Need Help With Pressure Signs ***pics***

riverwalker76 · April 10, 2010, 03:15 PM

I loaded up 2 lots of cartridges this afternoon using two different powders.

Are any of these showing pressure signs? If so, which ones & what are the determining factors ?

Group 1

Group 2

**Unclenick** · April 10, 2010, 03:27 PM

Primers alone are not always a great pressure sign, but if I had to pick one on that basis alone, I would say the one on the right end was looking a bit flatter than I usually like. Hard to say without being able to angle to look for mushrooming. Of course, if you went to a harder primer cup, that might go away.

What primers are you using?

riverwalker76 · April 10, 2010, 03:45 PM

I'm using CCI 450 SR Mag primers.

From my understanding they are about as thick as they come. Am I right?

They go from left to right ..... left would be the minimum load and far right would be .3 grains from Max. I noticed on both powders that the 4th & 5th cartridges had a little too much kick to them. I am firing them from an Ar-15, and 1 & 2 were pleasant to shoot while 3 was medium, and 4 & 5 were uncomfortable and the report was quite a lot louder.

Darksith · April 10, 2010, 05:30 PM

show us a side view although Im no expert thats for sure!

vladan · April 10, 2010, 05:36 PM

Your primers are all right, when I shoot some NATO surplus then you see flattened primers even in my AR15 that has NATO chamber ( most my rifles have wylde chamber)
Just for example, this is commercial round shot in my friend's DPMS carabine

**Unclenick** · April 10, 2010, 05:49 PM

Yeah, but that's a Winchester primer, known to be pretty soft in current production (some say softest currently in production; they thinned them to improve ignition reliability at one point). This is part of what makes primer reading so unreliable as a stand-alone pressure indicator.

The CCI's should be pretty hard. I don't know if their #41 military hard primer is any harder or not? They could be tried some if you can find them?

I see, in the first photo, what seems to be an extractor mark at about 10:00. I can't see it clearly in the light in the second photo, but in the first one it is probably validation that the load is a bit high in your gun. The problem with those marks is knowing whether you got them this time around or on a previous firing?

The fact that right end load is still below manual maximum is something I consider fairly meaningless. It's your gun's preference that matters. This is why we start with the bottom load and work up.

One rule of thumb I use as a cross check is that extremely accurate loads are seldom very high loads. How is the accuracy doing?

Also, do you have a chronograph? One sign of high pressure can be that your velocity exceeds the velocity for the same load in the manual. That only applies if your barrel is the same length or shorter. If it is longer, then you need to give the load and the test barrel length and your barrel length and we can figure out what it should be? Usually somewhere around an additional 25-30 fps per inch of barrel is OK to allow in a rifle.

mrawesome22 · April 10, 2010, 06:01 PM

As stated, flat primers are more of a sign of head space problems. Yours look fine. If you start seeing powder burns around the primer, your in WAY over max territory.

riverwalker76 · April 10, 2010, 06:37 PM

Ok ... where to start .....

1) I discussed primer thickness with Ken Kees of CCI a few weeks back. He is the QC Manager at their Lewiston, ID facility. He informed me of how the CCI Primer's cup thickness progress.

CCI SR/LR/LP/SP ~ Thinnest

CCI 41 & 34 (Milspec) ~ Medium Thickness

CCI Mag SR/LR/LP/SP ~ Thickest

I did not inquire about the Benchrest Primers as I do not use them. They never came up in the conversation.

2) I do have several thousand CCI 41 primers that I will load up tomorrow for another test run. I will use the same powder data, and check for accuracy on that go - round. Although, the lighter loads did seem to be more accurate even though I was only shooting at an old tree stump 30 yds. away.

3) The 2 pictures are two separate lots. The first picture is using Accurate 2230, and the second lot is using IMR 8208 XBR.

4) It may be hard to determine by extractor marks alone simply because I installed a new SOCOM Tactical Extractor Kit yesterday, and have only fired these lots through it. It may still be quite stiff at this point. The reason I installed the kit was because the old extractor spring and buffer were too weak. This new extractor setup really throws the brass out there.

5) I do not have a chrono, but have thought about investing in one sometime this summer.

6) Finally, I will load some more cartridges up tonight. This time I will use CCI 41 primers and see if I can't get an accuracy report tomorrow. I will also load up a few using the previous data, and see if I can find the most accurate load.

April 10, 2010, 03:15 PM	#1
riverwalker76 Senior Member Join Date: February 13, 2010 Location: Kentucky Posts: 993	Need Help With Pressure Signs *pics* I loaded up 2 lots of cartridges this afternoon using two different powders. Are any of these showing pressure signs? If so, which ones & what are the determining factors ? Group 1 Group 2 __________________ *Admiral Isoroku Yamamoto* - “You cannot invade the mainland United States. There would be a rifle behind each blade of grass.”

