1500fps 124gr 9mm major 186PF Jeez!

[bootcamp]

Hey all,

 

I'm new to 9mm major open but I have been reloading for over 10 years so I know all about load development and working up a load but I think my judgement was clouded on my recent 9 major gun purchase.  I bought the custom built gun from a guy who had it built from a local gunsmith and it was the previous owners backup gun and had no more than a dozen rounds through it.  I could tell due to the lack of wear marks on the barrel.  I spoke to both the owner and gunsmith in depth prior to purchase and both of them said the pistol needs to be broken in with hot ammo.  7.2 wac behind a 124gr pd jhp at 1.160 oal.  Previous owner said here i'll even give you some ammo.  He is in his 70's and retiring from open.  I pulled several and weighed the powder charges before taking a chance on them.

 

First outing shot about 50 rounds through it.  Indoor range and I couldn't setup chrono.  I was focused on function and accuracy and it's super accurate but I thought to myself, these rounds feel hot for sure.  Figured I'd stop here and bring the chrono out next time and maybe build up some lower ammo and do it the right way.  Inspected about a 10 brass cases I didn't see any pressure signs or flattened primers.

 

So built up some 6.8 & 7.0 with the same 124gr pd jhp and 1.160 length.  Setup the chrono.

 

6.8 results: 1371, 1358, 1370, 1380, 1367, 1374, 1354  All test rounds resulted in  power factor of 167 to 171.  No cracked cases or flattened primers

 

7.0 results: 1364, 1399, 1375, 1369, 1400, 1397 All test rounds resulted in power factor of 169 to 173.6.  No cracked cases or flattened primers

 

7.2 results: 1516  Eyes wide open at this point, I ran the calculator for a 188 power factor and immediately stopped.  Not sure why the drastic increase in velocity but needless to say I was a bit shocked and a bit thankful I still have my hands and eyes.  How dangerous was that because I honestly have no idea if 1500fps from a 124gr bullet is dangerous.  I'm just assuming it is based on how high the power factor is.  I'm quite happy with 6.8 and will probably continue to test with that charge.  The recoil was nice as well at 6.8 and the dot never left the window.  I definitely have mixed feelings about breaking this thing in further with that hot of ammo.

Edited June 11 by bootcamp

[shred]

In the old days we shot 180+ PF in 38 Supers, so while that load is going to be way overpressure, it's not an instant hand-grenade.

 

That said, if it won't run on 165PF loads, it's got problems and the nonsense about "break in" is just that.

 

 

 

[bootcamp]

12 minutes ago, shred said:

In the old days we shot 180+ PF in 38 Supers, so while that load is going to be way overpressure, it's not an instant hand-grenade.

 

That said, if it won't run on 165PF loads, it's got problems and the nonsense about "break in" is just that.

 

 

 

Thanks for the comeback Shred!  It actually ran great with 165-170 PF.  I ran the rest of the 6.8 ammo and it was quite accurate and cycled everything nicely.  It has a 10lb recoil spring in it now.  I wonder if it'll perform just as nice with an 8 or 9lb spring in it?

[Maximis228]

I run 7.1 of WAC under a 124 at 1.165 OAL. This comes out to 171-172 PF depending on the gun. I'm surprised you are seeing such a spike at 7.2. Ive been loading WAC for major open ammo for a decade. 

 

Typically, I use a 9 lb spring for major and 7 lb for minor.

 

Every barrel MFG will get different results. What barrel do you have? 

[shred]

10 minutes ago, bootcamp said:

Thanks for the comeback Shred!  It actually ran great with 165-170 PF.  I ran the rest of the 6.8 ammo and it was quite accurate and cycled everything nicely.  It has a 10lb recoil spring in it now.  I wonder if it'll perform just as nice with an 8 or 9lb spring in it?

I'd get a spring pack with 7-10 and try them to find the one you like.  Buy about 3 more of that one, swap one in and keep the pack somewhere to test again in a few months and see if anything (you or the gun) have changed enough to warrant switching.

 

[bootcamp]

45 minutes ago, Maximis228 said:

I run 7.1 of WAC under a 124 at 1.165 OAL. This comes out to 171-172 PF depending on the gun. I'm surprised you are seeing such a spike at 7.2. Ive been loading WAC for major open ammo for a decade. 

 

Typically, I use a 9 lb spring for major and 7 lb for minor.

