Home Forums Reloading Big Game Rifles Bullet seating depth

Hi guys,

I have reloaded a fair amount, but am by no means an expert. My experience has been to stick with a recommended C.O.L., and vary loads by varying powder weight until I find the best load.

This has served me well, but I feel I am missing the boat, by not playing with seating depth. I feel I can improve the accuracy of my pet loads by doing this, and maybe make a "poorer" load "better"
For example, I made 4 loads with 120 gr speer bullet in the 6.5x55. Used 42,43,44, and 45 gr of H4350 All at a recommended C.O.L of 2.995"

The best shooting load was the 43 gr load, 1.25 inches at 100 yds from my old M96 Swedish mauser. The 45 gr load shot 1.75"

I would like to get the 45 gr load to shoot better, and have the velocity and accuracy. After all, isn't that why we reload?

So my question is; How do I BEST go about finding the best seating depth?
Is there danger or risk to going too long or short?

Thanks for your input.

Trial and error is the only way that I know of. Each rifle will vary in leade distance.

Thanks Shootist. What I was considering, was to gently seat a bullet JUST inside the neck of an empty brass case. Chamber the round. When I extract the round, the seating depth should be max OAL.(assuming bullet does not stick in rifling)

Does this sound reasonable? Then I would load some at this lenght, and gradually work shorter until I find the load I want.

Would this work?

If you do that with a fired un-sized case, the bullet is to free to move around. If you do it with the us-sized case slightly bent to drag the bullet you could jam the lands just enough to pull the bullet enough to get a loaded round with a bullet that's just out to far. I have never used one of the tools to measure to the ogive on the bullet. Rather I use a cleaning rod with a plug in it and a bullet I want to use. Close the bolt on the rifle and slide the clean ing rod down the barrel until it contacts the bolt face. Mark the cleaning rod at the muzzle. Noe remove the bolt and drop a bullet into the chamber and hold it against the lands with a pencil. Re-insert the cleaning rod till it touch's the tip of the bullet. Again mark the rod. Now measure between the lines and that is your seating depth. Even though the bullet's may vary some in length, the seating plug will hit the same point on each bullet. It's simple, fast and deosn't require much thought.

The Hornady LNL tool will be the best $20something bucks you ever spent on reloading gear.

You hould be measuring to the ogive of the bullet and not the tip. Also you can try other powder charges closer to each other. Move in 0.5gr changes. I have had rifles that would show a difference with 0.3 changes in that case capacity.Rick.

I use the method described by DonFischer above.
Instead of marking the rod, I use two pieces of masking tape trueing up flush with the muzzle.
I start out with about .030" jump and often can stop there.
Some gun/bullet combos shoot best when seated at one caliber.
jmho
Tim

I'm old school. I seat the bullet in a sized preped case, leaving out powder and primer, until the bulleted round fits the magazine.
Then I smoke the bullet with a candle, butain lighter, magic marker and try to chamber the round. If the round will not chamber I seat the bullet a bit deeper and try again. Once I get the round to seat even if it's a bit stiff, that is my working point. I will re-smoke the bullet until I get an easy chambering and a small amount of rifling ehgagement on the bullet, I call the job finished.
I can start playing with powder to find the best load.

Jim

That old Swede has along throat meant for the old 160 gr rn military bullet.Seating depth of a 120 gr bullet is not going to help you much. You can't seat it out far enough to get even close to the lands.Even if you did, it would not have enough neck grip on the bullet to keep it there.

Plus the twist in that rifle needs a longer bullet.
Do one of two things. Switch to a 140 gr bullet.My prefernce is the Sierra Game King and run it at about 2650fps If the barrel is good enough,that should get you into the 1" group or less realm.If you want to get better,switch to the Nosler Accubond 130 gr bullet which is longer yet and run it at about 2800fps.That should get you in the 1/2 to 3/4 " group realm.

For the 140's I use 46 gr of H4831 and for the130's I use 47 gr of H4831. You might have to tweak that a little for your particular rifle.

