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Old July 12, 2012, 07:58 AM   #1
1stmar
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Excessive pressure from factory cartridges...

I went to the range to sight in a new scope and since I had some old (15 years) factory loads I figured I would use them for sighters. They were federal American eagle 150 gr. When I fired the first shot, I noticed the bolt lift was difficult, I thought it must be a fluke. So I fired another one and it was the same, I looked at the case rim and it had an extractor mark. I always leave a little lube in the barrel after cleaning (just run a wet patch through). Could that have contributed to the excessive pressure?
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Old July 12, 2012, 08:34 AM   #2
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Quote:
I always leave a little lube in the barrel after cleaning (just run a wet patch through).
Could that have contributed to the excessive pressure?
Just the opposite. My first shots/clean/light-lubed barrel are usually 20-40fps slower because
fouling has not yet impeded bullet acceleration. -- i.e., I'm running lower pressure.

If you have an extractor burnish, you are running 70,000+psi. What was the temperature?
(and what was the cartridge?)
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Old July 12, 2012, 08:42 AM   #3
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It was hot, probably 90ish. I fired reloads afterwards, no issue with those. 57gr of imr4350
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Old July 12, 2012, 12:16 PM   #4
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If you had lube in the chamber it could prevent the case from gripping the chamber wall so that it came back hard against the bolt causing the pressure signs you got. Not sure that explains the hard extraction though.
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Old July 12, 2012, 12:53 PM   #5
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I don't typically lube the chamber but there could have been some residue from the patch running through it. I'm going back tomorrow , can clean the chamber ahead of time. What's the conventional wisdom, these things ok for firing? I have never heard of powder changing its properties over time, especially in a sealed container (cartridge) where humidity would not effect it.
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Old July 12, 2012, 01:08 PM   #6
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Federal is notorious for overly soft brass that will do these kinds of things even with starting loads.

After trying to load Federal brass for 3 different cartridges, and having problems with all 3, I simply won't waste my time with their products.

Sent from HenseMod6.
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Old July 12, 2012, 02:25 PM   #7
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Powder certainly degrades over time but it's lifespan should be measured in decades, at least, with proper storage.

If there was enough lube in that chamber to provide that kind of bolt thrust, I'd say those cases would have to be well oiled when they came out. If they weren't, it's not a lube problem.

"Lube" is a relative term, anyway. Most lube are not meant to function at 60,000psi. Just because you got a little oil in there doesn't mean it works as a lube above 7-10,000 psi.

I always run a lubed patch through my chamber/barrel when I clean my guns. I've never had a problem anything like you describe.
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Old July 12, 2012, 03:52 PM   #8
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I vote for a factory max load right at the border, temperature effects that pushed it even closer to that rated edge,
and soft Federal brass that began to flow at slightly lower pressures than normal.

(postscript) bolt thrust even with well-oiled cases would be only a fraction of the pressure required to cause actual brass flow.
See http://www.varmintal.com/a243zold.htm
243 Win bolt thrust goes from 4,400lbs in a very rough chamber, to only 4,800 lbs in a fully-polished/actually-greased chamber

Last edited by mehavey; July 12, 2012 at 04:04 PM.
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Old July 12, 2012, 08:55 PM   #9
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Were the unfired rounds sitting in the sun or a closed car before you fired them? That might have caused high pressure.

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Old July 12, 2012, 09:26 PM   #10
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They were in my trunk for transit from my house to the range. It's seven miles, 10 min. Then unload the gear, maybe another 5-10. It's possible, but it was early in the morning, 10am, when I started to load up and head to the range. I'm not ruling it out, seems like a small window. I'm going try 1 more round and see.
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Old July 13, 2012, 11:01 AM   #11
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15 years may have allowed for some corrosion bonding between the bullets and brass. It's not uncommon for aged bullets to be harder to pull. That raises starting pressure. If you are a reloader, you can try seating the bullets in a tiny bit, like a hundredth of an inch or two to break any such bond, then see what happens.
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Old July 13, 2012, 11:56 AM   #12
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Wet oil in a bore will increase the resistance to passage of a rapidly moving bullet. What most 'fouling' shots do is remove that oil. It's much better for both accuracy and reduced carbon fouling if we remove any oily residue before firing.

