Fire Formed Cases .308

[amssmith]

Whether using manufacturer ammo or reloads the fire formed brass shows a ridge line around the lower part of the case head.

 

I've attached a couple of photos showing once fire home load brass. Hopefully they will be clear enough to see,

 

I would like to know if this is unusual, is the brass damaged or could I have a problem with the rifle chamber?

 

Appreciate any guidance

[sonic]

looks ok to me all my cases show a line like that.

 

this is an area that can tell you if a load is excessive if you measure the case at that point and compare to new unfired brass you'll get an idea of what is normal. brass expands to form a gas tight seal then springs back. overpressure shows as a larger measurement than your normal.

one other check is to get a safety pin or paperclip straighten it out then bend the end 90 deg. as you move the end over the inside of the case you can feel a case head separation before it shows on the outside.

 

Don't panic you won't have that problem looking at those cases. these are ways to check as the number of loadings increase that you brass is ok.

[jcampbellsmith]

Looks odd to me, but it's hard to tell from a photo. For the avoidance of doubt seek out an acknowledged professional and get the chamber checked out. Regards JCS

[Wildcat69]

I can't see a prob with your brass although your primers seems pretty cratered! These are signs of over pressure.

[sonic]

two cases of once fired ppu two three times fired federal all show same line its where the brass thickens towards the web.

[farmer7]

The cratering is probably from an oversized firing pin hole. My Remington .308 does that even with lighter loads, Remingtons are well known for it I believe. Not much sign of primer flattening either.

[gun nut]

Amsmith,

if you can feel a ridge in the brass, and it looks like you might be able to in the second photo, you have a problem. As stated previously, a lot of brass has a line in that same area, mine included, but your brass actually seems to widen at the "tide mark", if it does you need to seek professional advice to be on the safe side.

 

atb

 

Mike

[Andrew]

Your chamber is a little generous in the back end, perhaps??~Andrew

[DaveT]

Mine do the same and I always check for case head seperation onset and never encountered it ....and I load my Lapua brass at least 20 times ...admitedly mostly neck-sized only.

 

I put it down to first-firing stretch....I stand to be corrected on that but 'bottom-line' is that it does not appear to cause any problem

[kent]

Am I correct in seeing that the brass that is in the chamber is enlarging? Do you have any extraction difficulties after firing? I have never seen this, a line is quite normal in the area but not a definite ridge. With this occurring I should certainly not want to be the one behind the trigger without getting things checked out and a definite reason why. As has been mentioned I can only think "oversized chamber" but why? and is it round and central of out of round and correctly aligned to the bore? Is it an old gun someone has "worked on" a bit- If its new return it IMO.

 

Could I view and measure a single brass piece please that exhibits this for myself maybe?

[Andrew]

Am I correct in seeing that the brass that is in the chamber is enlarging? Do you have any extraction difficulties after firing? I have never seen this, a line is quite normal in the area but not a definite ridge. With this occurring I should certainly not want to be the one behind the trigger without getting things checked out and a definite reason why. As has been mentioned I can only think "oversized chamber" but why? and is it round and central of out of round and correctly aligned to the bore? Is it an old gun someone has "worked on" a bit- If its new return it IMO.

 

Could I view and measure a single brass piece please that exhibits this for myself maybe?

I have been shooting for quite some time and I have seen this often., mostly in military chambers, but in some factory rifles. Anyone who shoots Lee 303's or Candaian Ross rifles has seen it, for sure. I had a Anschutz .22 Hornet that did the same thing. It's annoying, but not fatal. Neck Size and keep shooting, or sell the rifle. A headspace check wouldn't hurt but it just looks like a fat chamber to me.~Andrew

[kent]

I have been shooting for quite some time and I have seen this often., mostly in military chambers, but in some factory rifles. Anyone who shoots Lee 303's or Candaian Ross rifles has seen it, for sure. I had a Anschutz .22 Hornet that did the same thing. It's annoying, but not fatal. Neck Size and keep shooting, or sell the rifle. A headspace check wouldn't hurt but it just looks like a fat chamber to me.~Andrew

So we are talking out of spec. chambers from the factory? If I ever get that the guns going back. it does seem slightly dodgy re-loading those cases to my mind as surely separation will occur fairly rapidly with repeated firings?

[amssmith]

Thanks for all your comments. Not sure I've come to a conclusion yet but let me answer as many of the points as I can and see where I go from here.

 

Rifle is Remington 700 action in a recent new custom build by a very capable gunsmith

 

Primers are CCI 200 and all look cratered in this way, even on minimum loads. When I look at the fired primer under a magnifying glass the curved contour around the edge can still be clearly seen, so I concluded not over pressure - am I correct in this conclusion?

 

Can definitely feel a ridge on the outside where it feels like the case has expanded. Yes is does feel it widens at the "tide mark"

 

Have used a bent paperclip and think I can feel a ridge on the inside. Certainly feels more of a ridge than a groove, but the only way to be sure would be to hacksaw one close to the ridge so can see inside properly. Would a ridge inside be ok as assuming a case separation would feel more like a crack/groove?

