Home Forums Reloading Big Game Rifles Runout after bullet seating

Color me stumped. I am reloading .308 Lapua brass with both Barnes and Hammer bullets. Brass was prepped with a Redding body die, and necks were sized using a Lee neck sizing die. I checked my brass after those steps and runout is basically nonexistent. I am then using a Forster Micro-seating die, and I am getting runout that fluctuates between essentially zero, to some that approach .007. I'm seating them carefully. I've tried seating part-way, turning the cartridge, and then seating the remainder of the way. The runout seems pretty random to me, as there are loads that are perfect. Any thoughts?

Strange, I'm using run of the mill cheap RCBS FL dies, that you can buy at Wally world. Those dies produce .003" and less TIR. That is with Sig Sauer 308win brass (since you are asking about 308 win). What concentricity gauge are you using? Sounds like your seater may not be adjusted properly, as that is when the poor TIR is seen in your set up. According to the OP.

A while back, my girlfriend was watching me load some ammo, and she asked a very valid question. She was wondering why my ammo shoots so much better than factor ammo. I pulled my concentricity gauge out, showed her how to use it. Had her spin some of her factory loaded .223 ammo for her AR, and the needle was jumping all over the place. I then handed her a box of my 308 win loads with 175 SMK's. She put one of those in the concentricity gauge, spun it, and said the gauge was broken. She said the "needle" was not moving. I said, dang it, try another one. She said, "same thing". I said, try a few more, you'll find one where the dial goes up a little bit. I then had to explain to her, what she was seeing. The ones where the "needle" was not moving, or just barely going up were the ones that were perfectly straight and very concentric. I told her that all of my ammo is like that, because I have my dies adjusted to minimize runout.

Moral of the story: You don't need fancy or expensive dies to produce absolutely straight ammo. You also don't need Lapua brass either. There are other brands of brass out there, that has worked just fine for years.

A lot of concentricity issues most guys see is because they don't have their dies set up properly.

Measure your neck walls all around with a ball mic.

I'm betting odds you'll find your "concentricity problem".

I've had the same issue. Usually my runout after bullet seating is 0 to 0.005. I straighten everything to 0.002 or better. OCD......

bsa1917hunter
OK, what is the secret with RCBS FL dies????

That is all I use for reloading, but never tried to check runout.

I would verify that all of the cases have uniform case mouth chamfer. I prefer a VLD chamfer tool. Verify the the case holder grooves are clean.

I would also clean the inside of the bullet seating plug and check that the bullet tip is not bottoming out inside the plug and causing a random tilt. If it is there may be a deeper VLD type plug available, or the existing one can be carefully drilled out to add clearance.

When you take the case neck and mash it down in a sizing die, the outside is perfectly concentric. The imperfections are being pushed into the inside of the neck. Then you seat a bullet that is encountering those imperfections in neck thickness as it is seated. No matter what brass you use, this is a thing.

The real question is, "how does the rifle shoot?" I've not found runout of up to around 0.007" to really make a hill of beans' difference in my rifles. Watch F-Class John and Erik Cortina, National and World Champion F-Class shooters respectively, and neither seems to think runout is that important, either. I did a blind experiment with Federal Gold Medal Match .308 Winchester. I measured runout of about 100 rounds of the same lot number. I took the twenty worst and sorted them in one lot. They ranged from 0.007-0.012" runout. I took the best lot of twenty that ranged from 0.000-0.003". I put them in identical boxes and marked the inside as the "good" box and the "bad" box. Outside the box there were no distinguishable differences. When I got to the range, I marked left target on one, and right target on the other. I shot five round groups for the entire box. There was no discernable difference in a factory 700 PSS. Both boxes grouped under 0.75" aggregate.

If you want every round to be perfect, you need to first turn necks to eliminate inconsistencies in neck thickness. I find that turning to 0.013-0.014" usually eliminates any irregularities and provides a uniform, clean release. Make sure to anneal brass every single time and do so exactly the same; not too long because brass will get too ductile. If you can afford an AMP, that is the best method. When setting up your FL die, make sure you bump your shoulder back consistently, with around 0.002" of set-back. You need to size with a bushing to size 0.002" but not use a resizing expander. Follow-up with an expander mandrel of 0.002" under bore diameter. I highly recommend trim/chamfur/deburr in one step with a trimmer that indexes off the shoulder and does not use a pilot. After that, lube the inside of the neck with something like Neolube #2. When you seat the bullet, use a in-line chamber die on an arbor press. IF you do not have one, a "competition" seater with a seating plug designed to match bullet design works well (you can even lap them to better match your specific bullet). That is how to get the best runout numbers on a gauge. This process won't necessarily make your groups smaller.

What adjustments have you performed specifically to minimize runout?

FWIW I FL size my Lapua .308 in my Redding bushing die without an expanding ball, and seat with my Redding Competition seater. I expect no more than .002 runout when randomly checked. It is usually in the .001 to .0015 range. I would not be concerned with significantly higher numbers if the rifle chamber has minimal clearance in its throat diameter though.

She's been rather busy,trying to get 108's in her 6x45 upper,the poor poor(literally) STUPID Fhuqk. Hint.



Fhuqking LAUGHING!............

OP said he's using a LCD for sizing the neck - so the INSIDE is perfectly concentric. If the outside is concentric too, then it's good brass - he said it's Lapua.

Agree that it is likely the long copper bullet bottoming out in the seating stem. Take your seating stem out and set it on a bullet and see if it bottoms out. Try it again with a lead core bullet and you should be able to tell the difference.

Can also see a crooked or inconsistent chamfer causing more resistance on one side when seating. I had to get a vld chamfer tool to get Barnes bullets to seat well in my 7-08 cases. I think on that one my expander ball might be undersize and making seating harder.

The simple process of partially seating a bullet in the case, then rotate the case, seat further down, rotate, then finish seating also reduces runout. Stepped seating reduces runout to about half of what happens when seating in one single motion

Have you proven this with runout tests on the same batch of brass?

Are you compressing your chosen powder charge?

Explain to me, if you will, how the Lee neck die makes the inside of the neck perfectly concentric. Explain to me how you can get perfectly concentric Lapua brass.

I've done this experiment with a large sample. No measurable difference in runout.

Where are you measuring runout on the loaded cartridge?

With a bushing die, the concentric bushing results in a uniform OD of the case neck, pushing irregularities to the inside. With a collet die, the concentric mandrel ensures uniformity of the ID of the case neck, pushing irregularities to the outside.

I was under the impression the Lee die uses collets with fingers over a mandrel. If he is measuring runout on the neck and getting zeros after this process, the inside cannot also be zeros unless he's turned the necks. Even Lapua brass has thickness variation.