Ran into signs of pressure sooner than expected with .300WSM. Need input

[Dentite]

Hey gang,

I've been a bit of lurker and finally registered. First post.

I got a Browning X bolt in .300 WSM recently I just shot it for the first time this weekend. I picked loads below published data limits and was surprised to see some signs of overpressure.

I loaded two batches, all with new Win brass, CCI magnum primers, Barnes 168 TTSX. Loaded to just fit in the magazine (which happened to be 0.020 off the lands).

I loaded some sighters and then some increasing powder charges to find out when I ran into pressure signs so I could know my upper limit and start developing an accurate load.

First batch was H4350. Hodgdon lists 61.0 as a start with a velocity of 2908 and a max of 64.5 and velocity of 3034 with a 168gr sierra HPBT.

I loaded up some sighters at 63.5gr H4350 and that was the only charge I ended up shooting as I started to get light ejector marks. No flattening of the primers or heavy bolt lift, but a light ejector mark on all but two of the 7 rounds fired.

My velocities: 2979, 2972, 2978, 2961, 2977, 2958, 2983.

Very happy with the consistency but I didn't expect ejector marks on the brass at that charge or velocity.

Next batch was RL17:

64.0gr sighters

3060, 3068, 3049. All with ejector marks with no other signs of overpressure.

85 degrees, 1200ft elevation.

So what do you guys think? I would appreciate any input, especially from those that reload this caliber with those powders. Of course I realize that each chamber and barrel can vary but I am curious what others are getting.

Thanks,

John

 

[dkhunt14]

The new brass is short on headspace so it fits all guns. If you sized it you might have bumped it even more. If it was pushed forward by the firing pin and fires sometimes it slams back against boltface and gives ejector marks. After they are fired you need to measure headspace and bump no more then 2 or 3 thousandths. Maybe your ejector is too stiff or not fully going into the bolt. Maybe the hole has a rough edge. I am not Familiar with the ejector on a Browning. Matt

 

[backwoods83]

The above statement is spot on, the only true ways to gauge pressure in a WSM especially when using winchester brass is to measure the case head expansion or a strain gauge if you have deeper pockets than most. We have ran our 31" test barrel in 300wsm up to 3070fps with 230 grain berger hybrids, I won't get into details about how thats possible but I will say the OAL exceeds 3.2", but 2780fps is doable with 230 hybrids in a standard chambered 26" barrel and 190 vlds can go 2960fps so you are far from pressure. Just resize the brass with a slight (.002") shoulder bump and try it over again. You may want to give Imr4350 a try as well.

 

[Bigeclipse]

Please remember book values come from that book makers specific rifle/chamber, brass, primer, powder/lot# and bullet lot# which can/will differ from your's. I also want to comment that it looks like you started right near the top of the load range. I would want to at least start below half way powder charge, maybe even at the lowest listed value and work up from there. Personally I load one bullet at the bottom value...then move up .5-1 grains until I start getting near mid to upper end. I may even cut back to .2-.5 grains from there until I find my rifles first signs of pressure. Many times this has been over book value, sometimes it has been well under for a certain powder/lot#. From that top value I back off a grain or so as my max safe value. Just my two cents.

 

[Canadian Bushman]

Would you mind posting pictures of the case heads?

Dk and backwoods are on it.
Ejector marks and primers are nice indicators but they dont always tell the whole story.

Also some monos generate more barrel pressure than lead core bullets so its not unusual to pressure out earlier than expected when using data obtained from lead core.
Hodgdon supplies some data from monos, it might help to cross reference.

 

[Dentite]

You guys are awesome. Thanks for taking the time to respond. I have some more questions and will take some photos and post later today when I'm done working.

Thanks,
John

 

[Punisher]

i have a different idea as i recently ran into the exat same thing with my 7mm mag.

so i went and talked to my 74 year old neighbor who has been benchrest shooting since the 1960's.

i had him look at my brass and he looked at it and said "yeah. that's typical with bad brass. shoot it twice more and that wont happen anymore."

he then told me to bring the brass lot to him to re-anneal afterwards.

he was spot on. after 2 more shots, i never saw another ejector mark and began buying nosler brass. the nosler brass never had an ejector mark either. only the winchester brass.

i think the huge demand on brass right now has led us into a market full of low quality control.

i would expect the same with your powder and bullets as well.

