Signs of pressure (opinions)

[bh-ltr]

Ok so I think I'm seeing enough sign of pressure that it has me wanting to go and rework my load. But I honestly don't want to give up any more velocity being that I'm shooting a 20" 308 as it is already. I'm also very happy with the performance of the load in my rifle. I've seen many people using loads much higher than mine and I'd like a second opinion.

I'm not sure if the case head line that I'm seeing is from pressure or from the sizer not going below that point. The primers are flattened a bit but you can see see a bit of the annulus remaining on the fired cases. Now that I look at these pictures its a bit easier to see the annulus on the fired casings than it was to my eye in that light. These pictures were taken with a high dynamic range application to try and help with any lighting issues.

Load Data:
Brass: Lapua
Caliber 308
Bullet: 175SMK
Powder Varget
Charge 44.5g
COAL 2.800" for magazine loading

Thanks for your input.

Loaded Rounds:

Fired Rounds:

Case Heads of Same Fired Rounds:

Case Heads of New Lapua Brass:

~Brett

 

[sierracharlie338]

Hard to tell from the pics on my phone screen but I run the same COAL and 44.3 gr of Vargetin mine. I wouldn't imagine it's too much for yours.

How many times has the brass been reloaded?


Sierracharlie out....

 

[bh-ltr]

This batch is on 3 reloadings.

 

[Timo Turl]

What bullet ? 44.5gr is a lot for a 208gr but not for a 155gr.

When you run your thumb over the fired primers are they a sharp/scratchy ?

 

[kmose73]

In order to tell if that ring is the beginning stages of case head separation, take a paper clip end bend a 90 right at the end. Then put it in the case and see if you can feel that line on the inside of the case. My gut feeling is that you are fine but can't tell from pics. Has the bolt opened hard? Are the primer loose?

 

[BuzzBoss915]

I don't really see anything of concern? Slight cratering around the firing pin detent in the primer. Everything else looks completely normal, to me. What is the problem, exactly, and I don't want to demonstrate my ignorance, but. What is an "annulus"? Are you referring to the bright ring on the case head of fired cases? If so, this is completely normal. Otherwise, I see no pressure signs whatsoever. BB

 

[demolitionman]

The bright ring is most likely a result of the sizing die leaving marks at the case head. You have some primer flattening but all my "hotter" loads exhibit that. I do know switching from federal 210's to cci200's resulted in less flattening and cratering with the same loads. Maybe cci primers have a harder metal?

 

[kmose73]

http://youtu.be/orJdUR_X67M

 

[bh-ltr]

What bullet ? 44.5gr is a lot for a 208gr but not for a 155gr.

When you run your thumb over the fired primers are they a sharp/scratchy ?

Bullet is a 175SMK. Sorry. I've added that to the original load data post. No primers aren't sharp or scratchy and I've not looked at pulled ones for the shoulder but I don't think they've flowed to that degree.

 

[bh-ltr]

In order to tell if that ring is the beginning stages of case head separation, take a paper clip end bend a 90 right at the end. Then put it in the case and see if you can feel that line on the inside of the case. My gut feeling is that you are fine but can't tell from pics. Has the bolt opened hard? Are the primer loose?

I'd heard of this before and have never tried it. When I get home I'll see if I can feel them. My feeling is also that its just where the body sizer die ends. Never had a sticky case and being that a lot of the shooting I've done with these was timed I'd be changing things fast! The only reason I'm body sizing and bumping the shoulders .002" now is to make sure I never have any hard bolt closures. No loose primers.. Mainly I'm about to change primers and work up to the same velocity and then load out 900 rounds and I want to make sure all is happy before doing so. I've been shooting this load for about 1000 rounds now and I don't think I have any issues but before fully committing I started to question myself and wanted to be SURE.

~Brett

 

[Timo Turl]

Bullet is a 175SMK. Sorry. I've added that to the original load data post. No primers aren't sharp or scratchy and I've not looked at pulled ones for the shoulder but I don't think they've flowed to that degree.

You should be fine at that load. Primers seem ok, brass looks normal. If bolt lift isn't sticky then soldier on but keep a close eye on it.

 

[bh-ltr]

I don't really see anything of concern? Slight cratering around the firing pin detent in the primer. Everything else looks completely normal, to me. What is the problem, exactly, and I don't want to demonstrate my ignorance, but. What is an "annulus"? Are you referring to the bright ring on the case head of fired cases? If so, this is completely normal. Otherwise, I see no pressure signs whatsoever. BB

Honestly at the moment there is no problem. Just that I'm over thinking things like I always do and I want to be sure. The technical mathmatical definition of an annulus is the area between two concentric circles. I'm using it to define the curved area that occurs between the back of the primer and the side walls.

Glad to hear that all looks good to you as well.

~Brett

 

[bh-ltr]

The bright ring is most likely a result of the sizing die leaving marks at the case head. You have some primer flattening but all my "hotter" loads exhibit that. I do know switching from federal 210's to cci200's resulted in less flattening and cratering with the same loads. Maybe cci primers have a harder metal?

Yea I'm about to switch from Federal 210's to Remington 9 1/2's. Mainly cause that was what I could find. I brick of 5000 Remington 9 1/2's became available and I jumped on it so I'm going to be using those for a while...

 

[bh-ltr]

Excessive Pressure Indicators - YouTube

Yes this was exactly the video that I watched that started me questioning what I had been seeing for a while. This video is what caused me to post this thread.

 

[rduckwor]

I run that very load in a 700 5R with 175SMK's and have seen no pressure issues.

