westernrover
Member
- Joined
- May 4, 2018
- Messages
- 1,613
I'm using a RCBS Summit press and a Redding Body Size Die to size Starline Grendel brass with a couple of firings. To measure, I'm using a Brown & Sharpe dial caliper with a Sinclair #30A insert that has the correct shoulder angle and measures off the shoulder. My base-to-shoulder is varying by as much as 4 thou.
I can see the fired brass doesn't all come out of the chamber with the same dimensions. If I take a half-dozen that come out at say 1.135" (for comparison) and I set the sizing die so that it bumps the first one to 1.133", the rest come out 1.131", 1.133", 1.132", 1.135", 1.135".
When Gavin at UR measured the Base to Shoulder on an RCBS Summit, he got 0.0006708" SD. I'm getting an SD more like 0.0015"
The Summit is a cam-over press, and I am camming over. The only adjustment on the Redding Body Die is the lock ring.
Redding provides the following instructions:
To set a Full Length/Body Die up to Cam-Over:
1) Install the appropriate Shellholder into the Ram of your Press.
2) Raise the Ram so that it is in its uppermost position.
3) Screw the Full Length Resizing Die/Body Die down into the press until it firmly contacts the Shellholder.
4) Back the Ram away from the Die.
5) Screw the Die down FURTHER into your press an additional 1/8th to ¼ turn.
Note that you will feel the Ram/Shellholder contact the resizing Die before the stroke is completed. Completing the Ram Stroke will feel as though you are snapping the latch on a toolbox.
I have it set up like this. For step 5, the additional amount I screw it down determines how far I bump the shoulder. Brand-new Starline brass measures about 8 thou shorter than the brass that comes out of my chamber -- understandable since it has to fit a lot of chambers. I only want to bump mine a couple thou from chamber-expanded, but my results seem wildly inconsistent.
I can see the fired brass doesn't all come out of the chamber with the same dimensions. If I take a half-dozen that come out at say 1.135" (for comparison) and I set the sizing die so that it bumps the first one to 1.133", the rest come out 1.131", 1.133", 1.132", 1.135", 1.135".
When Gavin at UR measured the Base to Shoulder on an RCBS Summit, he got 0.0006708" SD. I'm getting an SD more like 0.0015"
The Summit is a cam-over press, and I am camming over. The only adjustment on the Redding Body Die is the lock ring.
Redding provides the following instructions:
To set a Full Length/Body Die up to Cam-Over:
1) Install the appropriate Shellholder into the Ram of your Press.
2) Raise the Ram so that it is in its uppermost position.
3) Screw the Full Length Resizing Die/Body Die down into the press until it firmly contacts the Shellholder.
4) Back the Ram away from the Die.
5) Screw the Die down FURTHER into your press an additional 1/8th to ¼ turn.
Note that you will feel the Ram/Shellholder contact the resizing Die before the stroke is completed. Completing the Ram Stroke will feel as though you are snapping the latch on a toolbox.
I have it set up like this. For step 5, the additional amount I screw it down determines how far I bump the shoulder. Brand-new Starline brass measures about 8 thou shorter than the brass that comes out of my chamber -- understandable since it has to fit a lot of chambers. I only want to bump mine a couple thou from chamber-expanded, but my results seem wildly inconsistent.