Jump to content

9mm +p SAAMI Pressure Higher Than .357 Mag.?


Recommended Posts

I'm not very knowledgeable in this area and just recently stumbled across a SAAMI pressure spec chart. It says 9mm +p is 38,500 and .357 mag. is 35,000. WHAT?! .357 mag. has considerably more velocity and energy. 9mm +p also had slightly higher pressure than 10mm. Again,WHAT?! That's CRAZY! 

 

 

Link to post
Share on other sites

Would the additional case capacity of the .357 contribute anything to the increased velocity and energy with less pressure?  Also curious about default barrel length, if any.  Also kinda curious about type of handgun ... revolver vs. recoil operated auto pistol?  Does that enter into SAMMI pressure determination?  I dunno.

  • Like 1
Link to post
Share on other sites

+P gets around 38500 according to some sites out their, I did find this: http://www.handloads.com/forum/showthread.asp?topic=2&thread=1602

Post by Author halfway down  "Lee’s book MODERN RELOADING (the first edition)"

 

For the 9mm Parabellum, SAAMI max average pressure is 35,000 psi.
9mm +P the max average is 38,500 psi.
To the best of my (limited) knowledge, SAAMI has no standard for +P+ loadings in any caliber. For the +P+ loads I ran up, I used 42,000 psi as a basis for calculation. (This isn’t an endorsement, just a statement).

 

  • Like 1
Link to post
Share on other sites

Would the additional case capacity of the .357 contribute anything to the increased velocity and energy with less pressure?  Also curious about default barrel length, if any.  Also kinda curious about type of handgun ... revolver vs. recoil operated auto pistol?  Does that enter into SAMMI pressure determination?  I dunno.

Yes. The larger the case, the more power generated per pound of pressure.

 

The advantage of the smaller case is that it can handle higher pressures. That's the trade-off.

  • Like 1
Link to post
Share on other sites

I've been reloading 9mm since the late 80s and have found backing off the max load in the manuals by 5 to 8% delivers much better consistency in my old FN1911.  I have not reloaded since acquiring my Hi Point carbine or my Taurus G2s.  It will be interesting to see how they perform with various bullet weights and charges.  I'm sort of suspecting similar results to the FN; time will tell.

 

I noticed in one of the articles I got to following the link above that kept stating you MUST use .355 bullets when loading 9mm, but all of my manuals both new and old show .356.  I wonder why the discrepancy or if it was just a typo in the new literature.  I have always used .356.

 

I'm also wondering why there is really a need for the +P or +P+ when this video clearly demonstrates that a standard 9mm can easily kill at 400 meters when it penetrates 9+ inches of ballistic gel as well as 2.25" of wood.

Edited by CruisinTx2
  • Like 1
Link to post
Share on other sites

Just wondering what pressure very hot European SMG 9mm ammo runs at.  Also wonder if the future to be Hi Power could handle some of it.  Friends have a whole lot of very old Spanish SMG 9mm hard ball.

 

I've looked into that. Basically the European military stuff is mild +P by SAAMI specs. Some of the SMG specific 9mm is marked other than 9mm nato because it is way higher pressure while being visually and dimensionally identical. i.e. the Russian AP 9mm, etc. Those were usually marked on the ammo crates by designation and what specific model of weapons they were made to run in. Probably comparable to the "9mm Major" the race gun guys use. You could probably find a lot of information on pressures and what production guns can handle that on Brian Enos forums.

  • Like 1
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Chatbox

    Load More
    You don't have permission to chat.
×
×
  • Create New...