Testing loaded round runout concentricity from .003' to .045' at 1000yds.

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[ChevyU]

I started down that rabbit hole, but quickly realized there are other steps in reloading that gave better gains. Thanks for confirming 👍👍

[sawhill]

Hello Mr. John. I hope I took the right information from your video. We shoot local club matches at 100 and 150 yds. We shoot for all cash, anywhere from $100 to $200 dollars a shoot. To win, you need a perfect 50 at a hundred yards, and 48, 49, 50 at 150 yards What I took from the video is, concentricity's not going to get me into the high 90s. You and Eric have the most informative videos out here. Thanks.

[erich]

The chamber straightens a lot of that out. Your comment about the seating depth moving when you chamber these seems like the best explanation to me. A better test would be average budget reloader type runnout vs full OCD F-class reloader type runnout.

[kevingeary]

I've heard people saying it doesn't matter but thank you for the test to verify it!

[Lethalmuffin]

Wow. I just picked up a runout gauge and started stressing when I had a few bullets over .002 runout that wouldn’t seat in a headspace gauge.

This helps reduce that stress immensely knowing that the wobble will correct itself in the chamber sufficiently enough that I don’t need to redo all these bullets or adjust them down to .001

You’re doing a great service by showing us what we can do to streamline and I cannot thank you enough sir 🎩👌🏼

[MMBRM]

You can't say it does or doesn't matter unless you try it in multiple chambers and with multiple jump/jam configurations. Obviously a newer style match chamber with very tight free bore will be more forgiving(the bullet is physically prevented from being far out of concentricity) and if you are jamming the bullet in the lands the lead in/lands themselves will correct most concentricity issues. However, in a situation where you're jumping the bullet it definitely makes more of a difference. I've done extensive testing in benchrest guns and it definitely matters when you're trying to squeeze out every little bit of accuracy.

[unclenick]

One thing worth realizing is that the degree of the tilt effect on point of impact depends on the bullet shape, rotation rate, and its time of flight (TOF) to the target. The amount of off-axis bullet tip that gave A.A. Abatiello about 0.5 moa of group size increase with the old M1 Type 173-grain National Match bullet in 30-06 back in the 1960s (The American Rifleman article on this test was reprinted in the NRA book Handloading in 1981) fired at about 190, 000 rpm gave Harold Vaughn about 0.2 moa of group size increase in his book Rifle Accuracy Facts (25 years ago) shooting a stubbier 68-grain 6 mm BR bullet at about 167, 000 RPM (high side of runout marked on each cartridge and then rounds place in the chamber with the marks at 90° intervals around the clock to get worst-case impact). Vaughn's results would have been more like 0.27 moa if the RPM and TOF matched. In addition to spin rate and TOF, the lateral drift imparted is determined by how far the bullet's center of mass (CM) is from the geometric center of bullet tilt in the bore and the actual tilt angle remaining after entering the bore. The bigger the separation of CM and tilt axis, the further off the bore axis the CM is for each degree of in-bore tilt, the greater its rotational speed, and thus, the faster it is thrown tangentially away from the bore line at the moment the rifling lets go of it. That drift is on the order of a few inches per second, typically, and is too slow for drag to reduce it significantly before the bullet gets to the target.

[redrock]

The biggest issue with all of this is separating the noise. Assuming a perfectly built rifle, shooter ability and wind are the two biggest factors. The minutiae of reloading have a much smaller effect but are easier to measure and control. I suspect putting a lot more effort into shooter training and wind calls will give much larger gains.

[joearledge]

A lot of people have demonstrated that concentrisity doesn't matter(Johnnys Reloading Bench, Winning in the Wind, Bolt Action Reloading, and others I'm sure) they've done it with factory ammo and hand loads. Usually something like "the worst 5 cartridges with 0.003" to 0.005" vs the best 5 with less than 0.001" runout". Often there is no difference in the groups and sometimes the worst 5 cartridges shoot tighter and/or have better stats than the best 5. The problem with their videos is that most are hard to find because they don't have "runout" or "concentrisity" in the title. Most of the videos were being made for a different reason(testing a product or new bullet or just generic reloading) and they just happened to decide to do a concentrisity test. The videos are great, just not easy to find because concentrisity wasn't the primary subject of the video. Never have I ever seen someone shoot 0.020" to 0.040" visibly crooked rounds for groups, especially a precision long range competition shooter. I'm excited that people can easily find your video and that the concentrisity is worse than what a lot of plinkers are willing to chamber and it's at a longer range than 95% of people ever shoot. Translated to 100 yards the groups were 0.4" to 0.8" with rounds so crooked they would barely chamber. This is about the best evidence so far(also supported by the results of others) that if it's not visibly bent off to the side, it's fine, even for long range precision. The only caveat is if you shoot competition where 0.001" in group size difference matters, even then I'd question whether that difference was just by random chance or one of a dozen other factors. Great video Sir! Keep up the good work!

[TubeDobs]

Interesting to see SD and ES changes from the 3 groups. I sold my concentricity tool gauge loooong time ago.

[AutoTrickler]

Really interesting. Small samples, but the results beg for more testing. The small group was super small, and the large group also had a large ES and the group was vertical so it seems likely the vertical came from velocity spread. Whether the runout affected velocity spread… I would think not but maybe. I suggest if you feel like it do 20 rounds perfect vs. 20 rounds which are visibly crooked and if the results are different enough, we can run some stats on it.

[ff]

Thank you for conducting this test. Extremely valuable information.

[mikemcallister]

Greatly appreciate all the amazing videos. Learning a lot from these. Just tried the ThorroClean from your review and was very pleased with how a 22LR barrel came out. IT was very filthy, oh and I did get a good bore scope. Per your recommendation. Thanks for all that you do for us wannabe long rangers..

[elwhastrummer]

Good to know. And even better, it didn't take 40 minutes to explain. Thank You

[garysreloadingroom]

Interesting test John. You mentioned that you thought that the bullets on the rounds that were really out, could have been pushed back further into the case. Food for thought, the bullet could have been pushed more into alignment by the chamber as the bolt was closed. Regardless, it was a very interesting test. Thanks!

[DLN-ixvf]

I always thought the barrel would sort things out as the bullet travels down the bore twisting in the grooves !
Personally I think a major runout just tells you your equipment is wearing out that's all.

[maddan.]

Possibly some of that vertical could be attributed to the increasing velocity spreads as well as the runout.

[ls]

Excellent test, with nearly unbelievable results! Thanks for sharing & would love to see more testing-

[kajhelin]

Great test! Could you bend a few more cartridges? Chamber them. Remove them and measure run out again. If your bullet is .284" and freebore diameter is .285" the cartridges should measure only 0, 0005" of runout at the bearing surface. Brass springback not accounted for. The bearing surface might be 3/8" infront of the case mouth in your cartridge.

[DadWil]

Thank You for doing this test & demo...
I have not gotten to the point of even measuring the runout on my loads...
Like EC told us in one of his posts so much of this stuff does not matter..
well at least to nimrods like myself they don't matter...
BTW I like the beard contrary to what EC tells you.