I use a Hoppe's wet patch to dissolve and remove any dried oil and follow that with enough dry patches to totally wipe the bore out before shooting. My first shots typically land in the group, which is VERY nice for hunting!
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Old July 13, 2012, 12:01 PM   #13
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An alternative suggested in a Precision Shooting article some years ago is to use a synthetic oil. Slip 2000's gun oil was the one covered in that instance. Its vapor and burning temperatures are much higher than petroleum oils, so you get away from the carbon contribution issue. It needs to be very thin, of course, if you're not going to remove it for firing. Hydraulic pressure comes from a significant thickness being plowed into by the bullet. You can run and oily patch followed by a dry patch to thin it out well.
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Old July 13, 2012, 02:41 PM   #14
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Quote:
15 years may have allowed for some corrosion bonding between the bullets and brass. It's not uncommon for aged bullets to be harder to pull. That raises starting pressure. If you are a reloader, you can try seating the bullets in a tiny bit, like a hundredth of an inch or two to break any such bond, then see what happens
This is what really caused the M1903 blowups with the 1921 Tin Can ammunition. This stuff had tin coatings on the bullets and in time that migrated into the case necks causing a bore obstruction.

The Army ran a cover up blaming the civilians and their practice of greasing their bullets, something of which had been going on for decades without problems, but the real problem was the bore obstruction created by the "cold welding" of tin to the brass case neck.

There are a few M1903's blowup's due to the Tin Can ammunition in Hatcher's Notebook, you have to really look but they are there.

Any delay of bullet release will really spike pressures.
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Old July 13, 2012, 03:12 PM   #15
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15 years is a long time to have ammo laying around and trying to figure for sure if it really is factory are could it be reloads and forgotten after 15 years.
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Old July 13, 2012, 05:38 PM   #16
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15 years does not sound that old for ammo to me. Was the ammo stored in a climate controlled place? If it were for the 15 years left in somewhere exposed to a lot of heat. Then it could possibly have compromised it. Though I would say that is doubtful.

I have quite a bit of R-P CoreLokt that are older than I am. Grampa from what I remember bought it in the mid 1960's from a hardware store that was closing down. It was stored in semi climate controlled conditions. I still hunt with it due to the fact that it still works the same as it always has. I have fired in in quite a few guns with no problems. In fact I have all of the fired brass for if I decide to reload for it I have the brass. Though I have five thousand more rounds to go before I will consider it.
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Old July 13, 2012, 05:57 PM   #17
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It was not a climate controlled environment. I'm confident they weren't reloads, primer color is gold not silver. Coincidently, I have some rp corelokt still as well. I shot some of those as well, no issues. Storage and age was about the same.
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Old July 13, 2012, 06:52 PM   #18
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Just check, each of the 3 fired rounds had extractor marks. I pulled the bullet from one of the cartridges, 2 whacks with a hammer bullet came lose. I don't see anything noticeable.
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Old July 14, 2012, 07:34 AM   #19
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If that's the case and every round showed the problem, then cold bonded bullets don't seem likely to be the issue. You are then really down to one of two things: either soft Federal soft brass syndrome, or actual overpressure.

Dan Newberry flat out considers Federal brass unsuitable for reloading because of the softness. I've used it successfully in .308, but with very moderate loads. It doesn't really like running much over 45,000 psi if you expect to get any life out of it, though. In some chamberings Federal factory ammo is known to eject with loose primer pockets just from that first firing, at which point it's done. One classic sign you are reloading too warm for the brass is the primer pockets getting loose in fewer than five firings, so Federal runs warmer than is good for their own brass in some instances, and you may have found one.

