Pressure signs and Max plus loads

35WD

New member
I am shooting a CZ 550 HS Precision 22-250. I have been working with 55 and 60 grn bullets and Varget, H380 and Superperformance powders.

I loaded the max load of 41 grns of H380 under a 55 grn V-Max bullet and chronoed it in my 20 yard basement range. I got pretty close to the published 3,713 fps velocity. However, I got no signs of pressure. Primer is not flattened. No cratering on the firing pin impact. No leakage around the primer and pocket. Head stamp looks as good as new. Primer pocket has not loosened. No evidence of case separation. The case has not stretched. Bolt opens easily and extraction is a breeze.

So, I took the liberty of increasing the charge weight one half of a grn. No signs of pressure. I did this up to 44 grns of H380 and used the same Hornady case. Definitely a compressed load. Pretty impressive velocities too. Given my short range setting I have no clue about accuracy but I am testing that this weekend. Despite being 3 full grns in excess of max, still no signs of excess pressure.

If I am not getting any signs of excess pressure, can I safely load this round or am I missing something? Are max loads published by the bullet/powder folks with a safety factor in mind to keep the lawyers away?

By the way, I did shoot the factory Hornady Superperformance 22-250 50 grn. rounds and they chronoed around 3,850 fps.
 
Wow thats gotta be smokin. Did velocity keep increasing as charges went up or did it start to drop off. If the pressure signs arent there i say go for it. Thats if they shoot well. Are you loading them long.
 
The velocity kept increasing as I increased the charge weight. I did load them out long but I did not seat each one exactly the same. I had my seating depth set for factory specs and when I was doing my experimenting, I did not run the shell completely in the seating die; just kind of eye-balled it.

By the way, for those interested, the CZ 550 detach mag has a lot of space in it. You can really seat your bullets out and not run into space problems.

If they prove to be accurate I might load at 44 grns of H380. I am still not convinced it is all that good of an idea and can be convinced pretty easily that I should not go that high. It it is only a matter of barrel wear, I can live with that.
 
I wouldnt dare shoot that load in the summer time, you might see so e pressure then. The longer you load em the less chamber pressure you will get. Keep atleast a 1/4" of bearing surface. It will probably wear out the throat faster.
 
Quote:The longer you load em the less chamber pressure you will get...I think that is only true to a point..If you jamb the bullets into the lands, you can get an increased pressure spike that has no where to dissipate...
 
You are right OldTurtle. But he would most likely have to load them one at a time to get them that close to the lands. Depends on the lead in the chamber etc.
 
Load close to the lands and don't crimp. The Varget will be fine all summer and winter but the H380 is temperature sensitive and a winter load might blow in the summer. Not sure about OR but in MI I shoot +90F down to -30F some winters and only use extreme powders. If there are no pressure signs you are safe. I like to work up a safe max fps load and then play with OAL for accuracy.
 
I realize this is an old post but will add what I found with H380 and being sensitive to temperature. Loading for my savage in 243, powder charge was 1 grain under the max on 52gr VMax's. Shot great during the winter with no pressure signs. The same load this summer while shooting prairie dogs blew a primer out and ruined the firing pin. Thanks to Savage they repaired the bolt at no charge and said not to do it again. So I would be mighty concerned shooting that load in hot temperatures. I solved my problem by going to Varget. A coyote can't tell the difference in the bullet hitting them a few hundred feet per second slower.
 
Originally Posted By: 35WD
If I am not getting any signs of excess pressure, can I safely load this round or am I missing something? Are max loads published by the bullet/powder folks with a safety factor in mind to keep the lawyers away?

Don't confuse NOT blowing apart brass(tensile strength of 85,000psi) with not having "Excess" pressures.
 
Originally Posted By: 35WD

"Are max loads published by the bullet/powder folks with a safety factor in mind to keep the lawyers away?"



Never assume that there is headroom ("safety factor") in a loading manual - there are many good reasons the it is strongly recommended to drop 10% and work up in small increments.


.
 
I doubt it is mislabled.
In the newest Nosler book, using IDENTICAL components in the 55gr 243.
H414 & Win 760(same powder)there is a significant grain difference, which is just standard lot variation.
My jug of 760 chrono's much closer to the 414 data, from the start load working up. But I am 2.5 grains under book max before I hit problems.

414/760/380 are all quite old ball powders, with a large spec'd variation. That's why every book tells you to work-up carefully and not just use data as set in stone.
 
Originally Posted By: ackleymanSounds like you have a very slow lot of H380, that is perhaps mislabeled 414.

You won't know till you know.


Just for visual inspection the H-380 is a round ball powder, looks like little ball bearings.

On the other hand H-414 is a rolled [flattened] ball powder and is not perfectly round kernel to kernel.
 
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