 

Every barrel MFG will get different results. What barrel do you have? 

I was very surprised myself.  Especially after doing a pretty good search on here.  Lots of guys loading 7.2 wac.

 

Maybe there was some bullet set back on chambering?  I only loaded the one round via the magazine.  Could 1.160 compared to 1.165 really increase pressure that much?

 

im running a KKM precision 5” barrel attached to a egw 3 port comp with 1 side exit on each side at the last port in the comp.

 

[bootcamp]

45 minutes ago, shred said:

I'd get a spring pack with 7-10 and try them to find the one you like.  Buy about 3 more of that one, swap one in and keep the pack somewhere to test again in a few months and see if anything (you or the gun) have changed enough to warrant switching.

 

Thanks!  Would you get the variable rate springs or the conventional rate?  Why if one over the other?  I honestly don’t know why or how different the variable vs conventional springs work in the gun.

[bootcamp]

1 hour ago, Maximis228 said:

I run 7.1 of WAC under a 124 at 1.165 OAL. This comes out to 171-172 PF depending on the gun. I'm surprised you are seeing such a spike at 7.2. Ive been loading WAC for major open ammo for a decade. 

 

Typically, I use a 9 lb spring for major and 7 lb for minor.

 

Every barrel MFG will get different results. What barrel do you have? 

I forgot to add that I’m using the LTD pro chronograph.  Was shooting it about 5-7’ away.

[Maximis228]

1 hour ago, bootcamp said:

I was very surprised myself.  Especially after doing a pretty good search on here.  Lots of guys loading 7.2 wac.

 

Maybe there was some bullet set back on chambering?  I only loaded the one round via the magazine.  Could 1.160 compared to 1.165 really increase pressure that much?

 

im running a KKM precision 5” barrel attached to a egw 3 port comp with 1 side exit on each side at the last port in the comp.

 

 

I too am using 5 inch KKM Barrels (Island/Hybrid Barrels). Maybe you just have a really fast barrel? (Tight) 

[xjwalt666]

How is the crimp on the ammo you got from him? I had a batch where my crimp die was loose and turned down and was over crimping and I was getting a lot higher pressures with the same load as before the crimp messed up. Have you measured the brass to see what size it is?

[shred]

Take a round, measure the OAL and push it into the side of your bench, bullet first with two thumbs hard.  Measure again.  If it shortens up, you've got setback that needs to be fixed.

 

 

[bootcamp]

37 minutes ago, xjwalt666 said:

How is the crimp on the ammo you got from him? I had a batch where my crimp die was loose and turned down and was over crimping and I was getting a lot higher pressures with the same load as before the crimp messed up. Have you measured the brass to see what size it is?

.375-.376 for his stuff and .378 for mine.  Man this could be it.

 

Shred, I’ll test when i get back home.  Really curious if it’s one or the other.  100fps from 7.0 to 7.2 is crazy to me

Edited June 11 by bootcamp

[lefty o]

sometimes when you hit that magic point, in your case from 7.0 to 7.2 you can get very sudden large increases in pressure. its not a new phenomenon, but it is a sign , a big red stop sign.

[Joe4d]

you ran a ladder but didnt pay any attention to what the info was telling you.. I woulda never fired those 7.2 rounds.. 
Look at your Standard deviation,,  all was good on that 6.8 load,, 8.3 SD
but then it went way more open on the 7.0..  deviation doubled with not much increase in average.
THAT was your stop sign. On that day with those components, and length,  7.0 was probably it..
Ida gone home and loaded a box of 6.9 and chrono'd a handful at several different sessions to verify a good consistent 170, called it good.

[N3WWN]

Could the rounds loaded with 7.2 gr have been loaded into stepped brass?

 

 

(image found in another thread on this forum - one of the cases is a normal 9mm case and the rest are stepped)

 

Brass with this step ~1/2 way down the interior of the case has quite a reduced case volume compared with non-stepped (normal) brass which will result in increased pressure with the same powder charge and OAL.

 

I cull all stepped brass from my reloads after tumbling and would never use stepped brass for 9mm major.

[392heminut]

4 hours ago, N3WWN said:

Could the rounds loaded with 7.2 gr have been loaded into stepped brass?

 

 

(image found in another thread on this forum - one of the cases is a normal 9mm case and the rest are stepped)

 

Brass with this step ~1/2 way down the interior of the case has quite a reduced case volume compared with non-stepped (normal) brass which will result in increased pressure with the same powder charge and OAL.

