.308 Winchester Seating Depth

32-20

32-20

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Alright folks, I am very new to headspace measuring and what not. I have a few questions regarding my handloads. I hope this is the right area of the forum. Excuse me if it is not.

So I went ahead and bought a RCBS Headspace Mic. Following the instructions, I measured five new factory casings that were once fired in the gun that I will be hand loading for. My result was that I have a headspace of 1.6300" which by my numbers is the minimum according to ANSI. So far so good...Right?

Next, I went ahead and set my Redding full length sizer die so that the brass cases were sized to 1.6290". The instructions that came with my mic directed me to size .0010"-.0020" smaller than the headspace measurement obtained above. so I did. All is well so far...Right?

Next, using the Freebore tool from the mic set, I went through the motions of measuring the chamber to determine at what length the bullet touches the lands of the rifling. I'm not sure what this measurement is called but I will call it the Chamber Length. I took this measurement five times and the measurement on the Freebore tool was 0.2140". I hadn't thought that anything was out of the ordinary yet...But then again, I've never done this before...

Next, I went ahead and set up my bullet seating die. Carefully seating a bullet I measured the cartridge in the mic, the same way I measured the Freebore tool after compressing it in the chamber. From there I adjusted the seating die so that the cartridge measured 0.0100" shorter than the Freebore tool (0.2040"). The previous owner said that this rifle was most accurate if loaded to 0.0100" of the lands. I noted that the bullet didn't seat very far into the case at all. At this point I became suspisious.

NOTE : I am loading Hornady 150gr FMJ-BT bullets. They are awefully sleek and slender and come to a sharp point.

QUESTIONS :
The overall length of my cartridge measures 2.9930" and is too long for my clip. The bullet is only seated into the casing mouth by 0.1470". This seems like a very shallow bullet seat but by my meaurements (if I did them correctly) it should be correct.

  1. Does anybody see anything that I may have done wrong?
  2. Perhaps a different style of bullet would allow for a deeper seat while maintaining the Chamber Length.
 
You have done nothing wrong by the sounds of it.

Remember the 308 will shoot up to 200gr. bullets in some cases, so the leade in the chamber is often constructed to facilitate this.

Also most bullets regardless of weight have a different ogives, and melpates.
So this again will change your COL or length to the leade.

Not every bullet from a different manufacturer will shoot best seated the same distance from the leade of the rifling.

In a general use rifle I personally like to have at least 1/2 a caliber length of bullet bearing surface in the case neck. Having much less than that will someday cause you greif with a bullet getting out of alignment from the original seating position. For you this should be around 0.15"ish minimum.

And lastly sometimes the overall magazine or clip length will dictate what your COL will be.
 
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Not unusual for a round that is close to the rifling to be too long for the mag. You may have to make a choice.

You can seat deep for hunting (so mag works) and longer for accuracy needs.

if you use brass fired in your rifle, no need to worry about hadspace. Just neck size. The case will be a perfect fit.

The Over All Length of your round (OAL) can be started at, say 2.950 (very long) and chambered. If the bullet is engraved with rifling, seat anotehr bullet 25 thou shorter (a quarter tun of the seater stem is about 12 thou) and try again.

When you get a bullet seated so deep there are no rifling marks, try it again withthe ogive marked with a black felt marker. It will show faint marks. Note that OAL and use it as a reference. Seat 10 rounds 10 tou longer, the reference length, 10 thou deeper and 20 thou deeper. If find many bullet work best in my rifles when about 20 thouy 9or more) off the rifling.
 
It looks like the throat was made for longer bullets. If you don,t want to seat the bullet deeper, try another longer and / or heavier one.

Sometimes a jump gives quite good accuracy too. Seat to 1X the diameter, shoot and see the results.
 
Fully agree with the posts above. Looks like your magazine length will dictate your OAL for hunting purposes, unless you single load.

As a further check, take one of those lengthy rounds, made up with no powder, or primer, and smoke the bullet with a match till it's good and black.
Run it in and out of your chamber, and look for rifling marks on the bullet. Find none?
It's not hitting the rifling, is it?
Matches are cheaper than fancy gadgets.
 
I use the standard 2/3 x bore diameter of bullet in the neck. If that fits in the mag, great. If it doesn't, I seat it to where it does...Which with the .308 is about .205" of bullet in the neck...
 
Thanks for the help guys. It sounds like I've done all of my measuring correctly but in order to keep my bullet .010"-.020" off the lands of the rifling, I'll have to choose a different bullet. The Hornady 150gr FMJ-BT that I have is not shaped in such a way that I can achieve the results that I wish. It won't allow me to come anywhere near a seating depth of 2/3 x bore diameter without increasing the leade to a far greater distance than I'm striving for.

