I could have blew my gun up

[lugerstew]

I learned another reloading lesson a couple days ago.
About a year ago I had some sierra 100g BT spitzer bullets for my 243 that I decided I wasn't all that impressed with their accuracy. So I loaded up 50 of them in some FC brass that I was going to toss after I shot them. I was just going to use these for praire dogs or gun site in.
The load was approaching max at 40g of RL-16. I had loaded these before I replace the barrel on my remington 700 243 win. I had a gunsmith put a new Shaw barrel on after these rounds were loaded. Problem is I set the headspace for -.002 for the old Remington chamber and thought nothing of it.
I had shot about 30 of them in this new Shaw barrel and they seemed to shoot decent, except I always noticed it was slightly difficult to close the bolt. I had experimented with neck sizing before and just assumed these were tight because of that.
Well a couple days ago, my first round at the range was one of these in my new Shaw barrel, I pulled the trigger and it was definitely a good kick and a puff of powder smoke came back through the bolt. It was difficult to open the bolt, but when I did I noticed the primer fell out and there was an ejector mark on the base. I was kind of shocked, so I knew better than to fire any more of these.
I took them home and checked them out, they had the right amount of powder, the COAL had plenty of space in my Shaw barrel, but then I measured the headspacing with a comparator and found out all these rounds the shoulder was about .003 to .005 too far forward, compared with a fire formed round that I use all the time to measure for my Shaw barrel.
Only thing I can think of was when I closed the bolts on these rounds, I was putting a whole lot of neck tension on them, by jamming them too far forward into the chamber and one of them really didn't like that and it let me know by these results. I disassembled all of them.
From now on, when I load up a box of rounds just for shooting and scope site in, I'm going to write on the box which barrel they were sized for!!
I guess I was lucky but stupid.

[std7mag]

I'm not so certain that what you described would cause the issue you described.

I have had issues with Federal brass by not trimming soon enough.

Measure base to end of neck. I'd almost be willing to bet it's long.

[lugerstew]

I forgot to mention that was one of my first checks was that the brass was trimmed enough, all 50 measured from 2.035 to 2.040, even the one that blew the primer out, 2.045 is max.
I also measured the primer pocket, it was about .015 larger than a new primer diameter, I could lay a new primer in there and turn the brass over and it would just fall out.

[nhyrum]

You wouldn't be changing the neck tension on them unless there was some kind of carbon fouling or something reducing the diameter in the chamber at the neck. Having the shoulder a few thou long for the chamber won't change the amount of squeeze on the bullet, but it would change your case capacity, I don't know if it would be enough to actually matter though, but that's not something I'd routinely do.

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[Unclenick]

Not the neck tension, but when an over-length case is forced into a chamber, the chamber can act like a sizing die and can set the shoulder location back by extruding some of the excess shoulder brass up into the neck. That lengthened neck can push the bullet closer to the throat. That will raise pressure.

Loads have to be on the conservative side and usually sized like commercial ammo if you are going to use them in multiple chambers.

[lugerstew]

I guess I may never know what caused that scary event, but yes the round was near max, but I had already shot 30 of the 50 through this gun, also if the brass was extruded out, I'm not sure that would have cause very much overpressure, because that rounds ogive had at least .050 before it contacted the lands.

[Unclenick]

Doesn't sound like it should make a lot of difference, but how much it makes does vary with bullet shape, with more blunt ogives changing it more per inch of insertion. I don't know what your loading density is, but with 30-06, I've seen primers go from round edges to flat and seen velocity jump 80 fps all with the same load of 4895 just by having the powder back over the primer versus forward over the bullet. So a combination of these kinds of things may have been at play. Also, the speed with which you work the bolt can have an effect. Hatcher reported as much a 0.006" shoulder setback in the 30-06 just from having the bolt in an Enfield 1917 worked rapidly, and this was for standard ammunition.

Federal brass has a reputation for primer pockets expanding at what should be safe pressures. I recall one member talking about having a magnum chambering in which Federal's own boxed commercial load would result in a primer falling out on every shot and the brass being useless afterward, of course. But your sticky bolt lift says this was likely to be actual overpressure. Of course, we won't mention loading errors. None of us ever make those.

[nhyrum]

Originally Posted by Unclenick

Federal brass has a reputation for primer pockets expanding at what should be safe pressures. I recall one member talking about having a magnum chambering in which Federal's own boxed commercial load would result in a primer falling out on every shot and the brass being useless afterward, of course. But your sticky bolt lift says this was likely to be actual overpressure. Of course, we won't mention loading errors. None of us ever make those.

I've had that exact experience with Hornady brass/ammo in my 300 rum.

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[TX Nimrod]

… your sticky bolt lift says this was likely to be actual overpressure. Of course, we won't mention loading errors. None of us ever make those….

Actually, stucky bolt lift is usually caused by the case expanding excessively and not springing back once chamber pressure drops. If the brass was soft enough to drop a primer is was soft enough to stick in the chamber, regardless of the chamber pressure. I doubt that a “soft” case was the cause, but then I wasn’t there. Because the OP mentioned a “good kick” when he fired, I am inclined to believe he really did have an excessive pressure event. The most common cause of these is too much/wrong powder…





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[tangolima]

I don't think you can chamber a round if the shoulder is 0.003" to 0.005" too far forward. Your hand is most likely not strong enough to "size" the case down that much. It was an over pressure even.

