minimum bullet seating depth

[caustic]

is there a minimum depth that the bullet should be seated in to the neck or any safety issues aside from the bullet falling out, I'm trying to reach the lands of my 300 wm and from my measurements with a .01" off the lands the bullet will sit in the case roughly .1875" ----using berger 175gr.VLD I have not yet pressed one in to see how snug the bullet is as I thought I would pick some of your brains first.

Thanks

 

[wirehand]

Re: minimum bullet seating depth

Many sources state atleast the calibers worth into the case.

 

[caustic]

Re: minimum bullet seating depth

now is that from the base of the bullet or from the bearing surface---this bullet is a boat tail and tapers for about .140", the bearing surface is about .180" overall bullet seating from base of the bullet to case mouth .320"----good to go or not so good?

 

[TimK]

Re: minimum bullet seating depth

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: caustic</div><div class="ubbcode-body">now is that from the base of the bullet or from the bearing surface---this bullet is a boat tail and tapers for about .140", the bearing surface is about .180" overall bullet seating from base of the bullet to case mouth .320"----good to go or not so good? </div></div>

Excellent question, I was just wondering that myself last night. I hope you get an answer.

 

[Victor N TN]

Re: minimum bullet seating depth

Given the short case neck of the 300 WinMag, seating length is always a pain when I change to a new bullet.

 

[caustic]

Re: minimum bullet seating depth

I've been looking around for this answer and a fellow in another shooting forum had this to say about it.

"No. You only need them seated deeply enough that the bullet will not:

a) Be jammed into the throat, which raises pressure.

or

b) Won't come loose and fall out, with the exception described below.

Middleton Tompkins has more long range gold medals than anyone else, living or dead, as far as I know. At a clinic I attended he told us he sizes his case necks so the bullet slip in them under finger pressure. He seats them way out and lets their contact with the throat finish seating them as he closes the bolt. This technique requires you use a somewhat lower powder charge to compensate for the higher pressure throat contact causes. It has the drawback that if a cease-fire is called, you have to go to some trouble to unload the gun. The bullet usually sticks in the throat, so you must tip it muzzle-up first, then extract the case slowly or you will spill powder into your action. Then the bullet has to be knocked out of the throat with a cleaning rod.
__________________
Nick"

seem to be no danger in it at least, as long as the bullet stays in finger tight for target shooting , obviously for hunting/tactical in the field you'll need more a solid fit.

it would still be nice to hear what guys on the hide have to say .

 

[BobinNC]

Re: minimum bullet seating depth

caustic,

The general rule of thumb is one bullet diameter. So for a 30 cal case that's .308 of "bearing surface" inside the case....

However, the 300 Win Mag has a neck of only .263", less than one bullet diameter. So for a 300 Win Mag. .263" of bearing surface (not counting the boattail skirt)inside the case would be ideal.

You can cheat on that, a little, by the use of a simple $10. tool. It's called a Lee Factory Crimp Die and you don't need a crimping groove to use it.

Will this work in your case? Don't know unless you make some dummies and try it running them through. But your seating seems pretty shallow for my tastes.

Chasing the lands in some rifles with very long throats can be a pretty unrewarding exercise sometimes. Better to seat the bullet right for safety, and see what you get, then seating too shallow, just because 0.01" off the lands may produce magic.

If you want magic, buy a new barrel, and have said barrel throated to exactly the bullet to land distance desired.

Edit: I don't do benchrest, and there are specific loading techniques, used by folks experienced in shooting only on square ranges, loading one round carefully at a time, to produce tiny groups.

I'm a hunter and a sometime tactical shooter. My stuff has to work feeding from a mag box every time, sometimes feeding quite rapidly....So IMHO & YMMV

 

[muleman]

Re: minimum bullet seating depth

I'm curious what your getting for a max overall length? Book says max is 3.340, but with a 208 gr Amax mine touches lands at 3.650 which barely goes down in magazine what gives? New Rem 700 5R milspec 300 win mag. HELP ALSO???

 

[BobinNC]

Re: minimum bullet seating depth

muleman,

Not sure what your asking, but I will try:

The 300 Win Mag was originally designed for a 30-06 length mag box, which is around 3.350". Therefore book max is usually given at that length.

However, all Rem 700 long actions, are a so-called 375 H&H length action. The mag box is around 3.6" and change (I'm too lazy to go upstairs to look it up).

Remington also throats there barrels rather long, mostly to keep
enterprising reloaders from atomizing themselves, so that long throat is a sort of freebore.

In summary, your MAX COAL is always the lessor of your magazine box length, or your neck to lands distance, or keeping at least .263" of bullet in your 300 Mag case.

You set the MAX COAL, not a book.

Bob

 

[muleman]

Re: minimum bullet seating depth

Thanks Bob, I get what your saying I'm going to back off .010 and start there, definitely don't have a problem with seating depth in 208 Amax. Thanks Again Wayne

 

[Brain]

Re: minimum bullet seating depth

When you've seated them out too far, you'll get something that looks like this. This was caused by the bullet leaving the case mouth prior to a high enough pressure for full obturation. You can see a distinct line near the bottom of the case where gasses were sealed off from flowing any further back in the chamber.

You can only go so far in chasing the lands before running out of bearing surface in the case neck.

 

[caustic]

Re: minimum bullet seating depth

that looks quite bad... what happened to the action in this case? or was this a controlled test?

 

[muleman]

Re: minimum bullet seating depth

Man, thats nasty!! Give me some advice so I don't duplicate this. I have a 26" 300 WM 5R milspec barrel. I'm going with 208gr Amax, RL-22, 66gr. and work up from there. The COAL is 3.640 which is .010 off the lands, and they feed in magizine OK, not alot of space left. Anybody see a problem with this? Brian I don't have any idea what FULL OBTURATION is??? Wayne

 

[caustic]

Re: minimum bullet seating depth

FULL OBTURATION that he is referring to is when the case neck expands to seal off the chamber in the pic it shows the gases getting around the case neck all the way back to almost the base where there is a distinct line made where the case had a seal.


so what I take from the image is that If you don't have the bullet seated deep enough you will not produce enough pressure at the neck to ensure a good seal (now what exactly is enough pressure is what I'm going to slowly test buy seating bullets at different depths and inspecting the cases as I go, stopping at any sign of a hazard) hopefully I’ll be good to go to test accuracy from varying depths when at the lands if not I’ll have to settle for testing other options.

 

[Brain]

Re: minimum bullet seating depth

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: caustic</div><div class="ubbcode-body">that looks quite bad... what happened to the action in this case? or was this a controlled test? </div></div>

Much like an oil leak or a cut, it looks a lot worse than it really was. Nothing out of the ordinary observed when the round was fired to indicate anything abnormal had occurred.

If you look closely at the unfired case, you can see partial neck sizing. I was not full-length sizing these cases. Had I been, there might have been enough room for gases to move past the head area of the case and back into the action.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: caustic</div><div class="ubbcode-body">so what I take from the image is that If you don't have the bullet seated deep enough you will not produce enough pressure at the neck to ensure a good seal</div></div>

That is correct. There must be an adequate amount of bearing surface (BT not included) in the neck for pressure to expand the case sufficiently before the bullet moves forward and the bottom of the bearing surface reaches the mouth of the case.

In the example I posted above, an increase in seating depth (seating deeper) of only .067 was enough to allow for proper case expansion.