Extreme Reloading: Testing the effect of bullet run-out (ep. 09) 

Thank you Micah.

Good points DW None. I do rotate the case 180 and it seems to help. I see Hornaday recommends a special seating step for some of their bulllets. As always, thanks for watching.

Based on your first test, could we not hypothesize that IF we correct runout THEN we should see an increase in accuracy along that same linear data line?

@@billr4677 Hello Bill, There is a tolerance on run-out. In my experience, as long as run-out does not exceed 1 or 2 thousandths then yes, we should see good precision as a result. Of course, that assumes everything else was done correctly, good case prep, accurate powder charge, etc. Thanks for watching and posting.

I'm not convinced that any amount of runout really matters in a bolt gun. And maybe not in a gas gun either. Once the bullet engages the lands it can't do anything but travel straight through the bore. Wobbling or being "crooked" is impossible. Plus, the rifling imparts the necessary rotation to stabilize it. I'd love to see you load some rounds with .005+ runout, and see how the groups compare. My money says it won't make any difference.

@@randyemenhiser2573 shoot it out to 800m; will this still be the case? Likely not but how could you measure this given all the many variables. Actually wait we can. It’s called statistical probability. Now Is this a pretty safe statement? Don’t know as I don’t have that information. However to say the rifling imparted on the projectile would be the same between near 0 runout and say 5 thou, well.. that I don’t know either but if a bullet is traveling “crooked” even if for say .001” before striking the lands and grooves if all else is perfect WRT Barrel and the ogive then wouldn’t that affect its flight? I know an entire segment of the shooting community thinks it matters. Dose it really. Not to this gut.. I’m just not that good and it’s not my job to find out. I’m subscribed though. Just my 2c.

Hello Nick Thanks for watching and posting. I had not heard of that prior to your mentioning it. I did a quick search and see others are complaining about the lead sled but not so much for scopes but the stock. Coincidentally, I have started shooting much more from prone with bipod and rear bag. I think I do every bit as good that way.

Some rifle/bullet combinations are more sensitive to bullet seating depth (CBTO) and run out than others. Bullets using a secant ogive tend to me more sensitive (you can tell a secant ogive bullet by the abrupt change in angle along the bullet's length as it transitions from the bearing surface to the nose... it almost looks like a rocket cone). Berger bullets tend to be quite consistent as you noted.

Hello Jack, Thanks for watching and posting your question. Group #1 was different from groups 2 and 3 in its bullets seating depth (COAL). That group used by old, standard seating depth with a jump to the lands of 0.147". Groups 2 and 3 had the same jump of 0.020". The difference between these was in run-out where group #3 had between 0.001 and 0.002" run out. Group #2 was highly concentric with effectively no measurable run-out. The difference in velocity might be a bit misleading. Statistically there is no difference in muzzle velocity between these groups when we use a 95% confidence level. This is where we apply +/- 1.96 SD to the mean. When we do this, we end of with error bars that overlap. I was thinking group #2 would simply do best all around. It did not, which indicates there is a tolerance to run-out. Excessive run-out may affect group size but up to 0.002" run-out did not show a difference. Thanks again for watching.

I agree with you. It takes a lot of run-out to make a difference. A barrel with a good or even reasonable leade will correct for even moderate run-out errors. Thanks for watching and posting.

Yes, the rest moves under recoil. The question is has the bullet exited the muzzle prior to the recoil impulse moving the rest? If so, then the rest can move and have no effect on bullet point of impact. As long as the sights are properly aligned for the next shot then each group is acceptable.

Lots of tests on this and it is agreed the barrel moves long before the bullet exits@@sdkweber

@@rgthomson1 I read about this in Hatcher's Notebook and he provided a calculation to determine movement. The conclusion of Hatcher was that movement of the barrel prior to bullet exit is very small and negligible. Do you have some more recent papers you could post/share the URL to? I would be interested to read these.

Yes, "out of round" as they say or not a perfect circle. Thanks for watching.

Yep, as it turns out not enough run-out to show a difference. But that is good to know as it shows there is a tolerance factory with bullet run-out.

Thanks Garrett and thanks for watching. I do most of my videos on my Ruger Precision Rifle but this Ruger no. 1 has shot a 0.6 MOA group and my RPR has a hard time beating it. One advantage of the no. 1 is the fact I can seat the bullet however I wish to affect the best precision. With a magazine fed bolt I am limited and in fact the closest I can get the Sierra TMK to the lands is 0.147" I do like my bolt action rifles and I have several but like Col. Whelen said, only accurate rifles are interesting.

@@sdkweber amen to that! Thanks for the reply. I agree entirely :)

@@GarrettHamilton Thanks again for watching and posting.

Most rifles cannot shoot 0.5 MOA 5-shot groups let alone 0.5 MOA groups 100% of the time . I am nearly certain you are very new to shooting and when we test two different loads we are looking for differences in how the loads perform. In other words is one better than the other?

@@sdkweber with all due respect, I would expect that if you have the finest reloading tools etc. that you would be able to get to those numbers at least 50% of the time. I was at the range a couple of days ago shooting off my hunting load of 10 rounds of 120gr. TTSX in my CZ550 6.5 x 55mm. Wanted to get rid of them as I was not happy with the load (all around 0.007" runout), without trying on a very windy day I got a 10 shot group of 1.8MOA, laterally dispersed. I am NOT a good shooter, I then tried a target load that I wanted to develop but needed to get a speed on, they were 123gr. SMK (.005" runout) and got .84 MOA. Finally, before going home, I wanted to get rid of 5 rounds I had downloaded for my grandson. No science involved I merely dropped by 2.5gr. of powder to minimise recoil for him, 5 were left. 180gr. Game Kings in my 30-06 CZ550, the group size was 1.3MOA (runout was not measured). While a way off the 0.5MOA these are results were more wanting to gather speed data more than shooting tight groups. When I apply myself the 6.5mm does .6MOA more often than it does not, the 30-06 is a MOA rifle but I think it is better than that, I believe I am the problem. My contention is that at these group sizes, are you measuring your, ability to shoot sub- MOA or the loads. To accurately test loads one needs to be able to shoot. So in my case I find that my shooting ability cannot resolve the minute reloading nuances. You appear to be in the same boat. We shoot at 100m and the there is precious little in reloading that can open a group like that other than pooer shooting. In my experince +-0.3gr. of powder won't, 0.007 or 0.001" runout wont, 0.001" difference in neck tension wont. So we will probably agree to disagree.

@@andrewleigh3 We are always constrained by the inherent limitations of the rifle. In this case, the Ruger no. 1 gives me about 1.5 MOA. Not much I can do to improve that but sometimes I can do a little better. It sounds like your CZ is a good shooter. Keep that one and carry on.