 

Absolutely no hard bolt / extraction problems

 

Sonic your cases seem to show a tide mark but can't tell if there is a ridge as appears on my brass?

 

 

I'm neck sizing only

 

Haven't yet had time to measure the outer dimension of an unfired Winchester case to compare, but had assumed there would be some expansion on original dimensions and this was a natural part of the fire forming process. Think I must be misunderstand? Or should I be measuring end on as in the second picture ?

 

It looks like my chamber may be a little generous nearest to the head, which may be causing the ridge, but my concern is this could create an unnecessary weakness in the brass that wouldn't otherwise occur, creating a dangerous situation

 

 

 

[gun nut]

If it's a new build Andy I'd be taking it back, why would you put up with an oversize chamber on a custom rifle?????

 

 

Mike

[The Gun Pimp]

Whether using manufacturer ammo or reloads the fire formed brass shows a ridge line around the lower part of the case head.

 

I've attached a couple of photos showing once fire home load brass. Hopefully they will be clear enough to see,

 

I would like to know if this is unusual, is the brass damaged or could I have a problem with the rifle chamber?

 

Appreciate any guidance

 

The case has expanded - as it should but, the thick bit at the bottom doesn't. Nothing to worry about. Run it through the f/l die and all will be well.

[sonic]

My cases show a line but its not a ridge as such. the reloads show the line more but its in the same place as the ppu.

my lee book shows 308/243 case dimension just above the extractor groove as .470"

PPU 100gn .243 .469"

" " fired .470"

 

FC reload .243 .469"

" " fired .470

 

saami spec at that point is .4714" + .002 max

without measuring its hard to say if you have a problem.

 

you can feel where the line is with a paper clip a safety pin with a sharp point is easier to tell if a split is starting.look at this http://t3.gstatic.com/images?q=tbn:ANd9GcR7rIyZwDB1h9wMimQmyJwstSKlAAOOaeY7Jma_AcwcZ3Opc_1f9w

you can see the change in thickness that causes the line to show. But if it is a step/ridge then I would assume that this is stretching beyond normal at this point.

[kent]

If it's a new build Andy I'd be taking it back, why would you put up with an oversize chamber on a custom rifle?????

 

 

Mike

 

Heck no I wouldn't be having that! I haven't measured one of these but as the "ramp" can be seen in the photo then I figure its got to be out of spec.

[kent]

The case has expanded - as it should but, the thick bit at the bottom doesn't. Nothing to worry about. Run it through the f/l die and all will be well.

 

Have a closer look at those thumbnails, I am seeing a quite pronounced ridge- more evident in the first picture

[amssmith]

So here's the conclusion I've come to having consider all the feedback .

 

The gun is not unsafe. Full resizing will sort the immediate issue but longer term I anticipate it will reduce the life of the brass and does create an unnecessary stress point. I do want to neck size only, so another element in my decision making.

 

Bottom line is something's not as it should be as the chamber appears it could have a small step in profile. I've had a very helpful discussion with my gunsmith and he has suggested he take the rifle back and either recut the chamber, or if required, replace the barrel, or give a full refund on the rifle should I prefer. All cost borne by him, so couldn't ask for a better and prefessional attitude.

 

Thanks to all for your opinion and input, really helpful in shaping my understanding of the various issues in play

 

Will post an update once the true problem has been diagnosed

[sonic]

You can't ask for more than that. A sign of a good gunsmith (or any other trade) the man that says ok I'll sort it. when things aren't right.

 

A minimum spec case in a max spec chamber especially with a remi 700 type bolt could give the ridge effect. but be safe.

your right case life would suffer if FL sized every time.

 

I'm not sure a step but if you take the bolt out and put a case in and if I'm on the right lines the ridge will be just outside the bolt support.

The bolt supports the head and the rest stretches to fit the chamber. hence the step. in the case.

[kent]

So here's the conclusion I've come to having consider all the feedback . The gun is not unsafe. Full resizing will sort the immediate issue but longer term I anticipate it will reduce the life of the brass and does create an unnecessary stress point. I do want to neck size only, so another element in my decision making. Bottom line is something's not as it should be as the chamber appears it could have a small step in profile. I've had a very helpful discussion with my gunsmith and he has suggested he take the rifle back and either recut the chamber, or if required, replace the barrel, or give a full refund on the rifle should I prefer. All cost borne by him, so couldn't ask for a better and prefessional attitude. Thanks to all for your opinion and input, really helpful in shaping my understanding of the various issues in play Will post an update once the true problem has been diagnosed

 

The guy who never made a mistake never made anything! That is the correct way to handle such a matter 100% if you had previously named the smith it shouldn't reflect badly on him in my eyes. Though there is no need as he obviously is not one to avoid.

[amssmith]

The Gunsmith made a great effort to educate me on how this could have happened. I think I understood the majority but still much to learn. Bottom line is a didn't expect anything other than a positive response from him, but the value of this forum is there's a collective knowledge willing to share, so the positive is I've learned a great deal overall and anticipate the fix will be straightforward