Question Regarding Primer Blanking….

[Texas10]

This a new rifle, less than 200 rounds down the tube. Model 12 FV in 223. Getting primer blanking (piercing) and partial blanking (cratering) even at low pressures. Primers are not flattened.

Also had two FTF but can't rule out shooter slamming the bolt closed a little too hard for the light trigger setting (accutrigger, NOT Target Accutrigger). Non firing rounds were ejected and checked for primer hit. None were noted.

I read that a light striker hit can cause this, not sure why but guess it has to do with not driving the cartridge forward against the shoulder far enough. I decided to disassemble the bolt and remove any excessive preservative oil, on the theory it was causing firing pin to move sluggishly.

I also disassembled the bolt head and used the opportunity to check headspace without the extractor or ejector mucking up the test. Headspace measured .004 using the Scotch tape method ( closed with effort on two layers of tape, would not close on three) with once fired brass (in the subject gun).

Firing pin protrusion measured .055, and Dia. measured .067 with some clearance noted between pin and hole, can't measure exactly.

Rounds that showed the most blanking also shot the tightest groups at 3250 fps using 25.0 gr of IMR3031 and CCI 400 primer, Federal brass from once fired from American Eagle varmint load.

FWIW: I also have a 12 BVSS in 223 and have a box of 100 rounds of this brass that is on its 9 reloading cycle and 100 rounds of new brass on its first reload. All new brass shows partial blanking, with some flattening with same load that older brass shoots with no flattening or partial blanking. I've never experienced a blanked primer in the BVSS.

All brass prepped after initial firing and weight sorted to +- .5 grain.

Any ideas or suggestions would be greatly appreciated


Edited to correct pin dia. measurement

[adammiddagh]

What bullet are you using? Jamming bullets into lands?
My books make it look like any bullet over 50gr is pushing max load.

If you have a little excess slop around the firing pin and are near max, could explain piercing/cratering.
Otherwise I would look for a bur/edge on the firing pin tip.

Firing pin protrusion could be backed down some, but if memory serves, the firing pin normally stops after denting .020-.025" into the primer. Any extra protrusion is normally wasted.

Have you installed a bolt lift kit? The kit adds tension to the fp spring, you could compensate by adding a washer to the BAS equivalent to the height increase of the kit.

As for new vs old brass, you might be noticing a difference in capacity. New would have less than multiple full length sizings with trimming. Just a thought.

The ftf with no primer mark could be a trigger pull dropping and catching on the accutrigger blade. If it had dropped on the bolt close, there would have been no click when pulling the trigger.

Just a few things to think about,
Adam.

PS
I have multiple reloading books I could check, Lee, Hornady, Nosler, Berger, Hodgdons, and Barnes. Plus some cast data.


Edit, I would hate to think it with CCI, but it is possible to get a bad batch of primers.

[Texas10]

Those are some good suggestions, Adam.

Bullet is 53 gr V-max set .020 off lands, but slightly deeper than book COL, which may be part of the problem…too much pressure. Used 1 y/o Hornaday manual for loading information. I'm below book max, but of course every gun is different. I have Nosler and Lee too.
Checked the firing pin with 10X glass at disassembly. Looked fine.
Never FL size brass, only neck size, even the 9th cycle brass shows no growth.
Interesting, about the CCI primers. Can try BR-4 primer, but won't they just mask the issue, assuming there is an issue?

Please tell me more about the bolt lift kit.

The light striker hit theory comes from book 'Metallic Cartridge Handloading' by Mic McPherson

[adammiddagh]

I have never had a batch of bad primers, from anyone, but it is possible. I would bet you could contact CCI with your lot number and see if they are having any issues. I would suspect the cups are the same on the BR4 primers, just a more consistent charge loaded into them.

The bolt lift kit is something that some people add to make lifting the bolt handle smoother/easier. What I use is a 38/357 case head cut off just over the head. I drop it in under the BAS into the firing pin sleeve. The Rim sits on the sleeve. With the primer pocket to the rear, I drop an appropriate size ball bearing into the pocket and add a touch of grease. I add a washer to the BAS to remove the extra tension from the spring. The idea is that instead of rotating the sleeve against the outside of the BAS, you rotate it on the bearing in the center, making it easier. If you have disassembled your bolt, you would notice the extra parts if they were their.

