Reloading .308 - OAL and chamber Q

BLACKBRIAR

BLACKBRIAR

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Looking for some insight. Just reloading some .308 for my 700 for testing. After measuring the chamber length with a Hornady OAL gauge I get a measurement of 2.330" using Hornady 168gn BTHP. I'm seating them .020 off the lands therefore 2.310". From a visual standpoint the bullet it looks odd. My concern is not having the bullet seated deep enough where there is sufficient neck tension. I measured the contact depth (case mouth to where the boatail starts) and I get ~.207"

Does the OAL of the chamber seem reasonable?
Should I seat farther off the lands to begin with?
Can anyone provide a comparison with similar components?

new rifle, unfired
Brass Hornady Match - prepped to spec.
 
From what I understand, the diameter of the bullet should be the minimum amount of bullet seated into the casing.
But I've been wrong before.
 
The Hornady 9th edition manual lists the OAL for the 168gn BTHP as 2.800..............

Is there a typo and your 3 really an 8???

The shortest and lightest bullet in the manual for the .308 is the 110 FMJ and its OAL is 2.515

You could do it the old fashioned way and just bump a fired case enough in the die to hold the bullet and chamber a test round and measure the OAL with the rifling seating the bullet.
 
Sorry for the confusion. My OAL measurements were with a bullet comparator on the ogive. If I measure old school, tip to base, I get essentially 2.900 A pick of 3 random measured of 2.899, 2.904, 2.905"

This demonstrates the inconsistency of bullet lengths you get by measuring to the tip. Ogive measurements were all equal.
 
Forgive me if I'm wrong, but someone once told me that factory barrels are usually set pretty far forward, and obtaining .020" off the lands isn't always feesable?
 
bigedp51 said:
The Hornady 9th edition manual lists the OAL for the 168gn BTHP as 2.800..............

Is there a typo and your 3 really an 8???

The shortest and lightest bullet in the manual for the .308 is the 110 FMJ and its OAL is 2.515

You could do it the old fashioned way and just bump a fired case enough in the die to hold the bullet and chamber a test round and measure the OAL with the rifling seating the bullet.
Click to expand...

1. Take an old piece of brass, and hacksaw 2 cuts into the neck. It should be snug, but loose enough to pull out a projectile with your hands.
2. Chamber said riggins with a projectile a minimum of 5 times....GENTLY, each time measuring the OAL of the completed riggins.
3. Calculate mean average, use your judgement based on your results to seat how deep or long you wish to.
4. Make a "template round" using a piece of brass and sacrificing one projectile. This is used to setup your die.
4.a Seat the round in your press
4.b Insert die, loosen off seating riggins
4.c Stroke your press..... lol
4.d Screw in seating riggins back into the die until it makes contact with your template round
5. Die is setup for YOUR custom OAL requirements.

In my case my magic number is 2.83" and I have templates made up for each projectile that I reload...with the measurements clearly indicated. I also have a template if I am loading to factory specification in the event that I could be sharing ammunition with someone else.
 
If you don't have a load yet, stop worrying about the OAL being just off the lands. That's a load tweaking technique that comes after you have a load. Use the OAL with bullet given in your manual.
 
Who is on first?? Op is measuring his OAL with a comparator from case head to ogive.
OP, remember that if you used a heavier bullet you would have lots more length to seat in the neck. I've heard the same rule (already posted above) that the bullet should be a least 1 caliber length into the neck. All reports I've heard say powder choice and charge is first on the list to establish an accurate load. Seating depth often seems to make a quite small difference in accuracy compared to other factors.
 
sunray said:
If you don't have a load yet, stop worrying about the OAL being just off the lands. That's a load tweaking technique that comes after you have a load. Use the OAL with bullet given in your manual.
Click to expand...

I actually measure every chamber for every bullet with an OAL gauge before working up a load and like the OP I start about 20-25 thou off the lands. It's a two minute procedure that is very useful in initial load development IMHO. I can't see a reason not to do it in the initial load development. It surprises me how many people don't measure OAL for their specific chamber. With that said, something sounds off with his numbers.
 
emerson said:
Who is on first?? Op is measuring his OAL with a comparator from case head to ogive.
OP, remember that if you used a heavier bullet you would have lots more length to seat in the neck. I've heard the same rule (already posted above) that the bullet should be a least 1 caliber length into the neck. All reports I've heard say powder choice and charge is first on the list to establish an accurate load. Seating depth often seems to make a quite small difference in accuracy compared to other factors.
Click to expand...

Sounds to me like he's using an overall length gauge and not a comparator but if he is measuring to ogive that could explain his number.

**** ooops disregard......read his follow up post....my bad.
 
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Remington's chamber throat is designed by a lawyer. 2.900"sounds about right. max length to fit the magazine is about 2.825".

That is enough neck tension to hold the bullet for accurate, single shot use. If you go deeper there is a danger of having the bullet stick in the barrel if you open the bolt on a live round. messy....
 
klink1983 said:
1. Take an old piece of brass, and hacksaw 2 cuts into the neck. It should be snug, but loose enough to pull out a projectile with your hands.
2. Chamber said riggins with a projectile a minimum of 5 times....GENTLY, each time measuring the OAL of the completed riggins.
3. Calculate mean average, use your judgement based on your results to seat how deep or long you wish to.
4. Make a "template round" using a piece of brass and sacrificing one projectile. This is used to setup your die.
4.a Seat the round in your press
4.b Insert die, loosen off seating riggins
4.c Stroke your press..... lol
4.d Screw in seating riggins back into the die until it makes contact with your template round
5. Die is setup for YOUR custom OAL requirements.

In my case my magic number is 2.83" and I have templates made up for each projectile that I reload...with the measurements clearly indicated. I also have a template if I am loading to factory specification in the event that I could be sharing ammunition with someone else.
Click to expand...

I used this method on my new 700 SPS TAC AAC-SD .308 and I got an average length of 2.959" with a 168 A-Max. I do think getting .020-.030" from the lands is doable for me. I will try a 2.830" OAL since it is about the max that will function in my magazine but that is still a 0.130" jump. Maybe a different projectile will get me a little closer.
 
Sierra Bullets Tech Newletter Volume 9, No. 3 states:
"It is highly recommended that a bullet be seated so that it has at least one bullet diameter amount of the bearing surface in contact with the neck of the cartridge case. This helps to provide uniform tension as well as to hold the bullet concentric with the case and will help accuracy considerably"
Some people quote Sierra recommending 80% of bullet diameter so maybe a later technical bulletin says differently.
 
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