How much is too much?(fire forming) Update

[MUP]

I'm experiencing early signs of case head separation in my Ruger Precision Rifle in 6.5 Creedmoor. 2x loaded from factory brass and pronounced ring and groove just above the base. I checked my other fired cases to the shoulder and compared them to some of the factory ammo dimensions and found a difference of between .006"-.008". That seems to me a huge stretch initially for fireforming, isn't it? Anyway, I checked my headspace and it's right at .003" using the primer/bolt method. Part 2 of the story: I've shot some 140 gr ELD-Ms with no issues so far, 3x fired, but the issues I'm having are happening with the 153 gr ATips at Hornady max recommended load data (42.9 gr Hornady Superformance, started mid range and worked up). Am I pushing these too hard, or is the extreme length the brass is stretching at fireforming playing more into this, or a combination of both? Any insight appreciated.

MUP

 

[Brians356]

It's all too easy to assume a prominent expansion ring indicates an incipient head separation. Unless your rifle was chambered by a fly-by-night gunsmith, it's unlikely you've got excessive headspace (as you've determined.) SAAMI spec usually allows for about .008" headspace.
-

 

[MUP]

Definitely case head separation, nearly in two pieces this morning on the first shot. Stopped immediately. I could just about twist the case the rest of the way apart by hand, that's how pronounced it is. What I'm left wondering is, with headspace determined to be .003", within reasonable spec, is this just a case of too much case stretch initially from the factory ammo I'm shooting to obtain cases to load, or am I over charged for the 153 gr ATip? Or maybe a combination of both? I was at 2450 fps at the muzzle, well under what Hornady calls out for that load, IIRC close to 2650.

 

[MUP]

This is the load data pdf I'm going off of.

 

[Brians356]

Definitely case head separation, nearly in two pieces this morning on the first shot. Stopped immediately. I could just about twist the case the rest of the way apart by hand, that's how pronounced it is. What I'm left wondering is, with headspace determined to be .003", within reasonable spec, is this just a case of too much case stretch initially from the factory ammo I'm shooting to obtain cases to load, or am I over charged for the 153 gr ATip? Or maybe a combination of both? I was at 2450 fps at the muzzle, well under what Hornady calls out for that load, IIRC close to 2650.

I'm sure I'm about to be 'splained otherwise, but it'd be news to me that a hot but not crazy load in new cases, in a good chamber, will induce a head separation. A hot Hornady Superformance factory load (if they still sell them) should be just fine in a Ruger rifle.
-
-

 

[Brians356]

This is the load data pdf I'm going off of.

No PDF attached.
-

 

[Webster]

I'm experiencing early signs of case head separation in my Ruger Precision Rifle in 6.5 Creedmoor. 2x loaded from factory brass and pronounced ring and groove just above the base. I checked my other fired cases to the shoulder and compared them to some of the factory ammo dimensions and found a difference of between .006"-.008". That seems to me a huge stretch initially for fireforming, isn't it? Anyway, I checked my headspace and it's right at .003" using the primer/bolt method. Part 2 of the story: I've shot some 140 gr ELD-Ms with no issues so far, 3x fired, but the issues I'm having are happening with the 153 gr ATips at Hornady max recommended load data (42.9 gr Hornady Superformance, started mid range and worked up). Am I pushing these too hard, or is the extreme length the brass is stretching at fireforming playing more into this, or a combination of both? Any insight appreciated.

MUP

I alway jam 0.010" into the lands when FF to ensure the case head is against the bolt face.

 

[MUP]

You would think so. I'm just trying to find out what caused this one. This rifle has less than 100 rounds fired from it. I'm pretty sure it has to do with my loads using the 153 gr ATips, as I've shot 40 or so Hornady Black and elds, along with another 40 handloads using the 140 gr ELD-Ms. The pdf I tried to attach was for 147-153 gr bullets, and shows 42.9 gr Superformance as max load.

 

[MUP]

Sorry guys, it's taking 10 minutes for my reply to post, crappy service here in these hills.

 

[MUP]

The point I'm driving at is, that if the goal to increase loadings per case is by bumping the shoulder back .001"-.002" to keep from working the brass too much, is it feasible that this initial stretching of up to .008" may have been a key factor in these case failures?

 

[Uncle Ed]

The point I'm driving at is, that if the goal to increase loadings per case is by bumping the shoulder back .001"-.002" to keep from working the brass too much, is it feasible that this initial stretching of up to .008" may have been a key factor in these case failures?

I have had new cases over .009 shorter than a GO gauge and did not have any case head separations.

