I've been working up a load this summer for my 264 wm with 150 gr matrix. Finally settled on a really nice load. The only issue I have is the load is pretty hot. I'm starting to get a little bit of primer flow. If I back it off .5gr it opens up to about .5 moa. I don't want to eat up brass but it's hard to walk away from this kind of accuracy. I'm open to opinions and suggestions...
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Got a minor dilema...
- Thread starter J300UM
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FearNoWind
Well-Known Member
Your image isn't straight on so it's difficult to determine the scale but when I scale this out as close as I can I come up with about .375 MOA. The difference between that and .5 MOA is pretty minimal and, if you sincerely believe you're pushing the limits of the load, I'd recommend backing it down to where you feel it's within an absolute safe range. I don't know what a "little bit" of primer flow is, but if you're that deep into your pressures you probably exceeded safe max. further back then you realize. I'd try backing it down and working on seating depth. I'll wager you can still get these kinds of results. 
Edges of the primer indentation raised a little. Half a grain lower didn't show anything like that pressure wise. Edges of the primer were still round. That pic is at a bit of an angle. That group is .286. Got the sweet spot on the seating depth already so I'm going to work backwards in charge weight in search of a lower node. Thanks for the reply!Your image isn't straight on so it's difficult to determine the scale but when I scale this out as close as I can I come up with about .375 MOA. The difference between that and .5 MOA is pretty minimal and, if you sincerely believe you're pushing the limits of the load, I'd recommend backing it down to where you feel it's within an absolute safe range. I don't know what a "little bit" of primer flow is, but if you're that deep into your pressures you probably exceeded safe max. further back then you realize. I'd try backing it down and working on seating depth. I'll wager you can still get these kinds of results.
dok7mm
Well-Known Member
Good advice from FearNoWind. You didn't mention your load or shooting conditions, but I agree that you may have to back it off, if you're reading pressure signs correctly. Have you run that load over a chronograph?
My chrony went haywire last week so it's gonna get replaced here real soon. That load was 68 gr of retumbo. Temp was 66 degrees this afternoon and overcast so heat wouldn't have been an issue. I know retumbo can be somewhat "spikey" from past experience but I've never seen that kind of difference over .5 grain. Bolt lift and extraction were still nice and easy as well.
dok7mm
Well-Known Member
You are about 4.0 grs over Hogdon's data for max load for 150 Matrix w/ Retumbo. I know they can be a little conservative, but 4.0 grains is quite a bit high, considering the bearing surface of the bullet you're using. I would definitely back off and start over. Be safe.
I didn't know hogdon listed data for the 150s. I've been running the 140 gr accubond over 69gr retumbo (same keg I'm using right now) for the last few years in this rifle. That was giving me right at 3200 fps which is pretty common for that bullet weight. That bullet actually has a longer bearing surface than the matrix I'm running now. The brass I'm using for that load has 4 firings and the pockets are still good. I always figured a long throated chamber and slow lot of powder were the culprits behind the higher charge for pretty much average velocities. Just don't want you to think I'm running this thing at .1 gr shy of full ******. As of now I'm not over pressure to the point of sticky bolt lift but I know the load I'm at now is gonna be hard on brass. My op was more of a "what would you do" sacrifice brass life for accuracy or seek out a lower node and save the brass.
Rich Coyle
Well-Known Member
How hard is it to get new brass? If you are not swiping brass with the ejector hole, I don't think you are too high in pressure.
J300, nice group. You didn't mention what brand of brass. Perhaps another node can be found with lower charge weight. I'm going to test .264 loads Sunday with Retumbo in Norma brass. Will test some loads with H1000 also. If we don't get a promising load perhaps we'll try the Matrix.
That is a fine looking group, there is certainly a similar node a little lower. Your rifle shoots well.
My 264Win didn't make it to 68.5g of Retumbo with 233g-235g Nosler brass and the 140 Berger hybrid.
Also, in virgin brass the load I worked up to showed no visible sign of problems. I thought I had a real winner, I did not. Upon reloading the same load it was clear I was out of bounds. I have found that virgin brass tends to mask pressure signs that upon a second firing tend to show up.
Good luck! My 264win is my favorite rifle!
My 264Win didn't make it to 68.5g of Retumbo with 233g-235g Nosler brass and the 140 Berger hybrid.
Also, in virgin brass the load I worked up to showed no visible sign of problems. I thought I had a real winner, I did not. Upon reloading the same load it was clear I was out of bounds. I have found that virgin brass tends to mask pressure signs that upon a second firing tend to show up.
Good luck! My 264win is my favorite rifle!
It's mine as well! I've found the same thing with virgin brass. I'm guessing the brass stretching upon firing creates a pressure buffer of sorts. I usually do all my seating depth testing while I'm fire forming my brass to try to keep my round count to a minimum as these barrels certainly don't last forever!
Brass isn't too hard to get. No ejector marks or swiped brass showing up.
eshorebwhntr
Well-Known Member
Primer cratering in and of itself isn't always an over pressure sign. Soft primer cups and a firing pin hole that is too large can also be the culprit. If the bolt lift is ok and not sticky and you're not toasting your primer pockets in 1-2 firings you're probably ok.
Good luck and stay safe.
Good luck and stay safe.
I use Newberry's method for determining optimum charge weight and it has been my experience I get a low charge accuracy node and a high charge accuracy node for all my rifles. I've always opted for the higher powder charge and never had any problems but it stands to reason you may have a second accuracy node at a lesser charge. I would not arbitrarily lower the charge without testing for another accuracy node.
