Case swelling above the case webbing

[Savage Fanatic]

Is it possible for a chamber to be with in tolerances as per SAAMI. And still be out of spec?

I had my .308 out at the range today sighting in with Fed. GM 168gr Match.

At first I didn't pay much attention to a distinctive swell line just above the web. At first I though it was a little lube or something of that nature in the chamber.

But after the 10th round the swell hadn't dissipated. What is wierd about this the swell line dosen't go all the way around the case as you would see on a belted mag. It goes 2/3 to 3/4 of the way then stop.

Going on a wild though that there might my something wrong with the factory loads I tried some hand loads I worked up using Nosler 168gr Comp. with 43-44gr BL-C(2).

Ironicly I got the same effects using the BL-C(2) as I did with Factory loads. The set backs were that my groups opened up to the size of a silver dollar and the BL-C(2) didn't burn as clean as the factory blend.

Or do I need to look else where?

 

[Savage Fanatic]

Finally got the camera to work, here are a couple of pics of what I was explaining. The questionable swelling is just above the extractor grove.

Even the manufacture is uncertain why this is occurring.

 

[Desert Fox]

There's nothing wrong with your chamber. The problem is the brass. Try Lapua or Norma brass and I guarranty you, you wont have this problem. The reason for the swelling is that the brass wall thickness is not consistent all around. Upon firing, the brass will conformed to the shape of your chamber. If the wall thickness is thinner on one side, it will expand first , and the result is an uneven expansion. This can be eliminated by having your rifle rechambered to minimum spec. or buy quality brass.

 

[fredj338]

My vote is your chamber is max. SAAMI spec. I have seen an exageragted version in a M1 chambered for .308. It shouldn't hurt anything but your accuracy will never be as good as it could be w/ the chamber on the min. side of spec.

 

[Savage Fanatic]

My vote is your chamber is max. SAAMI spec. I have seen an exageragted version in a M1 chambered for .308. It shouldn't hurt anything but your accuracy will never be as good as it could be w/ the chamber on the min. side of spec.

The rifle is due back to the manufacture with in the next two days. After discussing what I was seeing with the manufacture.

Their Director of Customer Service asked me to ship the rifle back so that their Master Gunsmith can go over it. And if they see anything that they don't like they will rebarrel it.

If they feel that there is nothing wrong with it, I will have someone such as Hart prepare the action and rebarrel it.

 

[SOTN]

Savage Fanatic:

Those cases look perfectly NORMAL to me.

The case expands when it is fired, but it cannot expand the web of the case which isn't, for lack of a better term, "hollow". Except for the primer hole, it's pretty much solid. The ring, shows you the dividing line between where it expanded, and where it can't.

Stick something down inside the case from the neck and see how far it goes, then check the same distance on the outside of the case, and you'll find that it goes as far as the ring.

Smitty of the North

 

[rick smith]

I am with Smitty on this one, looks normal to me. Chamber wasn't polished very well but sure won't hurt anything. You got any measurements on the area in question, before and after firing? Can you actually feel a swelling?Rick.

 

[Brian]

Yeah, it looks normal to me, too, but I'd have to see it live and feel it to be sure.

If you're worried about a case head separation, take a piece of stiff wire -- like a straightened paper clip -- and bend it to 90 degrees about 1/4 inch from one of its ends. Then, insert the 1/4 inch "hook" into the case mouth to the web, and pull the end of the (bent) wire up the inside wall of the case towards the shoulder. Feel for it to grab in a groove, about where your pressure ring is. If you feel it catch in a groove, discard the case. (You'll know it if you feel it.)

I've been reloading a long time, and always check for incipient case head separation this way. I've only found one bad case this way, and I've kept it on hand as a teaching tool.

You're right and very smart to be careful about anything that just doesn't seem right to you. Good for you.

 

[Ol` Joe]

This is normal to see on a fired case. The line is the spot where case wall expansion stops because of the head being solid as the other poster states. There has to be a bit of room for the case to expand and then contract to allow it to be withdrawn from the chamber. A few thousanths variation between the expanded and unexpanded portions of the case really seem to stand out, although in reality they don`t amout to much.

Ken Waters, the old reloading guru called this a "pressure ring" and used it along with a 0.0001" capable mic to estimate pressures in his handloads. The process is still used quite a bit in some circles, and there are "how to`s" out there on the web. Run a search on Google and you should find lots of info on this.

 

[Guest]

Yep...I agree! Looks very normal to me !

 

[Wboo]

I have a 280AI and mine look near the same except that you can see a definate swell about 1/3 around fired case. Inserting a sharp pic tool to feel for prior head separation I feel the "catch". This brass came with the rifle and I do not know how many firings they have had. His reloads I actually had one partially separate.
A little history..... Fall of 05 I bought a 280 RCBS imp. Real nice shooter and the cases I reloaded in it never came out looking anything but normal. The rifle was stolen last Dec and after settling with my Insurance I went looking for another. I found one built by RK gunsmithing here in Nampa ID. I bought it from the man who had it made for him. I got his dies, brass, hand loads etc... I took it out to the desert and shot it back in Jan and was ho-hum about it's accuracy. I thought, OK, now I am going to work up some 160 grain Partition loads in it. Tonight I sat down, put the 8MM Lebel stuff away and pulled out all the empty brass for the 280AI. I was inspecting them and became concerned when I noticed even the loads I developed for the stolen rifle, the cases were showing the same swell, same area on the pressure ring that werent there on previous firings from the stolen 280 RCBS imp. It's Very visible and I am concerned. Should I take this back to the smith that put this together or scrap it all and start with brand new brass? My brass had only been fired twice and neck sized only. It seems from looking at the fired brass from this chamber that the chamber is not quite true. Any ideas out there?

 

[rick smith]

I would section a couple of cases at least one cut infront of the expansion ring and one lengthwise. Take careful measurements of several uncut cases and compare your measurements. Your eyes can be fooled as to what is happening.
Second I would take a chamber cast for inspection and measurement.

What seems to escape some folks is you can't have brass swelling up larger than the base and expect to be able to extract that case after being fired. Kinda like forcing your hand into a jar, making a fist and trying to pull the jar off your hand.Rick.

 

[Wboo]

I understand what your saying Rick. I think I will do just that this next weekend and post results and possibly some photos.