.308 COL question

[Carcaju]

Howdy fellas... I would like to load the Barnes TTSX??? 165gr boat tail in my .308win. I am using Win748. Has anyone here used this load? What were your results? Accuracy and knock down?

I have a book that tells me the amount of powder to use but nothing on cartridge overall length. These bullets are quite like. Can anyone give me the COL for this bullet/powder?

Many Thanks!

 

[curseyou]

The COL doesn't vary based on powder and bullet. You start with the SAMMI specification of 2.490 min and 2.810 max. Then you can tailor your COL to your rifle's chamber/magazine requirements. This can be a bit of a rabbit hole, because oal isn't important except for clearing your magazine. What is important is the gap between the bullets ogive and where it engages the lands of your barrel. You'll likely need a bullet comparator to measure it.

 

[Carcaju]

Thanks. I tried once to figure out distance between ogive and lands using candle soot. Didn't work very well. Is there a standard sweet spot 3-4000's? I am shooting a Mohawk 600.

 

[blargon]

Ive found ttsx like a bit of a jump, 30-50 thou...this can be a pain if your rifle has a short throat.

 

[klink1983]

Howdy fellas... I would like to load the Barnes TTSX??? 165gr boat tail in my .308win. I am using Win748. Has anyone here used this load? What were your results? Accuracy and knock down?

I have a book that tells me the amount of powder to use but nothing on cartridge overall length. These bullets are quite like. Can anyone give me the COL for this bullet/powder?

Many Thanks!

I'm new to reloading and a buddy of mine who is the Rainman of ballistics and reloading showed me a trick. He took a piece of brass, and cut the neck with a hacksaw....4 incisions total about half way down the neck. He then chambered it 4 or 5 times with a projectile, calculated the average of the total chamberings and that gave me a best possible OAL. So now when I reload I setup my seating die this way. I made a dummy round with this oal and set my OAL about 1/1000 short just to be safe.

Just remember, that if you are loading one particular projectile and switch to another, you more than likely will have to reset your die to reflect your "best OAL" with that projectile. I learned this the other night as a matter of fact. I loaded 20 rounds to confirm a recent load test that I did, I loaded up 10 168gr HPBT Hornady Match, and another 10 Hornady Amax. The Amax is just a bit longer to put my OAL about 3 or 4/1000 out of whack, just enough to make the round unable to chamber in my rifle. I haven't shot this 20 yet on account of garbage weather where I am but I'm looking forward to it.

 

[rodregier]

I never had much success with bullet marking and max length for throat in rifle cartridges.

The technique I use is to make up a dummy and seat the projectile as long as possible. I then drop that into the chamber and
see if the bullet catches in the chamber throat. Seat .005 deeper and try again until it no longer catches.

At that point, try closing the bolt and confirm the length didn't get any shorter. That is very close to the max for that projectile and your chamber's throat.

You can then seat deeper to pick the jump you want from there. I like say 0.015 jump to allow a bit of tolerance for dirt, etc.
(It really bites to chamber a round, unload it and discover the bullet was left behind in the throat, spilling powder into the action,
and requiring a cleaning rode to punch the hung projectile out).

A bigger jump with the Barnes solid copper projectiles sounds like a good idea to me, they get a large pressure spike when being pushed into the throat by the burning propellant.

 

[klink1983]

I never had much success with bullet marking and max length for throat in rifle cartridges.

The technique I use is to make up a dummy and seat the projectile as long as possible. I then drop that into the chamber and
see if the bullet catches in the chamber throat. Seat .005 deeper and try again until it no longer catches.

At that point, try closing the bolt and confirm the length didn't get any shorter. That is very close to the max for that projectile and your chamber's throat.

You can then seat deeper to pick the jump you want from there. I like say 0.015 jump to allow a bit of tolerance for dirt, etc.
(It really bites to chamber a round, unload it and discover the bullet was left behind in the throat, spilling powder into the action,
and requiring a cleaning rode to punch the hung projectile out).

A bigger jump with the Barnes solid copper projectiles sounds like a good idea to me, they get a large pressure spike when being pushed into the throat by the burning propellant.

I don't know what I did on my last batch (I've only made 2 batches so far) but I had one round that wouldn't chamber all the way. I eventually did get the bolt to close but it wasn't easy, so I chose not to fire the round. Length is fine from what I have measured, case was trimmed and deburred to spec...... not a bloody clue, so now I have 44.1gr of Varget "unaccounted for."

 

[maynard]

I don't know what I did on my last batch (I've only made 2 batches so far) but I had one round that wouldn't chamber all the way. I eventually did get the bolt to close but it wasn't easy, so I chose not to fire the round. Length is fine from what I have measured, case was trimmed and deburred to spec...... not a bloody clue, so now I have 44.1gr of Varget "unaccounted for."

Your case was not resized all the way.

You guys that are talking about .003-.004 out of whack on your COL, that means nothing. Measure a few bullets and see how far they are off. The measurement that is important is to the ogive of the bullet. This will give you more consistant seating depths than to the end of the bullet. If you really want to measure COL, just about .308 diameter in a .308 Win case will load from a mag and chamber at 2.800 inches. Where the bullet is seated for the most accuracy is different from rifle to rifle. While one rifle might like Barne's bullets .040" off the lands. That same rifle might like SGK's .005" off the lands.

 

[swissinn]

I think as a general rule solid bullets need to be jumped. I had some for my 338 and Boretech said a MIN of 50-70 thousandths off the lands. I didnt believe them and loaded 5 each at 5 thou increments from touching the lands...guess which ones were by far the most accurate. 65 thou off the lands won hands down. This would be almost unheard of with jacketed bullets.