Home Forums Reloading Big Game Rifles Effects of runout on precision

Moral of the story. Keep your runout less than .003", by whatever means/method you like. As long as that method is consistent. If you are not checking the rounout of your loaded ammo, then why mess with fancy equipment at all? I've shot ammo with a lot of runout and compared it to ammo with less runout and some groups were cut in half by the straighter ammo. Expensive die sets and stuff like that, that require all kinds of bushings and stuff should be left to benchrest shooters with benchrest rifles. But runout has an effect on accuracy/precision more than most think.

Here's an example of a hunting rifle (Ruger M77 MK2 300RSAUM) that I found brass with inconsistent neck thickness to be the issue. This in turn has a direct impact on runout. I threw out some brass that was really bad, giving more than .006" TIR. You can't get rid of inconsistent neck thickness issues with a fancy die. No matter how hard you try. It's just not going to happen.

Poor runout:


Acceptable runout:


And then checking the straighter ammo at 400 yards:

Holding less than 3/4 moa at 400 yards is acceptable enough for the hunting I do.

A double check of the straighter ammo:

Still holding 3/4 moa at 400 yards.


This is just a hunting rifle, but it plainly shows how runout affects the groups. Other groups shot with the poor runout showed the same results. I threw those targets away, they were so bad.

Interesting to see everyones opinions on the topic. I just bought a Redding FL bushing die to reload for my GAP Crusader. Using "standard" Redding sizing die, I was getting lots of .4moa groups. Not all the time mind you, but quite often! I'll be out to the range tomorrow with the same load, but brass resized with the new bushing die to see if there is any difference. For those interested, this load performs well on every .308 I've shot it through. YMMV, of course.

168 Z-max, 42.2gr IMR4064, Lapua brass and CCI 200.

Interesting to see everyones opinions on the topic. I just bought a Redding FL bushing die to reload for my GAP Crusader. Using "standard" Redding sizing die, I was getting lots of .4moa groups. Not all the time mind you, but quite often! I'll be out to the range tomorrow with the same load, but brass resized with the new bushing die to see if there is any difference. For those interested, this load performs well on every .308 I've shot it through. YMMV, of course.

168 Z-max, 42.2gr IMR4064, Lapua brass and CCI 200.

Moral of the story. Keep your runout less than .003", by whatever means/method you like. As long as that method is consistent. If you are not checking the rounout of your loaded ammo, then why mess with fancy equipment at all? I've shot ammo with a lot of runout and compared it to ammo with less runout and some groups were cut in half by the straighter ammo. Expensive die sets and stuff like that, that require all kinds of bushings and stuff should be left to benchrest shooters with benchrest rifles. But runout has an effect on accuracy/precision more than most think.

Here's an example of a hunting rifle (Ruger M77 MK2 300RSAUM) that I found brass with inconsistent neck thickness to be the issue. This in turn has a direct impact on runout. I threw out some brass that was really bad, giving more than .006" TIR. You can't get rid of inconsistent neck thickness issues with a fancy die. No matter how hard you try. It's just not going to happen.

Poor runout:


Acceptable runout:


And then checking the straighter ammo at 400 yards:

Holding less than 3/4 moa at 400 yards is acceptable enough for the hunting I do.

A double check of the straighter ammo:

Still holding 3/4 moa at 400 yards.


This is just a hunting rifle, but it plainly shows how runout affects the groups. Other groups shot with the poor runout showed the same results. I threw those targets away, they were so bad.

Not measuring for runout doesn't mean there is runout.

Exactly, why measure if it dont matter.

Exactly, why measure if it dont matter.

I didn't say it doesn't matter.

Sure...necks are anealed, I do this after every firing, air cooled. I find anealing helps with consistant bullet steat depth. I also find that before sizeing and pulling the case over the expander ball, I use a very LIGHT lube of Imperial wax, applied with a cotton swab,to lube inside of the neck..then the outside of the case. Over the years, I`ve gotten a "feel" for this. Thoses who have it know. what I`m endvering to do is keep the case concentrict. I wipe the outside of the case clean, then into the trimmer. Mostly because of the pressures I run, and how I have my die set up, this only requires a touch up. After sizing, and this is step is I think, important, I put a very good champher on the inside ot the neck, then outside. I then take OOO steelwool and polish the champher, getting it smooth for the seating process. Prime and fill. The case goes into the press, I sellect a bullet at of 20, that have already been chosen for consistant BTO, place on the neck and guided into the seat die with my fingers. I then run the case and bullet up to meet the seat stem. When I contact the stem, I stop, and GENTLY, using my fingers, lift the press handle just a little and drop it on the bullet, GENTLY, several times. If you can picture this, what I`m doing is aligning bullet, die stem and case. Should you do this a bit ,you can feel the process. I do Not start the seating process until I`ve done this. Start the bullet down the case neck about half way, turn case 1/2 turn and complete the seat. Check bullet seat depth.

I`ve never checked my run out.

This sounds very time consuming but is really not. Just part of my process, and goes quickly.

YMMV
,

I'd be surprised if a 1000 yard competitor assembled cartridges with much runout anyway. With my simple gear I have no problems at all assembling stuff to .002" or less, maybe .003" if I'm using "lesser brass" that hasn't been culled.

I don't have to measure every cartridge every time. I use it as a diagnostic tool to evaluate components and procedures. When I know I'm assembling straight ammunition then I know runout isn't there to affect things. I don't have to be concerned with whether or not a particular rifle is affected by it or not.