Pressure signs even with factory loads?

[mnshooter]

I just finished shooting my new Savage 10FCP and noticed that I have a shiny ejector mark on the headstamp of some of my brass. Handloads and factory Federal Gold Match.
To make a long story longer, I started my session with 5 rounds of the GMM, then proceeded with my handloads from lightest to heaviest charges, 5 rounds each, relpacing the fired brass exactly where it was removed from my ammo boxes. Then I started over, GMM first.......
The first sets of 5 mostly don't show any marks on the headstamp, but the 2nd set definatly does, even on the factory loaded rounds.
I'm fairly new to this and a bit paranoid something is wrong with my new rifle. The only thing I can tell you is that although I did a pretty good job of cleaning the bore throughout my session, I did fail to ever clean the bolt face. If that has anything to do with it or not, I don't know, thats why I'm here.
Any more experienced opinions than mine would sure be appreciated.
I posted in th handloading forum only because I figured handloaders would have more experience with pressure signs and (hopefully) false pressure signs.

Thanks for any input

 

[Cypress]

I'm not sure what the marks look like but try chambering a round and not firing. A few of my guns (including Savages) will mar or shine up a case as I chamber it and close the bolt. Just a thought!!!

 

[mnshooter]

Tried that, no marks. It's been suggested elsewhere that I may not have done a very good job cleaning the chamber while shooting. I cleaned the bore quite often but did not mop the chamber. Maybe sovent or dirt there causing problems?

 

[308sc]

could be fine grit...but I doubt a solvent would cause what you are describing, clean out your chamber...and if that does not work let a gunsmith look it over...but it may go away with time, and long as the cases don't look weird and your primer are not blown out it could just be a little burr in there from the factory that may rectify itself in time.

 

[machinisttx]

I have seen pressure signs with factory ammo, but the were mostly limited to higher pressure cartridges and possibly due to inexperience on the part of the factory. I saw some of the 5.7x28 ammo that had exhibited enough pressure signs that I wouldn't have continued firing the ammo or the gun. It wasn't mine and I didn't shoot it.

Something else-- Most people clean their rifles a lot more than they need to. The only time I'll really clean mine is if I'm switching brands of bullets or groups start getting bigger. Some rifles won't shoot worth a darn with a clean barrel, but if it's somewhat fouled will produce tiny little bullet clusters on the target.

Clean the chamber and have the headspace checked, it might be running on the tight side.

 

[Soybomb]

I think the whole idea of pressure signs is deceptive. You won't always see "pressure signs" even with significantly over pressure ammo and they can show up even with in spec ammo that isn't over pressure.

 

[mnshooter]

Not sure if it's relevent or a separate issue or no issue at all, but after looking closely at the fired cases, there are three or four scratches right at the junction between the shoulder and the body. Maybe a couple thousandths deep and wide and .020 long. Can barely feel them with the pad of my finger, but definitaly feel them with a fingernail. And only on fired cases, not just chambered and ejected.
Is this a problem?
http://i271.photobucket.com/albums/jj155/jeffincr/scratches.jpg
http://i271.photobucket.com/albums/jj155/jeffincr/ejector.jpg

 

[kk5ib]

Scratches on brass

MNShooter, I think I can identify the scratches on the shoulder of your fired brass. If it is on all the rounds, that could be caused by a gouge or chatter marks in the chamber. I have similiar marks in my Remington 7400 30-06. Sent the rifle back under warranty but they would not rebarrel it. The marks on the brass almost are pushed back in in resizing. Just a little thing that takes away some of the fun.
Darryl

 

[243winxb]

There are at least 2 types of ejectors The opening/hole on the bolt face for the ejector will show on the head of the brass . A Remington or Sako ejector will leave a round shiny mark on the brass head as they use a plunger type. As long as the brass does not flow into the void, pressure should be ok. Hard extraction and primer are a better indication of to hot. The claw type extractor will make a mark on the brass head when loading single shot as it must snap over the brass head. On controlled feed type bolts like Mauser/M70win pre64 the extractor will not slip over the case head when loading single shot, they must take the round from the magazine. AS for the marks in the shoulder area. A good cleaning with a 45cal or chamber brush might help. Clean you dies the same way.

