Why the heck am I getting swipe marks on my brass

[TBass]

So I am reloading for a Christensen Arms rifle in 6.5 PRC. In the past some 6.5 Nosler factory loads were shot in the gun and it had swipe mark on the back of the brass. I assumed that the 6.5 Nosler ammo just might be too hot (although it shot extremely well).

Well I am now working up a load for the rifle. I am reloading using H1000 and shooting the 156 Berger EOL. I started with 54.5 grains of H1000… which is the starting load recommendation per Berger.

For some reason I am still getting the swipe marks on the bottom of my brass (even at the lowest charge level)… and yet, I really don’t think I am getting pressures that are too high. What can cause the swipe marks on the brass?

Side note – the sharpie marks on the case represent the powder charge in each case.

 

[BBob]

Any idea what the velocity is? Primers are flattening and getting some cratering/flow around the pin. Looks like pushing the pressure to me.

 

[WeiserBucks]

They're over pressure in soft Hornady brass.

 

[Ryan Avery]

Both Nosler and Hornady brass is soft and will show pressure early. I am using 56.5 with ADG and 156s, with no pressure signs.

Another thing to look for is a carbon ring. 6.5 PRC and SAUMs have been the worst for me.

 

[TBass]

I am going to run the starting load over the chrony. And I agree that they appear to be signs of pressure... it just seems unusual that it would be showing signs right from the get go. Based on what Berger sent me, the estimated velocity is only going to be about 2600 fps.

I will also check for the carbon ring. The rifle only has 100 rounds or so through it... but I will still check it.

 

[eoperator]

Bullet jambed in rifling? lube on brass?

Looks like hornady brass on the edge of pressure to me.

 

[TBass]

No lube on the brass. Shoulders bumped .003" (I tried .002) but they averaged .003"

Bullet is off the lands.

I am thinking that I'll have to try some different brass.

I guess I would have thought that I would have seen more profound changes in the brass or heavier bolt as worked up in powder charge.

 

[TBass]

So I guess that leads to another questions. If your brass is showing the type of pressure that you saw in the picture above, would you not consider any of these loads safe and viable?

Because the 56.5 grains is consistently shooting light out. Several 3 shot groups were shot and all were under 1/2"

 

[woods89]

I don't want to give you a false sense of security here, but I have a custom built on a Rem M7 action that swipes everything. I use Lapua brass, and it will swipe the case on sedate loads with fully round primer edges. At this point I watch for other pressure signs and try to stay a bit under, and go shoot.
I'm open to advice, if I'm doing something really wrong, but my brass seems to be holding up just fine. I've just decided it's part of this rifle, but I'm interested to hear others opinions

 

[Ryan Avery]

So I guess that leads to another questions. If your brass is showing the type of pressure that you saw in the picture above, would you not consider any of these loads safe and viable?

Because the 56.5 grains is consistently shooting light out. Several 3 shot groups were shot and all were under 1/2"

I would and have hunted with loads like that. To each their own.

 

[Ucsdryder]

I would and have hunted with loads like that. To each their own.

Same here. Only issue I’ve seen is brass seems to have a pretty short life. I’d be curious to hear what the MV is with these loads.

 

[Kindo]

Not sure if this makes any sense or not but I’m currently building some loads for a CA MPR and have been shooting some Norma rounds that I got cheap for the brass. Closing the bolt seemed a bit stiff on them but they’re factory loads.

After shooting them through a chrono with expected results, the bolt lift seemed a bit stiff again and I had swipe marks but no other pressure signs and the velocity was mediocre as expected.

Just took them home to process last night and found the factory brass was at 2.35 or so if I recall correctly. Could CA have tight/short throats and there be a constant pressure on soft brass to leave a swipe that way?

 

[MT257]

How do they chamber? Easy or tight? Do you get any of those markings by just chambering and not firing the round? How is your bolt lift when shooting them?

Buddy of mine had a CA and was getting brass swipe. Contacted CA an found out chamber was a bit short.

 

[WeiserBucks]

How do they chamber? Easy or tight? Do you get any of those markings by just chambering and not firing the round? How is your bolt lift when shooting them?

Buddy of mine had a CA and was getting brass swipe. Contacted CA an found out chamber was a bit short.

You can't get an ejector mark without firing the round.

 

[TBass]

I’ll see if those marks occur when chambering factor round and not firing them. And Kindo brings up some good points as well.

I can tell you that the shoulders are pushed back .003”… they are not jammed into the lands, and there is no unexpected resistance when chambering and closing the bolt.

I’ll get some chrony numbers to see if the velocity is substantially off from where i think they are going to be… and maybe try to track down some better brass and start from scratch on load development

 

[MT257]

You can't get an ejector mark without firing the round.

I’m not referring to the ejector mark. This was from the CA that was not cut correct. The swipe occurred during chambering.

 

[TBass]

MT257 - did he send the gun back?… or did he just deal with it?

 

[MT257]

MT257 - did he send the gun back?… or did he just deal with it?

He sent it back to them.

 

[Kindo]

I’m not referring to the ejector mark. This was from the CA that was not cut correct. The swipe occurred during chambering. View attachment 431983

This is what I was referring to in my previous comment as well. I got the same thing, but only with brass that was too long (factory load with brass over SAAMI spec.

 

[MT257]

This is what I was referring to in my previous comment as well. I got the same thing, but only with brass that was too long (factory load with brass over SAAMI spec.

Did you see it on all of the factory ammo you tried? This one didn't seem to do it every one but maybe every third one.