Home Forums Reloading Big Game Rifles Blew my first primer today.

I hope i never do that ever again. So i was trying to find max charge with imr 7828 100 grain partitions .010 jammed .5 grain increments started at 42 grains made it to book max no problems. 46 grains is.5 grains over max still had no pressure signs at all, this was Federal brass. 46.5 grains Pow. this scared the FLAWK out of me.Any way i am going to go with book max and do .005 off lands and 0.10 off tomorrow. So flame away what did i do wrong.

Yeah, everybody knows it's the lawyers that come up with the book max.

IF YOU'RE GOING TO JAM THE LANDS AND KEEP ADDING POWDER...you're going to blow a primer. powdr

NVhntr I take 100 percent full responsibility for my own actions.

I saw it here some were on the fire that you can not always rely on visual pressure signs. this qualifies there was absolutely no visual pressure signs before the primer blew.

What gun? Chamber?

243 win vanguard S2

The blown primer was a very good high pressure sign. P.O. Ackley told me something like, "Run it up till you blow a primer and back off a grain and there you are." One of my friends sorta does it that way. He doesn't reload. He gets one firing from new brass because the primer pocket won't hold a primer after that.

Actually you should never rely on visual pressure signs, if you have them you are way into the danger zone already. Glad you weren't hurt.

You didn't post any speeds. I think a chrony is a required tool if your gonna lean on things. Speed is a pressure sign! Even that ain't foolproof I'm told....

A penguin was driving across the country when he had engine trouble. He coasted into a small town filling station and left his car with the mechanic. He set out to explore the town. He stopped in at the local malt shop and then headed back to the garage. The mechanic was coming out from beneath the car just as he arrived and said, "Looks like you blew a seal." The penguin wiped his face with his wing and said, "No, I just had an ice cream cone."

Skate on thin ice and sooner or later you will fall through it.

You get used to it after a while.

Congrats on popping your cherry.




Dave

Partitions create high pressures in my experience. I tend to be more cautious with them. The big thing to me is being jammed though. Not surprised you had issues at only 1 grain over. Book max is certainly not for jamming a load. I am surprised you had no signs. Bolt was easy, no ejector marks, no flat primer? Good reminder for all of us.

I think adding chrono data to your situation may have helped to prevent.

What a bunch of Nancy's.

There's a reason I keep a hammer in my range bag. It ain't for hangin' targets!




Clark

Before computers entered the manufacturing scene, pressure signs were used by us tinkerers to determine what is "too much". With tighter tolerances in manufacturing, you / we really NEED a chrony as a check on data used. Like powdr kindly reminds us, we are screwing around when trying to see how much you can get away with (using old rules-of-thumb.) It really is rocket science...

if i blew a primer i would be backing down more 1/2 a grain.....

You should think about spending what time you have left golfing.

Folks have already covered the fallacy of visual pressure signs. I believe Mule Deer (John Barsness) reported that "visual pressure signs" don't generally show up until pressures get up to about 70,000 psi.


"So flame away what did i do wrong."

Well, if you weren't using a chronograph that is probably the first thing that would need to be corrected. Velocity and pressure are pretty well correlated given reasonable powders for the bullet and case, i.e. getting only 2700 fps with a 150 grain bullet and Bullseye powder in the .30-06 is not really a good thing.

While manuals will show different powder charges to reach the same velocity with their different bullets, most of them will agree fairly well on a certain maximum velocity you are likely to safely attain with the powders listed. E.g., most manuals will agree that 2900 to maybe 3000 fps is the best you're going to do with a 100 grain bullet in a .243. If the Hornady manual says you should get 3000 fps with a 100 grain bullet and 40 grains of a certain powder, and you are using their bullet and getting 3000 fps with 39 grains, it's time to stop adding powder no matter what the manual's max charge is.

It's still not hard and fast - you really have to use the exact same components as the manuals to get pretty close to the same pressures they got at the same speeds they got, and even then variations in barrel length and chamber and barrel dimension are likely to cause some difference in the velocity - and pressure - you get.



Bottom line, though, is that a good reliable chronograph is your best friend for keeping you out of trouble and the most reliable way the average handloader has today to stay in a safe area.*

One last thing - don't chase those last 50 fps. It's not worth it.






*Pressure testing equipment is available but you still don't see the average handloader with that kind of setup, and even then there are lively discussions about how accurate they are, or rather how accurately the individual can read them.