High Pressure, what signs to look for?

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schlaggerman

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Just test fired some reloads, 27grs. of W748 behind a 55gr. Hornady spire point. I had no signs of high pressure; no primer cratering, no split necks, no extraction problems. According to manuals this should be a very hot load. Are there other high pressure signs I should be looking for?
 
Unfortunately, not every load will give obvious pressure signs. Some folks try measuring the web expansion, but even this can be tricky. The other thing to remember is that 27grains of WW748 may be quite safe in the winter time, but what about those 95 degree summer days?
John
 
I've been loading 26.5 gr. with a 55 gr. Speer bullet for years and it's not a hot load in any of my rifles (it's actually the min load in the #11 manual). I'm using a CCI mag. primer with it, and it's fine on hot days.

Some of the manuals are a lot more "conservative" than others. You should run some across a chrony and see what you're getting.

In my Hornady 3rd edition, 55 gr. spire point with W748 shows a min load at 23.0 gr. (2800 fps) and a max. load at 27.7 gr. (3300 fps).

That was in a 24" 1:12 test barrel with a Rem. 7 1/2 primer.

Speer lists 26.5 gr. (2913 fps) to 28.5 gr. (3126 fps) of W748 for all 3 of their 55 gr. bullets, using a #450 mag. primer out of an 18 1/2" Mini 14 barrel.

That seems more realistic, based on what I'm seeing.

Of course, the two bullets are not the same, but I have real doubts thats' going to make a huge difference in pressures. If you take a set of cases and run that load 3 or 4 times without the primer pockets getting loose, you're not near max pressure. Just creep it up slow until you find the best accuracy and quit. You may already be beyond that point right now, but ladder test .2 and .4 gr. lower and higher (while watching for pressure signs) and see. 27 gr. ain't going to hurt your rifle, so relax.
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Originally Posted By: Evil_Lurker
Some of the manuals are a lot more "conservative" than others. You should run some across a chrony and see what you're getting.



Amen.

27.8 grains is max in my Lyman 49th.
 
Sorry to take so long to finish my post. Fall of 05 we did some pressure testing with WW748 in the .223. This was in preparation for an article that came out in Precision Shooting (J. Buchanan and J. Riley "A Viscoelastic Approach to Pressure..". We were trying to find a way to quantify temperature sensitivity, we were not successful and had to leave that part out. nevertheless, WW748 was one of those powders that showed extreme sensitivity. It was right up there with H-414 and the VV 500 series. My comment is this; if there were a powder I was going to run hot, this is not it.
John
 
Quote:My comment is this; if there were a powder I was going to run hot, this is not it.


Okay, point taken. Thanks, that's valuable info to know. I do my development in the summer for that very reason, but since I hunt in colder weather, I'd be losing velocity and that's not a good formula for accuracy.
Back to IMR 4895 I guess.
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When primer pockets start to get squishy... you better back off. Other than that... it's pretty tough to tell what's going on from an internall pressure stand point. I usually let the chronograph and primer pockets decide what's safe and what's not.

If velocity is high... typically, you don't have a "fast barrel"... you have more pressure. If you don't make it to a projected velocity (that you think is reasonable) before you start to lose brass to loose primer pockets... then switch powders.

For the .223 I'd look at Benchmark or something like that for a little more temp stability. RE12 and RE15 have been good to me too.

Originally Posted By: Evil_LurkerSome of the manuals are a lot more "conservative" than others.

Oh... and Dude... "Conservitave" is not the prefered nomenclature... "safe", please.

 
Quote:""safe", please."

According to all the manuals I have, all the "max" loads are considered safe. "These data do not exceed the SAAMI pressure maximum of 52000 cup for ths cartridge" kinda implies that.

"Conservative" is an accurate description, I'd say.
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Thanks for the info on the primer pockets guys. Also very good info about the sensitivity to temperature of W748. I think I will back down my load to 26.7gr. until more testing can be done in the warm months, unfortunately that's a long way off here in northern Wisconsin. When spring arrives I will also give a few other powders a try. I was strongly considering Varget,I have that powder on hand as I use it for another caliber I reload for. Any thoughts on Varget and the .223?
 
Originally Posted By: Evil_Lurker Quote:""safe", please."

According to all the manuals I have, all the "max" loads are considered safe. "These data do not exceed the SAAMI pressure maximum of 52000 cup for ths cartridge" kinda implies that.

"Conservative" is an accurate description, I'd say.
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For the most part, I agree with you (well, don't know about that "conservative" thing
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) The problem arises when some one has a chamber with max head space, short freebore, or possibly they are bumping the shoulder a bit too much or even their scale is off a couple tenths. Of course my favorite one of all, speaking from experience (wound up short on ammo on a nice PD shoot) the ever changing powder lot numbers. All of these things, or possibly these things combined can make for a lousy day in field. This is why all the manuals say (most of the time) not to start at max; start low and work up.

John
 
Quote:This is why all the manuals say (most of the time) not to start at max; start low and work up.


I agree. I've never heard of anyone blowing an action apart using a load from the manual, though. There's a fair amount of "safety factor" built into the SAAMI specs, and the loading manuals add some more by keeping the loads under the SAAMI specs.

Starting right off at their max. data isn't a bright way to approach reloading, though. I'd never recommend that.
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"High pressure,what other signs to look for".....
having the floorplate bulged or blown off would be a sign...(grin)...we are fortunate that the gun manuf's build such stout firearms...but keep in mind if you change ANY component of your load,back down a grain or two & work ur way back up a half a grain at a time....especially if you change case manuf...a diff in case capacity or bullet seating depth can play [beeep] with pressure curves...also,a change in powder lot#...if ya buy one pounders & buy 2 or 3 - select ones with same lot #.
 
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