Brass mouth damage

B

Bighead4

New member
After firing, all my brass shows a bit of damage to the case mouth. Looks like the case maybe hits the end of the chamber. New untrimmed or trimmed old brass all show this condition. Trimmed some cases short and same thing still happened. Requires me to square ends and bevel each time I reload.

Chambered some new, sized brass to see if ejectors or port was culprit. No marks of any kind noted to beveled case mouth.

This is a rebarreled 222. Thinking the chamber is reamed too short.

Any experts with clues or opinions?
 
A little more

Does the rifle have to be fired to cause the "damage"?

Does the bolt resist closing more so on loaded vs unloaded cases?

What is the chamber neck diameter and what is the neck diameter of a loaded round?

Can you show a picture of a damaged case?
 
I have the exact same condition with a rebarrelled .222.
Anxiously awaiting.................
 
Are you guys looking at the shiny end of the cartridge mouth? If so, I'll bet you are putting your fired cases in your MTM box with the neck down. Which incidentally is the best way....keeps bugs and spiders out!
 
Yes, it is the shiny end of the case mouth, but it is not even and around the whole mouth.
Not putting the cases mouth down, the case has the marks on it as soon as extracted after firing.
Brand new chamber, brand new reamer.
 
Joe said:
Yes, it is the shiny end of the case mouth, but it is not even and around the whole mouth.
Not putting the cases mouth down, the case has the marks on it as soon as extracted after firing.
Brand new chamber, brand new reamer.
Click to expand...
You need to know your chamber OAL (overall length) then trim your brass to about 0.010"-).012" short of that. Keep in mind the shiny surface on the case neck rim can't be from the end of the chamber neck because the chamber neck ends in a 45 degree bevel.
 
It may be a carbon build-up in the void just ahead of the where the cartridge neck ends. This happened to me with my 6 Dasher. A borescope allowed me to see the black carbon deposit in the neck area.
 
222.jpg
This is a case that is damaged on the rim as I previously stated. The shiny spots at 5,7,8,9 show the problem but it is difficult to photograph. Keep them cards and letters coming. Good info received and I thank you. Hope the image uploaded, guess we will see.
 
Looks too long to me. The tell tale sign is that the edges are rounded inward. Let me guess, it doesn't shoot worth a darn or throws wild shots? The problem is most likely due to oversizing - possibly due to a poor match between the chamber and the sizing die.

I can't tell from the photo, but are you also getting a bright ring around the case, approximately .4" -.6" from the base? If so, that could be a sign of impending case head separation. Basically, you are pushing the neck back too far when you resize (possibly because the back of the case is sticking if you don't size it to that extent?)

When the firing pin hits the primer, it pushes the case forward in the chamber, if the headspace is not so far off, the round will still go bang. The case neck expands, locking the case forward, but as the pressure builds, it causes the rear of the case to push back into the chamber. The neck, remember, is held by pressure to the chamber walls, so it doesn't move. The net effect is that the case expands. The next time you reload, you move the shoulder back again, thereby elongating the neck, which eventually contacts the sloped end of the chamber causing the dings you're seeing in the picture.

Fix? Get a small base sizer or a custom sizer designed to squeeze the base of the case while not pushing the shoulder back.
 
I am guessing you have a 700 Remington or action with a plunger ejector in the bolt face and as you pull the bolt back the side pressure first drags front of cartridge to side of shoulder then back of chamber mouth then on side of receiver before it is ejected. Remove the ejector and see if it goes away.
BV
 
Brian Voelker said:
I am guessing you have a 700 Remington or action with a plunger ejector in the bolt face and as you pull the bolt back the side pressure first drags front of cartridge to side of shoulder then back of chamber mouth then on side of receiver before it is ejected. Remove the ejector and see if it goes away.
BV
Click to expand...
Brian I think you just won the prize, if they (Joe and Bighead4) know they have the correct length brass. Like I said above, the only way to know for sure is to know the chamber length (from the reamer drawing) and to know the brass length.

Removing the ejector pin is not really necessary to see if Brian is right, When you start lifting the bolt handle reach across with your other hand and keep the cartridge mostly straignt until it clears the ejection port.

From the photo it is hard to tell. I'm like Mike, it looks like the brass is rounded on the end. Are you using a crimp seating die and getting into the crimp section of the die?

Good try on the photo but it is too blurry.
 
I'll try removing the ejector. We're expecting a storm and school might be closed friday so I might get some range time earlier than expected.
Brass is trimmed to .010" under specs.
As I said, the chamber is brand new, the reamer is brand new, and I also had a -.0025" resize reamer made at the same time, also brand new.
The brass is brand new Lapua .222 brass, and this was the first firing.
I did try to keep the brass straight just after lifting the bolt handle, but don't entirely trust that I was able to keep it straight.
My seater die is not a crimp die. It is a wilson type seater made with the chambering reamer, also brand new.
I loaded and fireformed 20 cases, all had the same condition.
 
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Bighead's case damage

There are 2 of us with the same type problem. Joe has a much newer chamber problem than do I. I have a 40-50 year old 722 action. I do not know the specs of the rebarreled neck chamber, but the OAL as best I can measure is 1.710. Book OAL is 1.700. The mouth damage is scattered all around and does not appear to be pushing inward but on the lip surface as rough spots. By chambering new, sized brass with no damage have I not eliminated the extractor and port as the culprits? Also, headspace measures well within specs.

This old rag is a pretty good shooter but somewhat erratic. Some groups are pretty small but usually 1 shot will open up the group to 1/2" or more. There are no appreciable bright spots near the web as someone surmised. I have never had a case separation but have had necks to split on well used cases. I usually can get 10 or more reloads if cases are annealed. HOWEVER, full case loads, within book max, will flatten the primers so loads are backed off to near minimum book. Those heavy loads are not as accurate as lighter loads. I have also experienced the phenomenon of the best groups (under .20) coming from 80% loads while fireforming new cases. These cases also show damage to the lip. This accuracy cannot be duplicated on fired cases.

Sizing - Have used standard full length dies, neck dies, Lee collet dies. All result in damaged lips. None show much better accuracy than the other. Have new Redding-S full length die with neck bushings and a body die. Will begin sizing with them when all of your opinions and suggestions are digested.

Look forward to more input and thanks. Bighead4
 
case mouth damage

Just lately rebarrelled and rechambered a Remington 40X to .220 Beggs. Was experiencing the same case mouth damage reported here. Couldn't determine the cause but in order to keep from throwing ejected brass across the room, I trimmed the ejector spring a couple of coils. Now the brass just jumps out onto the benchtop
and Lo and Behold, No case mouth damage!
Quig
 
Here's a quick way to find out what the problem is.
1. Will a bullet go back into a fired case with little to no resisitance. If not, your cases are too long.
2. If the damage is a scrape on the shoulder or a dinged neck it's from the case clearing the chamber and hitting the edge of the bolt rail in the action. Reduce or remove ejector spring and/or round off the corner inside the action.

I get 3 or 4 calls every year about this. Anymore I automatically cut a couple of coils off the ejector spring before shipping a rifle.

Dave
 
ejector springs and M700's

My wife's 6mmBR was having the same problems. I removed the ejector spring and the problem went away. BTW, I put the plunger back in, jsut with no spring.

On a Savage I had built by Larry Racine, he cut a few coils off the same spring and I have no problems with fired brass.

:):):)
 
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