Is this cratering I should worry about?

[targetterror]

I loaded up some 7mm 162gr Amax bullets and noticed a slight rim/crater on the higher charge. The gun is a 7mm-08 Stevens 200, stock sporter weight barrel. The load was a 308 Lake City surplus case sized down to 7mm (and trimmed appropriately), CCI 200 primer, and IMR 4064 at 38.0 grains and 39.0 grains, seated to 2.925" (about .025" off the lands), which fits in the magazine fine. The photos below are representative of the other rounds I loaded (3 at 38.0 grains, about 15 at 39.0 grains).

Conditions were cold - about 20 degrees F. I experienced no difficult bolt lift or extraction. The 39.0 grain load is a hammer, doing 1 MOA or better at 200 yards. I'd like to keep it if it is not putting me into any dangerous pressure areas.


Here is the 38.0 grain charge. Everything looks fine to my eye

Here is the 39.0 grain charge. You can see a very small crater/rim right around the firing pin indent. It feels almost like a burr, and will catch my finger nail if I run it over it. It is very slight, however.

Here are the above 2 rounds, as well as a round on the right loaded with a 120gr Nosler BT, same case, with 43.0 grains of Reloader 15, seated to 2.850 inches. It has a very slight rim/burr, but small enough that I had not paid it any heed.

Any ideas? Hodgdon's list a max load of IMR 4064 as 39.5 grains, though with a COL of 2.875". I know that the Lake City is military brass with reduced internal dimensions, but I would think that would be offset at least somewhat by loading the bullet out farther. Also, I would have expected the primer to flatten significantly more if there was a high pressure issue. But, I don't really know, that's why I'm asking!

Thanks in advance.

 

[flashhole]

Re: Is this cratering I should worry about?

You are not near excessive pressure with those loads. I look for flattening of the primers long before I look for cratering around the firing pin. Your fired loads have the same round shoulder on the primer as before you fired them. You are not too hot. If you are getting good accuracy call it quits.

 

[targetterror]

Re: Is this cratering I should worry about?

Thanks, that is very reassuring. Any idea why I am getting that ridge?

 

[vman]

Re: Is this cratering I should worry about?

Those primers are normal and within normal pressure levels

 

[SnkBit]

Re: Is this cratering I should worry about?

How are you getting pictures that good? You must have a much nicer camera than I do or you have a lot more skill.

 

[M855]

Re: Is this cratering I should worry about?

Win primers are a little soft,rems are not alot better, the wolf/tula primers seem to not crater as bad,I just picked up the same rifle and shot 130gr boatails I used varget,imr4064 and imr 8208xbr,the 8208xbr was the best shooting load ymmv

 

[former naval person]

Re: Is this cratering I should worry about?

You also have two different year lots on those cases...04 and 07. Try weighing them empty then fill with H2O and see what difference you have in water capacity.

 

[targetterror]

Re: Is this cratering I should worry about?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">You also have two different year lots on those cases...04 and 07. Try weighing them empty then fill with H2O and see what difference you have in water capacity.</div></div>

I purchased the brass as once fired, and have been using it without sorting it. So, I imagine I have a more or less even distribution of years between the test groups. I'm sure there is a difference, but it hasn't been enough for me to notice in practical terms.

 

[targetterror]

Re: Is this cratering I should worry about?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: M855</div><div class="ubbcode-body">Win primers are a little soft,rems are not alot better, the wolf/tula primers seem to not crater as bad,I just picked up the same rifle and shot 130gr boatails I used varget,imr4064 and imr 8208xbr,the 8208xbr was the best shooting load ymmv</div></div>

Interesting. I tried some Reloader 17 and the accuracy was not very good. What sort of velocity are you getting with the 8208? I haven't chronoed these loads yet, but I'm hoping the IMR 4064 is around 2550-2600.

 

[targetterror]

Re: Is this cratering I should worry about?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SnkBit</div><div class="ubbcode-body">How are you getting pictures that good? You must have a much nicer camera than I do or you have a lot more skill.</div></div>

While I won't say I <span style="font-style: italic">don't </span>have more skill

, there is only so much you can do with macro photography without special equipment. I'm using a Nikon D200 with a flash and (most importantly) extension rings. These are literally just rings of metal that position your lens farther away from the camera body, which allows you to focus closer. I got the rings on ebay for under $10 shipped. The lens was just a Nikon 50mm AF 1.8.

Depth of field is absurdly narrow, so you focus moving the whole camera in and out and hope you nail it!

That said, lots of point and shoots have good macro modes these days, though I don't know how they would compare to I used.

 

[fish30114]

Re: Is this cratering I should worry about?

First of all, I would not say that is normal, but I would also say I would be comfortable with that load. Cratering CAN be and often is a sign of high pressure, but many knowledgeable folks (like Hornady) point to cratering most often being a GUN issue, not a pressure issue. Your firing pin strikes are consistently off center, I don't think it's a big issue, but if your are looking for gilded edge accuracy, I would be looking at having my firing pin bushed, and a new spring installed, and checking firing pin protrusion--having it checked for me

I'm not talented enough to be comfortable checking that myself LOL

I would probably leave it alone if it is shooting good enough to satisfy you, and I wouldn't worry about sorting that brass if it is shooting good enough either--BUT--if you are looking for every little bit, I'd do the previous mentioned on the bolt, and sort the brass!

Lastly, as others mentioned--DAMN those are great pics! I need the photography for dummies and limited budget intel. The one nice camera I had just got jacked from my Land Cruiser, along with my briefcase, my laptop and two pairs of sunglasses--that sucked enough, but the window and damage to the door ran $2360
at least insurance covered that! I don't know if it was capable of pictures approaching that, but it was a $399 Nikon digital from Best Buy--I'd be interested to know if a camera of that caliber is capable of pictures approaching those....

Good luck with your rig, and sorry to ramble off about the camera thing!

 

[crumpmd]

Re: Is this cratering I should worry about?

Those primers are fine. That load is safe and like everyone else has said, go shoot it. If I were looking at them for you I would just make sure the bullet was off the lands a couple thousandths.(never hurts to double check)

 

[M855]

Re: Is this cratering I should worry about?

TT,I didnt chrno the loads,this is a $179(Academy Sports) beater,woods,hunting/200yard rifle at 100 yards all shots are touching I call it moa of deer or hog

 

[fish30114]

Re: Is this cratering I should worry about?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: M855</div><div class="ubbcode-body">TT,I didnt chrno the loads,this is a $179(Academy Sports) beater,woods,hunting/200yard rifle at 100 yards all shots are touching I call it moa of deer or hog </div></div>

MOA of deer or hog, MY FOOT,--'at 100 yards all shots touching' is damn near bench rest caliber--good shooting!