Concentricity guage
- Thread starter tim
- Start date
A chambered BR round cant run out much after the bolt is closed.
We fire our cases with very high pressure and after they are fired they rebound/ shrink back very very little. The fired round brass is within .0005 say of the true chamber size. We size the neck only 3/4 (approx) of the way down the neck and that sized area may only have .002 clearance in the chamber. The real game changer here is that we jam our bullets into the very precise lands/throat area sometimes pushing the bullet back a few thousandths. It is impossible given those close clearances to have a bullet run out .004 to .005 etc etc. There isnt that much clearance anywhere in the chambered round physical clearances. The body fits within .0005 or so. The lower part of the neck that is not sized is very close to dead nuts chamber size. You could possibly seat a bullet crooked but if your seating in the lands that bullet will recenter to its physical clearance AFTER seating hard into the lands. The loaded round concentricity is within the tolerances of the total of the clearances of the chamber/brass fit.
Wallydog
We fire our cases with very high pressure and after they are fired they rebound/ shrink back very very little. The fired round brass is within .0005 say of the true chamber size. We size the neck only 3/4 (approx) of the way down the neck and that sized area may only have .002 clearance in the chamber. The real game changer here is that we jam our bullets into the very precise lands/throat area sometimes pushing the bullet back a few thousandths. It is impossible given those close clearances to have a bullet run out .004 to .005 etc etc. There isnt that much clearance anywhere in the chambered round physical clearances. The body fits within .0005 or so. The lower part of the neck that is not sized is very close to dead nuts chamber size. You could possibly seat a bullet crooked but if your seating in the lands that bullet will recenter to its physical clearance AFTER seating hard into the lands. The loaded round concentricity is within the tolerances of the total of the clearances of the chamber/brass fit.
Wallydog
The gauge may be, showing misalignment (out of parallel/tilt), as opposed to concentricity (or, a combination thereof). A tilted bullet may result in what the gurus call, "in-bore-yaw", which means that the center-of-gravity will be off-set (eccentric), or, out of balance (the bullet WILL swage & conform the the hole). Thus, unless the misaligned bullets are indexed, one could expect greater dispersion, due to random inertial moment toward the off-set.RG
As Leon Spinks would say: "Aboulooby!"
BillBrawand
New member
realy isnt the barrel corect the runout
Hi Tim,
I have a NECO and a 21st Century. I like the 21st century better. They do help to identify problem areas in your reloading set up. My problem areas were neck bushings that weren't quite right( run out top and bottom when fitted to a trued mandrel and indicated on the lathe) and a Wilson mic top seater that had been dropped on the concrete about 6 times over the last 10 years.
Joel
I have a NECO and a 21st Century. I like the 21st century better. They do help to identify problem areas in your reloading set up. My problem areas were neck bushings that weren't quite right( run out top and bottom when fitted to a trued mandrel and indicated on the lathe) and a Wilson mic top seater that had been dropped on the concrete about 6 times over the last 10 years.
Joel
Thanks buddy
Pete Wass
Well-known member
I once has a large bore balrrel
that has about a 2" choke in the muzzle end of it. I always figured the reason the rifle shot so well was that 2" of tight choke. Any yawing that might have occurred behind it was quickly righted. It occurs to me folks pay way too little attention the the muzzle end of their CF barrels.
Pete
that has about a 2" choke in the muzzle end of it. I always figured the reason the rifle shot so well was that 2" of tight choke. Any yawing that might have occurred behind it was quickly righted. It occurs to me folks pay way too little attention the the muzzle end of their CF barrels.
Pete
Concentricity gauge
I use the older Sinclair gauge. When checking concentricity of 22-250 cases I discovered that my Redding bushing sizing die induced runout (RO). It went from .0005" RO out of the gun to .004" -.005" RO after using the Redding die. After running the same cases thru a Forster FL die it reduced the excessive RO down to .003".
When I took a fired case with .0005" RO and ran it thru the Forster FL sizing die the RO stayed the same. I really wanted the Redding die to work but nothing I tried made for improvement.
Now I only use Forster FL sizing dies.
But as others have said concentricity gauges (on my reloading bench) are used to determine if loading procedures are working well.
I use the older Sinclair gauge. When checking concentricity of 22-250 cases I discovered that my Redding bushing sizing die induced runout (RO). It went from .0005" RO out of the gun to .004" -.005" RO after using the Redding die. After running the same cases thru a Forster FL die it reduced the excessive RO down to .003".
When I took a fired case with .0005" RO and ran it thru the Forster FL sizing die the RO stayed the same. I really wanted the Redding die to work but nothing I tried made for improvement.
Now I only use Forster FL sizing dies.
But as others have said concentricity gauges (on my reloading bench) are used to determine if loading procedures are working well.
shootsteady
Member
RCBS Casemaster /upgrade
I upgraded mine.... now takes proper readings. I use Forster neck turning pilots for neck thickness. The pilot in the pic is a custom pilot. The forster can't use the collar due to the shoulder on the pilot.
I upgraded mine.... now takes proper readings. I use Forster neck turning pilots for neck thickness. The pilot in the pic is a custom pilot. The forster can't use the collar due to the shoulder on the pilot.
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