Hi guys, new here. I guess I will just jump right into it.

I need help with my seating depth…

I recently inherited my Grandfathers 1979 Browning BBR .300 Win Mag and I am trying to work up a load for my upcoming elk trip in October.

I am shooting 200 gr Accubonds and Hornady brass. I checked where my bullet is contacting the lands and it shows it is touching them at 3.653”. Here is the method I used to check the depth: http://www.youtube.com/watch?v=J1yBCarMgZQ

Problem is, the Nosler recommendation says max C.O.L. is 3.340” and the max length my magazine will hold is 3.370”.

If I set the bullet at 3.370” that will put the bullet .283” off the lands. That seems pretty far to me….

What would you guys do?? Any recommendations would be helpful.

Thanks,
Trent

I'm just new at reloading myself, but I have had the experience that with some guns, bullet seating depth improves groups; and with others, not so much. The ones where it seems to work for me, I have them out near .020 from where your length gage says you have. With my Mark Vs, factory ammo is .080 from what the OAL gage reads and I never put those guys out there at .020.

What if ya went with another bullet? Would that let ya fill that clip with a longer shell?

Set col so the round works in the mag, make a couple of rounds and see if they work well then you are repeating.

Fug the old "seat to the lands" BS
Many chamber / bullet combo's have a even longer jump, and they shoot very well that way.

Seat to 3.340, find the powder type and charge your rifle prefers. If that's still not good enough, try a different bullet.

Once you've found the "best" combo, and if your still not happy, than adjust your seating depth by .010 in both directions to fine tune the barrel harmonics.

Still not happy, drop a few hundred on a quality barrel, and another few hundred on having a top accuracy gunsmith install it (expect to wait a couple years for them to get around to your job, as the good ones are that backed up with work)

BTW, you need about .030 end clearance in the mag, to insure proper function (something to think about when going longer on OAL)

Your mag box dictates your max length

I have rifles that have the same issue as yours and they shoot very good

Load your new rounds tho the book length you mention and go try them

quote:

Problem is, the Nosler recommendation says max C.O.L. is 3.340” and the max length my magazine will hold is 3.370”.

Nosler does not recommend any seating depth in their manual. The 3.340 you speak of if simply the SAAMI specs for Ammunition Manufactures, it has nothing to do with the handloader.

If you want to know what OAL Nolser recommends go to page 43 of Nosler #6.

As others has stated, seat to Mag length and work up your loads, then if you wish you can seat deeper in hopes of fine tuning your accuracy. Seating deeper will decrease pressures not increase them. If you go the other way, that is to seat deep and then increase OAL you will increase pressures. So it's best to start long and then reduce.

quote:

Nosler does not recommend any seating depth in their manual. The 3.340 you speak of if simply the SAAMI specs for Ammunition Manufactures, it has nothing to do with the handloader.

If you want to know what OAL Nolser recommends go to page 43 of Nosler #6.

I looked in the Nosler and Hornady book and also looked it up on Hodgdon's website, they all said max C.O.L. was 3.340''. That is just what I read, sorry if I quoted something wrong.


Thanks everyone for the response, this helps a lot. I will start with the recommendation and go from there.

Thanks again,
Trent

quote:

Originally posted by Broncho10:

quote:

Nosler does not recommend any seating depth in their manual. The 3.340 you speak of if simply the SAAMI specs for Ammunition Manufactures, it has nothing to do with the handloader.

If you want to know what OAL Nolser recommends go to page 43 of Nosler #6.

I looked in the Nosler and Hornady book and also looked it up on Hodgdon's website, they all said max C.O.L. was 3.340''. That is just what I read, sorry if I quoted something wrong.


Thanks everyone for the response, this helps a lot. I will start with the recommendation and go from there.

Thanks again,
Trent

3.340 is the SAAMI Max for the 30-06, it is for Ammunition manufactures so their ammo will fit in the chamber of every 30-06 rifle ever made, it has nothing to do with handloaded ammo, unless you plan on selling it and need it to fit into every rifle ever made.

This is from Accurate Powders.

SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a
guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of the barrel, 3)
ogive or profile of the projectile and 4) position of cannelure or crimp groove.



If you have Nolser #6 go to page 43 and see what they recommend for your OAL.

I use a system to develop loads which works very well in any rifle I've ever used it. It's a 2-phase process. Firstly, I determine what the maximum COL is for the specific rifle and bullet. Max COL is basically the longest cartridge that will travel freely all the way to the bottom of the mag and back up without binding, AND not engage the rifling. Any longer than that has to be a jam waiting to happen. An aside here - I can't recall ever finding a rifle / load combo where the bullet would engage the rifling and still work through the mag.

Once I've determined max COL, I load up batches of 5 at max COL, incrementally increasing the powder charge between batches (0.5gr increments). These I fire over my chronograph, logging results as I go (and watching carefully for pressure signs). I go through my targets and notes, looking for a load which is:

- In the ballpark of expected velocities
- A fair group relative to the rest
- Of a relatively low extreme spread

Generally but not always, there is a direct correlation between group size and extreme spread. ie loads with a smaller difference between min and max velocities will give a better group.

Once I've determined an optimal powder charge, I go back to the bench and load up batches of 5 with the same powder charge, but shortening the COL by 0.25mm between batches. Then it's back to the range and fire these for group. You could chronograph them, but I don't find the shorter COL has a real effect on velocities. Having said that, I set up the chrono if only for completeness of records.

Now, the best group is the one I go with - it may or may not be the best that rifle will do with that specific powder, but it works for me.

Work to a length that will function well through your magazine. You really haven't any other choice unless you want a longer jump.
FWIW, while getting reasonably close to the lands is desirable. it is by no means the end-all of accuracy. Ask some of the Weatherby owners.
If you're talking about a hunting load, utter reliability is your #1 priority. Even at the expense of a bit of accuracy.

Another great option for those short magazines is the 180 nosler partition protected point. The bullet was made for the 300 mag. and can be seated down to 3.340 if required to fit the magazine. Seating the 200 AB clear down to 3.370 eats up too much powder capacity. Decent velocity may be difficult to achieve with the 200AB. The 180 PT protected point is made for short mags. and does not eat up space in the case.

Browning 300 Win Mag, BAR, RCBS made reloading dies for all the BAR rifles, legend has it the full length sizer dies were small base dies. As with the difference between the M1 Garand chamber and the 03 and M1917 30/06 chambers, the difference is small, a micrometer that does not get below .0005 thousandths is not capable to measure the difference.

Again, I am the fan of the running start, I want bullet jump, I make transfer gages, I determine the distance from the head of the case to the beginning of the rifling with a modified case then transfer the measurements of the modified case to the seating die, I control seating depth (off the lands)by adjusting the height of the seater stem above the die.

F. Guffey

You might try this method.
http://02b0516.netsolhost.com/...llets-in-your-rifle/

I tried it for Berger bullets as well as others too.I had my chronograph set up when I was testing the same power charge but at different seating depths.My velocities were lowest with the deeper seated bullets and increased the closer I seated to the lands.

I would keep it really simple

1. This is a hunting rifle and not a benchrest rifle.
2. The magazine is the limiting factor so you cannot control that - I would first develop accurate loads with the rifle and see if I can keep 3 shots within 1.5 inches regularly with a cold barrel . If the answer is yes - then I am ready to go hunting.
3. The projectile is the key variable if the barrel is a shooter. So I will make sure I pick the projectile that the barrel likes. Then the powder & load to achieve best accuracy & optimal safe velocity. Again - just go hunting
4. I would make sure that my reloads are sized to feed smoothly. No sticky feeds, no stuck cases, no rounds that are hard to close the bolt on etc. Again - just go hunting!
5. If the rifle will not shoot 1.5" groups at 100 meters with any projectile, then you have a problem.

If I was setting the barrel back, I'd go back 0.28 inch and rechamber it and try the above. I would have a MINIMUM 0.030 inch off the lands for soft point hunting ammo and 0.050 inch for TSX and similar hard bullets.

Good luck!