April 10, 2010, 03:27 PM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,060	Primers alone are not always a great pressure sign, but if I had to pick one on that basis alone, I would say the one on the right end was looking a bit flatter than I usually like. Hard to say without being able to angle to look for mushrooming. Of course, if you went to a harder primer cup, that might go away. What primers are you using? __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

April 10, 2010, 03:45 PM	#3
riverwalker76 Senior Member Join Date: February 13, 2010 Location: Kentucky Posts: 993	I'm using CCI 450 SR Mag primers. From my understanding they are about as thick as they come. Am I right? They go from left to right ..... left would be the minimum load and far right would be .3 grains from Max. I noticed on both powders that the 4th & 5th cartridges had a little too much kick to them. I am firing them from an Ar-15, and 1 & 2 were pleasant to shoot while 3 was medium, and 4 & 5 were uncomfortable and the report was quite a lot louder. __________________ *Admiral Isoroku Yamamoto* - “You cannot invade the mainland United States. There would be a rifle behind each blade of grass.”

April 10, 2010, 05:49 PM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,060	Yeah, but that's a Winchester primer, known to be pretty soft in current production (some say softest currently in production; they thinned them to improve ignition reliability at one point). This is part of what makes primer reading so unreliable as a stand-alone pressure indicator. The CCI's should be pretty hard. I don't know if their #41 military hard primer is any harder or not? They could be tried some if you can find them? I see, in the first photo, what seems to be an extractor mark at about 10:00. I can't see it clearly in the light in the second photo, but in the first one it is probably validation that the load is a bit high in your gun. The problem with those marks is knowing whether you got them this time around or on a previous firing? The fact that right end load is still below manual maximum is something I consider fairly meaningless. It's your gun's preference that matters. This is why we start with the bottom load and work up. One rule of thumb I use as a cross check is that extremely accurate loads are seldom very high loads. How is the accuracy doing? Also, do you have a chronograph? One sign of high pressure can be that your velocity exceeds the velocity for the same load in the manual. That only applies if your barrel is the same length or shorter. If it is longer, then you need to give the load and the test barrel length and your barrel length and we can figure out what it should be? Usually somewhere around an additional 25-30 fps per inch of barrel is OK to allow in a rifle. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

April 10, 2010, 06:37 PM	#8
riverwalker76 Senior Member Join Date: February 13, 2010 Location: Kentucky Posts: 993	Ok ... where to start ..... 1) I discussed primer thickness with Ken Kees of CCI a few weeks back. He is the QC Manager at their Lewiston, ID facility. He informed me of how the CCI Primer's cup thickness progress. CCI SR/LR/LP/SP ~ Thinnest CCI 41 & 34 (Milspec) ~ Medium Thickness CCI Mag SR/LR/LP/SP ~ Thickest I did not inquire about the Benchrest Primers as I do not use them. They never came up in the conversation. 2) I do have several thousand CCI 41 primers that I will load up tomorrow for another test run. I will use the same powder data, and check for accuracy on that go - round. Although, the lighter loads did seem to be more accurate even though I was only shooting at an old tree stump 30 yds. away. 3) The 2 pictures are two separate lots. The first picture is using Accurate 2230, and the second lot is using IMR 8208 XBR. 4) It may be hard to determine by extractor marks alone simply because I installed a new SOCOM Tactical Extractor Kit yesterday, and have only fired these lots through it. It may still be quite stiff at this point. The reason I installed the kit was because the old extractor spring and buffer were too weak. This new extractor setup really throws the brass out there. 5) I do not have a chrono, but have thought about investing in one sometime this summer. 6) Finally, I will load some more cartridges up tonight. This time I will use CCI 41 primers and see if I can't get an accuracy report tomorrow. I will also load up a few using the previous data, and see if I can find the most accurate load. __________________ *Admiral Isoroku Yamamoto* - “You cannot invade the mainland United States. There would be a rifle behind each blade of grass.”

April 10, 2010, 05:30 PM	#4
Darksith Member Join Date: September 7, 2009 Posts: 68	show us a side view although Im no expert thats for sure!

April 10, 2010, 06:01 PM	#7
mrawesome22 Senior Member Join Date: November 9, 2005 Location: Ohio, Appalachia's foothills. Posts: 3,779	As stated, flat primers are more of a sign of head space problems. Yours look fine. If you start seeing powder burns around the primer, your in WAY over max territory.