Question on bullet seating depth

[oaklandraider76]

I've been a shooter all my life however I am a beginning reloader. I am taking it one step at a time and I am laser focused on safety. I am in the process of loading some Barnes 168 gr TSX rounds (.308) and have a question about seating depth. As you can see from the attached picture, these bullets are long and seat very deeply within the neck of the cartridge. The C.O.A.L. of this load is 2.80" using new Nosler brass with a cartridge length of 1.99". I check the case dimensions with a Wilson case gauge and I'm loading according to the Barnes data = starting load of 40.1 grains of Varget powder. So, my question is this: is it OK to seat a bullet this deeply? Thanks for any input. (I plan on shooting these out of my Larue PredatOBR with a 16.5" barrel)

 

[std7mag]

My question revolves more along your stated 2.80" COAL.
How close to your lands is that?
Meaning Barnes recommends a jump of 0.050" off the lands.
Doing that, your COAL may be even shorter.

 

[oaklandraider76]

My question revolves more along your stated 2.80" COAL.
How close to your lands is that?
Meaning Barnes recommends a jump of 0.050" off the lands.
Doing that, your COAL may be even shorter.

Thanks for your reply. I'm not sure as to how close the bullet is to the lands. My main concern is that pushing the bullet this far into the case may cause unexpected jumps in pressure. Do you see a problem here?

 

[Jager]

You should be fine.

When referencing book data you want to understand how closely, or not, your set of components and your gun equates to the components that the load source used.

The 2.80" COAL that you're using is shorter than the 2.810 that Barnes specs. That oftentimes might be a caution, because you'll be generating higher pressures with the bullet seated deeper. But in this case it's too small a difference to matter.

Let us know how the PredatOBR shoots. I have a LaRue 18" OBR in .308 and it's an exceptional rifle.

Here's a QL print of the rough neighborhood you're looking at...

 

[PigButtons]

While having the base of the bullet that deep in the case is not considered optimal, it is not a safety issue.
But to address the issue of jump you can take a fired empty case before sizing the neck and slip a bullet in but leave it long. Then push it into the chamber and gently close the bolt. Gently extract the case and measure the COAL. This is your approximate length to the lands.

 

[Beiruty]

Start 2gr below max and increase by 0.3gr and look for the sign of pressure

 

[oaklandraider76]

You should be fine.

When referencing book data you want to understand how closely, or not, your set of components and your gun equates to the components that the load source used.

The 2.80" COAL that you're using is shorter than the 2.810 that Barnes specs. That oftentimes might be a caution, because you'll be generating higher pressures with the bullet seated deeper. But in this case it's too small a difference to matter.

Let us know how the PredatOBR shoots. I have a LaRue 18" OBR in .308 and it's an exceptional rifle.

Here's a QL print of the rough neighborhood you're looking at...

View attachment 1280617

Thanks!

 

[rckendall]

I ran your info through QuickLOAD and it shows 47505 PSI pressure and a 97.1 Fill ratio. Max pressure is 62000. With a fill ratio of 97.1% you should be good. Just make sure you are not compressing the powder (crunching).

Richard

 

[oaklandraider76]

While having the base of the bullet that deep in the case is not considered optimal, it is not a safety issue.
But to address the issue of jump you can take a fired empty case before sizing the neck and slip a bullet in but leave it long. Then push it into the chamber and gently close the bolt. Gently extract the case and measure the COAL. This is your approximate length to the lands.

Since I'm constrained by the length of the magazine I can't move the bullet out any more.

 

[strut64]

Reloading guides often specify cartridge overall length. That is the dimension to insure that the cartridge can fit in the magazine

The next consideration is how long can your cartridge can be chamber freely. Not bind on the chamber or jammed in the rifling. You must be able to insert the cartridge and close the bolt. Then after chambering remove the cartridge freely.

Final consideration is the bullet "jump or jam". Some bullets based on their design like to be at or even enter the rifling. On the other hand some like to have free space for the bullet to jump before engaging the rifling. That dimension is called the Cartridge Base To Ogive. - CBTO.

The best discussion about this is by the Berger Bullet Co website.

.

