how to tell 9mm overpressure?

[Axis II]

I just reloaded my first 15 9mm reloads 124gr extreme plated, 4.2gr hp-38 seated to 1.140 with mixed brass and Sellier and bellot primers.

4.0gr sounded a little light yesterday so I went to 4.2gr and they cycled fine and sounded fine. the reason I'm asking is 4.4gr is max and I'm only 2/10th away from that. so how do I know If say 4.2gr is too hot? brass looked okay to me. gun is 4.5inch barrel M&P.

 

[Sauer Grapes]

Stay within the data and you'll be fine.
Signs? Flat primer which still isn't always an issue. Primer starts getting creators.
All my hand load self defense ammo is right at max data and still shows nothing in the primer or function of gun. Primers are only slightly flattened. For plated bullets, I use jacketed data. Never had an issue.

 

[Axis II]

the S-B primers I'm using flatten out when I prime the cases so I can tell with that. cci doesn't do it but these do. no creators in them either. I just don't want a long term issue to screw up my gun.

 

[Skinnedknuckles]

Remember that the same primers are used in +P loads. They are also use in other even higher pressure cartridges so don't expect much useful pressure information from them. As Sauer Grapes stated, we just need to color within the lines and we'll be OK. BTW, after a fair amount of experimenting my favorite load is 4.3 gr HP-38/Win 231 under a 124 gr plated bullet for most of my pistols. YMMV.

 

[Dudedog]

Yep the S+Bs start out flat....no nice rounded edges like CCIs but the price is right and they shoot great.

 

[LocoGringo]

What if load data isn't provided? I'm loading with a combination of components that even the powder manufacturer doesn't have data for. I was told, "pick a load between 124 grain and 147 grain, start low and work up". I'm loading 135 grain black bullets over Silhouette powder.

 

[Walkalong]

how to tell 9mm overpressure?

You can't until it is way over the limit. Stick with published data.

What if load data isn't provided?

Watch brass ejection, FPS over the chrono compared to data with a similar burn speed powder and bullet weight. Watch how clean it leaves the brass. But basically, we're guessing when we do that. It can be an educated guess, but it is still a guess.

 

[ArchAngelCD]

Considering Hodgdon is giving us a range of only .5gr in that cartridge combination being .2gr from the published max isn't that close to max. In the 9mm a good way to tell if your load us too hot us where the brass lands. If it's flying 10+ feet away and all over you know you are getting hot. I charge up to 4.4gr and I don't think it's too hot, you should be fine @4.2gr especially since your OAL is longer that used by Hodgdon.

 

[murf]

A chronograph is the best way to check loads for overpressure. If your reload velocity is faster than the "book" velocity, you will be overpressure (99.99 percent of the time).

murf

 

[boom boom]

Primer cup deformation is more useful in determining overpressure in rifles than in pistols but chronographs are the gold standard outside of actual pressure testing using chamber sensors. At the pressures needed for that pistol primer cup to deform would be grossly excessive in 9mm ("Most primers are made with cartridge brass (70% copper, 30% zinc), which can vary from 46,000 psi, soft, to 76,000 psi tensile strength when fully hardened.) from http://bulletin.accurateshooter.com/2012/03/primers-and-pressure-analysis-by-james-calhoon/

Another way to measure pressure is to measure brass cartridge head changes in measurement which requires considerable expertise and care (see Waters for details).

 

[ny32182]

Another vote for flat primers and chrono being the two best things to look for/use.

In my experience, virtually all published pistol data is extremely conservative, so if you are within a published load, you are probably not even anywhere close to danger.

 

[Dog Soldier]

I would judge pressures differently. A fully supported ramped barrel will hold pressure better than a non ramped chamber. The bulged case webs experienced in Glock reloads may not occur in a fully supported chamber using the same loads.

 

[Axis II]

Considering Hodgdon is giving us a range of only .5gr in that cartridge combination being .2gr from the published max isn't that close to max. In the 9mm a good way to tell if your load us too hot us where the brass lands. If it's flying 10+ feet away and all over you know you are getting hot. I charge up to 4.4gr and I don't think it's too hot, you should be fine @4.2gr especially since your OAL is longer that used by Hodgdon.

brass lands about 3 ft away and seems to be in the same 2ft square.

 

[GRIZ22]

A chronograph is the best way to check loads for overpressure. If your reload velocity is faster than the "book" velocity, you will be overpressure (99.99 percent of the time).

murf

Generally yes. You can have high pressure with what seem to be a "normal" velocity.

 

[Rule3]

Looking at primers on handgun rounds is like reading tea leaves.

It is not gonna tell you much until it is so far over it is a real problem!

 

[Ironicaintit]

Generally yes. You can have high pressure with what seem to be a "normal" velocity.

So long as you are using "correct" powders, then yeah.

Looking at primers on handgun rounds is like reading tea leaves.

It is not gonna tell you much until it is so far over it is a real problem!

I think it can be done. So long as all else is consistent, same primer brand and type, same powder, same brass, same projectile seated to the same OAL; small variations in the fired primers appearance can tell ya some things.
I wouldn't want to rely on it solely, but it can help you figure out what's what.

 

[Rule3]

See Walkalongs post # 7 above

Quote:

"You can't until it is way over the limit. Stick with published data."

 

[Tcruse]

For XTreme Plated 124g, S&B Primers, and HP-38 I find 4.8g (near published max) gives best accuracy. Have shot about 2K and have had no issues. Also, I reload aluminum cases from time to time without issues.
You might get a copy of "Loading 9mm Luger for Accuracy" by Charles Petty to get a handle on other experiences.

 

[lbs]

Google search comes up with nothing for the book .

 

[Axis II]

For XTreme Plated 124g, S&B Primers, and HP-38 I find 4.8g (near published max) gives best accuracy. Have shot about 2K and have had no issues. Also, I reload aluminum cases from time to time without issues.
You might get a copy of "Loading 9mm Luger for Accuracy" by Charles Petty to get a handle on other experiences.

ive got the accuracy part down. I shot 10 for accuracy last night at about 15-20ft and all 10 I could cover with a baseball. 4.4gr is max for that load per hodgdon btw.

 

[Dudedog]

Chrono won't tell you pressure but will give you info to think about.
4.2 should be fine at that OAL with a 125 RN.
4.4 seemed fine for me and when chroned the vels were as expected. (can't find my 4.4 data)
Springfield 9mm 1911, S+B primers, mixed range brass, Xtreme 124 RN
String: 1
Date: 2/28/2016
Time: 8:46:42 AM
Grains: 124
Hi Vel: 1035
Low Vel: 977
Ave Vel: 1008
Ext Spread: 58
Std Dev: 23
XTREME 1.12 OAl 4.3 HP38
Velocity Power Factor Ft/Lbs
1035 128.34 294.92
995 123.38 272.565
977 121.148 262.792
1026 127.224 289.813
1010 125.24 280.845

So with this load I could probably go .2 to .3 more and still be ok.

 

[ArchAngelCD]

brass lands about 3 ft away and seems to be in the same 2ft square.

That sounds good to me especially if your load is accurate.