Overpressure/flattened primers on factory ammo????

[MarTay6]

I am a novice reloader, but have been studying for a long time, so when I start to reload, I'd be capable- safe- and effective.
I have a new rifle that I just shot for the first time last week- I've been working on getting it together for 2 years... it's a 6.5 Creedmoor, based on a Savage Single Shot Target Action, tuned and trued by Fred- at Sharpshooter Supply, with a Bartlein barrel on it which he installed/headspaced before sending it off to Masterclass Stocks to be fit to a stock.
I shot it for the first time last week, 20 rounds of Hornady 140 Gr A-MAX ammo, to get it sighted in, start getting used to the gun. Have about 200 rounds of Hornady brass, and 4 different high quality bullets to start reloading with.
However, today I inspected the brass I fired last week- again, Hornady factory rounds- and discovered that the primers were seriously flattened. To confirm- again, I'm a novice- I watched a few videos on YouTube that dealt with identifying high pressure condition indications on the primers.
My primers had no rounding whatsoever... they were completely flattened. Definite unsafe pressures according to everything I referenced to.
There were no indications like the bolt sticking- or tough extraction- and the brass itself in around the rim looked perfectly fine. Just the flattened primers.
Is this normal- to find factory ammo too hot???
Thanks for any advice.
Wes

 

[JohnKielly]

It is more likely to find factory ammunition to be somewhat undersized for your chamber which results in sequence:

The firing pin pushes the case forward then fires the round
The primer backs out to take up the space behind the case
The case expands back to fit the chamber causing the primer to "rivet" and flatten out to fill the entire primer pocket.

Works the same if you resize brass beyond what's needed for the chamber's dimensions.

 

[M-61]

It is more likely to find factory ammunition to be somewhat undersized for your chamber which results in sequence:

The firing pin pushes the case forward then fires the round
The primer backs out to take up the space behind the case
The case expands back to fit the chamber causing the primer to "rivet" and flatten out to fill the entire primer pocket.

Works the same if you resize brass beyond what's needed for the chamber's dimensions.

+1..To the above.
It's good that you observed it but I would not agree with you that the you have "factory ammo too hot"

 

[MarTay6]

Well, as I said- I'm a novice- hence the question!!
So I would guess that I'm o.k. shooting factory ammo? And if I'm reloading the same/new Hornady factory brass- how am I supposed to monitor pressures??
Wes

 

[savagedasher]

Being it is a custom gun the free bore could be short. and the chamber is tight. Check a fired case for size. and pull a bullet and check if the bullet is in the lands. Larry

 

[d.id]

The last "factory ammo" rifle I ever fired was a sako 300wsm that flattened primers in factory ammo every time. No problems for hundreds of rounds.
When I switched to hand loads I just neck sized the brass and watched for normal pressure signs and even with full tilt loads it never flattens primers.
P.S. do not buy a chronograph to try and diagnose this issue......one thing has nothing to do with the other.

 

[MagnumManiac]

Severely flattened primers on factory ammo suggests to me that you have an excessive headspace condition, get your headspace checked.
If you can, measure a fired case and compare to an unfired case, this will tell you if you have excessive headspace.
If you FL size that brass, it will most likely pull in 2 on the next firing if you do have excessive headspace.

Cheers.

 

[amlevin]

Severely flattened primers on factory ammo suggests to me that you have an excessive headspace condition, get your headspace checked.
If you can, measure a fired case and compare to an unfired case, this will tell you if you have excessive headspace.
If you FL size that brass, it will most likely pull in 2 on the next firing if you do have excessive headspace.

Cheers.

Or--- His headspace could be perfect and the factory ammo just sized so it will fit in any rifle, even those that have minimum headspace.

Chances are at this once fired brass could be reloaded with the components of an unfired round from the same box (powder, bullet, and pushed out unfired primer), fired in the same rifle after full length sizing (with the die adjusted so it only pushes shoulder back 2-3 thousandths, and ALL pressure signs go away.

Rather than messing with all that, why not just measure the fired case with a "headspace" measuring tool and compare it with an unfired round? Good chance the fired round is just fine and the factory round is a lot shorter at the datum point.

 

[hdbiker1]

Probably not an over pressure issue, but a factory sizing issue. If I were that concerned, I would pull down one of the factory rnds to just a primed piece of brass and fire it. Then look to see if the primer backed out any.

 

[MarTay6]

AMLEVIN- re. your comment

why not just measure the fired case with a "headspace" measuring tool

- what is that??? Not heard of one of those...
Ordering go/no go gauges to double check the headspacing on the gun. I assumed it was set correctly by the builder, now its time to double check.
Go gauges are out of stock everywhere... about 4 weeks to restock. :-[
Wes

 

[gotcha]

I believe AMLEVIN is referring to a CARTRIDGE H/S tool like the Hornady LNL gauge attached to a Caliper as opposed to a CHAMBER H/S tool like go & no-go gauges...................... The Cartridge H/S gauge allows you to measure from a datum point on the shoulder of the case to the base of the case. This allows you to adjust shoulder "bump" in order to set precise clearance in the chamber.............. Also to make comparative measurements between fired & unfired or sized cases.

