Ejector mark ?

[bgavin]

I’m trying to work up a load for a new keystone barrel. It’s a 6.5 creedmoor at 26 inches and shoots factory hornady 140 eld great.

Lapua sp brass full length resized to saami specs
cci br4
40.6 grains h4350
seated 25 thousandths off lands and tried 31 thousandths off which is factory hornady eld length.

I got some Lapua brass and started at 40 grains. I found a good node at 40.6 h4350 but I noticed that I’m getting ejector marks on all of them and sticky bolt every once in a while. I loaded fifty to shoot at both seating depths this past weekend to confirm. It shot great groups and the muzzle velocity is around 2750 fps. Any ideas why I'm running in to pressure signs with this low of a powder charge?

Thanks

 

[Supersubes]

What do you mean when you say resized to saami specs? How are you measuring this, and how does that compare to your actual chamber size(which is all that matters)?

 

[918v]

Yeah

 

[bgavin]

FL resize and shoulder bumped back to 1.5 I think my friend said.

 

[bgavin]

I'm sure i have the terminology wrong and explaining wrong. I'm new to this bare with me on the stupid questions.

 

[1J04]

I'm sure i have the terminology wrong and explaining wrong. I'm new to this bare with me on the stupid questions.

Not a stupid question at all. Actually a damn important one. What they're trying to get at is if you've got or made a Headspace issue. Was this Lapua Brass fire formed in "your" rifle, and if so can you elaborate on the load information for that?

 

[bgavin]

The 100 I reloaded this past weekend were new Lapua brass and ran them through Rcbs
Full length resizer and used standard shell holder

My lands are 2.225 with hornady gauge and the loads were seated at 2.194 and 2.200. Using cci br4’s and 40.6 h4350.

We measured the shoulder today from the Lapua on first firing and it had stretches 7 thousandths if I remember correctly. I left my notes at friends house.

 

[918v]

You should have left the shoulder alone.

 

[1J04]

1. Is this a gas gun or bolt?

2. Why did you FL size the new brass? And if you actually did 'run them through your FL die" and set the shoulder back you started off on the wrong foot. If you only ran the expander through the neck to round it out that's another thing.

3. I'm coming up with more questions than I think you're prepared to answer. You're not the guy behind the press correct? You may want to have the guy who may or may not know what he's doing chime in. You're gonna get inundated with questions you're just not gonna be able to answer, and that gets old fast.

4. Toss up a pic of the gun and the case head if ya would.

 

[Precision Underground]

1. Is this a gas gun or bolt?

2. Why did you FL size the new brass? And if you actually did 'run them through your FL die" and set the shoulder back you started off on the wrong foot. If you only ran the expander through the neck to round it out that's another thing.

3. I'm coming up with more questions than I think you're prepared to answer. You're not the guy behind the press correct? You may want to have the guy who may or may not know what he's doing chime in. You're gonna get inundated with questions you're just not gonna be able to answer, and that gets old fast.

4. Toss up a pic of the gun and the case head if ya would.

This. And 2750 from 40gr of 4350 does not sound right at all unless you are using a 32” barrel. I have had some hot 4350 lately...but not that hot.

 

[MangoFett]

Also, when you say the brass grew I think it's important we know how you're measuring this. I'm assuming it's with something that measures off the datum to the base of the shell but j just want to make sure.

Generally just load up the new brass and if you feel inclined then run a ball or mandrel through it but don't size it- there's no need. Size it so that the datum to base length is shortened by 2-4 thousandths.

(Datum gauge size should be .400)

 

[Sutherlandsd]

This. And 2750 from 40gr of 4350 does not sound right at all unless you are using a 32” barrel. I have had some hot 4350 lately...but not that hot.

I get 2740 out of a 26" bartlein with 40.4gr h4350. Even Hodgdon book shows max charge of 40.4 shooting 2707.

With new reloaders more often than not when I see unusual pressure signs its because they are in the lands. The hornady tool isnt what I would call a precision way of finding the lands. Most often I see people jamming the shit out of the bullet in the lands and calling that where its kissing the lands which is usually in reality deep into the lands.

Chamber a round and look at the bullet see if it is marked by the lands.

Learn from Alex Wheeler how to find your lands.

 

[Precision Underground]

I get 2740 out of a 26" bartlein with 40.4gr h4350. Even Hodgdon book shows max charge of 40.4 shooting 2707.

With new reloaders more often than not when I see unusual pressure signs its because they are in the lands. The hornady tool isnt what I would call a precision way of finding the lands. Most often I see people jamming the shit out of the bullet in the lands and calling that where its kissing the lands which is usually in reality deep into the lands.

Chamber a round and look at the bullet see if it is marked by the lands.

Learn from Alex Wheeler how to find your lands.

Man my 8# jug must have been slow. I just changed barrels but was at 42gr and 2730. 24”.

I had a few 1# jugs that were def faster but not that fast.

 

[Sutherlandsd]

I'm up in the Smokies also though so altitude may have something to do with the speed. My bartlein though has been far from a speedy barrel, I have a proof coming this week that I hope is a hot rod.

