Seating depth constancy

[Grimstod]

Ok I got both a revelation and a few questions here. I was recently forced, through various circumstances, to use a Lee press. Two of them actually. I took my Forester dies with me and after re setting them for seating depth I seated about 30 rounds. When I started checking them with my Hornady comparator I was shocked to see how much the seating depth varies. It was like 6 thousandths from round to round. So when I got home I pulled the remaining rounds and reseated them with my Redding Press. I started checking them and noted that they were jumping around a bit to, not nearly as badly but still sometimes it was like 3 thousandths of difference. So naturally I starting self examining.
1. I checked all the linkage. It was all good.
2. I tried to make my stroke with the handle as consistent and smooth as posable.
After I did this it got better. now I only see about a .001 of variance.

Now is these are my questions.
1. Did I do the right thing with concentrating on my stroke with the handle?
2. Am I making a big deal out of nothing?
3. Should I, and can I do anything els to get more constancy?

 

[butchlambert]

Not sure how accurate your measuring equip is, but how much is .006?

 

[Patch700]

I'm going to venture a guess that your comparator tool is not contacting the same area as the seating stem in your forster seating die... Been there done that .

Also , if your seating stem is leaving a slight ring mark where it's contacting the bullet after seating you may need to either polish it some more or look closer at your neck tensions (annealing) .

 

[jonbearman]

Without sorting your bullets by ogive length you will get variation in seating depth.

 

[Grimstod]

Here is what I am using.

Lapua Brass brand new from the factory never fired.
I uses .001 of neck tension set with a Redding Type S bushing die. Bushing size 0.329
Bullets are the Berger 185gr VLD Hunter
A set of these to check them with.

Patch700 There are the slightest markings on them from the seating stem. I have not polished it yet. Guess I will have to do that. I forgot about it. lol

 

[Grimstod]

Without sorting your bullets by ogive length you will get variation in seating depth.

Jon I bet your right to. Unfortunately I don't have enough bullets to sort Got to get some more. All the market indications seam to say that prices will be dropping soon and I have been waiting on purchasing a lot of components in hopes that I can get some big lots for a little less. Maybe now is a good time to start getting some big lots of bullets.

 

[Patch700]

In your comparator kit they give you a blank drilled quite small so as to allow you to make your own... You might want to take that one and open it up to a size that is larger than the one they recommend for 30 cals. Or it could be the other instance where the seating stem is contacting too high up on the bullet and the polishing could alleviate that problem. Good luck

 

[chapstix97]

I would make a guess that the new unfired brass neck has too much neck/inconsistent tension. I'd run it through a neck expander. When I didn't own a neck expander I'd run the button down the neck only with out resizing to get a consistent tension.

 

[BoydAllen]

If you are working with new, out of the box Lapua brass, expand the necks with an expanding die and mandrel using lube. Remove the lube and dry lube the necks before seating. Set the body of the seater so that it lightly toggles at the top of the ram stroke, and while you are at it, if the shell holder moves the sleeve upward in the die, shorten it (the sleeve)slightly until the case does. Also make sure that you have a proper chamfer on the inside of your necks, and have deburred the bottom of the chamfer. When you pulled and reseated the bullets, the necks would have been larger for the second seating, and with that reduction of the force required to seat your bullets, which should reduce the variation in seated length. If your bullets are all made using the same die (Ask the mfg. about this.) then their ogive to base lengths should be pretty uniform, if they are not, then you might try sorting on that basis to see if this helps.

 

[Erik Cortina]

Lapua Brass brand new from the factory never fired.
I uses .001 of neck tension set with a Redding Type S bushing die. Bushing size 0.329

Did you expand the necks first?

 

[Dos XX]

185 gr bullets, .308 caliber?

.329 bushing?

 

[Erik Cortina]

Are you turning necks? .329" bushing sounds really small.

 

[Sonic Crack]

If your compressing the powder at all .001 neck tension will not hold the bullet in place. Try more neck tension

 

[Martin52]

New Lapua brass typically has a neck thickness of around 0.015 so sizing this down with a 0.329 bushing will leave you an internal neck diameter of about 0.299 (.329 resized outside neck diameter less 2 x 0.015).

A loaded round will be approx. 0.337 so you'll have about 0.008 neck tension.

Try a 0.335 bushing or a Lee Collet die or, as Boyd suggests, just use an expander mandrel.

This assumes you're not turning your case necks.

Martin

 

[223Randy]

What Lee press where you using? i reloaded on a four position turret that has a bit of play in the turret, .006 is exactly what i get from it as well. switched to a single stage press (solidcast) and down to .002 with every thing being the same. ( i am checking to the tip so i would expect the point that the die contacts the bullet is even closer).

 

[savagedasher]

Seating pressure is the problem . Neck size , annealing or the finish inside the neck of the brass, along with compress load. All will cause the problem.. Larry

 

[skiutah02]

I'll add to those who suggest a 0.335 or 0.336 bushing for Lapua brass in 308. I use a 0.336 for 0.001" tension for my (unturned) necks for new (if need to round the neck - which is rare) or fire-formed Lapua. For Winchester I need a 0.331 bushing so 0.329 seems very tight. Drew