308 OAL with 178 AMAX

T

TFLDisco

Inactive
Hey guys, first time poster.

I am new to reloading and figured I would start with an older Savage 110S 308 that I have and develop a load for this gun.

The question I am having is regarding the measurements I am getting on where my lands are.

When I measure the lands, I am getting OAL measurements (to the ogive) of 2.304 to 2.308". This gives me an OAL of 2.935" into the lands. Is this a safe OAL? This seems quite long.

I don't know the full history of this barrel, but I would assume that is has seen a few matches. It still shoots better than me though.

Is this normal to have OAL this long for these bullets? As a side note, it is even longer for 175 TMK.
 
"...to the ogive..." Forget the ogive. OAL is measured from the pointy part to the flat part.
The whole off-the -ands thing is a load tweaking technique done after you have a load. It's a 100% trial and error thing too. Every chamber is slightly different and every rifle prefers a different distance off-the-lands. Isn't necessary anyway. Nor do you want the bullet to actually be touching the lands either. Isn't a safety issue though.
Max OAL for .308 is 2.810". Loading to that length at least until you've worked up the load will save you a lot of mucking around.
A 175 grain bullet will be a wee bit shorter than a 178. Only way you can have a .308" cylinder of different weights is with different lengths.
178 is kind of an odd weight anyway. Suspect it's more of a Hornady proprietary thing than anything else.
 
I was just checking how close I was to the lands at 2.800in for my rifle. I was expecting a much lower number, but at 2.800in it means I am 0.135" off the lands. This is even higher for 175 TMK.

I can easily start at 2.800 or 2.810 and adjust powder at that point, but it seems like I would want to start with a longer OAL to get closer to the lands, but it seems long.

Using the ogive was just how I measured it, but ogive to tip was added to get OAL.
 
Hey guys, first time poster.

I am new to reloading and figured I would start with an older Savage 110S 308 that I have and develop a load for this gun.

The question I am having is regarding the measurements I am getting on where my lands are.

When I measure the lands, I am getting OAL measurements (to the ogive) of 2.304 to 2.308". This gives me an OAL of 2.935" into the lands. Is this a safe OAL? This seems quite long.

I don't know the full history of this barrel, but I would assume that is has seen a few matches. It still shoots better than me though.

Is this normal to have OAL this long for these bullets? As a side note, it is even longer for 175 TMK.
Click to expand...


Most of us on here measure cartridge base to ogive, or CBTO. The reason is because it is more consistent than overall lenght. Bullet tips can have a lot less uniformity and it doesn't really affect accuracy, but the ogives need to be consistent. CBTO is more useful than OAL. T'Oheir on this forum doesn't like to use it or cite it but most of the rest of us do. OAL IS important however for determining if the round will fit and feed in your magazine. But, if you are single shot shooting it for competition, it is irrelevant.


Now, to your question. The distance from the lands for a bullet seated to SAAMI can vary greatly depending upon the bullet shape. SAAMI specs ensure that a cartrige will most likely fit and feed in any chamber or magazine. But, the beauty of handloading is you can customize it to your chamber. The distance you describe isn't that long.
I have been working on a .300 win mag load for a few months now and the SAAMI for my cartridge OAL is 3.340, but I am seating them to 3.6240. So, almost 1/3" longer!!! Now that is long. But, I'm only .020 from the lands. Why? Because it is more accurate at that jump AND it allows more powder in the case. The only real rule for how deeply a bullet must be seated is that you have at least 1 caliber's length of bearing surface below the end of the neck i.e. if it is a .308, you need .308" of the bearing surface below the end of the neck.

The pressures cited in manuals are guides. Even if you follow them to the letter, the pressure in your gun could be vastly different. Then, if you start changing seating depth it changes even more. As a general rule, as you seat the bullet longer, the pressure for the exact same powder charge goes down...to a point. Once you are at or even jamming into the lands, the pressure goes back up, and usually quickly. The benefits of seating long go just beyond improving accuracy, you can often get more velocity at lower pressures because you are increasing case capacity...think of it like going from a .25-06 to a .25-06 Ackley Improved without modifying the case (obviously not to that extreme but Im just using the example to make a point).