 

[watercam]

Try 4-DProducts - they rent reamers and gauges. He may have a set for you. $8 for seven days.

 

[MarTay6]

Thanks for the inputs, folks- I appreciate your responses. Found a set of Foster Go/NoGo/Field gauges on eBay, will have them next week. Cancelled the B/O from Midway, will return the other one when it arrives... it already shipped.
Have the Hornady attachment for the calipers, I believe- I'm kind of in a mess- moved last year, just getting settled- trying to get all my reloading things together that I got before I moved/for when I retired!!
Starting to take some measurements....
Wes

 

[MarTay6]

I removed some of the primers from the brass, and I was right... they are indeed slightly flanged.
Wes

 

[searcher]

Amlevin's last comment is sound advice. Use a Hornady headspace guage set (about $40.00 from Sinclair International) and is something (or similar from another manufacturer) you should have as an aid for setting all your sizing dies. It is common to see .010" difference in the base-to-shoulder measurement from new, unfired brass to that of fired brass. The manufacturers need to make the ammo fit about any chamber within specs. Sometimes, that measurement can be so excessive that every primer in any factory ammo will flatten, as will subsequent handloads unless the bullets are jambed into the rifling to allow the case to fully form to the chamber. I have a Ruger M77 in .257 Roberts that flattened all primers in factory ammo and I recently ran a lot of ammo through a Christensen Arms .243 that did the same thing. If, after measuring the differences in shoulder length, the difference is .010" or less, to me, an excessive headspace condition is probably not the issue. I would then run chronograph to see if your velocity is running well over that of factory published specs for your ammo and barrel length, there may very well be a pressure problem using that ammo in your gun. Contrary to popular opinion, all ammo, just because it is factory - is not well-suited to all barrels. Usually though, the problems do tend to be gun-related more so than ammo when it comes to factory ammo and custom barrels. Not always a bad thing f you reload.

 

[MarTay6]

Thanks for all the advice here, folks- I am in the process of studying headspacing- and what happens when a round is fired- how cartridges are measured for both proper sizing and bullet seating. Have the Hornady Lock-N-Load gauge, and am getting the associated parts and pieces to go with it. Am going to send a couple of rounds of my once-fired ammo to Hornady to get set up to use on their measuring device- so that the cartridge will exactly fit my chamber...
Wes

 

[JarheadAZ]

Some of the Hornady factory ammo is loaded to Superformance specs, which not only flattens primers in my guns (a .25-06 included), it even has crimped primers.

If you find crimped primers, you're going to need to remove those crimps. I suggest using a cutter instead of a swage.

Your next step would be to incrementally pressure test the brass and primers with your chosen bullet, stopping once you find enough pressure to partially, but not completely, flatten the primers (leave some roundness in the fired primers). A partially flattened primer informs you that you are nearing max, and might just as well stop there.

Flat primers could be an indication of an excessive charge, or might also indicate that the bullet you're working with may need to be shot with smaller charges. If your comfort level is lacking, it could definitely pay to get some onsite help from a more experienced handloader.

Greg Langelius

 

[hogan]

ALL factory ammo will chamber in a Minimum OAL chamber. That is the Go-Gauge dimension. Go dimension is smallest for factory ammunition spec.

Who knows what Hornady is doing? Maybe a soft primer cup. They do load some pretty hot specialty ctgs. Call them and ask... Might have a bad lot # of ammo...

Shown your casings to your gunsmith?

Fired any other ammo?

If seeing only the flattened primer detail as a pressure sign, have you inspected all your fired cases carefully with a magnifier? Seeing boltface indents on the case itself? Any rings on the cases? Did your scrub the chamber well before intial firing? Cleaned your bore thoroughly also? Need a larger OD brush for your chamber. Maybe there was preservative grease applied? Only one way to be sure. Never shoot a rifle bore that is wet with oil or greased.

Gunsmith and Hornady are your resources to find out what's really going on.

 

[Vinootz]

Go to a competent Gun smith

 

[Richard Coody]

After firing you said the rifle cycled normally no sticky bolt? If so you have no problems. I shoot Hornady factory ammo in a couple of my rifles and flattened primers are common. SAAMI spec ammo.

You are headed in the right direction. Learn about headspace. Study what fully fireformed brass is. Try chambering a piece of this fired but unsized brass. If it chambers easily then it isn't fully fireformed. You have the perfect chamber gauge. Your rifles chamber. Saami specs mean nothing to the reloader.

Hornady brass is soft. I have rifles that shoot factory Hornady as good as my reloads. I think that soft brass and the way it conforms to the chamber upon firing is part of that. That said I don't reload Hornady brass. For me it doesn't last long. Rather spend a little more and have brass that last