 

[Statusquo]

Are you loading 140's and not a heavier bullet?

 

[bgavin]

Are you loading 140's and not a heavier bullet?

Only have the 140 eld's.

 

[bgavin]

1. Is this a gas gun or bolt?

2. Why did you FL size the new brass? And if you actually did 'run them through your FL die" and set the shoulder back you started off on the wrong foot. If you only ran the expander through the neck to round it out that's another thing.

3. I'm coming up with more questions than I think you're prepared to answer. You're not the guy behind the press correct? You may want to have the guy who may or may not know what he's doing chime in. You're gonna get inundated with questions you're just not gonna be able to answer, and that gets old fast.

4. Toss up a pic of the gun and the case head if ya would.

Your right on not being prepared to answer. I'm learning as I go.

I think I really screwed up and fl resized and bumped the shoulder back instead of using the expander. I did this several weeks ago and was working major hours. My friend wasn't there that afternoon and I think I fl sized with the standard shell holder. I was trying to get brass prepped and ready when I had a little time. This is most likely where I screwed up. I'm going to see if he has a new piece of brass to measure and compare. I'm measuring with the hornady gauge off the shoulder to the bottom of the case.

Thanks all for helping.

 

[Sheldon N]

I think I really screwed up and fl resized and bumped the shoulder back instead of using the expander. I did this several weeks ago and was working major hours. My friend wasn't there that afternoon and I think I fl sized with the standard shell holder. I was trying to get brass prepped and ready when I had a little time. This is most likely where I screwed up. I'm going to see if he has a new piece of brass to measure and compare. I'm measuring with the hornady gauge off the shoulder to the bottom of the case.

To expand on the advice above... We suspect that you are seeing pressure signs because your brass has too much headspace in the chamber. Like 918v said you should have left the virgin brass alone and not bumped the shoulder. Too much headspace can give the symptom of excess pressure.

Here's what you should do....

Take a fired piece of brass from your rifle.... knock the primer out, then measure the shoulder with the comparator. That number is going to be close to your chamber size. It actually may be a bit shorter than your chamber because the brass has not fully expanded. That takes a couple firings usually.

You want to bump the shoulder on your brass roughly 0.002 back from the size of your chamber. It's all about creating adequate, but minimal clearance around the brass so that it chambers effortlessly but also doesn't have far to move when it expands when being fired. Too much clearance will stretch the brass and eventually tear it in half (case head separation). You've got some nice Lapua brass, don't want to mess it up with too much headspace.

Once you've got the brass sizing sorted, you can also look at distance to lands like Spife linked to above. That may be another issue... jamming bullet into rifling can lead to excess pressure.

Final tip I'd offer is to consider stripping the firing pin and ejector plunger out of your bolt so you can feel the brass chambering effort... it's a good way to tell if you have interference between brass and chamber. It also can help you figure out exactly what shoulder distance is the max length in your chamber. As you adjust the sizing die there's a point where the headspace gets longer before it starts to bump the shoulder (diameter squeezing pushes shoulder forward). You can use that longer headspace piece of brass to see if it chambers or has bolt resistance. A video that shows what the "feel" method in combination with measurements is here...

 

[bgavin]

To expand on the advice above... We suspect that you are seeing pressure signs because your brass has too much headspace in the chamber. Like 918v said you should have left the virgin brass alone and not bumped the shoulder. Too much headspace can give the symptom of excess pressure.

Here's what you should do....

Take a fired piece of brass from your rifle.... knock the primer out, then measure the shoulder with the comparator. That number is going to be close to your chamber size. It actually may be a bit shorter than your chamber because the brass has not fully expanded. That takes a couple firings usually.

You want to bump the shoulder on your brass roughly 0.002 back from the size of your chamber. It's all about creating adequate, but minimal clearance around the brass so that it chambers effortlessly but also doesn't have far to move when it expands when being fired. Too much clearance will stretch the brass and eventually tear it in half (case head separation). You've got some nice Lapua brass, don't want to mess it up with too much headspace.

Once you've got the brass sizing sorted, you can also look at distance to lands like Spife linked to above. That may be another issue... jamming bullet into rifling can lead to excess pressure.

Final tip I'd offer is to consider stripping the firing pin and ejector plunger out of your bolt so you can feel the brass chambering effort... it's a good way to tell if you have interference between brass and chamber. It also can help you figure out exactly what shoulder distance is the max length in your chamber. As you adjust the sizing die there's a point where the headspace gets longer before it starts to bump the shoulder (diameter squeezing pushes shoulder forward). You can use that longer headspace piece of brass to see if it chambers or has bolt resistance. A video that shows what the "feel" method in combination with measurements is here...

Thank you!

 

[kissmyrebelass]

Something else to check: It's possible neck od could be too large. That would also cause excessive pressure at what should be a mild load. See if a bullet falls through a fired, not resized neck.

 

[bgavin]

Something else to check: It's possible neck od could be too large. That would also cause excessive pressure at what should be a mild load. See if a bullet falls through a fired, not resized neck.

Will do.

Thanks

 

[JOE62]

That's good advice about the case getting longer before it gets shorter. Hang in there and don't get discouraged.