All of this brings us back in the end to the rules of safe reloading which are known to be that: 1) no matter what the manual, or internet, or anything else says, always start low on powder and work your way up looking for pressure. 2) If you change anything about your load like powder brand, primer, brass case, or bullet, repeat rule #1. 3) if you change anything like seating depth, etc, see rule #1. If you change powder lots, or brass case lots, do a modified version of rule #1. If you want to try the load in a different chamber, see rule #1. You getting the idea? becuase if you follow that, and backoff when the pressure tells you too, you will stay safe and your expensive firearms will stay intact. :) I have loads that are safely well above the manuals maximum because deminsions are different in that case, and I have an AR 10 with a short throat and tight chamber that shows pressure around the mid-point of most recommended powder ranges.
 
Last edited:
Mississippi, thanks for your reply.

Just to clarify, I was measuring the dimensions to the lands by using the Hornady dummy round and measuring the distance from the base to the ogive. I then measured the bullet itself (base to tip and base to ogive). Then subtracted them to get ogive to tip. I added this value to get OAL. Simple math.

My questions were really to get guidance if I should start building a load AT 2.800 OAL (or the equivalent CBTO) or start closer to the lands. This gives me two primary variables; powder and setting depth. I was planning on starting with 90-100 rounds with batches of 10 (3 different powder charges and 3 setting depths).

The last question I had was regarding measuring seating depth. I started trying to "push" it into the lands and could not get a consistent reading, so the method I used was to "lock in" the tool and test to see if the bullet would stay in the lands and gradually increase the distance (5-10 thou at a time) until it stopped. Is this reading accurate or on the low or high side. If anything, I would think it is a tiny bit on the low side (meaning it is still a hair from "being in the lands").
 
The last question I had was regarding measuring seating depth. I started trying to "push" it into the lands and could not get a consistent reading, so the method I used was to "lock in" the tool and test to see if the bullet would stay in the lands and gradually increase the distance (5-10 thou at a time) until it stopped. Is this reading accurate or on the low or high side. If anything, I would think it is a tiny bit on the low side (meaning it is still a hair from "being in the lands").
Click to expand...


Only adjust one variable at a time. You can read the Berger load development instructions as they work for any bullet. Then once you have the most accurate jump, adjust powder. It's been my experience that the most accurate jump is the same regardless of powder charge. Then adjust powder.
 
I used the Hornady length Gage, it will get you in the ball park. I find using your sized brass , sized to .001 case headspace then seating a bullet long , chamber to hit the lands , clean the rifling marks with 0000 steel wool , lowering & cleaning until you know exactly where your rifling starts. Then you can see if your rifle shoots best with a jump or jam.
 
First I ask why are you or feel you need to load the cartridge at the lands ? I highly recommend against it if you are new to reloading . I always recommend new guys to load to manual spec . Having a jump to the lands even if it's only .020 is better to start with . It gives you some pressure wiggle room .
 
I agree with Metal God

The good news is per CW308, the Hornady tool only gets you close, you are not really in the lands.

You want to find them thar lands? Take a bullet, put it in a sized case (FL)

Seat it about .150 longer than the book says to the tip (from the bullet base to the tip)

Then carefully close the bolt, stop when the bolt stops moving.

Amended: Critical: hat the round that is stuck is to be tapped back out not further in!

You will probably have to tap the bolt handle with a soft device (hammer wood handled, screw driver ) to get the stuck round to come back out.

Then repeat, but seat the bullet .020 deeper.

At some point you will be able to close the bolt all the way and turn the bolt handle down. If no stick, that is your real COAL.

It has to be a squeeze down neck as you are yanking on the bullet. So you measure when it comes out to and make sure its the same length it went in.

If its longer than it pulled the bullet out a bit. Ok, just seat deeper.

But if you are new to this, then make sure you are a good .020 off them.
 
Last edited:
Even the Hornady gage will not give you a perfect reading unless you send them a bullet fired from your gun they modify and send back to you. Or you know someone with a lathe to make one for you

Just my nickle but when I am shooting a new bullet for the first time I start about 30 thousandths back from whatever the standard Hornady gage shows as touching or the spec whichever is closer. Once I settle on my powder and load I then fine tune using distance from lands.

I have one gun that shoots the best at 35 thousandths for one bullet and load with a different bullet and load it prefers 5 to 10. In my experiance a 178 SMK it will be more jump tolerant than if you were shooting a 150 or 155.5 grain scenar
 
You must log in or register to reply here.
Back
Top