Lee and Hodgdons seem to be using the same data. Hornady is a little hotter. My Hornady 9th Ed lists 2.24" col(ar mag length), max 25.5gr, 3400fps. Lee/Hodgdons list 24.5gr compacted as max at 3260 fps(granted that Lee is listing 53gr jacketed and Hodgdons is listing 53gr Sierra HP).

The Federal 223 brass could have slightly less case capacity than the Winchester cases that the Federal cases you are using. You can google 223 case weights and find average weights of multiple brands and compare to yours. I have been using a rough estimate of 7gr of brass is worth 1 gr of powder. With that said, different brass alloys can weigh different and have the same case capacity(thought it was worth mentioning).

So, with lot differences in powder, case capacity differences, bullet seating differences, primmer differences, and chamber differences; sneaking over max load is possible. Also, the way you weigh your charges could have an effect. If using a digital scale, make sure to calibrate at the start of a loading session and again over time(I am lax, but try to re calibrate every 20 minutes or so). If using volume drop, you could easily end up with +/- .3-.5gr on extreme spreads(when I was doing this, I always dumped the throws back that cut hard).

With that said, I would not think you are up to the point were you should be piercing primers yet.

Where would I start, check with CCI and/or try the other primers. If you still get pierced primers and are confident that you are not over max, I would adjust the front adjustment of the firing pin to a protrusion of .035-.040"(shouldn't change anything noticeable), and possibly back off the rear firing pin adjustment to reduce the amount of distance/tension the spring is pulled back(hit the primers softer, normally I adjust the rear so the retaining pin/side pin will spin freely and not bind in the triangle cut in the bolt body(maximizes travel)).

Hope that helps,
Adam.

PS
Remember that all advice typed at 4am should be taken with a grain of salt.

Edit.
Just a thought, you are full length sizing when you switch brass between barrels, right? A fire formed case may not like a different chamber. If the brass is slightly over-sized/too long for the new chamber, I could imagine the extra force put on the shoulder could pinch the neck slightly tighter than desired.

[Texas10]

Wow, lots to digest there, Adam.

According to what I've read, the CCI BR4 and Magnum primers have thicker cups than standard. I have both of those and notice by strike patterns that they are indeed thicker. However, my issue seems to be a light striker hit so thicker might result in more FTF?

The bolt lift mod sounds interesting, may try that. Is it an available kit/part from Savage?

According to the Hornaday 9th addition, I'm near max however, this charge weight shoots very well out the BVSS. But it's not the same gun so maybe at bit too hot for this gun however, I see no primer flattening going on. Just Blanking. No soot around primer pocket either, except sooty hole in middle. Bolt looks fine. Did find some powder residue on firing pin at disassembly. Charge weight is slightly compressed at the bullet seating depth we're using (book recommended value).

Federal Brass is military grade, so thicker cases and less capacity than WW. All brass is dedicated to the particular gun, never mixed. Won't fit anyway as shot brass out of the BVSS will not chamber adequately in the FV. A bit too tight in the chamber. All brass is sorted by weight at initial cleanup after first firing. Two of the 100 round batches I have are sorted to within .5 grain and this batch is within 1 grain. I also have a batch of 100 Hornaday brass but the weight spread on those is much larger, so I don't use them much. I don't FL size as these are bolt guns. If I ever do notice a firm bolt close, I'll FL size and trim. But so far I've not seen any substantial growth in these cases. All are within +- .001 of base to shoulder size per SAMMI spec. and trimmed with WFT that references off shoulder, not base.

All charges are weighed using a Hornaday balance beam scale to less than .1 grain accuracy. Scale is checked for zero before each use. The particular node we are working on has a fairly large window. The recommended loads for 3200 and 3300 shot the same <1/3 moa groups. We picked 3250 fps as the sweet spot to fine tune the load. Unfortunately I do not have a Chronograph to check actual velocity.

Are there any instructions/videos you can point me to to adjust the firing pin protrusion? I've read .040 to.045 is optimum so this one is set a bit long by those recommendations. It may also help to re-profile the tip.

[darkker]

Otherwise I would look for a bur/edge on the firing pin tip.

Firing pin protrusion could be backed down some, but if memory serves, the firing pin normally stops after denting .020-.025" into the primer.

Some very good possibilities.

Bullet is 53 gr V-max set .020 off lands, but slightly deeper than book COL, which may be part of the problem…too much pressure. Used 1 y/o Hornaday manual for loading information. I'm below book max, but of course every gun is different. I have Nosler and Lee too.

