Pressure signs with low charges

[Coyotefurharvester]

Hornady cartridge gauge or the comparator bushings? And yes are you seating primers below flush with face of cartridge?

 

[JJK]

Hodgdon is showing 40 grains as max on your Creedmoor ingredients.

41.5 gn is the max charge per Hornady 12th edition. I expected some signs with the hot loads; it was the mild loads that caught me off guard.

 

[Kracken McGraw]

41.5 gn is the max charge per Hornady 12th edition. I expected some signs with the hot loads; it was the mild loads that caught me off guard.

I see that too in my new edition. Strange Hodgdon load data is usually on the warm side, might be a interesting question to ask them.

 

[209jones]

My first inclination is leaning towards the CBTD being a bit short and the primers backing out, but not quite enough to do the serious pancake. Used CCI400 in 223 and 218Bee, never had an issue. Never really ran hot loads in either one other than once with L'il Gun in the Bee, no issues there, and they were HOT, 250fps plus over max before they got flat, so, I don't know about 400's not standing up. My 6.5CM brass is all LRP, so, can't comment on them in that.

 

[Mark611]

When I load for my 6.5CM, with 41gns of LR16 using Starline brass, I seat my primers 4k under the head, I mainly shoot the 147gn Hornady ELDM bullets because my barrel likes them, my hand loads are 9k longer than a factory loaded Hornady 147gn ELDM bullet from base to Ogive measurement, I have a long jump in my factory chambered Savage, this is where the node is for my barrel where I want to run it for now, I started it at 10k off the touch of the lands, and worked my way down at 3k increment's and found a few nodes all the way down to -80k off the touch which is where I'm at, at 9k over the factory ammo from base to ogive measurement, this produces a group about the size of a nickel at 100yds, for 5shot groups, I have no pressure signs, nor did I have any from the start, every barrel and every chamber is different, so are bullets, my loads run in the 2730fps range across my CHRONY, there's to many variables to consider when chasing down the signs you are having, you could have a tight bore, improper sizing, seating depth to long, your powder charge is close to max to begin with, the ejector mark tells that, I use 3 powder scales to check my loads before I pour them into a case, I have an A&D HR100AZ Lab scale, backed by an old Redding and a LYMAN M5 both are tuned beam scales to make sure my A&D is correct! I know this is OCD for most folks, but it makes me feel better knowing my powder charges are correct +or- 600ths of a grain, that's my tolerance, I know OCD, you don't want to know about my brass prep, YMMV

 

[ISS]

think SEE*.

* Secondary Explosion Excursion. It's when the charge is light enough to lay across the case and the flame dances across instead of thru the powder charge.

 

[209jones]

think SEE*.

* Secondary Explosion Excursion. It's when the charge is light enough to lay across the case and the flame dances across instead of thru the powder charge.

Only thing that makes me question that thought is as I understand it, SEE is very often associated with ringing a chamber IIRC?

 

[charlie b]

SEE is a controversial subject. Takes a specific powder, load density, and chamber to see it at all. Usually it results in simply a bit higher velocity, not a destructive event. I've experienced it with one specific load out of thousands of reduced loads in pistols and rifles. Lots of people claim it is the reason for a gun being destroyed when the real reason is they double charged (or over charged) a case. Chamber ringing usually occurs when people use fillers incorrectly.

The real problem with lower density loads is large velocity spread. It can be 'fixed' in two ways. Using a filler is the simple way, but, the filler must be done correctly. Visit the Cast Boolit forum for a good lesson on that, especially with bottle neck cartridges. The other way, which was how I approached it, was controlling the orientation of the cartridge when shooting. Tip the cartridge up, lower it slowly for chambering and slowly move it into the chamber. Or, raise the muzzle up at least 45deg, then lower slowly until it is on target. Either way it keeps the powder over the primer.

Using very light charges of fast powders can also easily be done. They are 'designed' to ignite all the powder at once. Great for plinking loads or for a 'squirrel load' when hunting with a big game rifle. 5 to 10gn of a pistol powder.

Primers. Low density and/or low pressure loads create a situation where the initial primer ignition can push the case forward, then powder ignition pushes the case back, flattening the primer a bit. Different charge levels stretch a case body if the pressure is sufficient. When loading cast bullets with large primers I enlarged the flash hole. Small primers did not seem to show this effect.

 

[L.Sherm]

Lower density loads, 400's and 6.5 primers in 223 cases are just a problem waiting to happen.