338 Edge Pressure Signs

[smrkovsky]

I have a question for all you Edge guys. I finally finished my Edge build, and am very excited about the potential of this weapon. I have begun my normal barrel break-in routine of 1 shot clean, 1 shot, clean for about 20 rounds, and then 3 shots, clean for another 15 rounds. I'm using Rem 300 UM brass, Federal mag primers, 92 grns of H-1000 with the 300 SMK. COAL 3.77, which is all my Wyatt's box mag will hold. The problem is, about every 5 or 6 shots, I completely flatten a primer and crack a case. What's the deal with that? From scanning this site, religiously, I concluded that 92 grns of H-1000 should be fine with the 300 SMK, but it seems to be "too hot" for my rig. Maybe I have a defective batch of brass. Do any of you guys have any suggestions?

Thanks in advance.

Smrkovsky

 

[AJ Peacock]

What is your velocity? I know that Dogdinger's Edge shoots faster than mine and will get a sticky bolt lift before mine will. I'd definitely run it over a Chrony and see what is happening. Probably back off a grain as well until I got it figured out. AJ

 

[6.5x300]

Where is the crack? Neck I assume? Did you anneal the necks before sizing up and after? What did you use to size up with? First I have heard of this as I shoot the standard load as well from both 300 and 375 RUM brass. For sure shoot over a crony. I would hope a solution will present it's self to you.

Good luck should be a sweet shooting gun.

 

[smrkovsky]

The crack is approx 1/2" above the base of the case, almost all the way around. Going off memory, the load chronographed around 2800-2825 fps.

 

[AJ Peacock]

The crack is approx 1/2" above the base of the case, almost all the way around. Going off memory, the load chronographed around 2800-2825 fps.

That is a bit faster than either of the Edge's I've worked with are chrono'ing for the same load. Our longest barrel is 28". If you have a 30" barrel, that speed is right in there for the load. In my opinion, you are on the hot end for your rifle. My rifle runs 2750 with that load in a 28" barrel. Is this new brass, has it been fired in a 300Rum before you necked it up?

AJ

 

[Down Under Hunter]

That load is the same I use in my 30 " barrel at 2834. The load looks hot on paper to me for the shorter barrel ? What variation spread are you getting on average from round to round ? You may be getting an odd hot one that is causing the grief if you are not in single figure or low teen fps spread ?

Other than whats already been said, I ain't got no more ideas !

DUH

 

[6.5x300]

I'm stumped. It is the same load I use out of 30" Pac-Nor=2890 fps for me and have not noticed any pressure. Is the brass new? If it is not the brass and your loads are correct I would have it checked out by whoever built the riffle or a knowledgeble smith.

 

[smrkovsky]

The brass is brand new. It will be going along good, under .75 moa, for 4 or 5 shots, and then I will get a flyer. Open the bolt to see a completely flattened primer and a cracked case, whereas, the other 4-5 pieces look great. I guess I will have to back off a grain or so and see what happens. The action was barreled by Hart, so I'm confident they did an excellent job. I'll give them a call to see if they have any advice.

Thanks to all of you for your input.

 

[AJ Peacock]

The brass is brand new. It will be going along good, under .75 moa, for 4 or 5 shots, and then I will get a flyer. Open the bolt to see a completely flattened primer and a cracked case, whereas, the other 4-5 pieces look great. I guess I will have to back off a grain or so and see what happens. The action was barreled by Hart, so I'm confident they did an excellent job. I'll give them a call to see if they have any advice.

Thanks to all of you for your input.

You might be closer to the lands than you think and are getting one that is nearly touching and causing the pressure spike.

I'd find out how much jump I was getting. It may be as simple as seating .005"
deeper to get out of that zone.

AJ

 

[groper]

during your reloading, is there any chance your dumping more powder into the odd case that ends up splitting? how are you measuring your powder? i know some of the electronic scales can be out by quite alot between loads despite paying good money for them... i doubt any other reason could casue this besides alot more powder or different type of powder, in the cases that split/sticky bolt and flattened pirmer...

 

[300rum]

Dear smrkovsky;

I shoot 30in Barell 1-9.4 twis Rock Crick with muzzle brake DE style with
Rem Brass,
CCI 250M primers
300SMK
92gr H1000 (93.5 very hot load)
3.75 OAL
0.07 off the land
2815fps

As AJ sad, you are too close to the land, and some ogives touching the land.
Be aware not all round are the same lenght. Some are shorter other are longer (I think this are the one with cracked cases)
Take 2 empty cases and reload 2 dummy roands:
1 with shorter ogives and one with longer ogive.
take a marker and cover completely the ogive with it.
Insert the dummy case in action and close the bolt.
Extract the bolt and see if you have land marks on the ogive.
If you see the marks on the case with longer ogive you are touching the land my friend.
back off till you barelly see marks on ogive(this is the lenght of your case without touching the land) and from there back off 0.010 and you will be fine.

 

[orwapitihunter]

I see this is somewhat of an old post but if you haven't figured out your problem, I think you have too much headspace. The crack you are seeing is a partial case head seperation. If the chamber is set up correctly then you are pushing the shoulder back when you are resizing your cases. When you do that the cartridge is moved forward by the fireing pin strike. The primer ignites, the pressure builds and the thin/soft front portion of the case grips the chamber wall. As pressure continues to build the primer is pushed back out of the primer pocket, and the rear of the case is slammed back into the bolt face. This streches the case infront of the thicker web and flattens the primer. If the case streches too much it seperates.

 

[Michael Eichele]

I see this is somewhat of an old post but if you haven't figured out your problem, I think you have too much headspace. The crack you are seeing is a partial case head seperation. If the chamber is set up correctly then you are pushing the shoulder back when you are resizing your cases. When you do that the cartridge is moved forward by the fireing pin strike. The primer ignites, the pressure builds and the thin/soft front portion of the case grips the chamber wall. As pressure continues to build the primer is pushed back out of the primer pocket, and the rear of the case is slammed back into the bolt face. This streches the case infront of the thicker web and flattens the primer. If the case streches too much it seperates.

Thats what I was thinking. Either a chamber is too long or the shoulder is getting bumped too much. I have had this problem before in one of my 300 RUM barrels.

Also as stated before, DO NOT underestimate the value of a chrony. You will not know what the problem is until you know the velocity. It is either the rifle or the load. Possibly both but you wont know until you verify the velocity.

AJ stated that he was runninig 2750 in a 28" barrel and that is within 2 FPS of where I am at. Most 30" barrel users are running 2820-2850. A few are getting a bit more. That gives you an idea of where your velocity should be. Also there have been some hot lots of H1000 out there recently.

 

[far east]

hi, with 338E ,i'am using vitha 24n41 , 94.5grs, with 300grs lapua in archer border barrel,30". no pressure signs , v= 2722fps. very good precision about 1800meters.