, 30-06, with jacketed and cast bullets.
The down ide is all cases need to be uniform length, and no balls to the wall loads

We follow a simple procedure.

All brass is trimmed.

I actually separate brass by weight too.

All these are within one grain of weight.

Under normal conditions, I load everything to the maximum allowed for that cartridge.

Certain bullets - lighter ones - don’t work this way.

So I make sure to seat one caliber in the case.

I am sure the shape of the bullet might have an effect on the seating.

So my suggestion is try whatever works for you.

One can never shoot too much

Hi Saeed,
Firstly, thankyou for testing another aspect of cartridge / reloading physics. Always interesting although I must admit I sometimes struggle to distinguish much from your results as nearly all the groups you shoot are much, much better than those I ever achieve. Makes me think either you are a bloody good shooter, or handloader, or both, although far too modest to admit as much But anyway, it leads to my question.
After assembling these results what conclusions have you drawn yourself from this particular test re seating depth ? Would you amend any of your current loading practises as a result ?

This is actually the second test I did on this.

Previously I tried a 222 Remington.

Same results.

For my bench guns, I always seat the bullets to touch the rifling.

It is easy to do, and as they are single shot, there is no problem on feeding.

For other guns, I have followed a simple rule.

Load each round to the maximum allowed for it.

Sometimes that is not possible with light bullets.

In this case I seat the bullet one caliber into the case.

This has worked for me so far, and I honestly cannot see - from my own results - that I should change that.

The good groups you see are mainly due to an accurate rifle, and I do tend to makes sure the variables are as small as possible.

Shooting indoor helps too.

quote:

In this case I seat the bullet one caliber into the case.

Appreciate your comments thanks Saeed.

In regard to the above statement how do you calculate this with Boattail bullets. Does the "one calibre" measurement include the boattail length or is measurement taken only on the bullet bearing surface ?

quote:

Originally posted by 30.06king:

quote:

In this case I seat the bullet one caliber into the case.

Appreciate your comments thanks Saeed.

In regard to the above statement how do you calculate this with Boattail bullets. Does the "one calibre" measurement include the boattail length or is measurement taken only on the bullet bearing surface ?

It should be one caliber of tension surface, so that does not include the boat tail.

What I do is put a boat tail bullet in the case, by hand, and measure how long that is.

Then substract a caliber length from it and that gives me a number to substract a caliber length from to get the over all length..

Not sure how all this works, but in theory it is supposed to keep the bullet straight.