Thread: 284 seating depth query

Hi folks.

So my 284win is off to gunworks in a fortnight for its new Shillen barrel.

I've been asked to provide a dummy round which I've done.

What I've done is seated the 162gr eld M so where the straight part of the bullet starts to boat tail inwards is in line with where the neck and the shoulder of the case(Lapua) meet. What I'm asking is should I seat it deeper?

I think I've seated it correctly for a dummy round for them to ream out to. The action is a remington 700 LA.

I've done 5 dummy rounds to check for cycling and fitting in the magazine too.

Next time I have a barrel fitted I will have it done the way that is described in 'the Texas Warehouse' article, which explains how turning two tapers on the barrel and action locate and centralise the barrel. Even if this superior step is dispensed with, 'Lapping' the tenon threads as also described in the article was shown to be a big improvement

That position of that part of the boat tail at the shoulder neck junction supposedly gives the most efficient gas turbulance. How they know that I don't know.
I went thru this when I got my 284 built. Another forum member is currently going thru the same process for a 284.
Mine was for 180 Bergers, but I was trying to get a compromise so that I could shoot the 180s and lighter projectiles.

With your setup, if donuts form the boat tail may not run into them, just.

You still need to take a guess on jump to be added to the dummy cartridge length and advise your smith.

Originally Posted by Rock river arms hunter

Hi folks.

So my 284win is off to gunworks in a fortnight for its new Shillen barrel.

I've been asked to provide a dummy round which I've done.

What I've done is seated the 162gr eld M so where the straight part of the bullet starts to boat tail inwards is in line with where the neck and the shoulder of the case(Lapua) meet. What I'm asking is should I seat it deeper?Attachment 231038

I think I've seated it correctly for a dummy round for them to ream out to. The action is a remington 700 LA.

I've done 5 dummy rounds to check for cycling and fitting in the magazine too.

FYI you have the bullet siiting too deep into your vernier jaws. It's is not reading a correct measure. Your actual length will be longer than 3.2".

Originally Posted by kiwijames

FYI you have the bullet siiting too deep into your vernier jaws. It's is not reading a correct measure. Your actual length will be longer than 3.2".

Bummer!

So I measure off the longer Parr of the vernier below where I have it?

Yep

And send the gunsmith a dummy round.

Originally Posted by zimmer

You still need to take a guess on jump to be added to the dummy cartridge length and advise your smith.

Don't forget this bit.
Without any further instruction it's odd-on that Gunworks would cut the freebore to have your dummy rounds just touching the rifling. If you then decide to experiment with some jump during load development - and anecdotally most shooters are jumping the 162 ELD-m - then the shank-boattail junction will move from level with the case-shoulder junction back into the case by the same amount.

Originally Posted by Puffin

Don't forget this bit.
Without any further instruction it's odd-on that Gunworks would cut the freebore to have your dummy rounds just touching the rifling. If you then decide to experiment with some jump during load development - and anecdotally most shooters are jumping the 162 ELD-m - then the shank-boattail junction will move from level with the case-shoulder junction back into the case by the same amount.

Gunworks didn’t even use my dummy round, they chambered it way shorter. Let’s just say I wouldn’t be using them again.

When I had my 284 barrel chambered, I seated the projectile with the boat tail level with the base of the neck as you have done and sent the dummy round and barrel to Mitch Maxberry in Wellington who did the work and did it well. Seated at the base of the neck, a 162eldm is about 10 thou off the lands and shoots great right there. Whatever reamer he has seems to be about the right throat length for the ELD-M.

If you are running converted 6.5-284 cases, I'd stay clear of the neck/shoulder junction. Genuine .284 cases should be OK.

Originally Posted by SixtyTen

When I had my 284 barrel chambered, I seated the projectile with the boat tail level with the base of the neck as you have done and sent the dummy round and barrel to Mitch Maxberry in Wellington who did the work and did it well. Seated at the base of the neck, a 162eldm is about 10 thou off the lands and shoots great right there. Whatever reamer he has seems to be about the right throat length for the ELD-M.

He may have used a throating reamer.

I'm running straight 284 lapua cases.

I've sent the rifle off and asked them to chamber for 10 though longer jump so thanks for all the advice folks!

Greg at custom guns was bloody helpful with this project too.

Will send pics through once she is done and keep an eye out for a article in R+R early next year.