bigedp51
Well-Known Member
- Joined
- Dec 10, 2010
- Messages
- 1,022
When dealing with runout I prefer to start with the Redding neck thickness gauge. The case below has .004 neck variation and will always cause problems even if neck turned. The problem with this type case is the thinner side of the case will expand more when fired and cause the case to warp and become banana shaped. So step one is find the cases with the least amount of neck thickness variations.
The case below has .0025 neck thickness variation and even after neck turning the bullet is not in alignment with the case. "BUT" with a full length resized case the rear of the case is supported by the bolt face and by the bullet in the throat. Meaning the case body is not touching the chamber walls and minimizing the cases effects on runout. This is where the Hornady gauge comes into play because the case is being held like it would be in your chamber. And give you a good idea if your runout will effect you accuracy. NOTE: The military considers .003 or less runout match grade ammunition.
Next resize the case and check your neck runout after sizing to see if the die is inducing the runout. If your runout is more than your neck thickness variations there is a good chance your expander is pulling the necks off center.
For runout gauges I prefer the Redding neck thickness gauge, and with one twist of the case you know the quality of your brass. And the Sinclair runout gauge is all the normal reloader needs. With these two gauges you will be to measure, sort and troubleshoot your runout problems.
I highly recommend Forster full length resizing dies with the high mounted expander for producing resized cases with the least amount of neck runout.
Below my soon to be replaced RCBS case mastering gauge, the V blocks are painted aluminium. And after a few years of use the brass case drags on the bare aluminium and makes it hard to get accurate readings. And the Sinclair unit has ball bearings for the case to spin on. Also you can see the Hornady gauge in the background and the Sinclair gauge would be much better than either one I have.
In closing half your runout problems will be from non-uniform brass and the other half will be problems created during sizing and seating. And your gauges will tell you where the problem starts.
The case below has .0025 neck thickness variation and even after neck turning the bullet is not in alignment with the case. "BUT" with a full length resized case the rear of the case is supported by the bolt face and by the bullet in the throat. Meaning the case body is not touching the chamber walls and minimizing the cases effects on runout. This is where the Hornady gauge comes into play because the case is being held like it would be in your chamber. And give you a good idea if your runout will effect you accuracy. NOTE: The military considers .003 or less runout match grade ammunition.
Next resize the case and check your neck runout after sizing to see if the die is inducing the runout. If your runout is more than your neck thickness variations there is a good chance your expander is pulling the necks off center.
For runout gauges I prefer the Redding neck thickness gauge, and with one twist of the case you know the quality of your brass. And the Sinclair runout gauge is all the normal reloader needs. With these two gauges you will be to measure, sort and troubleshoot your runout problems.
I highly recommend Forster full length resizing dies with the high mounted expander for producing resized cases with the least amount of neck runout.
Below my soon to be replaced RCBS case mastering gauge, the V blocks are painted aluminium. And after a few years of use the brass case drags on the bare aluminium and makes it hard to get accurate readings. And the Sinclair unit has ball bearings for the case to spin on. Also you can see the Hornady gauge in the background and the Sinclair gauge would be much better than either one I have.
In closing half your runout problems will be from non-uniform brass and the other half will be problems created during sizing and seating. And your gauges will tell you where the problem starts.