I have been using the Stoney Point OAL gauge (now Hornady) for at least 20 years. It is the most accurate way to gauge seating depth relative to the lands. I am on my second one (that little strip that holds the threaded piece eventually fatigues and breaks). That said, the last several factory barrels in new rifles all have had leades long enough that magazine length has become the primary determiner of COAL for me. I still measure them all, but even with TTSXs I end up seating bullets as long as they will reliably cycle and feed through the magazine.

I also use the smoked bullet approach, like arkypete. Some of my rifles have a long throat, leade. Some I am limited by the magazine length. I find that my loads that shoot well are typically just off the lands. Like, the bullet engages the rifling only slightly marking the "smoke," and then I screw the seating plug in jut a smidge -- a highly technical term -- and when the smoke is not disturbed, I am good to go.

Instead of smoking,I just use a black magic marker. Lot faster

Thanks for all the replies everyone!

Saddlesore, I recognize what you said, about the twist and original bullet being heavier for this milsurp. I have used 140 gr bullets, with good luck, and also purchased some 130 accubonds for use, but haven't loaded them yet.

The deal is, I have a couple hundred 120 gr speers on hand that I bought to develop a light-recoiling youth load for the swede. Instead, I bought the kids a ,243 win youth model Savage, as the swede was a bit physically heavy for them at the time. Honestly, I can live with the 1.25 inches I am getting with the lighter, slower load. And the "slower" load is 2625 fps (book) so not really "slow" . I just wanted to learn about bullet seating, and hopefully spice up the load to use up the remaining 120 gr bullets I have.

Thanks for the input, it is appreciated.

For starters, you have more room with H4350 if you wish. Nosler 6 lists a max load of 47.0 with their 120's.

Or, you can stay with the 45 grs for now and fiddle with seating depth and see what happens.

Where is 2.995 in relation to the lands in your rifle? I always start at about .010 off the lands and go from there. Basically, only one way to move from there. I load up some loads with at least a couple different powders and shoot some groups. If something looks promising, I load more with the same charge and seat the bullets deeper a quarter turn of the seater die for every three rounds (don't forget to mark them with a sharpie).

Shoot a few groups and see what happens.

Different powders, different COAL, different rifles......you know how that goes...

CLB.With the 6.5 Swede sportorized, original barrel,there is no way the OP can get to even close to .010.

With 140's my max COAL is 3.040 and that does not have the recomended 1 bullet dia neck engagement. Anything longer and the bullet won't stay straight.Even worse for a 120 gr. Stepping up to the Accubond and going to the 130 gr. It can be accomplished with a COAL of 3.175. At least with my rifle.
Don't know if Nosler makes a 120 gr in the Accubond.

I think the Accubond is about the longest bullet you can find for the 6.5. Don't know about Barnes or the E-tip though.

.010 in my post was just a reference as to what I do......

I only have 4 different 0.264" bullets in inventory as follows:

1. Barnes TSX - 120 grain BTHP -- 1.253"
2. Sierra Pro Hunter - 120 grain FB -- 1.085"
3. Sierra Match King - 107 grain BTHP-- 1.231"
4. Sierra Game King - 140 grain BTSP -- 1.250"

I didn't write it down in my notes, but I think my 6.5 Swede Tikka T3 uses an OAL of around 3.140". It shoots the 140 Sierras into 9/16" group at 100 from an improvised rest. Serious enough for the deer I shoot. Think I am using IMR4831 at a 1/2 grain less than max load IIRC. Whatever the velocity is, it kills deer fine.

The 130 gr AB is 1.323 long,including the plastic tip.

The COL is the max length of the cartridge for it to fit in the magazine. This length is given in loading manuals to fit into a factory magazine, as set by the SAAMI.

It doesn't effect seating deep or shallow seating when you are trying for the best load.

When I do that, I usually try several different seating depth until I find one (if I do) that groups like I want it to.

I load single shot when I do this, so I do not pay any attention to COL.

However, by doing it this way, you might find that the cartridge that shoots the best is too long for your magazine. I have had this happen and your only choice is to seat the bullet deeper if you want to use the rifle as a repeater.

Take all the guess work out of it and use the Hornady oal gauge and the Hornady bullet caparator. When used together its perfect!