What Should Fired Brass Show On V-Blocks For Case Runout?

[Savage 12BVSS]

Lets say you loaded up some loads in new brass and fired it, right out of chamber what should it show for neck straightness? Should they all be the same or vary? Just waded thru the drifts and cleaned off the bench and shot in my target scope on my gun that I plan on doing last powder charge and seating depth ladder's on. New norma brass chamber formed and right into the gunshop where my v-block's with dial indicator is. Ran everyone thru and they are all .0004 runout exactly, no more no less. This don't seem bad being less than 1/2 thousandth, what does everyone think? It's a McGowan barrel in 7mm-08 and I never checked it at this point before. It's alway's after sizing, loading, and seating bullet, than I check runout before firing.

 

[bigedp51]

Your fired runout is what it is, and now is your baseline, what is your neck runout after resizing and again after bullet seating?

The U.S. Military considers match grade ammunition to have .003 or less runout.

 

[Savage 12BVSS]

Will post that up tomorrow morning, just got my case master back to use again and the hornady I've been using only works with bullet in case loaded round. With the case master I will post after resizing case and again after bullet seating. I try to keep it .001 or less for loaded rounds, probably not that it needs to be but one less thing to consider. I was worried the chamber might be causing me problems. I saw someone post it should be zero out of fired chamber so it made be think.

 

[Savage 12BVSS]

OK went down and finished the cases, ran them thru lee collet dies and the runout was now .0004 to .0003 for all of them. Then I got them ready and seated bullets in them with a forster benchrest seater. With one seating stroke in one position they were steady at .001, if I turned the case to three different positions seating they averaged .0008. So everything was in acceptable range and none required any adjusting. This was my worst cartridge for not loading straight, the press helped, the collet dies helped, and turning the seater in thirds also made a measurable difference.

Life is good except 10 inches of snow tonight so there goes shooting for a while.

 

[cape cove]

Those are great #'s . Your getting 10 inches we are slated for 45 cm(18 inches). Same storm affecting the east. Yuck

 

[Savage 12BVSS]

Wow can't say I like snow much by this time of year, thrill is gone. I just broke trails to the target boards and cleaned the bench all off, dug the seat out of the crust. Oh well ladder tests will have to wait.

Thanks I was hoping it was the dies and not the chamber. Those collets were nice, you're the man. I haven't tried the sinclair mandrels yet, may not at this point at least. Hope you got a plow or someone that comes and plows you! Dave

 

[Mikecr]

It's normal to have very low TIR with cases pulled smoking from a chamber (your best die).
Whatever we do from there messes things up(never improving).

 

[Savage 12BVSS]

It's normal to have very low TIR with cases pulled smoking from a chamber (your best die).
Whatever we do from there messes things up(never improving).

Well the neck sizer did not cause any increase what so ever, the seater added the increased TIR that I will live with at this point.

 

[Mikecr]

Seems good
What is the runout as measured off exposed bearing of seated bullets?

 

[Savage 12BVSS]

Once I figured out to move the cartridge position three different times (about 120 degrees) They averaged .0008 measured right about 1/4" off case edge.

 

[bigedp51]

What runout gauge are you using that reads in .0001???

I drink a lot of coffee and I'm happy if I see .001 runout with my coffee induced shaking finger.

 

[Buster Hemlock]

What I believe you have found is that your chamber was cut concentricly. The brass will form to chamber dimensions when fired. If you size things and your runout increases then you may have a issue with your dies. Once you seat a bullet and measure things if your runout grows you either have an issue with your seater or your brass needs neck turned. Runout of loaded rounds at or below .001" is really good.

 

[Mikecr]

I hope you're not lying to us with averaging, subtracting, or funny math.
TIR is just that, full spread of the indicator off a v-block gage.

 

[Savage 12BVSS]

What runout gauge are you using that reads in .0001???

I'm using the guage on an rcbs casemaster, maybe I am showing the numbers incorrectly. Not a machinist so this is hard to describe when below one thousandth's, when I measured the case mouth's after firing they were slightly below 1/2 thousandth's (what I called .0004). When I ran them thru a lee collet neck sizer they were pretty much unchanged. When I seated bullets in the case's with the forster seater they went to one thousandth's (.001) with a couple a little under and one slightly over. At that point I tried turning the cases in thirds as I seated bullets, they got better with all under one thousand's runout (.0008), taken on the bullet side near as I can figure to the ogive (maybe 1/3 way down seated bullet) That's good as I can explain this. I apologize for any incorrect figure's I have no reason to lie. Thats all there is to it.

What I believe you have found is that your chamber was cut concentricly.

Yes I agree with you 100% that is why all this happened in the first place, the McGowen barrel was a train wreck when I got it and I trusted my gunsmith when he fixed it. He recrowned and rechambered it before it ever went on the rifle, as I read on here and learned not all chamber's are straight and can produce unconcentric brass out of the chamber. This entire deal was to really see if that was the case, I had to get the casemaster back cause the hornady won't do a case only.