high pressure signs / tell tales

[sauer]

ok the devils spawn ( kids) have me up since 3am ...again

 

so as usual raking thru the site.

 

 

i know i have got some load development to do on the .22-250 ( when i can get a bloody chance )

 

and started to think bout excessive loads an realised i dont know too much bout what to look out for

 

 

know some basic signs ...but better start at the beginning and soak up the info from the far more experienced on here

 

what do you guys keep an eye out for to tell you your on the limit load wise???

 

 

sauer / paul

[Elwood]

Primers are a good indicator, hopefully the picture below copied from accurate shooter shows you what to look for. Sticky bolt lift is another way of telling you that you have reached or gone beyond what is safe.

 

I was also told and read that if you're using a chronograph and your velocity starts to drop with increased loads that this can also be down to high pressure.

 

[baldie]

Primers will crater in any rifle that doesn,t have an ultra close fit between the firing pin and the pin hole. Especially prevalent in remingtons, and other factory rifles. Its something i personally do not put too much importance on. The same with flattened primers. They tell you that you are pretty near, but every one of my rifles/loads flattens its primer. Gas leakage around the edge is another thing, and is next door to piercing the primer, or having it blow out.A definate pressure sign.

Ejector marks or/and shinyness on the case head are a good indicator not to go any further, but the best is a stiff bolt.You should back the load off immediatly if you get this.

Just to throw another spanner in there...you will get two different sets of results with standard primers, and benchrest primers. I use nothing but benchrest primers in everything [apart from the .338 ] because they have a thicker cup, and withstand higher pressures.

Its common sense really. There is no point in owning a ferrari, and driving it like a granny. You want the cartridge running at its most accurate obviously, but a lot of modern cartridges such as the 6.5x47 etc, dont attain that blistering accuracy, until full velocities are reached.

[Andrew]

All that Baldie said.

 

If you have a chronograph, the velocities won't lessen, but the increase noted for each incremental powder increase may lessen. I have experienced this many times myself.

 

The easiest way to avoid high pressure signs is to stay away from maximum loads. I know that every rifle is different but if you have a 22-250 with a SAAMI spec chamber, using a bullet of X-weight, using a charge of Hodgdon's powder gleaned from Hodgdon's data sheet, you can be pretty sure that the maximum load listed is damned close to maximum pressures. There will be nothing that exempts your rifle from the law of physics without some serious study before hand.

 

At the higher end of the charge scale there is little velocity gained. What is gained it wear on the brass, wear on the throat, and most overlooked, wear on the breeching mechanism. Because a hot load worked fine today doesn't mean is won't wreck your gun later. A rifles breeching mechanism is structural. If you stress it too often you can get a catastrophic failure. At the Aberdeen Proving grounds the U.S. Army conducted many tests on this subject using breeching mechanisms from small arms to field pieces and the results were the same. Over stressed breeching mechanisms will eventually let go. The alarming statistic was that identical arms did not let go at exactly the same degree of abuse: Some sooner, others later. Some developed headspace gradually, some just let go.

 

Some of us older hunters might have encountered a shooting or hunting partner that bragged of running hot loads for years that were "perfectly fine" and suddenly one day the rifle shows up with headspace, or blows a case head. The shooter quickly blames the powder maker or anyone else but his own foolishness.

 

I have a Pressure Trace unit that directly measures chamber pressure and barrel pressure curves then transmits the data to a PC for analysis. I used to want to place the PE sensors on every barrel I own but at nearly $90US each (and an extensive battery of rifles) that got pricey. Now I stick to loads that are off of maximum and keep the Pressure Trace for experimental use only. I keep my money, my guns, and my peace of mind.~Andrew