 

[mnshooter]

Looking back, some things are adding up here. My groups would range from 1/2 5 shot groups to 2 1/2". I chalked it up to the shooter.
While cleaning the copper fouling out the other night, I noticed that the scope was leaning noticably to the right when viewed from the butt end of the rifle. I thought to myself what a lousy job they did mounting the scope. Tried to move it by hand but would not move, so I remounted it.
Now I wonder if the barrel is backing out, causing the scope to lean and a headspace problem.

 

[243winxb]

Some holes in the receiver go into the chamber area, and some are also blind holes. If screws are to long they can even stop the bolt from working. Also the screws might be to long for a blind hole, the screw bottoms out before the screw tightens the base mount.

 

[mkl]

Next time you shoot, take along a micrometer. Quoting from the old Speer manual #8:

When the pressure for a load causes the head of the case to increase in diameter measurably, then the load is excessive for the case being used. An increase in head diameter of .001" would more than indicate excessive pressure.

The case head is the surface on which the caliber stamp is imprinted, in other words the "rim."

Speer says to back off at least 6% from any load that gives case head expansion and call that the maximum for that case/primer/powder/bullet/gun combination.

Be sure to measure the before and after at the same place on the head.

I've used the above method and it does work when used for high pressure cartridges such as the 243, 308, 30-06, etc. In one case I recall getting a .001" expansion when I was still two grains under the suggested maximum load for the 243 Win load I was testing.

I would not use this method on cartridges with a designed operating pressure of less than about 55,000 psi, since you would be well exceeding the maximum safe pressure of your gun before you got any expansion.

 

[243winxb]

The marks on you brass at the shoulder, could it be coming from dirt from when you adjusted the mount? If the mounting holes go throught into the chamber area?

 

[243winxb]

I noticed that the scope was leaning noticably to the right when viewed from the butt end of the rifle.

If you mean pointing to the right? This happens if there is no windage adjustment in the mounts. As long as you don't run out of adjustment with the scopes windage knob your ok.

 

[mnshooter]

All this happened before adjusting the mount.
I'm going to try it again tonite and see If I get the same thing.

 

[jeepmor]

Not sure if this helps or not, but I had a friend take his scope off his Savage rifle, mix up the machine screws, then reassemble the thing. The (empty) chamber would not open at all. He pulled the scope back off, figured it out, and got it straigtened out.

My ruger used to put a nice scratch on my brass until I figured out where it was coming from. A few moments with some emery cloth and it was fixed. This might be the same type of issue, there could be some residual crud from manufacturing in the chamber that is stuck there. A probe with a small awl or the like to reach in and feel the crud might just do the trick to pop it loose. It might be in there to firmly to break loose with a cleaning brush.

Just thinking out loud here, if I'm way off base, I apologize in advance.

 

[243winxb]

When the pressure for a load causes the head of the case to increase in diameter measurably, then the load is excessive for the case being used. An increase in head diameter of .001" would MORE THAN indicate excessive pressure

Note, this is a bottle neck type case like 30-06 or 243win. mkl Looking at my Speer manual #8 your above quote is correct, but i think the measurement is taken on the web just in front of the extractor groove. The web is part of the head as shown on page 27. The rim gets more abuse as its in contact with the bolt face and i feel not the correct place to measure,if your going to use that method at all. Maybe i have been thinking wrong all these year. In modern times of today there have been different studies on the subject i am sure, who is correct, not sure. I don't want any increase in the web/head area.

 

[mkl]

Note, this is a bottle neck type case like 30-06 or 243win.

243 is absolutely correct. Since his head picture showed he was using a 308 Win. I thought the information might be of use to him.

Note that I added a last paragraph "revision" to try and further clarify on what type of cartridge this may be appropriate.

I also have measured the web as well as the head/rim. Been so long since I got an expansion sign on the head, I honestly cannot remember if the web showed one also.

Speer may be trying to indicate that the head would expand before the web because of the thinner ring of brass around the primer pocket. Don't know. What I do know is that any expansion in the head/rim/web area is not a good thing...

 

[243winxb]

http://www.thehighroad.org/showthread.php?t=375160 Subject, high pressure and working up a load.