runout of ammo

[CPT.CRAZY]

Are any of you checking and adjusting the runout of your ammo ? If so are you seeing a improvement in your long range (600+ yards) groups? How are you measuring this, I saw Hornady is making a tool and was wandering if it is worth the time to do this.

[NugginFutz]

I have the Hornady Concentricity Tool, and do use it on my bolt gun fodder. I have two that will consistently shoot bug holes @ 100 yards (pics of .308 at bottom).

I did try using it on a some loads for my 264LBC. First, the runout on the ammo was not terribly noticeable. Most of the ammo was within .005", with some as far out as .010". I corrected a set of 50 rounds to <= .003" and shot some pretty good groups with it. Do I have any quantitative data? No, and I wish I did. The reason I say that is my most recent outing with my 264LBC was something less than satisfying. The ammo had been loaded without being trued. Groups were in the neighborhood of 1", whereas before I had shot sub 1/2" groups with relative ease.

So, Capt Crazy, I have given you a classic "Microsoft Tech Support Response" - a completely accurate and yet utterly useless answer to your question, as it relates to your Grendel.

At some point in the near future, I will make an honest effort to shoot some side by side tests, with a willing accomplice to hand me test mags without telling me which group is being shot. Then I will (hopefully) have your answer.

As far as my bolt guns go, I can safely say it helps to correct the runout. Here are some back to back .308 groups, shot just last week. New Lapua brass with the rifle's favorite load. I'd dialed in scope offsets between groups in an effort to better center the group.




ETA:
I can add this: After a dozen or so rounds, once I get the feel for the particular cartridge I'm truing, it takes only a few seconds to determine if the round is not in tolerance (my choice is <= .003), and another 3-5 seconds to correct it. I suppose I can process an entire box of 100 rounds this way in about 10 minutes, assuming about 50% getting the full treatment.

[Savage Shooter]

I always check runout of all my rifle loads using Hornady's Concentricity tool. Although the instructions say to try for less than .003, with Hornady seater dies, I usually get less than .003 runout except for an occasional odd one, which I can correct using the tool. However, I admit that I have not done extensive testing to check if a batch of rounds with runout > 0.003 shoots significantly worse than those with .001 runout. My usual long distance shooting is prairie dogs at 300 - 600 yards which is more demanding than steel gongs or medium or big game at 600+ yards, so I check for runout as a matter of habit.

[Savage Shooter]

I just read NF's post and I also have had experience with groups "blowing up" when I didn't check for concentricity. I often check for runout days after I finish reloading and sometimes forget to do so before shooting them. Last week, I was fine tuning a load in my .223 around a node that had shown promise during OCW development, shooting loads 0.1 gr above, below and at the powder weight that I had zeroed in on, but the groups were 1 - 1.5 MOA vs. the 0.75 MOA that I had gotten in the first round of my OCW testing. It puzzled me, but then I checked my reloading notes and realized I had not trued them up. Just like NF, I can't definitively say that excessive runout variation was the cause, but perhaps it was. Because it takes only a few minutes to check and adjust concentricity, I realize that I need to change my reloading process and adjust concentricity immediately after loading all my rounds, so I don't forget.

[LR1955]

Are any of you checking and adjusting the runout of your ammo ? If so are you seeing a improvement in your long range (600+ yards) groups? How are you measuring this, I saw Hornady is making a tool and was wandering if it is worth the time to do this.

CC:

Yes, it does have a impact on accuracy. I would say it is worth the effort if you are shooting a very serious bench rest competition where the difference between first and last place is being measured with micrometers.

With a gas gun at 600 yards? A person would be hard pressed to prove absolutely that one shot out of X number went bad because of run out.

With a gas gun, I bet your run out will be altered via the self loading process of stripping the bullet and slamming its tip against a feed ramp or part of the barrel itself as it loads. You may want to check to see how much this process alters your run out before spending money and time on a run out tool and wasting precious more minutes of your life doing something that doesn't show a bit of a difference in practical terms.

Maybe thirty years ago when presses and dies were not as precise as today but today you have some very good dies and presses that produce ammo so good in tolerances that the process of measuring run out on each round of ammo is no longer necessary.

What we used to do was to seat the bullet about half way then turn the cartridge 180 degrees and finish seating it. This was the standard procedure many years ago when we really did have problems with run out due to the quality of dies and presses (ram alignment). We also got around this by using the Bonnanza Co Ax press where your dies float enough in the die holder that they automatically align with the cartridge. I still use one.

I have watched the bench rest guys load on the range and have yet to see any of them check for run out before shooting the ammo. That could be an indicator or maybe it is that their brass and dies are so good it isn't necessary. Or maybe their chambers and barrels are so good it isn't necessary.

Anyway, if you are worried about it, do the half turn thing when seating the bullet. No need to measure or go through another process.

LR1955

[Savage Shooter]

I do the "half turn thing" when seating bullets in all my rifle cartridges. (Although I have the Lock-N-Load progressive press, I single stage load all my rifle cartridges and only use the multi-stage capability of my press when reloading 9mm and .40 S&W). Also, with the Hornady dies, which have the in-line bullet seating system, plus the "half-turn" technique, most rounds measure less than the target .003" of run-out. So, although I still do it (because it doesn't take a lot of time and I am accustomed to doing it for my bolt gun cartridges), I would tend to agree with LR that it's probably not necessary (or won't make a difference) for your Grendel.

