Runout guage

G

gunner52

Guest
I use two runout gauges to check loads and was wondering witch one is best. I have a Hornady concentricity guage and a RCBS runout guage as well. Both use a diff. technique as you all are aware and the results are far diff. on each. I size fireformed brass with a Lee neck sizing collet die and all is .002 TIR or under when I start. I am using a Redding competition seater. I see as much as .003 variation between the two guages. Witch guage is the best one to use and witch one is telling me the truth? It makes sense to me that when the cartridge is at rest in the chamber, the important thing would be the alignment of the bullet with the brass. Or is it from the tip to the base? Thank you in advance.
 
I hate to be a spoil sport, but there are problems with both, the surfaces of the that the case must slide on the RCBS do not allow the case to slide nearly as easily as the bearing balls, that are used on the Sinclair tool., and the Hornady supports cases by their rims, which may not be concentric with the bodies of cases due to asymmetrical stretching under firing of the back of the case. Anyone who has closely examined a case that was fired in a generously dimensioned factory chamber has seen that in the area just in front of the solid head, the case may be bulged more visibly on one side than the other.

Getting back to your question, I have gauges that support entirely off the body of the case, and one (a H&H) that supports on the bullet tip and the back of the case, just in front of the solid head. I don't think the differences in the numbers produced by the different support systems are important, as long as you compare "apples to apples". They both have their place. The fellow that makes the H&H would tell you that the Sinclair's support system depends on the shoulder of the case being perfectly round, and that if is not, that readings will be inaccurate. On the other hand, the Sinclair allows you to measure a case without the bullet, something that can come in handy.
 
Thank you for your reply. I have modified my RCBS and have 4 bearings supporting the front and back of the taper. I check the case before loading for neck runnout and cull anything over .0025 if it is a unfired, and .002 if fireformed. Should I rely on the Hornady after loading? Thanks again.
Brad
 
I would look for a loaded round that looked perfect on the modified RCBS and check it on the Hornady, to see if there was a difference. As I said, I don't like where the Hornady supports cases at the back. What are you using your ammo for? I have seen some good varmint shooting done with cases that had not been fire formed, and looked pretty ugly on a gauge. On the other hand, I would not use a case that had not been previously fired in competition.
 
I like the paragraph in Tony Boyer book, were a gentlemen told tony he needed one of his run out checker tools that this fella had made, or at least was selling. Tony let him check his ammo, and sure enough, there was about .004 or .005 "or whatever it was" run-out on tony's ammo. Tony then took that ammo to the range and shot a dot with it. Tony decided he really didn't need one of those tools. I am not tony Boyer by a long shot, but i don't miss not having one anymore. Just one more thing!
Mr Allen has spent a lot of time with these things and knows the ends and out with them. his advise or opinions are very sound. Lee
 
skeetlee said:
I like the paragraph in Tony Boyer book, were a gentlemen told tony he needed one of his run out checker tools that this fella had made, or at least was selling. Tony let him check his ammo, and sure enough, there was about .004 or .005 "or whatever it was" run-out on tony's ammo. Tony then took that ammo to the range and shot a dot with it. Tony decided he really didn't need one of those tools. I am not tony Boyer by a long shot, but i don't miss not having one anymore. Just one more thing!
Mr Allen has spent a lot of time with these things and knows the ends and out with them. his advise or opinions are very sound. Lee
Click to expand...

It is always fun to watch Tony and John cruise the tents. The guy who had that tent/table sold several of those tools, but as PT Barnum said " a fool born..."
 
I for one, have a hard time understanding the difference between having a very true chamber and feeding it crooked ammo,
or say having a crooked chamber and feeding it true ammo. If its all meaningless, we could just load with $ 19.95 dies.
To assume that all concentricity gauges yield usefull info is a mistake. We also have no idea if all guns react
to crooked ammo in the same way. For that matter , might be some bullets survive that better than others. It doesn't
hurt to turn over all the rocks you can.
 
I read Tony's comment about the non-importance of straight ammo. If I remember correctly the amount of runout that he mentioned was well beyond the worst that can be obtained with any of the dies I have used to load 6PP ammunition, which made me wonder how he got his to be that crooked. The other couple of things that I noticed were that he made no mention of what sort of neck clearance he was using, and where he was seating his bullets relative to the rifling. Here is why these matter. If he was seating into the rifling, and had the usual slim loaded round neck clearance, measuring one of those crooked rounds, that shot so well, AFTER chambering it, and removing it without shooting it, would have shown him that it had been straightened by being chambered. I have done the experiment. Try it if you like. Now here is the reason that I bring this up. If someone is jumping and/or running more neck clearance, the straightening would probably not have happened.

Benchrest has, and will always be a game of follow the leader, but it is also a game where small details matter a lot.

I use a lot of neck tension because someone who shot a lot better than I, told me 133 likes that. I shoot flat base bullets because I tried BTs before the current super short BTs were common, and the longer ones didn't work as well, as FBs, for me. As a result, (high neck tension with FB bullets) my loose fitting Wilson seater was leaving something on the table as far as concentricity was concerned. Switching to a tight clearance, Neilson seater gave me straighter ammunition, and seems to have improved accuracy, slightly. I always try to make ammo as straight as I can. If that makes me gullible, so be it.
 
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