Home Forums Reloading Big Game Rifles Forming 7-08 brass from Lapua .308 Win Brass???

I purchased some .308 Win Lapua brass this past summer and have full length resized them to 7-08. I had always used RP brass with excellenct results but I got caught up in the excitement to try something new. Now I have a couple of questions.

1. Will it stretch to the standard length? Right now the brass is considerably shorter than trim length should be.

2. How much difference in capacity is there? I noticed pressure signs with my initial firings. I used a mild charge of IMR 4895 with 140 grain bullets to fire the first few rounds.

Thanks for the help!

Firehawk

Some years ago, 7-08 brass was unavailable where I lived in Manitoba, so I used WW brass in .308. Worked fine. Trimmed the brass after full length sizing. The neck length will grow somewhat as you use the cases, but watch out for neck thickness. I read somewhere that necking down can produce more uniform cases. Try it, the capacity should be okay especially if you are using match brass like Lapua.

Try seating your bullets as far out so they jam into the lands when firing them for the first time.(with a start load of course)This will keep the case tight against the bolt face and you will get a better fire formed case. Lapua brass is pretty concentric and it wont always be neccesary to cut the necks. If you do cut the necks, cut all the way into the beginning of the shoulder junction - this will prevent doughnut formation inside the case at the neck shoulder juntion after several reloads.

Since you're necking down you don't have to jam the bullets to get a good fit. Just size the brass in stages until you get it where the bolt will just close with a little feel. You'll then have zero headspace. The goal is to initially size a secondary shoulder onto the neck of each case (where the not fully sized neck goes from 30 to 7mm) to control headspace on the first firing.


mathman

Firehawk, I just went through this myself. I purchased some .308 Lapua Brass and Necked it down to 7mm-08. Here is what I have found so far:

After necking down the new Lapua .308 brass, the overall length of the 7mm-08 brass was 2.012". Based upon information and recommendations I got from here, I decided to load them as normal for my favorite hunting load and use them for mule deer this year. I fired about 8 rounds to make sure that the groups were reasonably accurate and found that they were fine - in fact, I harvested a nice forked-horn buck out in the desert this year using a Barnes 140 gr TSX. Anyway, the once fired brass averaged 2.014-2.015" in length. Putting through my reloading press and the RCBS Competition sizing die, the overall length changed to 2.018". So far, because the accuracy (about .75 to 1" in my rifle) has not been a problem, I am not going to worry about trim length for the time being. By the way the case is stretching, I probably have at least two more firings before I need to worry about it, although I always measure my cases prior to reloading to make sure they are within OAL spec (2.025" trim length). I haven't had any pressure problems surface.

Anyway, thought I would share. Good luck.
Elk

Anyway,

By the way, I am about 0.05" off the rifling and use Varget at a near max load. I can't imagine you would get pressure signs unless you are hard up against the rifling or using a magnum primer or some other issue. I believe my previous brass was Remington.

Good luck
Elk

Thanks for the advice! I loaded up the next 20 pieces with some 139 grain SSTs that I could never get to shoot. I figured that I could at least get them "shaped" for my chamber with the first round and then start loading for accuracy.

Laughing Elk- I was quite surprised to see pressure signs. I have loaded 10 rounds up with the Lapua brass and Varget with 140 btips to see how they do. I stayed off of the max loads just to watch out for pressure signs until I figure out this brass.

Primer pockets are sure tight though. I loaded up some of my RP brass also and was surprised at how much easier the primer was seated. Not that the Lapua brass made it "hard", just that it definitely took more pressure to make it seat fully.

Firehawk

I outside neck turned my lapua case necks after once firing them in my 7-08, going a bit into the shoulder junction, to prevent any doughnut formation.Check your fired brass by dropping a bullet into the case mouths. If it drops through, no problem. If they stick a bit at the neck/shoulder junction, it could be doughnut forming, which might be the cause of your pressure problem.

Thomast has good advice for you too Fire Hawk. I also neck turn, but only about 10-20%. Most of what is turned is down near the shoulder junction - just seems to be the nature of Lapua. Anyway, out of curiosity what exactly are you seeing for pressure signs? Hard bolt handle lift? Extractor or bolt shine near the primer cup? Flattened primers? Bulging at the cartridge base? Let us know.
Elk

After the ten shots I fired, most had a bit of shine on the headstamp area, Primers had flattened and the firing pin mark had a bit of a crater on the edges on the spent primer.

Seems textbook pressure signs to me. I don't have a neck turner yet, but maybe I will need to pick one up. Any suggestions? I already have a Lyman trimmer, is there an attachment for it?

Firehawk

Okay. Neck turning won't make that big a difference. My suggestions are as follows:
1. Check your seating depth. Make sure your bullets aren't tight-up against the lands of your barrel. This will bump pressure substantially. There are numerous ways to measure seating depth and several good articles on how to do it reasonably well without special tools. I personally use a bullet comparator and chamber gauge (see Hornady's website as they just bought out stoney point).
2. check to make sure you are using a non-magnum primer. I tend to use Federal 210 Gold Match primers. They are standard large rifle primers which are sorted/manufactured to match tolerances.
3. Change your powder. Powders are all different for a reason. With my 7mm-08 I use Varget and get great consistency with it. I just got back from the range and fired two- three round groups at the same target rapid fire, using my favorite load with 140 grain Barnes TSX bullets. I had one flier and the group measures 1.183" at 100 yards. Without the flier, the other five rounds measure 0.617" - not too bad.

Anyway start from there and use caution. Refer to reloading manuals.
Good luck,
Elk

I bought some 308 Lapua brass when I bought my wife a 7-08 to keep it separate from my WW/R-P brass I was using in my 7-08. After about 3 loads, some of the cases needed to be trimmed, and a few after trimming will not feed. I had assumed this was due to neck thickness. Haven't bothered with cutting the neck thickness down, since don't have a tool for it and it is only a few so far. Haven't experienced any pressure differences between Lapua and the other two. If I had it to do over, I would not have purchased the Lapua brass for this application.

Try to put a bullet into a fired Lapua case neck. As long as the neck has not been bent the bullet should go in and out freely. If it does the necks are not too tight. The chambering difficulty with the trimmed cases might be from a burr or flare caused by trimming or inside neck chamfering.

As to the need to trim the brass that might be due to a bulge in the rifles chamber. When a chamber is on the large side the fired case will bulge working the metal there and making the case longer.

That and a dragging expander button and you can get rapid case length growth even though the 7mm-08's case is supposed to be 2.035" long and the 308 2.015" How long were they and what did you trim them to?

An easy way to tell ammo apart is to use different bullets. Some bullets look different but behave about the same. I am thinking of Ballistic Tips and their coated brothers the Combined Technology or Interlocks and SST's.