Seating the bullets deeper into the case will not cause increased pressure, it will cause lower pressure. "Book max" is the biggest tripping point most run into. Unless you are using the now very old A-Squared manual, NO ONE lists lot numbers of components tested. Your powder company likely also won't list nominal burning rate variations or BD's. So assuming that your powder has the same burning rate, and therefore you can match book load grains is very foolish. In the newest Norma manual there is a very good discussion on how moisture content will greatly change the burning rate of powder, even from a SEALED container.

I see no primer flattening going on.

Federal Brass is military grade, so thicker cases and less capacity than WW. All brass is sorted by weight at initial cleanup after first firing.

All charges are weighed using a Hornaday balance beam scale to less than .1 grain accuracy. Unfortunately I do not have a Chronograph to check actual velocity.

Looking at the primers is NOT a reliable indicator of pressures, never has been.
The argument about military cases being less capacity in the 223 is mostly hooey. I called all the US makers about 3 years ago now, they all make A case, that can fit multiple applications; not unlike an oil filter for your car, it just gets different headstamps. The next problem is who makes what. Olin(winchester) sold their case business around a decade ago now, and it is all least-cost bidding. So what "their" brass is, is a moving target. Weighing it isn't as helpful as many would want you to believe, as there are many different "recipies" to make it; as was shown in an accurate shooter article not long ago. Same with alloy and heat treat spec, so going back to not reliably reading pressures from brass/primers. If you want to know capacity you need to measure it, not weigh it. However if the mfgr won't tell you what the nominal variance allowed is, what you see may or may not be "ok".

From the only one who does list nominal powder specs(Western), the regular variance of powder BR is something on the order of 5-8%, so chasing grains to the 0.1gr is chasing ghosts. Extruded powder also has it's BR controlled by geometry. So the same "weight" of powder can yield you differing pressures and burning speeds. Having a consistent volume will keep things more in check, and have less aggrevation with case volume differences.

Without a Chronograph, you have no reliable way to know what your pressures truly are. THAT is the inexpensive, reliable way to know. Because most folks use pressure barrels and universal receivers with SAAMI minimum spec dimensions, if you match or exceed book velocity REGARDLESS of grains of powder, you have exceeded book pressure in a mass produced rifle.

This is a now very old chart that I have seen multiple times and places. I *THINK* accurateshooter originally did it, but am not sure who to credit for it.

[Texas10]

Thanks Darkker, been hoping you'd weigh in on this issue. I appreciate any and all advise, Adam has been very helpful, and I know your advice comes from decades of experience.

My issue seems to be a light primer strike, not an overpressure event. The partial blanking, as well as blanking appear on lower pressure loads too, starting at 3100 fps. The powder I am using is from a lot I bought new in Fall of 2014 and have been using ever since. It's properties are fairly familiar to me by now, and I have load recipes on spread sheet with results from then to compare. That being said, this is a new gun showing something I've only read about before. And I recognize that my storage system may not be the best, but I see none of the typical overpressure signs such as flatten primers, loose pockets, stretched cases, hard bolt lift, etc. I have experienced those, but again, not seeing any of that on these loads.

I see another thread about light primer strike on this forum, but it didn't seem to get much traction. Is this a rare event? Again, my diagnosis of light primer strike come from my newly purchased text by Mic McPherson, "Metallic Cartridge Hand loading".

Looking forward to your comments.

PS. I see a chronograph in my future. Barrel mounted type, perhaps.

[darkker]

Thanks Darkker, been hoping you'd weigh in on this issue. I appreciate any and all advise, Adam has been very helpful, and I know your advice comes from decades of experience.

...Suuuure, call me out on how old I am

The underlying issue is the load I think. 25gr of 3031 for a 53gr bullet is currently over Hodgy max, but this really just speaks to the powders actual burning rate again. Until you can verify the actual velocity compared to your data, who knows where you are in the realm of pressure. MZ5 bought a magnetospeed recently, they seem to work quite well. Simply as a comment about them for you to consider, not to sway one way or the other:
On his Predator it caused a very large difference in the POI with and without it attached. The other thing he noticed was that the powder was causing some erosion on it. I believe they sell replacement pieces knowing that it is a consumable, just considerations to consider.
Light or heavy strikes aren't that uncommon, IME with Savage rifles. But since it is very quick and simple to adjust the protrusion, I don't know that it is worth loosing too much sleep over. If you leave the rifle cocked for long periods, you can have the FP spring to take a "set" or "sag", causing low energy and light strikes also.

