Pressure signs with low charges

[JJK]

Hello, new to the forum. Looking to get a more seasoned opinion on pressure signs seen in the pics, one batch of 6.5 CM's (Rem700) and a .223 Rem (Ruger American g1) batch. The colors around the primers are from colored Sharpie markers that I use to mark different charges within the lot of 50 rounds. I typically do 5 batches of 10 rounds for load development, with the cases on the left being the starting charges (per Hornady 12th edition) and working up to a step under max charge on the right. I'm curious as to why I'm seeing pressure signs with the low to mid charges (flat & cratered primers), and the signs don't seem to be consistent within the same charge weight.

6.5 cases have been fired 4 times, using CCI-BR2's and H-4350, starting at 35.6 gn, working up to 41.5 gn, pushing Hornady 140 ELD-Ms.

The 223 cases have been fired 3 times using CCI 400's and H335, starting at 22.3 gn, working up to 24.3 gn, pushing Hornady 52 BTHP-M.

Both are factory rifles minus stock swaps and are producing sub-MOA groups and decent chronograph data. I'm just wondering if I'm misreading the pressure signs and would like a second (or 50, lol) opinion.

 

[243winxb]

223 cases have been fired 3 times using CCI 400

CCI 400 show pressure @40,000 PSI. If it bothers you, go to a thicker primer cup in a mag primer.

6.5 CM's

Harder to read this primer. Watch for increased bolt lift, after firing.

https://www.thehighroad.org/index.php?media/albums/high-pressure-signs.148/

 

[Mark611]

What is your barrel length on the 6.5mm, what is your seating depth on the bullets, how are you measuring your powder and with what? have you run this ammo over a CHRONY?

 

[Coyotefurharvester]

How are you resizing the brass? How much bolt face/cartridge face clearance? The 400 issue is easy to fix.

 

[JJK]

What is your barrel length on the 6.5mm, what is your seating depth on the bullets, how are you measuring your powder and with what? have you run this ammo over a CHRONY?

The 6.5CM has a 20" 1:8" twist factory barrel, seated to mag length (2.825" COAL). Powder is measured with an FX-120i that I picked up a few months ago, new, and I hold myself to a +/- 0.02 gn tolerance on the charge with a manual trickler (auto trickler V4 ordered and is on the way). Shots were chronographed with a Garmin Xero C1. Best SD was 7.2 with the 41.5 gn charge, 23.2 ES. Worst was the starting 35.6 gn charge with a 17.2 SD and 67.1 ES.

 

[JJK]

How are you resizing the brass? How much bolt face/cartridge face clearance? The 400 issue is easy to fix.

Full-length size with a Hornady match-grade bushing die for the 6.5 CM (223 Rem is a Hornady custom grade die) on a single-stage press. I spot check the brass after sizing with a cartridge gauge, and all seat well there. I don't have an actual headspace measurement, but it passes with the Forster go/no-go gauges I have.

I have some CCI 450's that I will probably make the full switch to for the .223 loads once I've shot the 400's I have left.

 

[Webster]

Chart from Straightshooter1 posted 23 Mar 2021

 

[Webster]

Hello, new to the forum. Looking to get a more seasoned opinion on pressure signs seen in the pics, one batch of 6.5 CM's (Rem700) and a .223 Rem (Ruger American g1) batch. The colors around the primers are from colored Sharpie markers that I use to mark different charges within the lot of 50 rounds. I typically do 5 batches of 10 rounds for load development, with the cases on the left being the starting charges (per Hornady 12th edition) and working up to a step under max charge on the right. I'm curious as to why I'm seeing pressure signs with the low to mid charges (flat & cratered primers), and the signs don't seem to be consistent within the same charge weight.

6.5 cases have been fired 4 times, using CCI-BR2's and H-4350, starting at 35.6 gn, working up to 41.5 gn, pushing Hornady 140 ELD-Ms.

The 223 cases have been fired 3 times using CCI 400's and H335, starting at 22.3 gn, working up to 24.3 gn, pushing Hornady 52 BTHP-M.

Both are factory rifles minus stock swaps and are producing sub-MOA groups and decent chronograph data. I'm just wondering if I'm misreading the pressure signs and would like a second (or 50, lol) opinion.

Been reloading since 1970. I never used CCI 400 primers. Never saw primers that looked like yours. Very flat no sign of ejector swipe. Your 223 loads are under max load in my Berger manual. Like someone else said go to a thicker primer cup. Buy a pk of 100 and give it a try. Don't try to push the loads up, go for accuracy with decent fps. It's a factory rifle for hunting or casual target shooting. Don't get obsessed with SD and ES. Small groups are all that matter. All the powders in my Berger manual for 52 gr bullets give about the same max FPS.

Even though CCI 400 are thinner cups, I would think they would be made to function without getting that flat with normal loads???

 

[Chaotik]

Was there stiff bolt lift?
A shooter at the range last week blanked a primer with a charge he has fired many times. He was getting stiff bolt lift and stuck bolt with his normal loads. His problem was that he had lube (or oil) in the chamber; the case could not expand and the force was transferred back to the case head and blew the primer out. Once he thoroughly cleaned the chamber, removed part of the primer that had lodged under the extractor, and removed a rogue piece of primer hiding in the chamber, the problem did not recur.

 

[JJK]

Been reloading since 1970. I never used CCI 400 primers. Never saw primers that looked like yours. Very flat no sign of ejector swipe. Your 223 loads are under max load in my Berger manual. Like someone else said go to a thicker primer cup. Buy a pk of 100 and give it a try. Don't try to push the loads up, go for accuracy with decent fps. It's a factory rifle for hunting or casual target shooting. Don't get obsessed with SD and ES. Small groups are all that matter. All the powders in my Berger manual for 52 gr bullets give about the same max FPS.

Even though CCI 400 are thinner cups, I would think they would be made to function without getting that flat with normal loads???

Yeah, all the loads are within limits per the book, just trying to find what combo the rifle likes the most. Did you have a bad experience with CCI400's and swore them off, or just never used them at all?

 

[JJK]

Was there stiff bolt lift?
A shooter at the range last week blanked a primer with a charge he has fired many times. He was getting stiff bolt lift and stuck bolt with his normal loads. His problem was that he had lube (or oil) in the chamber; the case could not expand and the force was transferred back to the case head and blew the primer out. Once he thoroughly cleaned the chamber the problem did not recur.

Bolt lift was normal. Both rifles are about to get a deep cleaning, but it's only been maybe 200 rounds since they were cleaned last. I'm going to borescope them first just to make sure there isn't anything crazy going on in there. I don't tend to saturate the barrel/chamber when cleaning is complete either. Usually, patch the barrel down with some isopropyl after cleaning, then just a quick light oil patch to protect it.

 

[Coyotefurharvester]

What cartridge gauge? Have you compared brass fitment with the case gauge to chamber fit(with stripped bolt)?