flat primer question

[WV1951]

First reloads and I have a safety question. As I moved up in loads and still below max.(22.0 to 24.5), the primer indent becomes rough to the touch on the last two loads(5th and 6th rows). Also, I have read about primer flattening and pressure signs. Have looked at a number of pics and not sure if I am getting close to the unsafe side yet. I started below recommended min. and went up in .5 gr increments. I stopped at 24.5 and 26.0 is Hodgdon recommended max. I am using H4895, CCI 400 primers, and 69 gr SMK. 12FV, 26" barell. Approx. .020 off the lands.
I have read that CCI 400 primers can be a bit soft.
I would like to go 25.0 and 25.5, but do not want to operate unsafely. There is no case swiping or any indication of primer piercing, just the rough edge on the primers at 24.0 and 24.5.
The last row on the right is factory Black Hills








http://i55.photobucket.com/albums/g152/mandn1951/IMG_2823_zpsvoqkppcu.jpg[/URL]

http://i55.photobucket.com/albums/g152/mandn1951/IMG_2824_zpszuaagoea.jpg (http://s55.photobucket.com/user/mandn1951/media/IMG_2824_zpszuaagoea.jpg.html)

[Texas10]

What do they look like under 20X magnification? A raised ring around the primer dent? Pull a primer and remove the anvil. Look at the inside of the primer. Do you see a "moat" around the raised primer dent? Your primers still have rounded edges, and do not appear "flattened". They appear to be Federal with 'FC" visible. Are you using brass saved from off the shelf ammo?. American Eagle? Did it have a crimped primer? Good stuff.

Any pressure, low or high is going to try to move the metal cup into the space between the firing pin and hole it protrudes from. If this gap is more than .002, you may see these "classic signs of pressure" beginning to form well below max operating pressures. CCI cups are thicker than WSR and are nickel plated. BR-4 cups are thicker still, and so are CCI 450's.

My 12FV in 223 was experiencing cratering (also called partial blanking) and perforation of the primer (also called blanking) at loads in the mid range of load charts using CCI-400 primers. Upon close investigation I found the firing pin was undersize by .0025 making the gap between the bolt head and firing pin .007. WAY TOO MUCH!

You can pull the firing pin and measure the tip with a micrometer. To measure the hole in the bolt head, you can use a selection of drill bits, carefully measuring the shanks to get a very close idea of the fit to the hole. Or buy or get access to a pin gage set or have your machinist or gunsmith measure it for you.

You can order a firing pin from Savage by signing a release of liability.

You can also have your bolt head bushed to remove excessive clearance. All depends upon how much coin you have available.

Other things that can raise pressures and cause primer issues are seating the bullet too deep in the case, seating the bullet into the lands, using Military brass (which is thicker and therefor has less internal volume), leaving the loaded rounds in a hot environment, or a hot barrel. And about a thousand other things.

Varget or 8208XBR will also work well with that load.

[Zero333]

All you need to know about reading pressure signs is in this link...

https://www.primalrights.com/articles/understanding-pressure

Primers can lie, not always but often enough.

[bigedp51]

Zero333

Thank you for posting that link, I saw it before and forgot to bookmark it.

[WV1951]

Texas10,
Magnification doesn't show any more than a very slight raised crater edge with a little roughness on the raised edge. They are FC from once fired Black Hills factory rounds.
Since all of the other factory rounds I have fired in the past have looked fine, and based on the info in the link that Zero 333 provided(I had previously read), I will try again. I just remembered that the rounds with the small cratering had to be neck bumped with my full length sizing die and I may not have cleaned enough to fully remove the lube. This would be a no-no and could have allowed the case to move in the chamber when fired. The cases with no cratering were neck sized only. With magnification, I see no indication of extractor impression or case wiping. All of the cases look alike. I am going to start at 24.0 again with absolutely clean brass, and go up .1 gr at a time.

Oh, BTW. I also have Varget.

Zero333,
Thanks for the link. I also bookmarked this, although I did read it previously. It is a lot to digest, and a trained eye and experience goes a long way with this information.

My main observation was that the primers did show a bit more flattening than my factory rounds, and I was wondering if this is inherent in CCI 400 primers. I am OCD safety wise, and don't want any surprises.

One more pic that has a little more magnification.
http://i55.photobucket.com/albums/g152/mandn1951/IMG_2838_zpshptvlyfq.jpg (http://s55.photobucket.com/user/mandn1951/media/IMG_2838_zpshptvlyfq.jpg.html)

[gbflyer]

Chronograph is your friend. If you're over speed with any given powder, chances are you're over pressure...or close to being that way.

[wfournier]

I saw similar things with some test loads that were almost identical, 12fv shooting Hornady Custom Comp 69g with varget and cci 400s. Starting loads (per the Lee manual 24g) showed some cratering, I stopped when I got to 25 and had one blank on me. I loaded some more at 23.5g (.5g under the starting load) and they seemed fine but maybe still a touch hot.