Again, I'm not soap boxing that people running high pressures are the scourge of the earth, just that what many use as an indicator isn't a reliable thing. Load how you would like to, as long as you understand what is really happening. If you want to KNOW, get a Pressure Trace. If you want a cheap, reliable way of being very close, buy a Chrono and work from the bottom upwards. If you work from the bottom up with any data, then you can see where your powder is compared to what was tested.
We substituted a bullet with VERY different construction(against mfgr warnings), and used middle of the road data. Simply using a chrono on that set, not starting at the bottom will give a false set of security.
The loads showed no "Signs" whatsoever that there was a problem.

[adammiddagh]

You said your ftf had no dent on the primer. That leads me to think that the sear was caught on the accutrigger. So i would almost disregard them.

If you do that, then the cratering and piercing sound like a load issue to me.

i will reread this post afterwork and see if I can add any more.

[Texas10]

We started this load work up using Hornaday 9th addition load data. Their test gun was a Winchester 700, 12 twist, 26 inch barrel. We're shooting a 9 twist 26 inch barrel, so a fairly close match. By comparison, Lee is using an AR15 with 20 inch bbl, and something called a Universal Receiver with a 24 inch, 12 twist barrel. Their load data does not distinguish between the two. We loaded for 5 shot groups, at each powder charge weight.

We started at 22.9 grains of IMR 3031 for a published velocity of 3000 fps. Those primers show partial blanking (cratering). First blanking (piercing) showed at shot #3 at 3300 fps and again at shot #2 at 3350 fps (25.0 gr) and all 5 primers shot at 25.5 gr and 3400 fps were blanked.

We explored a lower node shooting 10 rounds at 3150 fps, 23.8 gr. He (my son) started that set with a very nice 4 shot clover leaf measuring .320 with shot #1 hanging a bit further out. The second group was similar but slightly looser. Again, one shot hanging a bit further out. He's new to shooting so I see this as more an indication of skills/experience, and not so much as load capability.

I don't see any references in his notes about cleaning between groups so barrel fouling may be an issue with group size later in the string. Maybe we need to focus on the lower node. Those primers do show partial blanking, though.

[Nor Cal Mikie]

All brass prepped after inital firing????
Could be something as simple as the shoulders being pushed back too far when the brass is resized, case moving back in the chamber on firing and primers being pierced. Keep it simple!

[adammiddagh]

The cratering and piercing could be unrelated. The cratering can be caused by sloppy fit between firing pin and bolt head. The cratering could be masking the point where you cross the line and start getting pierced primers. I have one gun that leaves cratering on all but starting loads, but has never pierced a primer.

I don't want to sound like a ........
But when 5 shots at published max all have pierced primers, should be a strong indicator that it is too hot.

[adammiddagh]

Here are some pics of a DIY Bolt Lift Kit made from a 38/357 cartridge and small ball bearing.





If you do this, you need to take the additional tension off somewhere. By either shortening the BAS or cocking sleeve; or simply by installing a washer under the BAS.
The extra tension on the firing pin spring shouldn't hurt anything, but makes this modification less effective.

[adammiddagh]

Here is a link with a good description of the firing pin adjustments.

http://www.switchbarrel.com/Spring.htm


Factory likes .055" or so. Most others like .035-.045"
Pay close attention to the last couple of steps were you set travel, make sure the cocking pin has wiggle room when done and not tight to bolt body when decocked.


Also, did you get a chance to investigate if CCI had a bad batch of primers?

Just noticed the difference in twist rate between the guns. Could that account for some pressure difference?

[Texas10]

You're covering it all pretty well, Adam. Lots of good ideas there, I really appreciate your efforts. I like the bolt lift idea and will start work on it. Got lot's of ball bearings laying around. BTW: Nice pics!

Mike, the brass was only neck sized after initial firing in the subject gun. It has never been FL sized, but measures spot on and chambers easily.

We shot again today with two loads, one at 23.5 gr and another at 25.0 which gave us so much trouble last time. Both he and the gun/load shot well, producing impressively small groups, with the lower charge weight shooting the best, so that's the one we'll book for future use.

The hotter load was problematic again. Blanking and something new that I've never seen, a blanked primer that is also dimpled inward. Not flattened, but pushed inward, even on some that weren't also blanked.

All loads exhibited partial blanking, so it looks to me like a case of too large of hole in the bolt head surrounding the striker. Does anyone know if that would be a warranty issue? Or as Adam suggests, a bad batch of CCI primers.

