How Hot is TOO Hot? (Warning, not to be used as load data)

[dieselrealtor]

Any information posted below is the posters own experience & not to be considered a recommended load or viable load data. Anything above published loads by manufacterer is considered dangerous & possibly deadly. YOU are responsible for your own actions.


After reading several threads on WC842 I picked up from an Ingo'er a while back that got it from Profire. I was working up a load to be a general all around load to load up 8#, around 2000+ for bulk/store away ammo.

Processed 1x fired LC brass trimmed to 1.75" +/- .003
S&B spp
55gr Hornady fmjbt wc
2.25 oal
crimped in the cannelure Lee collet crimp die

At 25.2gr + or so speeds on the high end 10' away from muzzle were just over 3000fps from 16" barrel, carbine length gas system.

Worked up to 25.4 gr & noticed some pressure signs with flowing primers (ridge) after depriming, however the load didn't "feel" much different than some Wolf gold factory that I had shot.

My plan is to back off till the primer looks normal (not flowing into a mushroom), would like decent velocity to shoot out to 300m or so.

Curious what others experiences are for serious pressure signs & how far from that "line" do some people run loads?

Do the CCI 5.56 primers make much of a difference in hot loads?

Thanks in advance.

 

[Leadeye]

I've been reloading pushing 50 years and have seen "the published top" change over that time. I figure it's just the litigious times we live in. Signs for me are like what you described, primer flowing/flattening, hard extraction, and a general feeling. That said I've gone way past the published limits with some firearms like the 357 DE.

 

[jrh84]

My service rifle loads are above published book max, but they are safe in my rifle. They're safe in the middle of summer after a 20 round string.

The signs I usually see are cratered and flattened primers. With CCI 41's, I'll get them pretty flat, but no major issues. Some of that is probably due to me reaming the crimp out of the primer pockets, which opens the entry up a little bit and promotes flattening. When I tried those same loads with CCI 400's, I was getting severe cratering, and was piercing them pretty regularly. Not cool. I stopped before I did any damage to my bolt, and I definitely backed off the charge a bit, and went to CCI 41's exclusively. There is a difference.

 

[Clay Pigeon]

Just remember that a flat primer might not be over pressure, it easily could be the shoulder was pushed back to far. When that case is fired the firing pin pushes the case forward and during ignition that equal and opposite reaction happens and the primer goes backwards and the case stays forward. When pressure builds the primer is pushed back and hits the breach and gets flattened and then the case goes backwards when the bullet leaves the case and pushes the primer back into the case. The case is now against the breach and the bullet is moving down the bore. End result is a flattened primer without excessive pressure.

 

[JUGGERSEVENSIXTWO]

I would do a ladder test and look for the accuracy node.Spped without accuracy is nothing.You may not see the pressure at all.Then kaboom
Stay safe.work up your loads

 

[Sniper 79]

JUGGERSEVENSIXTWO has the answer above.

 

[Hohn]

Reading pressure is a bit of voodoo. I think the only truly valid answer is that by the time you see pressure signs, you are well over SAAMI max. Now, keep in mind SAAMI is like the UL of the arms world, and like that agency it's there to protect the SAAMI members from lawsuits and promote standardization.

I'm still a new loader, but I've learned enough to know that load data is a guide, not a rule book. I've personally run charges nearly 2.5gr over "book max" with mild primer pressure signs and I only saw actual pressure signs several tenths hotter-- nearly 3 gr over book max.

You need to consider all the sources of variation that the "book" accounts for. They must ensure a stastistically significant sample has an average pressure below some value (MAP) along with condemnation limit levels (max probable lot mean or MPLM) and max probable sample mean (MPSM). They must stay below these limits while protecting for the max headspace in the tightest bore with the largest acceptable bullet OD and lot to lot powder, primer, and brass variations.

All that to say that the book data is the lowest common denominator. The "book max" is the highest level that isn't likely to cause problems in *any* rifle with *any* combination of brass and powder and primer variations.

One you get a feel for the pressure tolerance of a given barrel and brass, I think it's probably safe to start closer to the middle of a charge range and not work up from the very bottom. In my AR, for example, I've run charges with several powders well over book max without any more pressure signs than you'd see in a box of mk262 from Black Hills. So that history makes me comfortable starting closer to the middle.

But in my new CBI barrel, I had no history at all and started low. As it turns out, comically low. Like sooty necks and 2300fps low.


If you are paying attention to your brass, you can see pressure signs. Not just primer signs or ejector swipes, but a longer case when measured to the shoulder. Or a significantly larger diameter just above the case rim. Pay attention when decapping-- are they coming out VERY easily? Than you you might be overpressure even with no "signs" because you're killing the primer pockets.

I generally work up in 2% increments until I'm over the book max, then I'll go in smaller increments. So a charge weight of 25gr range might justify going up in 0.5gr increments until you are toward the upper end, then drop down to 0.3 or 0.2gr increments.


Finally, there's the "litmus test" for pressure of spraying your ammo with water. If a wet round doesn't show pressure, you don't have pressure.

 

[SSE]

All good stuff above and I will add, if you think you might be running high then use one single case and reload it over and over till the primer pocket gets loose. If I get 10 or more loads than it is not TOO hot. Watch for other signs as well.