Regarding my barrel throat being made for larger bullets. I really can't say for sure but being a heavy barrel, it may very well be. Just a hunch though.

Thanks again!!
- Dan
 
Maybe it is just me but I've been over these posts a few times and I'm still not comfortable about what is going on. Maybe I'm misreading things and part of the problem might be that I haven't used 'some' of the tools being used. But what worries me is that I haven't owned a 308 chamber in which the bullet wouldn't touch the lands until there was too little neck holding the bullet. (I have run into the magazine problem, but it isn't clear to me that this is what is going on.) With really heavy bullets I've always had to seat them further in and 150 grainers don't qualify as heavy in a 308 imho. I can't reach the lands in my 340 Wea because it does have a lot of freebore as I understand Weatherby's do. I have seen it in rifles that were badly throated too. I might be way off base here, but what kind of rifle is it and how many rounds have been through it? If the rifle has a custom barrel, what kind is it and how has it been reamed?
The previous posts that advocate locating the lands really are making a good point. Ive always done this using the methods mentioned in the posts recommending that it be done and then located the lands in relation to the point where the ogive of the bullet meets the caliber width using a simple guage and a vernier caliper. If the bullet has to be seated too far out, e.g. because of freebore or throating, I just use the COL listed in the loading manuals, which should also fit the mag, but I would really want to know more about the barrel and might even make a cast of the chamber. What am I missing here? Hope I'm not too far out on this, but I don't see what harm there can be in asking. Sincerely, Fred
 
Thank you for your concern Fred. It's always nice to know that there are still folks who care about the safety of strangers.

To answer a few of your questions. It is a mid 90's Savage 110C and it has had roughly 350 rounds fired through it. The rifle does have a mid/heavy barrel on it which is the stock barrel. I purchased this rifle from a fellow CGN'er a short while back and he told me that he was getting the most accurate handloads from Berger 168 VLD bullets, 44.5grs Varget powder and by seating the bullets .010" off the lands. I'm simply trying to load to .010" of the lands with Hornady FMJ-BT 150gr bullets.

Cheers!!
- Dan
 
Fear not, this question comes up here regular as clockwork.
The different shapes of bullets available today make for some loads that are incredibly long overall for the cartridge, if you are stretching out there for the lands.
On many rifles the mag becomes the limiting factor.
But do double check, using one of the traditional methods listed above, like my smoke method, to ensure that you didn't screw up your measurements.
 
Thanks again John. In fact, I went ahead and lightly seated a bullet into a case and then chambered it to finish off the seating process. My measurements were correct. Using the Hornady 150gr FMJ-BT's, with the bullet touching the lands I achieve an overall cartridge length of 2.9750". The bullet itself measure 1.1260" in length while the case measures 2.0100" in length. With a little math (2.9750 - 2.0100 - 1.1260 = -0.1610) it wasn't hard to see that the bullet is only being seated 0.1610" deep. The boat tail on this bullet is about 0.1400" long as far as I can tell. Not a very deep seat at all...I think I'll look for them Berger VLD 168gr Hollow Points now...

Cheers!
- Dan
 
Well I had a look at norma match, and book values, and figured , what am I doing getting right up to the lands:rolleyes::D , so I backed off to book value, and its longer than match , and shoots great with long bullets that have a lot of contact. 168's or Barnes x , etc ...
 
32-20 said:
So what are you suggesting Levi? Not sure I follow...
Click to expand...

I would just go with the overall length the load book gives for that bullet, lee is great for this, they give min oal, so you don't mess up and cause much pressure, I stay at the aol of the longest combo or saami specs for that load.
This works, but not all the time, as different powders burn different, and the rate of burn also..
A bit of looking at data, and books, you will come up with a proper depth for your load, without creaping right up to the lands, and remember barnes x and similar shoot better with a bit of a jump to the rifling..
And should you mess up , and seat to deep, a tap on the puller, and you can try again
 
32-20 said. "In fact, I went ahead and lightly seated a bullet into a case and then chambered it to finish off the seating process."

This is what I have always done. Then I am finished. No measuring anything else, that's it. However, firstly it may be too long for the mag, so would then go back to mag length. Or, if there was not enugh bullet in the neck, seat until there was.
If all is well, I would probably leave them touching the lands.
As we all know, there is such a difference in bullets, as well as chambers and throats.
 
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