Flattened Primers

[tweek1142]

I recently bought a new Remington 700 SPS SS in 300 WSM. I'm using Winchester brass and Nosler 150's.

with the following loads i'm getting flattened primers

IMR 4350 63.5gr = flattened primer
RL 17 64gr = flattened primer
IMR 4064 58.5gr = flattened primers

OAL = 2.835 Ogive Length = 2.207
Primers = WRLM

these loads aren't hot by my book. I have checked the head spacing and its good. The brass was all new winchester brass.

any help would be great.

thanks

 

[Trickymissfit]

I recently bought a new Remington 700 SPS SS in 300 WSM. I'm using Winchester brass and Nosler 150's.

with the following loads i'm getting flattened primers

IMR 4350 63.5gr = flattened primer
RL 17 64gr = flattened primer
IMR 4064 58.5gr = flattened primers

OAL = 2.835 Ogive Length = 2.207
Primers = WRLM

these loads aren't hot by my book. I have checked the head spacing and its good. The brass was all new winchester brass.

any help would be great.

thanks

that's a big fat case, and you might want to see if another grain and a half of powder helps (4350) with a mag primer. Sometimes too light of a load will build up excessive pressures. I'd have started with AA 4350 as it's slightly faster than the IMR, but Magpro would have been my starting point.
gary

 

[boomtube]

"I have checked the head spacing and its good. "

What "head spacing" did you check, pre-fired cases vs. post-fired cases or chamber?

 

[tweek1142]

I took the rifle to Hart's in Nescopeck Pa. They told me that my head spacing was .004 longer and said that it passed the "field Gauge"

 

[boomtube]

Chamber (real headspace) is pretty much irrelivant to a good hand loader, we make our sized cases fit our chamber.

What you have is excess case headspace for your ammo, meaning you're setting the shoulders back much too far, allowing primers to back way out and then get flattened as the case head flows back to the bolt face. That excessive case stretching will soon cause you a head seperation if you don't correct it.

A turn of a die changes its position right at .072". Back your sizer up maybe a half turn (31 thou) and size a case, then see if it will chamber smoothly; probably won't. Turn the die down about 16th turn (4 1/2 thou) and try again, keep repeating that until you can close the bolt with just a touch of drag on the empty case. Size the rest of your cases and try your loads again, the primers will proably be fine.

 

[tweek1142]

So I'm going to be partial sizing correct? I started to do this and the case that fit the best without doing a full length size had a little bump on the side of the case neck right below the line where the neck was being resized. Is this ok to use? Because the closer I get to where the base of the neck and the shoulder meet the harder it gets to close the bolt so I ended up full length sizing which put me back to square one lol

Thanks for the help in advance

 

[Truc]

all that means is you are not sizing the entire neck, no problem with that, when adjusting your die, remove the firing pin so you can feel the case as you close the bolt just ever so slightly or another words, don't let the bolt fall down on its own
​

 

[tweek1142]

Do I have to resize the entire neck? Or should I just buy a neck sizing die to make things easier and less confusing

 

[mrultramag]

I have a rem 700 in 257 bee. It shows cratered primers no matter what the load... poor firing pin fit dimensions by Rem... I learned to ignore it. I use a chronograph so I know when I'm up to snuff in velocity... But I don't push it... There's no free lunch.

 

[tweek1142]

I don't have cratered primers they are ust flattened. I think I'm going to pick up a neck sizing die. This way the shoulder won't get resized

 

[Fire306]

I used to get the flattened primers all the time, same as you, no craters just flattened.
I just accepted it, I had no other pressure signs at all. If accuracy was good, I used the load. I switched to neck sizing dies, and honestly couldn't see any improvements in accuracy or the primer issue.
I then heard a target shooter talking about reloading, and he spoke about neck sizing, should/can only be done 1-2 times before full length resizing, because as the brass flows to the shoulder area, neck sizing only will start to allow the shoulder to require jamming on bolt closure. This causes inconsistent neck tensions and hurts accuracy. Something I had noticed, after a few loadings the groups would start to open up.
So I searched online for a Headspace Gauge, that could be used for multiple calibers, and found this one.
w ww.larrywillis.com/
I couldn't be happier with the gauge, you simply measure the shoulder of a fired case, and adjust your full length die until you are bumping the shoulder back the desired amount. (.001")
This insures you are sizing your brass to your chamber.

Improper head spacing the way I understand anyways allows the case to move forward to contact at the shoulder when the firing pin strikes, then there is room between the case and the bolt face, which as the powder ignites the primer actually pushes out of the case to contact the bolt face before the brass stretches to take up the gap, which crushed the primer. This is one of the causes of flat primers, even without too much pressure.

 

[Trickymissfit]

read the thread again, and there's some interesting points being made. Over the years I have seen two rifles that came from the factory with a "dish" in the bolt head. Not much, but three or four thousandths dish in them. Being as the original poster has taken his rifle to someone that knows his business (Hart), we have to assume that the chamber is to spec because they said it was. That brings us back to square one again.

Normally a flattened primer is a sign of a few things happening after initial ignition of the primer:
1. Excessive pressures
2. loose primer pockets
3. with reference to excessive pressures, has the loader actually did an accurate inspection of the cases after firing? Could the grip on the bullet be excessively tight? Maybe one hell of a doughnut in the base of the neck? Or maybe the neck has expanded to the point that it is less than .0025" smaller than the chamber neck?

I have seen the wrong powder dumped in a bottle from the factory a couple times, but this is very rare and was easilly noticeable in the cases I saw. His loads are far enough down the load scale that even his measurer would still be in a safe range, so I think we can forget that as well.

Is it possible that the throat is so contaminated that it's causing a pressure spike? Is the chamber actually inline with the bore and also concentric with the bore. (I have seen this more than once)

Try this check:
lay a strip of masking tape along the barrel lengthwise. Run a very tight patch (lubed) thru the barrel with a good quality jag (I prefer Proshot). Mark on the tape the locations of the tight spots and where it loosens up. If you happen to start out with a very tight place in the area just after the throat you may have a problem. I have seen burrs left from reaming the chambers here, and that will cause an excessive pressure spike. You can take the further by "slugging" the barrel.
gary

 

[tweek1142]

If the chamber was not in line wouldn't i see this effect accuracy? As of now I get 1.75 - 2 inch groups at 200 yards. And this is without really tweaking my loads. I shot a couple loads with 67 grains of IMr 4350 which is at the higher end of load and I still got flat primers as expected. I was also expecting heavy bolt lift which I did not. So do I dare to just except the flat primers and have fun shooting?

 

[Trickymissfit]

If the chamber was not in line wouldn't i see this effect accuracy? As of now I get 1.75 - 2 inch groups at 200 yards. And this is without really tweaking my loads. I shot a couple loads with 67 grains of IMr 4350 which is at the higher end of load and I still got flat primers as expected. I was also expecting heavy bolt lift which I did not. So do I dare to just except the flat primers and have fun shooting?

with 2" groups at 200 yards, I'd guess your chamber is strait. Have you measured the primer pockets?
gary