 

[oaklandraider76]

I ran your info through QuickLOAD and it shows 47505 PSI pressure and a 97.1 Fill ratio. Max pressure is 62000. With a fill ratio of 97.1% you should be good. Just make sure you are not compressing the powder (crunching).

Richard

Thanks Richard. Would you mind running QL for 43 grains of Varget and everything else the same? I would purchase QL but they don't make a version for the MAC!

 

[rckendall]

Thanks Richard. Would you mind running QL for 43 grains of Varget and everything else the same? I would purchase QL but they don't make a version for the MAC!

At 43.0, you will compressing the load, 104% fill rate. Definitely crunching the powder. Pressure was 58,000 or so, but I wouldn't want to go that high. Fill rate of 100% is around 41.3 gn.

Be careful working your way up!

Richard

 

[oaklandraider76]

At 43.0, you will compressing the load, 104% fill rate. Definitely crunching the powder. Pressure was 58,000 or so, but I wouldn't want to go that high. Fill rate of 100% is around 41.3 gn.

Be careful working your way up!

Richard

Thanks Richard! The Barnes manual lists the maximum load as a compressed load with 44.5 grains of Varget, but I will definitely take your advice and carefully work up the ladder and look for signs of pressure at every step. The data below apply to the 168 gr TSX but the image was cut off when I took the screen shot.

 

[Kracken McGraw]

Thanks for your reply. I'm not sure as to how close the bullet is to the lands. My main concern is that pushing the bullet this far into the case may cause unexpected jumps in pressure. Do you see a problem here?View attachment 1280616

In that pic you have the .22 caliber bullet comparator on, it should be the 8-30 insert for .308. Find the lands like pig buttons told you, you need to do a search on how to do this. Don’t go shorter COL than what Barnes recommend for that bullet and caliber. Your bullet comparator will do you no good if you don’t know where the lands are.
edit: sorry I missed post nine about your magazine length restrictions, I would squeeze it in there as close as you could to Barnes recommend COL length.

 

[oaklandraider76]

In that pic you have the .22 caliber bullet comparator on, it should be the 8-30 insert for .308. Find the lands like pig buttons told you, you need to do a search on how to do this. Don’t go shorter COL than what Barnes recommend for that bullet and caliber. Your bullet comparator will do you no good if you don’t know where the lands are.

Thanks!

 

[HTSmith]

At 43.0, you will compressing the load, 104% fill rate. Definitely crunching the powder. Pressure was 58,000 or so, but I wouldn't want to go that high. Fill rate of 100% is around 41.3 gn.

Be careful working your way up!

Richard

What is the concern with a compressed load?

 

[oaklandraider76]

In that pic you have the .22 caliber bullet comparator on, it should be the 8-30 insert for .308. Find the lands like pig buttons told you, you need to do a search on how to do this. Don’t go shorter COL than what Barnes recommend for that bullet and caliber. Your bullet comparator will do you no good if you don’t know where the lands are.
edit: sorry I missed post nine about your magazine length restrictions, I would squeeze it in there as close as you could to Barnes recommend COL length.

Oops, yes I just picked up the wrong insert. I mainly use the comparator to maintain consistency between batches as the C.O.A.L. seems to vary some due to slight differences in the length of plastic/lead tipped bullets. I plan to use these loads in my Larue PredatOBR on deer and bear out to no more than 100 yards, so I really don't need the accuracy of a bolt gun. I don't think I could achieve that anyway due to my limitations as a shooter. Thanks for all the helpful input and advice.

 

[oaklandraider76]

What is the concern with a compressed load?

It seems like many of the maximum loads given in the table are compressed loads.

 

[dellet]

The only problem I see with this load is using the wrong bullet to extrapolate data.

The bullet in the top photo is not a TSX, it’s a TTSx. the second “T” is important as for Barnes that designates a tipped bullet.

If you note the Barnes data, the TTSX requires a much shorter COL, likely because it will jam at 2.810.

Make certain of your bullet part number before loading any thing.

This is where mixing data and components can get interesting.

 

[dcali]

There is nothing inherenly wrong with seating a bullet well into the case. For example, Sierra's 77 grain .224 is designed to be used in a magazine length .223, which puts it WAY into the case (There's more in the case than out of it). As long as the loading data accounts for this (a reloading manual should), you're fine. When you're learning, stick to the manuals. Start low and work up.