Overpressure signs

[randyman]

Does anyone have photos of what a primer or case looks like when you're approaching max loads? I've been staying within the printed SAAMI load range but I often hear folks loading till they see signs of overpressure. What does that look like? Thanks, Randy.

[Bill K]

Randy: I don't have a photo of what it can look like, but many of the good loading manual/books have photo's of what to watch for in the front portions of them. If someone does not come back with some photos on the thread, you might look at a couple of those manual/books. Bill K ( by the way received your PM)

[Rick in Oregon]

Randy, don't have photos, but primer flattening is not the only sign of high pressure.

But if your primers are flat with no radius on the edges, or if you see primer material being extruded into the firing pin recess, your pressures are much too high. Another sign is a reverse image imprinted on the primer from the bolt face in high relief.

If you keep your loads under book max, there really should not be any over pressure issues. Keep in mind that accuracy should always supersede speed.

[randyman]

Thanks Bill and Rick. I'm also doing some loads for the 20VT and am relying on powder charges that others have used. I know the general rule of starting low and building up but with some of my powders I'm not sure how far to go with them. I've used RL7, Accurate 2200 and IMR 4198. So far haven't exceeded 18 grains of any and don't see any signs of over pressure yet. I've found with my .204 that it doesn't like charges in the high end of the scale but prefers low to mid charges of powder. No squirrels to shoot this time of the year so I'm loading bullets and getting ready for spring. Randy.

[Bill K]

Randy: If you go to Accurate Shooter, and along the left edge of the page a listing of calibers is shown. Click on the 20 cal and you will find the 20 VT listed, along with some load data. Maybe that will aid you in load information. I pretty well stick with AA2200 in my 20 SCC and my accurate load is 20.3 grain, with the 32/34 grain bullets. You will want to start around 19.0 grains and work up in your standard VT. Just some thought/info. Bill K ( I bet Rick will offer some sage advice also on load areas in the VT, as he shoots that caliber often )

[terrace]

Picture of a picture

[randyman]

Thanks, that's what I was looking for. So far I'm not see anything like #3. Randy.

[jimreed1948]

Notice how flat the primer is and the ring around the indentation where the primer is struck. The blowout you see on the primer is where it struck the ejector. I had several blowouts that day with different loads. All in the exact same place.

If you go to this link: http://www.saubier.com/forum/showthread.php?t=34990 you'll see some of the hot loads I had.

While your over there, you'll finds lots of load data on the 20 VT.

[randyman]

Thanks Jim. I read all 3 pages on saubier and am wondering if you've heard back from Cooper yet on the status of the rifle? It sounds like you got a lot of good advice and hopefully have identified the problem. I recently was loading a hundred rounds with 2200 and .2 grain differences in powder. About half way thru I thought I'd check to see how close my lead-free bullets actually were to the 32 grains they were suppose to be. I was really surprised to see how much they varied. I emailed the place where I got them and was told a +/- .7 was normal! I had as much as 1.9 gr difference in the same batch of 100 bullets. Now I'm contemplating pulling all the bullets in the batch of 100 that I loaded so I can sort them for weight. I also checked base to ogive and found a wide variance there also. I'm pretty sure the rounds I've loaded in the past looking for what shoots best in my rifle has all been for naught due to inconsistent bullet weight and seating depths. Starting over is probably best. Randy.

[jimreed1948]

Thanks Jim. I read all 3 pages on saubier and am wondering if you've heard back from Cooper yet on the status of the rifle? It sounds like you got a lot of good advice and hopefully have identified the problem. Starting over is probably best. Randy.

I know the headspace was off and there was an issue with the ejector. I couldn't understand the high pressure signs I was seeing even though I new the headspacing was off, it wasn't by much. I looked at my scale and zeroed it. When the frame was perfectly balanced, the beam would not zero out. I found that I was throwing 19.5 grains of powder instead of 18.5 grains. I fixed the zero problem and then I borrowed a set of certified weights. Scale is now in good shape.

Will start over when rifle is returned. Haven't heard back from Cooper yet.

[skipper]

Let me add a little to this discussion, please. Wherever possible during load development, use a chronograph and keep detailed records of the speed vs. powder charge ratio. There should be a corresponding increase in speed relative to the increase in powder charge. Now it's not exactly a linear scale so there are some more advanced calculations necessary. I'm not going to attempt to explain all the variables. I DON"T want the responsibility for your own safety. With that said, while working your way up the ladder, make note of the increase in velocity per increase in powder charge. Whenever you are adding more powder and not gaining the same increase in velocity, you have probably already past safe limits for that particular rifle.

There are plenty of articles about bullet energy and other related topics. Please, do the research AND BE CAREFUL. We want you to stay around for a while. Every rifle is different and published minimums and maximums are generally within a conservative safety margin that the corporation's legal department can defend in a lawsuit. There are also considerations about slower burning powders in gas operated rifles, etc., etc., etc.

I just know I'm going to get flamed on this one.

[jsh]

Not flaming at all. I agree mostly with the statement.
When you quit seeing a speed gain with an increase in powders, to me means you have topped out with the combo. Not always a pressure top end.

The only rags I read anymore are Handloader and Rifle. There have been articles in both going over pressures. Looking at bolt lift, primer issues and swelling at the web have pretty much been proven not to be an absolute. When any of those signs show we are already wayyy over more times than not.

Something I see touched on very little is slow powders. They are not always a safe bet when starting low. To much air space/not enough pressure will show false high pressure signs. Basically doesn't let the brass do its job sealing and grabbing the chamber.

I have seen at the range guys that have reloads and say they are over pressure, but mid range in the book. Some times a load I use. Problem is excess lube on brass or a chamber with oil or solvent in it.

[MZ5]

Here's a good string on so-called pressure signs (including how useless they are; to be used only if one has absolutely nothing else):

https://www.shootersforum.com/handloadi ... signs.html