 

I cull all stepped brass from my reloads after tumbling and would never use stepped brass for 9mm major.

All of the stepped brass I've found is actually brass plated steel and is headstamped Xtreme-ST. I sort it with a magnet and throw that crap away!

[Braxton1]

Yeah, that Xtreme brass is stepped inside to prevent set-back whilst not requiring a crimp on plated bullets.  Good idea, but wreaks havoc on reloaders who've done their development on conventional brass.

[bootcamp]

23 hours ago, shred said:

Take a round, measure the OAL and push it into the side of your bench, bullet first with two thumbs hard.  Measure again.  If it shortens up, you've got setback that needs to be fixed.

 

 

Well the other guy's crimps are tight, maybe too tight.  I put a good amount of body weight behind my fingers trying to get the bullet to go in deeper and it wasn't budging.  Some of the rounds are 1.157-1.160.

 

 

[bootcamp]

20 hours ago, Joe4d said:

you ran a ladder but didnt pay any attention to what the info was telling you.. I woulda never fired those 7.2 rounds.. 
Look at your Standard deviation,,  all was good on that 6.8 load,, 8.3 SD
but then it went way more open on the 7.0..  deviation doubled with not much increase in average.
THAT was your stop sign. On that day with those components, and length,  7.0 was probably it..
Ida gone home and loaded a box of 6.9 and chrono'd a handful at several different sessions to verify a good consistent 170, called it good.

 

Well, I can say i'm a bit humbled by the knowledge you just dropped.  I've only ever reloaded my regular pistols and rifles within book specs and usually stopped when reliable cycling and accuracy was achieved which in most cases was a few notches above minimum.

 

I only purchased the chrono after diving into compeition shooting where power factor came into play which is all new to me.  What formula did you use to calculate standard deviation and what exactly does it mean?  I guess it's time to go to school!

[bootcamp]

7 hours ago, N3WWN said:

Could the rounds loaded with 7.2 gr have been loaded into stepped brass?

 

 

(image found in another thread on this forum - one of the cases is a normal 9mm case and the rest are stepped)

 

Brass with this step ~1/2 way down the interior of the case has quite a reduced case volume compared with non-stepped (normal) brass which will result in increased pressure with the same powder charge and OAL.

 

I cull all stepped brass from my reloads after tumbling and would never use stepped brass for 9mm major.

 

I just recently started picking up brass again and most recently started noticing this junk xtreme brass.  It does not size well and i've been culling them out of my brass pile.  Whatever happend to just FC, WIN, S&B, CCI and Blazer?  There's all sorts of junk brass now.  Even CBC isn't what it used to be and doesn't size right either.

[392heminut]

4 hours ago, bootcamp said:

 

I just recently started picking up brass again and most recently started noticing this junk xtreme brass.  It does not size well and i've been culling them out of my brass pile.  Whatever happend to just FC, WIN, S&B, CCI and Blazer?  There's all sorts of junk brass now.  Even CBC isn't what it used to be and doesn't size right either.

It's easy to sort that stuff out though, just use a magnet!

[ltdmstr]

Ammoload is also stepped brass. 

[36873687]

imt fm also stepped

[Haywizzle]

21 hours ago, bootcamp said:

 

I just recently started picking up brass again and most recently started noticing this junk xtreme brass.  It does not size well and i've been culling them out of my brass pile.  Whatever happend to just FC, WIN, S&B, CCI and Blazer?  There's all sorts of junk brass now.  Even CBC isn't what it used to be and doesn't size right either.

The covid ammo shortage happened and prices for 9mm got ridiculous so people started selling and buying any 9mm they could find. There is quite a lot of trash brass out there.

 

Even though my buddies think it's unnecessary, I hand sort headstamps in the winter when working overnight shifts. It keeps my presses running smooth. My open load gets the FC, RP, WIN and Blazer first before the minor loads.

[bootcamp]

5 minutes ago, Haywizzle said:

The covid ammo shortage happened and prices for 9mm got ridiculous so people started selling and buying any 9mm they could find. There is quite a lot of trash brass out there.

 

Even though my buddies think it's unnecessary, I hand sort headstamps in the winter when working overnight shifts. It keeps my presses running smooth. My open load gets the FC, RP, WIN and Blazer first before the minor loads.

 

Great tip thanks!