Sticky bolt lift can be due to stretching steel at excessive pressure, so that it lets the brass expand beyond its elastic limit, then snaps down on it making a tight clamp fit. But soft brass mimics that by being less elastic than normal brass, flowing out and not springing back as much, also resulting in a fairly tight fit even at pressures that don't over stress the gun steel. As an example, one board member had some old military brass that someone had apparently annealed in an oven instead of just at the necks (a big no-no, as the heads have to remain work hardened the way they come off the forming dies at the factory). Loads that should have been in the 40 grain range he could only load to about 32 grains before he got sticky bolt lift. The stuff was just flat out flowing tight into the chamber and not springing back normally. I sent him a few new military cases and they worked fine, and the commercial loads he'd tried were fine, so we know it wasn't the gun or his other load components. The old stuff had to be scrapped or used for catsneeze loads.

Bottom line here is to figure out what you should do with this ammo. The only way to know for sure that its the brass and only the brass that is unhappy with the pressures is to measure the pressure. I'm assuming you don't have a Pressure Trace instrument you could use to compare it to other loads in the gun. In that case I would call Federal, give them the lot number and explain the symptom and they will probably want to see and check the ammo. If there's ever been a recall on that lot, they will know, and it's worth finding that out for sure one way or the other. They may also offer to replace it with something newer, though I can't say for sure. In any event, it's good practice to make them aware of the issue.
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Old July 14, 2012, 08:41 AM   #20
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Thanks, I believe you are right. I only have 17 rds left, Ill probably dispose of it. I may pull all the bullets first. First I have heard of fed brass being so soft, good to know as I have a bunch.
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Old July 14, 2012, 08:56 AM   #21
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If you are going to pull all the bullets, then weigh all the powder, toss 5%, then divide the rest evenly among the remaining rounds, then reseat the bullets. That'll take peak pressure down about 10% and will probably clear up the symptoms. You could try the new charge with one round first, just to be sure the problem is gone and that you don't need another 5% reduction. With just 17 rounds left, you don't have enough to adjust the charges for peak accuracy.
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Old July 14, 2012, 10:50 AM   #22
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I tossed the powder, don't know what it is (47.5gr of ball) or how well it held up. Went through and separated all my 30-06 brass, 50% is rp, 10% is win and 40% is fc. I have enough to probably last a life time so I will use the rp and ww first. May never get to the fc. :-).

Thanks for the help
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Old July 14, 2012, 06:50 PM   #23
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Sorry to be late to the party. Now that you have pulled the bullets it is too late to do this with the troublesome ammunition, but it could be instructive to try it with another sample of ammo with similar powder.

Take a couple of rounds and leave them in a refrigerator overnight and take them to the range wrapped up in insulation. Compare velocities of ammo at 90 degrees to ammo that would be around 50 degrees by the time you shoot it.

Good luck.

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Old July 15, 2012, 12:38 PM   #24
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+1 on Slip 2000.
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Old July 15, 2012, 09:33 PM   #25
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Quote:
I tossed the powder, don't know what it is (47.5gr of ball) or how well it held up. Went through and separated all my 30-06 brass, 50% is rp, 10% is win and 40% is fc. I have enough to probably last a life time so I will use the rp and ww first. May never get to the fc. :-).
I have found R-P brass to have the longest case life of any of the major brands, in '06-class cartridges. It should last you a while. ...especially if you neck-size only, or just barely bump the shoulder when full-length sizing.

Definitely avoid FC brass for bottleneck cartridges, if you can. Between the ridiculously hot factory loads and the soft brass, it isn't good for much more than 2-3 loads (if you can even get that much out of it).

And... my personal experience with Federal factory ammo over the last 10-12 years hasn't been too great, anyway. Blown primers and loose primer pockets were common. Twice, I had headspace issues.
In one instance, it was with 8x57mm Mauser ammo that one of my brothers had bought to use in my rifle for a deer hunt. When he noticed that the shoulders were being pushed forward pretty far and that primers were backing out considerably at the same time, he came to me to see if I knew what the problem was. After a few measurements, we had an answer: Federal had formed the brass too short, which resulted in 0.130" headspace. That's one HUNDRED thirty thousandths!
The next, was with some .243 Win ammo, where they had done the opposite: The shoulder was 0.080" too far forward. So, the cartridges couldn't even chamber.
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