338LM Pressure Signs?

[Beneviolence]

Loading 338LM for a Savage 112 Magnum Target and I'm seeing flattened primers relatively early on, much before any sticky bolt. With these higher pressure cartridges, are flattened primers not the best indicators? Just due to soft primers?

H1000, 88gr
300gr SMK seated to 0.020" off the lands (3.690 COAL; 0.030" off the lands)
New Lapua brass
Winchester WLRM primers

For the above load data, I'm getting a very consistent 2690 ft/s out of a 26" 1:10 barrel. Even at 83gr I've seen flattened primers, and saw sticky bolt at 90gr with minor cratering. Never seen ejector marks though.

I'd rather get a consistent and accurate load than punish the brass & barrel for that extra 100ft/s and I know you do your own load development (and for good reason), but I'm just curious as to how plenty of people are doing 92gr and up.

Thanks for any advice.

 

[J E Custom]

The Lapua brass is some of the toughest and is slow to show pressure signs.

Most like to use Norma brass to indicate when pressure is reached. Then with the Max load established, they switch to there Lapua brass and do not exceed the load developed in the Norma brass.

Primers are not the last word, but they are good indicators along with velocities.

Just my opinion

J E CUSTOM

 

[gohring3006]

I noticed the primers are a little flat with my 112. But I was using Hornady brass to do the barrel break in. As soft as the Hornady is said to be, I had no other signs of pressure besides the flat primers. I'm inclined to believe it's the factory spec brass being sized to SAMMI and am certain this will stop once it's fire formed to my chamber and only set back .002" at the shoulder. I have since switched to Lapua brass though...

 

[Broz]

Get a magnifying glass. Look closely at the case head watching for a shadow of a circle from the ejector pin. If you plainly see a shadow of a full circle, you are at max. If you see any sign of smeared brass at this circle at all, back her down.

Jeff

 

[gohring3006]

Get a magnifying glass. Look closely at the case head watching for a shadow of a circle from the ejector pin. If you plainly see a shadow of a full circle, you are at max. If you see any sign of smeared brass at this circle at all, back her down.

Jeff

That's a good point Jeff.
My wife is a diamond jewler, and she has several of those little jewler magnifying glass eye pieces. I lifted one from her and it's invaluable in my load development..

 

[Beneviolence]

Thank you for the input. I just reviewed over the cases and I did see the 92gr had the ever so slightest amount of an ejector mark under the best lighting I could find; 91gr had absolutely nothing.


I'll do proper sizing on the once fired cases and see how it goes. To be honest, I think the first fire through may have had the bullet on the lands so I'm going to start at 83gr again, with the proper COAL/CBTO and watching the brass length as I hear Savages may have issues with that. I'll report back with results.

 

[Broz]

Thank you for the input. I just reviewed over the cases and I did see the 92gr had the ever so slightest amount of an ejector mark under the best lighting I could find; 91gr had absolutely nothing.


I'll do proper sizing on the once fired cases and see how it goes. To be honest, I think the first fire through may have had the bullet on the lands so I'm going to start at 83gr again, with the proper COAL/CBTO and watching the brass length as I hear Savages may have issues with that. I'll report back with results.

If you have any extraction issues bump the shoulders back to .0035" plus. Also expect a little pressure gain with fire formed brass. So yeas back off a bit. A piece of fine cand paper on a table top easily removes old ejector marks to start fresh.

Jeff

 

[toddc]

I bought one of these New Years eve and shot it yesterday.

Virgin Lapua brass. 3.715 COAL with 300SMK and H-1000 with same primer as OP.

88gr 2650
89 2670
90 2690
91 2750
92 2820

No pressure signs at all. Primers are pristine. Bolt lift didn't increase until 92. Still nothing even remotely scary at 92. Feels like it could take more but I will probably be done there. It's fast enough.

My Edges always started pressuring up much past 90 but at 2850 with a 30" tube. This is my 1st Lapua rig so I'm gonna take it easy and enjoy the brass.

According to the brass 92 gr would be livable but with a 300 SMK the accuracy matters more than the speed. I've chased speed a lot with the Edge and ES and accuracy matter a lot more.

 

[Beneviolence]

I bought one of these New Years eve and shot it yesterday.

Virgin Lapua brass. 3.715 COAL with 300SMK and H-1000 with same primer as OP.

88gr 2650
89 2670
90 2690
91 2750
92 2820

No pressure signs at all. Primers are pristine. Bolt lift didn't increase until 92. Still nothing even remotely scary at 92. Feels like it could take more but I will probably be done there. It's fast enough.

My Edges always started pressuring up much past 90 but at 2850 with a 30" tube. This is my 1st Lapua rig so I'm gonna take it easy and enjoy the brass.

According to the brass 92 gr would be livable but with a 300 SMK the accuracy matters more than the speed. I've chased speed a lot with the Edge and ES and accuracy matter a lot more.

What's your distance off the lands? With that COAL, I think I would just touching them. I want to get longer COAL but I don't want the pressure spikes of a zero jump to the lands.

@Broz, thanks for the input. I will try that offset for the brass.

 

[toddc]

What's your distance off the lands? With that COAL, I think I would just touching them. I want to get longer COAL but I don't want the pressure spikes of a zero jump to the lands.

@Broz, thanks for the input. I will try that offset for the brass.

I have had it 2 days lol. 3.715 doesn't seem excessive over the official 3.680. I don't have gauges for it and didn't have time to measure. I threw a dummy together and bumped back from a jam a smidge. Not real scientific but lots of people run the Lapua deep in the 7 or even 8s. These were more for barrel break in than anything so I haven't had time to digest the data and play with it. I usually run the 300 SMK with a 10+ jump and it shoots well in my Edges and other 338s.

 

[robert l]

not to change the subject but how do yall mark your brass for the round count on the brass.im not to keen on just scraching a line with a screw driver.any help would be great,thanks bob

 

[toddc]

not to change the subject but how do yall mark your brass for the round count on the brass.im not to keen on just scraching a line with a screw driver.any help would be great,thanks bob

I shoot all the way thru a lot of cases and then start over. I have also used colored primers but it gets wiped off.

 

[gohring3006]

I shoot all the way thru a lot of cases and then start over. I have also used colored primers but it gets wiped off.

I keep detailed log books for range time and the reloading room. I usually use 50 brass at a time. Mainly because my ammo boxes are 50 count. With the exception of the Lapua, it's a 20 count box. I don't see shooting my Lapua more than 20 times in a range session.

 

[toddc]

What's your distance off the lands? With that COAL, I think I would just touching them. I want to get longer COAL but I don't want the pressure spikes of a zero jump to the lands.

@Broz, thanks for the input. I will try that offset for the brass.

Measured lands today and I am .182 off at a COAL of 3.715 with the 300 SMK. A COAL of 3.897 gets me a jam with the 300 SMK. Your results will vary but hardly any stock rig is anywhere near the lands with a SAAMI COAL.
I am going to load up a test at .010 .040 .070 and .100.