Differences in 6.5CM cases made from Win .308, and .243.

[LoonWulf]

I was getting ready to make a batch of 6.5CM this morning, and while clearing off the bench I was bagging up some random .308s (which I don't shoot).
I decided to see how much work it would be to convert them to 6.5, and while I was at it I figured I'd do a .243 also.

I only did 1 case each of the .308 and .243, as I WAS supposed to be loading ammo, so this is obviously not any sort of in depth experiment.

The forming from for both the .243 and the .308 was accomplished in one pass.
It took me a min or so with my cheap Lyman bench case trimmer to shorten either.
If I do start using the .308s I pick up to make 6.5s I'll probably set up my little arrow saw to cut them down before hand, just to save the effort of trimming them with the trimmer, tho it isn't a whole lot of work.

Anyway here's the completed info for the .243, .308 (both win cases), a federal 6.5CM, and a Hornady 6.5CM.

All cases sized, water weights are averaged for 5 attempts (and rounded to nearest .5), and neck OD measured by caliper.

.243
Case weight: 169.4
Water Capacity till overflow: 51.5
Neck OD: .291

.308
Case weight: 160.2
Water Capacity till overflow: 53
Neck OD: .289

Fed 6.5CM
Case weight: 176.6
Water capacity till overflow: 52
Neck OD: .289

Hdy 6.5CM
Case weight: 156.1
Water capacity till overflow: 53
Neck OD: .290

Now again, this is a look at only a single case of each Cal and make.
Thus I'll probably convert all the .308s I have, and get in the future to 6.5CM.

I'll check the neck dia after I load a bullet in the .308 and try shoot them as a group at 100 just to see how that effects the grouping....again not scientific since there's only one of each, but it will be interesting to me.

 

[Nature Boy]

I’ve read about people doing this and I think there’s a bit more to it than just running it through the sizing die.

You could give it a quick google, but I seem to recall necks needing to be both trimmed and turned and a fire forming step to achieve the 40 deg. shoulder.

The thing I remember most about it is how it wasn’t worth the work, but that could apply to a lot of things we do in this ridiculous hobby

 

[dh1633pm]

I bet you can make a bunch. Good use for uneeded brass. I converted 22-250 with no ill effects when I couldn't find 6.5 brass. Can you show some pics?

 

[LoonWulf]

I’ve read about people doing this and I think there’s a bit more to it than just running it through the sizing die.

You could give it a quick google, but I seem to recall necks needing to be both trimmed and turned and a fire forming step to achieve the 40 deg. shoulder.

The thing I remember most about it is how it wasn’t worth the work, but that could apply to a lot of things we do in this ridiculous hobby

So far they seem to chamber fine in my Savage. I haven't seated a bullet tho to see if I'll need to turn necks....that will kill all enthusiasm I have.
I don't have any good way of measuring the shoulder angle, besides making a tracing and tossing a protractor on it, but eyeball says it's pretty close....if you trust duh eyeball....
Anyway it seems I have a pretty decent pile of .308s so I'll probably try make batch next time I feel like experimenting.

I bet you can make a bunch. Good use for uneeded brass. I converted 22-250 with no ill effects when I couldn't find 6.5 brass. Can you show some pics?

Yeah, for some reason I didn't think to take any. Ill go get some.

 

[dh1633pm]

Something that I did with my 22-250 conversions. I put about 10 grains of AA No 5, a primer, and the rest of the case with cream of wheat. Topped off with one square of toilet paper compressed in the end (used a nail head) to fireform one. It blew the sides out a bit and got the neck just right. First time around they would not hold the minimum amount of powder, afterwards they certainly would. With the tests you already performed, you know your good for capacity. If you can shoot easily where yours at, then no need to fireform, just shoot one to see the results for comparisons.

 

[LoonWulf]

I found an RP .243 I'd converted a while back for my old 6.5 in my random case drawer.....knew I'd done this before.
That jogged my memory, and I ran a few more .243s and .308s thru my sizer.
I got lucky on that .243 I ran earlier, and I remember this from before also, when forming the shoulder on the .243s they would almost always crush. I did a couple more then decided to quit wasting cases.
Triming them before hand helps, but what I can't remember is what die I ran the case thru to start the shoulder before.

The .308s we're one shot and done. I ran 3 more cases, an RP, PMC, and a Fed.
The RP, and Fed formed fine, the PMC shows stress fractures at the old neck/shoulder junction.
Haven't measured any of them, just wanted to see if I got lucky on the .308 also.

Sorry pictures are jumbled, I'll rearange, and lable them when I get a chance to sit at my computer.

 

[LoonWulf]

 

[Blue68f100]

I did that with some old 308W brass I had from the 60's. The wall thickness was where it needed turned to thin. Some of the newer brass is thin to start with and will work just fine. I annealed them before sizing, make it easier and no splits.

 

[LoonWulf]

Yeah I'll go thru clean, sort, and anneal all the .308s I'm gonna convert. I've got a pretty decent spread of them, so I'll check neck dias on each group to see where they end up.
I don't NEED to make 6.5s out of them, but since I have the cases I might as well use them.

I think first firing will finalize shoulder angles, and case taper, so I won't be using them for anything besides blasting at the range or shooting pigs (since the ranges are short) till I've had a chance to shoot them all at least once.

I fireform my .250AIs with COW, but that's a larger change and about as much fun as I want lol.

 

[Varminterror]

From what I’ve tried so far, both in making 6/6.5 creed and 6 SLR from 308win and 243win brass, there’s a need to expand and neck turn or size and ream the necks to eliminate the doughnut at the base of the neck. Not terribly onerous, but a step nonetheless, and often considered a terribly onerous step for guys who try to scrounge brass...

 

[farmerboy78]

I too did this before we had all the different makes of brass available now. early on all you had was hornady. I took norma .308 cases, one pass through the size, trimmed to length, and neck turned... it made really good brass that wasn't available... but nowadays, I would do it unless I had financial issues and couldn't buy any. LC match brass made really good creedmoor as well.

 

[LoonWulf]

Sounds like this may turn into a bit of an adventure.
More poking and proding to be done. I don't really want to turn or ream necks, but that's mostly because I don't have the tools for it. They arnt horribly expensive tho, and I guess I probably SHOULD own them.

 

[Varminterror]

My first neck reaming set up - and turning set up, was a black & decker power screwdriver and an RCBS Pro-Trim with their neck reaming & turning heads. Relatively cheap, since the Pro-Trim already had utility as a trimmer for me. The Forster handheld is great, but it's very time consuming to hand turn a 1,000rnd batch.

There are a few instances where a guy SHOULD neck turn or ream, and each reloader has to decide which method they trust - neck and ream or expand and turn. Personally, I haven't seen good results from using a conventional sizing die with the expander installed, followed by either reaming or turning. How they end up is just too arbitrary. More often, I expand then turn.

I don't believe I'd find value in making 6.5 creed long term, other than just to say I did. For 6 SLR, I necked then pushed Lapua Palma brass to get access to SRP's - which did pull the shoulder into the neck, and leave a substantial doughnut - same as it would for 6.5 creed.

 

[LoonWulf]

Thanks, Ive never really looked into it.
Ill obviously need to do more research, and probably play with it a bit.

 

[LoonWulf]

Neck turning that is.....
I totally agree not a lot of reason to go to the effort to convert cases to 6.5CM, since cases are readily available. I'm not even sure it really makes sense for me to bother converting the .308s, but otherwise they just sit here.

 

[dh1633pm]

Thanks for the pics. Looks pretty good.