My leading guess is that I was off when trying to find the lands and I'm actually in them causing high pressure (I hear people loading 25-26 of varget with 69g bullets all the time). A couple rounds there was a touch of resistance closing the bolt. I tried finding the lands today by using this (https://www.youtube.com/watch?v=Jv-D1mEI514) method but even with the firing pin and ejector removed the bolt on my gun is not slack enough for me to feel confident with that. For the time being I'm planning to load to SAMMI OAL limits and see how that works. I also picked up a chrono but haven't had a chance to shoot since getting it.

[WV1951]

I am pretty sure I have a good measurement to the lands. I made a dummy round, started long while marking the bullet and kept seating deeper until I was off the lands. It ended up being close to my dowel rod measurement. With that said, I have another thread going on about throat diameter. It appears my throat diameter is close enough to .224 that it scrapes on the bullet right next to the case mouth when I chamber. That could be causing a bit of a pressure spike, but that is speculation. You might try the same thing with a dummy round, completely mark the exposed bullet, chamber it and see if you are scraping on the throat.
If I can remember, I'll mock one up, take a pic, and post.

[WV1951]

This is what the freebore is doing to the bullet as I chamber a round. Is it too tight? I dunno. Is this contributing to some extra pressure? Dunno either.

http://i55.photobucket.com/albums/g152/mandn1951/IMG_2863_zpsw3hqmia9.jpg (http://s55.photobucket.com/user/mandn1951/media/IMG_2863_zpsw3hqmia9.jpg.html)

[Scott Evans]

Loose primer pockets will cause SR primers to flatten prematurely. Get a Swage Gauge and check your primer pockets.

[Arky 223]

+
WV that looks like you may have a carbon ring. Was this round hard to remove?

[bigedp51]

Tight throat or oversized bullet or ????
http://forum.accurateshooter.com/threads/tight-throat-or-oversized-bullet-or.3879398/

[WV1951]

Loose primer pockets will cause SR primers to flatten prematurely. Get a Swage Gauge and check your primer pockets.

This is all once fired FC brass and the primers seated quite nicely. I did take notice today that after seating a fresh batch that the CCI 400's do tend to look flatter at the start than my factory rounds.

[WV1951]

+
WV that looks like you may have a carbon ring. Was this round hard to remove?

It is a dummy round I made up just to get the pic. It was no more difficult to remove than any other round. It could be carboned up, but only a couple of hundred rounds down the tube.

I did learn something new today. I inserted a marked up bullet and inserted to the lands and drove in pretty hard. Just straight in and straight out. It did not score the circumference nearly as much, so I am thinking the scoring on the bullet is coming from the bolt rotation as it enters the freebore and maybe a very slightly out of round throat.

[WV1951]

Tight throat or oversized bullet or ????
http://forum.accurateshooter.com/threads/tight-throat-or-oversized-bullet-or.3879398/

That is a great and fair question. These are SMK's and I did check a small sample and they were all absolutely spot on.

[WV1951]

Was able to add some charge by backing off the lands. Primers all look the same as far as flatness is concerned, which I think is ok. I guess it wasn't fair to compare to the Black Hills factory primers. I continue to get cratering and a one near piercing with higher charges seated closer to the lands when doing a ladder. The more I back off, the more charge I can go. Still not close to max charge. Probably moot, because I don't think I can go max anyway without severely compressing the load. Looks like I will be mid charge anyway, so I should be ok.

[Texas10]

Your bullet scoring looks very familiar. Just went through this with a 243 I've been trouble shooting. I took a fire formed case and drill and tapped the flash hole so i could mount it on a segment of cleaning rod. Seated a bullet and slid it up the pipe. It was sticking severely as I tried to retract it, like it was in the lands, but I knew it was not even close.

Long story short, the die I was using was contributing to bullet run out, and that coupled with a chamber that is apparently off axis with the bore by several thousands made it so that if I slid my dummy round into the chamber, it would stick fiercely, but if I rotated it 180 degrees, no stick at all. Apparently that was when the run out of the bullet aligned with the off axis of the chamber. Only took me a month to figure that one out!

Has this rabbit hole no dang bottom?!

[WV1951]

Exact same thing I have experienced. I finally realized that when chambering the the bolt with no round or brass, it slid in and out quite easily. When I added a round, I felt some resistance when rotating the bolt down. I assumed this was reaching the lands. However, I felt the same resistance when chambering a case sans the bullet. What the heck. Pulled the bolt, and on the bottom of the bolt head I could see scoring from the front action screw. Hmmm. I pulled the action screw, and had to file down three separate times before the bolt would clear when rotated to lock it down with empty brass only. This told me that the bolt and throat is not lined up exactly. That would also explain why I thought the throat was undersized, due to the bullet rubbing on the throat when rotating the bolt to closed.
I doubt we are the only ones that have this problem.

[RC20]

Chronograph is your friend. If you're over speed with any given powder, chances are you're over pressure...or close to being that way.

Do not overlook this advice, it is one of the keys. Overpressure should be assess on bolt lift, velocity in excess of load (or a sudden jump) and not primers.

From the looks of it and your load level, it looks like a firing pin related issue.

[RC20]

Has this rabbit hole no dang bottom?!

Good work! Only a month? I have spent literally years hounding down a technical problem (not full time of course).

Its not that there is not a bottom, there are just a lot of them thar holes!