But, the engineer in me is likely to test some rounds at <.001 and > 0.010 (I'll likely have to intentionally make them bad) and see if there is a difference at 300 yards (the longest distance I have easy access to) before I give up not checking and correcting for run-out.

[SG4247]

I think runout matters.

This is a gas gun, and these targets cannot be coincidence. I have seen it repeated over and over again on my AR guns at 300 yards and beyond.

AVE R.O. = average runout measured at the bearing surface of the bullet, as referenced from the case outside diameter.

[CPT.CRAZY]

Well, I decided to get one of Hornady ' tools and give it a try. I've got some time on my "local" 600 yard range this weekend I will shoot corrected and in corrected loads and try to my opinion of if correcting the runout makes a measurable change in my groups.

[bwaites]

Well, I decided to get one of Hornady ' tools and give it a try. I've got some time on my "local" 600 yard range this weekend I will shoot corrected and in corrected loads and try to my opinion of if correcting the runout makes a measurable change in my groups.

To do a true test, you need to check while single loading, and while loading from a stacked magazine.

My experience is that if I REALLY want best groups, I run my ammo single load using a Bob Sled:

http://www.originalbobsled.com/ARSleds.aspx

I can shoot sub MOA from 100-300 easily running stacked ammo fed from a mag, so long as it is decent ammo for the rifle. Past 300, I start to see some fall off, probably because of the bullet slamming into the feed ramps and getting minutely upset. (I measured change in runout years ago, before and after feeding from a mag. There was anywhere from .003-.010 change in the runout.) I can shoot sub-MOA out to about 600 with good ammo fed from a mag, but the groups are opening compared to those fed from a sled.

You can improvise a sled simply leaving an unloaded mag in the well and sliding the round on top and forward, then dropping the bolt.

[SG4247]

The best tool for measuring case to bullet runout is found here:

http://www.21stcenturyshooting.com/Concentricity_Gauge.php

The Hornady gage does not locate or reference the functional case centerline from the proper datum.

[AZ. Old Guy]

I do the "half turn thing" when seating bullets in all my rifle cartridges. (Although I have the Lock-N-Load progressive press, I single stage load all my rifle cartridges and only use the multi-stage capability of my press when reloading 9mm and .40 S&W). Also, with the Hornady dies, which have the in-line bullet seating system, plus the "half-turn" technique, most rounds measure less than the target .003" of run-out. So, although I still do it (because it doesn't take a lot of time and I am accustomed to doing it for my bolt gun cartridges), I would tend to agree with LR that it's probably not necessary (or won't make a difference) for your Grendel.

But, the engineer in me is likely to test some rounds at <.001 and > 0.010 (I'll likely have to intentionally make them bad) and see if there is a difference at 300 yards (the longest distance I have easy access to) before I give up not checking and correcting for run-out.

I have always used the 180 turn when seating bullets. I started reloading about 40 years ago and was taught that by an Air Force Shooting Team marksman.

[Kikn]

I have always used the 180 turn when seating bullets. I started reloading about 40 years ago and was taught that by an Air Force Shooting Team marksman.

I do that to, but I didn't learn it from anyone. I just thought it would help to center the bullets. And for the most part they are all pretty close.

[SG4247]

If you are happy with your accuracy results, then there is no need to change anything.

But, if you start using that 21 Century or the Sinclair run out gauge and you will likely be disappointed in how good your runout isnt.

If its not being measured, then you don't really know.

I took me several weeks to revise my process to correct the runout I was inducing into my handloads. I was surprised by how what seemed like very small things, made a big difference in the final result.

[bwaites]

One of the things everyone forgets is that once you have a decent rifle, practice is WAY more important than trying to find a perfect load. Statistical analysis shows that if your rifle and ammo load is mechanically capable of 1 MOA, you are only 2.5% less likely to hit a 10" target at 700 yards than someone with a rifle capable of .1 MOA. That means that if both of you shoot 100 shots, he'll hit the target only 2 or 3 times more than you, assuming you both are equal skill wise. If you are an expert and he's a beginner, you will outshoot him EVERY time! At ranges past 500 yards, being able to read wind is FAR and away more important than any other factor, assuming 1 MOA capable rifles!

Accurate shooting is a VERY perishable skill! Shoot more!

[Savage Shooter]

To do a true test, you need to check while single loading, and while loading from a stacked magazine.

My experience is that if I REALLY want best groups, I run my ammo single load using a Bob Sled:

http://www.originalbobsled.com/ARSleds.aspx

You can improvise a sled simply leaving an unloaded mag in the well and sliding the round on top and forward, then dropping the bolt.

Good tip Bwaites - might have to go back to doing this. I use a Bobsled in my Savage bolt guns and I used to single feed my AR for load development leaving the unloaded mag in the well - but stopped doing that when I went to using the Caldwell rail mounted net so I didn't have to chase my brass. I do have a stand-alone net, which is not as effective in catching all the brass, but maybe I'll go back to single feed and using the stand-alone net during load development. Or, if you don't really see the effects of increased run-out until you get past 300 yards and my load development is at 100 yards, it won't matter.