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Pressure signs

FamilyMan

Sergeant
Full Member
Minuteman
Aug 3, 2011
720
0
Utah
Does anybody have any pictures they can post that shows a flattened primer and ejector swipe? i just started my first load development yesterday and because of time and inexperience i only made it through 1 string of 10 in H4350 for 95SMK .243. as i got to the max loads and max+ loads i couldn't tell that big of a difference in the primers just a little but when I got home and examined them a little closer i saw what i think is ejector swipe but i still can't tell very well between a flattened, cratered primer and a regular primer very well i even compared them to some factory loads. So if you have a couple pics of to show me "when i i see this...." you hit your pressure max. i would appreciate it. i will post pics of mine when icanget a camera to take a clear photo mine are all blury

Basic info
REM 700 .243 26" factory 1:9.125
winchester brass
CCI BR primer
H4350 Min 39g Max+43.5
70* Baro30.18 alt6500
 
Re: Pressure signs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: aloreman</div><div class="ubbcode-body">Primers mean shit</div></div> just read you second post how do i measure case head expansion and at what point is it too much?
 
Re: Pressure signs

here cheif

overpressure.jpg



pressuresigns.gif
 
Re: Pressure signs

Measure the case just ahead of the extractor groove. Measure first an unfired case and then the fired case. As you get close to max, you'll see the measurement grow. When you get to .001 increase, stop. The case will stop growing at that pressure. If you keep increasing the pressure, the case will keep growing until primers fall out.
 
Re: Pressure signs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: aloreman</div><div class="ubbcode-body">Most flattened primers are caused by excessive head space</div></div> Whats the likely hood of excessive head space on brand new brass right out the bag(Winchester). To me it would seem to be more likely, due to it needing to be sized to fit in all chambers.If that is true should all brass be fire formed?
 
Re: Pressure signs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">Note that none of Mallard's overpressure cases have primers with sharp corners.</div></div>
What do you mean sharp corners?
 
Re: Pressure signs

So these are the best pics i could come up with
IMG_1314.jpg

These are the lower three 39.5g, 40g, 40.5g,
IMG_1311.jpg

41g,41.5,42g max, 42.5max+
IMG_1309.jpg

42.5g max+, 43g max+, 43.5g max+

based on these where would you guys have stopped and felt you reached your max?
This was the results from the ladder test. i don't know if i can trust the 42,42.5 and the 43,43.5 groups because both of them i felt i pulled the lower weight shots up as broke it and probably pushed them closer together then they should be
Tested @ 300yds
IMG_1304.jpg

 
Re: Pressure signs

FamilyMan...not all chambers nor all brass fits together. I have a .35 Whelen Rifle and some Remington .35 Whelen brass that aren't compatible. I have to Neck Up to .40 caliber and size down for a false shoulder in order to avoid misfires. Excess headspace for a rifle and new brass? Happens. You have to learn how to deal with it.
 
Re: Pressure signs

If your chamber is cut to max sammi length and your brass comes sized to min sammi length the you could have a pile of excess headspace. After firing all of your new brass set your dies up to just bump the shoulder back .001 to .002.
 
Re: Pressure signs

Nothing your showing there has any pressure issues that I see. Keep on keeping on.
 
Re: Pressure signs

6mm and 6.5mm tend to produce primer craters at low pressure. Especially in rem actions. Something to factor into your decision making.
 
Re: Pressure signs

From what I was told by a knowledgable guy at the range is that while primer and ejector marks can hint at pressure, it is not a reliable indicator because all guns are different. He said the only realiable measure is what the other posters mentioned, Case head expansion. For example my 338 lapua doesn't flatten primers but leaves heavy extractor marks on all of my loads, starting from low to high (and factor loads). You can many times feel a bulge need the case head if you run your fingernail over the area. One you have a bulge, you have pressure.

That's what i was taught atleast.
 
Re: Pressure signs

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MALLARD</div><div class="ubbcode-body">6mm and 6.5mm tend to produce primer craters at low pressure. Especially in rem actions. Something to factor into your decision making.</div></div> That is really good info to know
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">Measure the case just ahead of the extractor groove. Measure first an unfired case and then the fired case. As you get close to max, you'll see the measurement grow. When you get to .001 increase, stop. The case will stop growing at that pressure. If you keep increasing the pressure, the case will keep growing until primers fall out.</div></div> I went back and measured the case head and no real signs of pressure. Thanks for all the feedback I feel alot more confident going forward with the rest of my loads. One last question is when you use case head exspansion as your indicator do you measure each case after it is fired as you work up the ladder or only on ones that start to show other signs first?