Anyway, I'm going to go with the lower velocity load, and wait to see how other loads shoot before getting too excited about this blanking stuff. I'll also try a BR4 primer and see how that shoots. Son goes back to college now, so I may have to sneek the gun out of the closet to have a "safety meeting" and "test fire" some loads. Wink-wink...

[adammiddagh]

Glad to see you found a direction to look. I cannot take too much credit for the pictures, I just googled them and selected the ones that showed the correct parts.

[Texas10]

Back out at the range with both model 12's Monday. Loaded up for the BVSS using the same load formula that saw all the blanking in the FV, and vise versa, worked up a load using a good BVSS formula using 8208XBR. Brass all dedicated to the rifles, no mixing. Same bullets, same primers, same brass mfg.

BVSS shot the IMR3031 loads perfectly using brass from second cycle and eleventh cycle Federal, and new unfired Winchester ( 3 slightly different loads).

FV still blanked and partially blanked primers even at low pressure/velocity loads. Didn't even shoot the loads within .5 gn of max per Hornaday manual.

Also got one FTF and when I tried to eject that round for inspection, my bolt would rotate only about 10 degrees before it would lock up. Not a stiff bolt, it freely rotated and then came to a hard stop. The round two shots before blanked the primer, so I was thinking a piece of the primer might have interfered with the bolt rotation. A couple of tries, and the bolt opened. I pulled it, and inverted the gun to clear any debris. No further issues with the bolt, but still encountered blanking at further reduced loads.

At home with the bolt on the bench, I pulled it apart and reduced the pin protrusion to .045. Cleaned and lubed it, and reassmebled.

If this doesn't do it, I'm at a loss. All the factory ammo (American Eagle Varmint tipped) shot well with no problems, and I've checked the base to shoulder length of the once shot brass, as well as headspace using the same once shot brass not resized. Measures about .004 to .005.

Could these symptoms be due to a tight bore dimension and too much pressure even at low book loads?

[LongRange]

Try backing the pin off a little more...I run mine at .030-.032...can you post a close up pic of the bolt head with the pin in the fired position?

[Texas10]

I'll work on the pic for you Longrange.

I plan to shoot similar loads at the reduced pin height and see how much difference that makes. And if that doesn't work, I'll reduce it further per your suggestion.

I'll also take the bolt head to a machine shop and pin gage the hole to check clearance to the firing pin. I'm getting a sizable lip on the crater formed during firing.

[LongRange]

You may need to have the hole bushed and the pin turned...Gre-tan rifles does this for $80 bucks but he is 5-8wks out right now...I'm going to have him do 2 bolts for me toward the end of the year.

[adammiddagh]

You may need to replace or bushing the bolt head and pin at this point. With the number of pierced primmers you have had could have erroded the parts a signifigant amount. You will be able to tell when you measure it. I don't know the clearance off the top of my head, but you should be able to find that with a quick search.

[BillPa]

I'm getting a sizable lip on the crater formed during firing.

..and here is one reason why. Two pins.


The tip of the left pin is ground more or less on a taper from the factory which extends ~.030-035" back from it's tip to the shank. On the right a pin I reground to a radius. From it's tip to the shank is about .015".
The same two pins (L-R) set to .020" protrusion in the same junk bolthead or about the maximum a pin will ever indent a primer., most times its in the .016"-.018" range.


Notice the gap between the pin-pin hole on the left and the lack of it with the radiused pin on the right. As I said prior, a pin will never indent a primer cup more then .020" so the pin on the left allows roughly .007" clearance around it and the hole for a primer cup to flow into. Add any chamfering on the edge of the pin hole in the mix the amount of that gap increases.

BTW, Sharpshooter mentioned this issue ten or so years ago. I ain't that there schmart 'nuf to figure this hear stuff out meself!

Bill

[Texas10]

Bill, your post is exactly what i've been thinking of, just couldn't remember where I'd read about re-profiling the pin. Thanks for that tip…pun intended..LOL

[Texas10]

Adam, I tore the bolt down and cleaned everything checking for damage. Launched my extractor ball bearing across the garage, but luckily found it. I think that's the third time now. It found a gap in the baggie I was using to catch all the parts during disasembly, so I ran right out an bought a power ball ticket…he-he.

[LongRange]

Bill, your post is exactly what i've been thinking of, just couldn't remember where I'd read about re-profiling the pin. Thanks for that tip…pun intended..LOL

i did this to my long action pin last night..ill shoot a couple of rounds this weekend and post up how it works out.