 

[lightman]

I don't see any problems, either. The slight cratering is pretty common with factory bolts, but not enough to worry me. I'm not sure that I would even call those fired primers flat, there is still a space around the annulus. There, I learned a new word! The ring around the case head ahead of the rim looks to be from the sizing die. I would start to worry if your cases showed shiney marks around the ejector, but yours don't. Another sign to watch for is shorter case life than you would expect. Like others have said, watch for sticky bolt lift, and carry on. Lightman

 

[Dacam]

IMO, the primers do look slightly flattened and have some cratering. Not really a concern though, pretty much looks like a slightly hot load should.
To me, I will run a lighter load. Alot of guys will run as hot as they can but I will run on the lower side.

Example: 24" barrel
175g 44.5g Varget = 2750
This load stays mach 1.2 at 975yds

175g 43.5 Varget = 2715
This load stays mach 1.2 st 950yds

You could even run lower loads like 43.0 or 42.8 and get out to 1000yds.

Why would I stress out my brass and barrel and use slightly more powder for a 25yd gain. Not really worth it IMO.
Lighter loads produce wonderfull groups and perform well at distances for 308.

 

[bh-ltr]

IMO, the primers do look slightly flattened and have some cratering. Not really a concern though, pretty much looks like a slightly hot load should.
To me, I will run a lighter load. Alot of guys will run as hot as they can but I will run on the lower side.

Example: 24" barrel
175g 44.5g Varget = 2750
This load stays mach 1.2 at 975yds

175g 43.5 Varget = 2715
This load stays mach 1.2 st 950yds

You could even run lower loads like 43.0 or 42.8 and get out to 1000yds.

Why would I stress out my brass and barrel and use slightly more powder for a 25yd gain. Not really worth it IMO.
Lighter loads produce wonderfull groups and perform well at distances for 308.

The reason for me was because with a 175g SMK 44.5g Varget I get 2563fps out of a 20" barrel. This setup goes subsonic right at 1K. Being that it is a 175SMK I've gotten multiple hits in a row onto a 18x30 humanoid last time I was out but the dope beyond 1K gets a little dicey. Looking at my notes from the last time out I the range to the target was 1147 and the dope was 14.8mil which is actually dead on with my Applied Ballistics app.

Also my rifle for some reason seemed to throw the lighter charges around a bit more. Here was the target after I did my OCW load test:

 

[bh-ltr]

Honestly now that I look at this set of targets again I forgot to look at the crossover between them and based on this I think I could also go to 44.3 and still have a good charge insensitivity against POI change. Not going to change pressure that much but hey it couldn't hurt.

 

[P7id10t]

I don't see any pressure problems. In my experience with higher pressure your primer shoulders will be reduced or non existent, and the primer dimple ridge will be pronounced.
Regarding the difference on your fired cases, I see similar difference in my brass when I do a full resize. Never sprayed on machinist's bluing to see what the sizer is actually doing, but I think it affects the case differently down at the head.

[edit]
D'oh! Being Lapua cases, your inside corner at the case head thickens significantly. Look inside with a bright flashlight and you will see. A FL resize will reflect this.

 

[bh-ltr]

Hard to tell much from the flashlight looking inside because the cases on the inside are still really black as I only tumble with dry media but I can't feel any line on the inside with the paperclip.

~Brett

 

[kmose73]

44.5 five would have been your best group if not for that one that energy high. I'd reshoot those three loads a couple time and get some averages.

 

[kmose73]

One that went high. Stupid spell check.

 

[LawnMM]

There is light ejector wipe on the case in the middle. If the bolt gets difficult to lift its a stiff load. You may have another issue, an improperly set sizing die. Have you measured how much your dies size the case with a bump gauge?

 

[P7id10t]

44.5 five would have been your best group if not for that one that energy high. I'd reshoot those three loads a couple time and get some averages.

Yeah, I get that energy high every time I piss on high tension power lines.

 

[bh-ltr]

There is light ejector wipe on the case in the middle. If the bolt gets difficult to lift its a stiff load. You may have another issue, an improperly set sizing die. Have you measured how much your dies size the case with a bump gauge?

i know that I'm setting the shoulder back by .002 but I don't know how much smaller the sides are getting I've not tried measuring that. Are you taking about the diameter of the casing? I always pretty much ignore that values because its based on the die and not really anything I have control over so I'm guessing you mean something else.

~Brett

 

[LawnMM]

i know that I'm setting the shoulder back by .002 but I don't know how much smaller the sides are getting I've not tried measuring that. Are you taking about the diameter of the casing? I always pretty much ignore that values because its based on the die and not really anything I have control over so I'm guessing you mean something else.

~Brett

How do you know its 0.002? Have you meaured after firing and then after sizing or did you use the 1/8th turn of the die method? If you checked with a bump gauge you are good. I've seen more than one reloading manual advocate the 1/8th turn of a die method and that is imprecise at best.

 

[bh-ltr]

How do you know its 0.002? Have you meaured after firing and then after sizing or did you use the 1/8th turn of the die method? If you checked with a bump gauge you are good. I've seen more than one reloading manual advocate the 1/8th turn of a die method and that is imprecise at best.

I have an attachment for my calipers that is setup to measure to a 308 shoulder. I measure after firing and then after sizing and I'm resizing an average of .002". Some are over by a half and some are under by a half but the average is .002". Well ok on the 30 that I measured not long ago the average was .00165" close enough.

~Brett

 

[LawnMM]

Yup, your dies are set! Do what somebody else already suggested, straighten a paper clip and put a small 90 degree bend at the end. I even sharpened the end to a point and drag it on the inside of the case. If the head is approaching separation you will be able to feel the dip where the line on the outside is. I consider the brass done at that point. If it feels smooth its just a mark from the sizing die.