6.5cm

[jhenryw]

Just getting into reloading for 6.5cm. Mainly shooting local competitions as well as varmit hunting, possible speed goats if I get a tag this year. What's the best way to measure headspace? Should I jist make rounds with Sammi OAL length.

 

[steelheadmike]

The answers to your two very different questions are comparator (sort of) and sometimes.

If you don’t know that you asked two very different questions, please go take a reloading class or at a minimum, start with a good online series.

I’m not trying to be a Richard, but it’s a best practice to have a fundamental level of knowledge before jumping in.

 

[Dave Thomas]

The Hornady comparator will work fine. Get one for measuring the bullet length and get the adapters for the shoulder.

 

[JFK]

If you are just starting I’d keep things simple. Fewer variables, focus on building a repeatable process. I loaded for many years just loading to book COL and ammo was very accurate.

I have a comparator and using it has only helped me with one rifle to get better accuracy. The creedmoors and other modern cartridges have tighter chamber specs, so loading to sammi is more likely than not to yield good results.

 

[jhenryw]

The answers to your two very different questions are comparator (sort of) and sometimes.

If you don’t know that you asked two very different questions, please go take a reloading class or at a minimum, start with a good online series.

I’m not trying to be a Richard, but it’s a best practice to have a fundamental level of knowledge before jumping in.

Thanks. I have both a shoulder and bullet comparator. Measuring fired brass and setting dies to push shoulders 2 thou back. I guess my question is OAL. Depending on what bullet is used, wouldn't the overall cartridge length change?

 

[steelheadmike]

Thanks. I have both a shoulder and bullet comparator. Measuring fired brass and setting dies to push shoulders 2 thou back. I guess my question is OAL. Depending on what bullet is used, wouldn't the overall cartridge length change?

Not really, shoulder bump and OAL are essentially unrelated.

You start with a fired case, then bump the shoulders 0.002”. After that, you trim, if needed. I trim mostly to maintain consistency in the brass; i.e., I’ll trim back to whatever my shortest brass is (typically a few thou over the book “trim to” length is. All this goes for any case, regardless of what bullet is going in.

Moving onto bullets, the book cartridge overall length (COAL) is now determined by how deep you seat your bullets. Nothing you have done to your brass at this point affects your COAL.

If you stick to book/saami length, different bullets will be deeper or shallower in the case and your jump will be different for each.

But, if you are able to load longer, you can. By controlling your seating depth you can adjust your jump and/or free up powder capacity. Depending on your rifle, you may end up maxing out your magazine length.

For example, in my 7-08, book coal is ~2.80”, regardless of bullet. This is to allow it to run in a true short action. But, in my Tikka, I can run it out to about ~2.95”, at which point I run out mag length and I’m pretty much jamming the bullet (depends a bit on the bullet).

Like others have said, get a comparator for both headspace and bullet ogive. This will allow you measure shoulder bump, cartridge base to ogive (CBTO), and COAL. All three measurements are for different data points to see how the cartridge/bullet is interacting with your rifle/chamber. Shoulder bump is headspace, CBTO is you distance off the lands, and COAL tells you if it will fit in the mag.

 

[S.Clancy]

I basically just load everything to just under sammi coal, that way I have a tiny bit of wiggle room in a saami magazine.

 

[bnewt3]

This question has been asked lots and lots including by myself. What ive gathered is 3 things:

1) Mag length is often your limiter, but generally .050" off the lands or functioning from the mag.....whichever is shorter is a good starting point.

2) there is a TON of conflicting info out there about seating depth. Some say it matters, some say it doesnt. There are reputable sources on both sides of this soooooooooo

3) What there is consensus about is that seating depth is low on the list of things you should be tuning, maybe the last thing, if ever. A 100% identical process round-to-round, bullet choice, primer choice, primer seating, powder selection, powder charge, neck tension, neck sizing method, etc, etc, etc, etc, etc, are likely to make larger differences in groups.

One thing I dont think is talked about enough within this sphere is the accuracy potential of the rifle the bullet is coming from and your expectations for it. Is it a hunting rifle, even a very nice one? Well then true .5 MOA(say 5 5-round groups averaged) is not reasonable to EXPECT. Maybe it can do it, just dont expect it. If its a custom, well-built comp gun, then you should expect exceptional accuracy, once you find the right load.

 

[wind gypsy]

Headspace is the distance measured from a closed chamber's breech face to the chamber feature that limits the insertion depth of a cartridge placed in it. Seems like you're talking about bullet seating depth and not headspace.

There's a bunch of different ways to measure seating depth to lands, I find the hornady modified case system simplest and dont find value in taking extra effort to maybe be a handful of thousandths more accurate in that measurement. The exact measurement doesnt matter if you're going to be multiple 0.010"s off the lands.