Your problem could be as simple as a bad batch of brass causing the case head separations. Meaning your cases are stretching beyond their elastic limits and this varies between brands and brass composition.

During the 1968 Congressional hearings on the M16 jamming problem, one of the problems was soft brass, and then the brass hardness was increased

 

[K22]

High Pressure issues: Are you experiencing hard bolt lift? Are you seeing ejector imprint on the base of the case? Are you experiencing hard extraction?

However, I don't believe a high pressure load would create a case head separation if your rifle's head space is within SAMMI specs. especially at the number of loadings you stated.

Case Issues:

What is the case head space measurements after firing with the primer removed? Measure at least 5 cases and double check the measurements.

Are all the cases of the same brand / lot?

How are you setting up your FL sizing die and what is your targeted shoulder set back? What are the case measurements after sizing of the 5 cases you checked after firing.

 

[Minshooter]

You would gain useful knowledge from a proper headspace measurement, using headspace gauges.
Pushing primers, comparing shoulder measurements with factory loads, etc., are never going
to guarantee a correct measurement. A chamber cast could also do it, but is much more work.

 

[MUP]

Thanks guys for all this very useful info! My target shoulder bump is .003" at present, so I could potentially back off that number .001" or maybe even try for .001" bump. I will be getting a HS gage to know for certain what the actual HS is, instead of relying on the primer/bolt face method. Yes, all brass is Hornady, from factory ammo first fired in this rifle. I appreciate your time taken to help me address this issue!

ETA: The .003" shoulder bump is consistent after sizing, I normally check every 3 cases.

 

[MUP]

No PDF attached.
-

 

[SmokinJoe]

If you are bumping shoulders back .003 from once fired brass, you may be creating your own headspace problem. I wouldn't advise bumping shoulders back until you have fired the brass enough to start feeling a bit of resistance when opening the bolt, then you know that the brass has reached full chamber size. You can also measure this by using the tape on the head method with once fired brass, adding layers of tape until the bolt shows resistance to closing. Then measure headspace over the taped case and you will have a good idea where you need to be. Another trick to preventing case stretch while FF, in addition to jamming the bullets, is to lubricate the cases with something like Hornady One Shot Cleaner & Libricant, but loads should be more moderate if you are going to do that to prevent excessive bolt thrust.

 

[AlNyhus]

If you are bumping shoulders back .003 from once fired brass, you may be creating your own headspace problem. I wouldn't advise bumping shoulders back until you have fired the brass enough to start feeling a bit of resistance when opening the bolt, then you know that the brass has reached full chamber size. You can also measure this by using the tape on the head method with once fired brass, adding layers of tape until the bolt shows resistance to closing. Then measure headspace over the taped case and you will have a good idea where you need to be. Another trick to preventing case stretch while FF, in addition to jamming the bullets, is to lubricate the cases with something like Hornady One Shot Cleaner & Libricant, but loads should be more moderate if you are going to do that to prevent excessive bolt thrust.

Follow Joe's advice on this...especially the lightly lubing of cases before the first firing.

To start with, get some quality brass like Lapua. And forget using the 'primer' method for setting case bump. Get the Hornady Headspace tool and know where you're at.

Good shootin'. -Al

 

[Richard Coody]

Thanks guys for all this very useful info! My target shoulder bump is .003" at present, so I could potentially back off that number .001" or maybe even try for .001" bump. I will be getting a HS gage to know for certain what the actual HS is, instead of relying on the primer/bolt face method. Yes, all brass is Hornady, from factory ammo first fired in this rifle. I appreciate your time taken to help me address this issue!

ETA: The .003" shoulder bump is consistent after sizing, I normally check every 3 cases.

1 to 2 thousandth bump

Dump the Hornady and buy lapua. Large primer or small primer available

6.5 Creedmoor

Despite a relatively short time on the marketplace, the 6.5 Creedmoor has made a tremendous splash in the field, rapidly becoming one of the most requested cases we hear about from shooters. Lapua’s 6.

www.lapua.com

 

[fatelvis]

Please chime in after you get your No-go gauge and try chambering it. I'm curious to see if your headspace is set correctly.

 

[dellet]

I would measure the new brass before any firings. Not uncommon to have factory brass below minimum length from base to shoulder datum to keep it safe in short chambers.

A high end load that has a max of 61,000 will have a mid range load that is pretty stout.

You mentioned .008” earlier, not sure if it was that much expansion on initial firing or not, but that’s a lot of movement in one firing if it’s at the wrong end of the case.

Lighter initial loads might be helpful if the headspace is excessive due to short brass.