.008 shoulder Bump?

[ajkellerusmc]

I thought I was using the correct insert as stated from Brownells where I got it from. I am going to turn it down on my Lathe untill I get contact at the center of the shoulder and try that.

 

[misterc01]

According to Sinclair web site the .308 insert is a bullet ogive comparator where the #20 insert is a bump comparator for a 20 degree shoulder up to 30 cal case.

You are correct. It is a bit confusing - I use this one and the Hornady comparator insert as ogive comparators. Using two give me two references. . However, when I inserted the case in the Sinclair, then it contacted at the midpoint as in the image I posted. I tool a step back and I wonder if problem is it is the might using the wrong tool. Check this image of the Hornady Head Space comparator.

 

[slikmrc]

I use both types of Hornady comparators. I'm having trouble understanding how the Sinclair .308 bullet comparator is fitting over the neck of a 30 caliber case. I have two Hornady 30 cal bullet comparators that measure .298, this is interesting.

 

[misterc01]

Jsut to muddy the waters a bit more, and bieng a bit of a gadget freak, when checking my headpace, I check it on an RCBS Precision Mic to check my before-and-after headspace (shoulder bump). Another useful tool is the Innovative Technolgy Digital Headspace Guage. I have that set to my once-fired case and use it as another cross check.

 

[ajkellerusmc]

I use both types of Hornady comparators. I'm having trouble understanding how the Sinclair .308 bullet comparator is fitting over the neck of a 30 caliber case. I have two Hornady 30 cal bullet comparators that measure .298, this is interesting.

These are my two sinclair inserts, the one on the left is aluminum and is for bullets and the one on the right is the shoulder bump gage of stainless steel. The bullet comarator cannot be used for bump measurements because the case will not fit into the hole in the comparator.

 

[Dean2]

I have a Hornady comparator. I never use it unless I run into some kind of a problem. Shoulder bump is measured by how far the shoulder neck junction and/or the shoulder itseld are pushed back. It is the point farthest from the rim that the case will headspace on for cartridges you have sized to space on the shoulder. You need to measure both dimensions if you are actually trying to figure things out correctly. You can push the shoulder back a long ways too far if you are leaving the neck shoulder junction interfering in the seating depth.

I often set my belted mags and Rimmed cartridges to space off the shoulder so I don't over size them. Works as long as there is a reasonable shoulder. Even the ones that I leave so they headspace off the belt or rim I size as little as possible. Once the cartridge fits in the chamber easily, and yours do after firing. bumping anything amounts to over sizing the case.

 

[slikmrc]

misterc's post #24 is the one that threw me, looks to be seating on the case neck/shoulder junction if that is a 308 case. Perhaps Sinclair makes two styles of shoulder bump comparators? Happy Easter to all.

 

[misterc01]

misterc's post #24 is the one that threw me, looks to be seating on the case neck/shoulder junction if that is a 308 case. Perhaps Sinclair makes two styles of shoulder bump comparators? Happy Easter to all.

My bad - after reading this, I went back and double-checked the insert and case, and somehow instead of a .308 case, I grabbed a 6.5 Creedmoor case instead. Let''s all pretend post #24 never existed! Hmmm - wonder if I can use a .308 insert for checking 6.5Cm headspace............

 

[slikmrc]

Thanks for clarifying that, would think with the .308 comparator on the 6.5 shoulder would work.