Ammunition Pressure Discussion

[new_user_RLTW]

Moderation Note:

Topic split, original post located here: First post, new owner, wth.

Title change to: Ammunition Pressure Discussion.

The original thread in its entirety can be found here: http://fnforum.net/forums/deprecate/...tml#post257803

[HK SD9 Tactical]

...I see chamber pressures have been posted of their loadings...

Where? I see the measured velocity and calculated impact energy but I do not see the pressures.

[Visceral_Malice]

Where? I see the measured velocity and calculated impact energy but I do not see the pressures.

I tried to find it on their site too and can't seem to. I know they posted it up at the other forum. I can link if its cool with the mods.

[HK SD9 Tactical]

I tried to find it on their site too and can't seem to. I know they posted it up at the other forum. I can link if its cool with the mods.

Go ahead. Can't guarantee if the link will stay active though.

[Visceral_Malice]

Here you go
http://www.*******************/viewt...hp?f=8&t=12142

I guess just fill in the *?

[HK SD9 Tactical]

Here you go
http://www.*******************/viewt...hp?f=8&t=12142

I guess just fill in the *?

That link is useless.

[jhs27275]

Wow, even when you fill it in it won't copy.

[jhs27275]

One more try.

Nope even filled I can't get it to copy.

[jhs27275]

Ok HK.

"Thank you for posting! Your post will not be visible until a moderator has approved it for posting."

[jhs27275]

The text from the link.

EA Pressures

Measuring system. RSI Pressure Trace II

Test weapons, both used
FsN Pistol modified to allow fitting of RSI strain gage
Locked breach pressure barrel fitted with RSI stain gage


These readings where from production lots this summer. Every lot of ammo loaded gets a test sample labeled and set aside with the following info
Load type
Date
Press#
Press operator
Temp
Humidity
BAR
Powder type
Powder Charge
COAL
Type of crimp
Bullet used

Of this test lot some are kept unfired. The brass from the test fired loads, After detailed inspection conducted in shop after test session, then gets returned to the box with the unfired ammo and put into storage. These are stored. I have storage units filled with these labeled boxes so that at anytime I can pull and retest to investigate any issues. There is also a daily load log that has all the above info with the addition of,
Powder lot number
Primer lot number
Bullet lot number
Brass lot number
Note section concerning any observations like, did you know that jacketed bullets from ALL the big name makers actually vary in diameter from one batch to another? This plays a role in our crimping since as a recently found out by a forum member crimping plays a very critical role in loading the 5.7x28


The last few rounds of testing where done outside in 30 to 40 degree temps so their pressures would not be accurate unless adjusted for ambient temp. These reading where taken on different days this summer but the ambient temps are listed.

10 rounds are fired from a box stock LOW round count FsN other then sensor. This is done to verify function also. It must be noted that there has been some material removed from the FsN frame to clear the sensor. The only possible affect this could have is to weaken the frame making this FsN MORE likely to have an issue.

10 rounds through pressure barrel.

It must be noted that the FsN is the determining factor here and not the pressure barrel since with the blow back operation the fixed pressure barrel does not give the same readings. Most of the below where fired at our indoor test range where temp and humidity are controlled. Latest where done outside at the range seen in our some of our vids since the back stop for out indoor range has repeatedly been literally decimated by our ammo and is waiting on what I hope to be steel armor plate that will hold up to more then a handful of testing rounds. The Lamar vids showing function of FsN with red dot was at our indoor range. As a side not if anyone here saw the damage created by my ammo to the 8 yes 8 backstops we have had to install you would crap yourselves and never doubt a claim about the 5.7x28 ever again.

50,000 psi is working max. Source is CIP.

S4M 48,500 psi 62F 33%H BAR

Devestator 48,000 psi 70F 42%H

Penetrator 49,000 psi 80F H missing on form

Pro1 49,886 psi 81F 49%H

Pro2 48,378 psi 75F 48%H

Pro3 47,000 psi 70F 47%H

Var1 48,715 psi 70F 48%H This is from our older Barnes load, the newer Berger are just a shade lower since I left the powder charge the same.

Var2 25,000 psi 70F 46%H

These numbers of course vary and change often, sometimes greatly. Whenever we get powder lot change we do a 50+ round test to see what the pressure difference is with the new lot. There ALWAYS is a difference. Not enough to really matter to the casual hand loader but enough to me. I then adjust the load recipes accordingly to get the pressure where I want it.

Hope this is informative.