10-30-2022, 02:51 PM
I know they advertise that, and maybe it's a decent one... but it's not worth it IMO, especially if you have more than 1 rifle. Maybe for folks who have 1 real-precision type gun and want everything to be match grade quality, but...
C Creek also makes a standard-modified 6mm Arc case that works for the hornady OAL comparator. I just got their standard modified case. What you're doing anyway is measuring things like bullet fit OAL's and a standard comparator case will tell you that.
If your barrel was made by a solid outfit the chamber is most likely fine (unless you have some evidence to the contrary), unless I see something way-off I don't worry about that. Instead I need COAL's for the different bullets so I don't jam one into the barrel lands and risk all the problem-"niceties" that causes (lol!), they can differ a lot one bullet-type to another. 100 tgk, 103 eldx, 95 Nosler BT, 90 Eldx, 108's, 95 Bergers, etc. From 2.140 to 3.338 OAL's, 6Arc has large spread of these, wider than most calibers IMO.
What you're thinking about is shoulder setback, that's where a fired case comes in. A fired case has a shoulder that pretty much tells you what the "datum" point is going to be for your chamber... so you can resize and set back a few 0.001's (0.003, or 0.005 like I do b/c I don't want to recalibrate for every chamber). Saami datum point (the 0.350 diameter on the shoulder, or "B") is 1.190-0.007. So you want that resize to get you back to there but more importantly, is the 0.003-0.005 (your choice) less than fired size shoulder measurement. For that you need to measure fired shoulders of a few cases out of that chamber, and that doesn't use a modified case, rather it is the Hornady lock/load head space comparator (or something equally good), using the 0.350 diameter or "B" insert and a digital caliper. Thing is, there's no guarantee that the "B" is exactly 0.350 (it's close) but that's fine because you're using it for your barrels... just can't do a 1:1 comparison for someone else's measurement (they should be close but no guarantee of being equal). Anyway that's how you find your chamber "size" but really it enables you to set your resizing die so as to get the small 0.001's setback you need for chamber fit plus longer brass life.
C Creek also makes a standard-modified 6mm Arc case that works for the hornady OAL comparator. I just got their standard modified case. What you're doing anyway is measuring things like bullet fit OAL's and a standard comparator case will tell you that.
If your barrel was made by a solid outfit the chamber is most likely fine (unless you have some evidence to the contrary), unless I see something way-off I don't worry about that. Instead I need COAL's for the different bullets so I don't jam one into the barrel lands and risk all the problem-"niceties" that causes (lol!), they can differ a lot one bullet-type to another. 100 tgk, 103 eldx, 95 Nosler BT, 90 Eldx, 108's, 95 Bergers, etc. From 2.140 to 3.338 OAL's, 6Arc has large spread of these, wider than most calibers IMO.
What you're thinking about is shoulder setback, that's where a fired case comes in. A fired case has a shoulder that pretty much tells you what the "datum" point is going to be for your chamber... so you can resize and set back a few 0.001's (0.003, or 0.005 like I do b/c I don't want to recalibrate for every chamber). Saami datum point (the 0.350 diameter on the shoulder, or "B") is 1.190-0.007. So you want that resize to get you back to there but more importantly, is the 0.003-0.005 (your choice) less than fired size shoulder measurement. For that you need to measure fired shoulders of a few cases out of that chamber, and that doesn't use a modified case, rather it is the Hornady lock/load head space comparator (or something equally good), using the 0.350 diameter or "B" insert and a digital caliper. Thing is, there's no guarantee that the "B" is exactly 0.350 (it's close) but that's fine because you're using it for your barrels... just can't do a 1:1 comparison for someone else's measurement (they should be close but no guarantee of being equal). Anyway that's how you find your chamber "size" but really it enables you to set your resizing die so as to get the small 0.001's setback you need for chamber fit plus longer brass life.