 

[RHC]

The new brass is short on headspace so it fits all guns. If you sized it you might have bumped it even more. If it was pushed forward by the firing pin and fires sometimes it slams back against boltface and gives ejector marks. After they are fired you need to measure headspace and bump no more then 2 or 3 thousandths. Maybe your ejector is too stiff or not fully going into the bolt. Maybe the hole has a rough edge. I am not Familiar with the ejector on a Browning. Matt

This ^.

 

[Dentite]

Okay guys, here are a few photos. The ejector marks are visible on most of the brass I fired but none are what I would call very obvious. I had to rotate the brass and vary the angle of the camera to capture them clearly. At the bench on the day of shooting, I studied each piece using the sun to reflect light back and rotating the brass to find the marks.







Here are some photos of the ejector and bolt face. The blue color is from the sharpie marker I used on the primers for identification.





My baseline for experience is handloading a .260Rem and a couple .223Rem. I handload other cartridges but spend the bulk of my accuracy efforts on those two.

With my .260 I did a pressure test where I started at the middle of published data and progressively worked up and I began to see signs of pressure very slowly and predictably. Started to slowly get ejector marks and slightly heavier bolt lift. The velocities indicated by my chronograph agreed that I was getting hot (nearing 3000 ft/sec with a 140 grain bullet and H4350 and a 26" barrel).

With my .223 Rem bolt action I always get a bit of primer cratering and flattening of the primers but as pressure goes up the cratering and flattening gets worse. Can't say I've every seen an ejector mark on my .223 brass even though its the same type as my .260.

Here's some .223 rounds that I recently fired and was surprised to see that my bread and butter load that previously gave 3100ft/sec and <0.5" groups had jumped up to 3220ft/sec. I had switched brass and it made more a difference than I had anticipated. I should have worked up the load again but I was lazy. Here's some .223 brass that was 3220 ft/sec or so. No heavy bolt lift, no visible ejector marks, but pretty heavy cratering of the primer indicating increased primer flow around the firing pin.

 

[Dentite]

I made a long post last night including photos of my brass and I got a message that it needed moderator approval before it will be posted. So hopefully it will show up soon and not vanish into the depths of the internet.

In the meantime...

The new brass is short on headspace so it fits all guns. If you sized it you might have bumped it even more. If it was pushed forward by the firing pin and fires sometimes it slams back against boltface and gives ejector marks. After they are fired you need to measure headspace and bump no more then 2 or 3 thousandths. Maybe your ejector is too stiff or not fully going into the bolt. Maybe the hole has a rough edge. I am not Familiar with the ejector on a Browning. Matt

I did resize the new brass with a plain old RCBS FL resizing die prior to the first firing. Most of my reloading for rifles has been FL resizing. I do have the Redding S type bushing die, body die and competition seater for a .260 Rem but the rifle is new and thus far I have only neck sized new Lapua brass and haven't used the body die yet to bump the shoulder.

I don't have any instruments to measure case expansion. I do have the Hornady comparator setup so I think I understand the concept. Any particular tools I should look at? Something like this? http://www.sinclairintl.com/reloadi...nady-lock-n-load-headspace-kit-prod55256.aspx

So when you say I need to bump the shoulder back, do I need to buy a body die like the Redding body die to bump the shoulder back and then resize the neck with something like the Redding S type bushing die separately? Or is it possible/practical to use the RCBS full length sizing die I already have and just screw it down in increments until I have bumped the shoulder back 2 or 3 thousandths? If so what about the expander ball? Use a universal decapper and leave out of the expander ball and see what the neck tension ends up like? Am I correct in assuming that using the FL die to bump the shoulder back that only part of the neck get resized as well?

Obviously I need help haha.

Thanks for any help guys.

John

 

[backwoods83]

From what little I can see of the case web I do not notice any sign of case head expansion. A picture from the side of the brass would be of more help. It looks as though your brass is just slamming into the bolt face, just repeat the process with only a slight shoulder bump and I bet your issue disappears.

 

[Dentite]

From what little I can see of the case web I do not notice any sign of case head expansion. A picture from the side of the brass would be of more help. It looks as though your brass is just slamming into the bolt face, just repeat the process with only a slight shoulder bump and I bet your issue disappears.

Thanks for the info.

What do you think? These are the same cases as pictured above. These cases were FL sized with RCBS full length sizing die and expander ball and fired once.



This is some of the same brass resized and not yet fired:

 

[backwoods83]

They look normal to me. Load and retest.

 

[Dentite]

They look normal to me. Load and retest.

Thanks for the input.