-TL

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[44 AMP]

Even though the action is the old one, a new barrel can act like a completely different gun. And we all know (or should know) the rule about just sticking a max or near max load into an untested gun....DON'T!

[lugerstew]

Your absolutely right 44AMP, I should have know not to fire these in a new barrel, especially a near max load.
I know these were long compared to my fire formed case that I use diligently to measure all my newly sized brass, and the bolt closed fine with some extra pressure.
I also would have thought an overcharge of powder, but I am very precise when it comes to powder charging, because it is the one step that scares me the most, an OVERCHARGE!.
I consider my powder charging method that I use on every single cartridge in my Rockchucker setup, from 380 pistol and 5 other pistol calibers and my 4 rifle cartridges to be 100% foolproof. I have never overcharged a round in 8 yrs of reloading, because I check every round 4 times each without fail.
I dump a charge in the manual scale pan that is about half a grain light, then I trickle it up to the charge I need. Then it goes directly to a digital scale and is rechecked for the correct charge, if it is over by more than a tenth of a grain then I correct it. I then set it in a loading block and continue to charge and weigh with both scales until I have charged all that are that weight. Then after they are all sitting in the loading block, I get my flashlight and check every one for the heighth of the powder. Then as I pick up each one to seat a bullet, I look inside one more time to see the correct level of powder, then seat the bullet. I know it is probably over cautious, but that is my system and has always been for every single round. So no overcharge, in my mind.
I wonder though, like nhyrum said, about a carbon build up in my chamber, so far I have not figured out a way to completely clean a rifle chamber, and I can see a carbon ring with my borescope. I clean the heck out of the barrel using a bore guide and BoreTech eliminator cleaner, but I feel the chamber doesn't get the cleaning it needs. So if anyone knows of a great way to completely clean a bolt action chamber, I would love to hear it.

[44 AMP]

So if anyone knows of a great way to completely clean a bolt action chamber, I would love to hear it.

Chamber brush.

[hounddawg]

I don't think you can chamber a round if the shoulder is 0.003" to 0.005" too far forward. Your hand is most likely not strong enough to "size" the case down that much. It was an over pressure even.

I agree, no way you could size that case down by closing the bolt unless you used a sledgehammer

[lugerstew]

Well, with two guys on here who have loaded a lot longer than me, telling me I can't close the bolt on the rounds that are .004 further in the shoulder than my fire formed chamber replica, that tells me that my replica is not right.
Maybe I didn't use a stout enough load to make the fireformed round, although, I thought it had to be close, because, if I size a case that is .001 longer than my replica, I can start to feel the extra exertion it takes to close the bolt. At.002 too long is where I draw the line, because it felt pretty darn tight.
When I was neck sizing, at .002 too long, I would do a FL resize again.
Wow, this means for over a year now, when I thought I had set the shoulder back .002, they must have been .003 to .005 setback.
Thanks

[nhyrum]

A fire formed case won't be an exact blueprint of the chamber, the brass does spring back a little, not to mention the shrinkage from cooling. So while the brass might be 3-5 thou longer than the fire formed case, it won't be getting sized in the chamber that much

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[TX Nimrod]

… I wonder though, like nhyrum said, about a carbon build up in my chamber, so far I have not figured out a way to completely clean a rifle chamber, and I can see a carbon ring with my borescope. I clean the heck out of the barrel using a bore guide and BoreTech eliminator cleaner, but I feel the chamber doesn't get the cleaning it needs…

I cannot see how minor carbon buildup in a new barrel which had not shown pressure issues before could cause such a severe overpressure event. We are talking extreme expansion of the case head with a single firing, likely well in excess of 75,000 psi. Even a new barrel with slightly tighter dimensions should not give such excessive pressures, and of course it did not with his other ammunition. If the OP is positive that his charge weight was exactly correct, then Occam’s razor says (kinda) that he used the wrong powder.







.

[Unclenick]

Originally Posted by TXNimrod

Actually, stucky bolt lift is usually caused by the case expanding excessively and not springing back once chamber pressure drops.

The brass can't expand excessively unless the steel around it has first also expanded excessively. Steel is more elastic than brass, so it can spring back more, clamping down on the expanded brass. But the steel expansion is why this is generally considered a pressure sign. Another cause of difficult bolt lift is case head brass flowing into bolt face features (around the extractor if it is not flush with bolt face or isn't a close fit, or flow into the ejector tunnel) so that the bolt is having to scrape or smear the brass flowed into those features to open. This can feel sticky and examining the brass reveals it pretty clearly.

Originally Posted by tangolima

I don't think you can chamber a round if the shoulder is 0.003" to 0.005" too far forward.

Usually, you can. This is why, looking at the SAAMI drawings for many rounds, the maximum head-to-shoulder datum on the case is longer than the minimum chamber headspace. In the case of the 243 Win, the cartridge maximum is +0.004" over chamber minimum and is still considered compatible by SAAMI. The idea is the chamber can absorb some extra brass by virtue of being a little wider than the cartridge, so the brass between the head and shoulder can be squeezed out fatter into that gap by the bolt lugs closing.

[jetinteriorguy]

I bet the problem is the RE16. It’s the only powder I’ve ever used in over 30 years that showed serious over pressure before getting to the midpoint of the appropriate load data.

[lugerstew]

TX Nimrod
I can assure you I didn't load the wrong powder, besides my strict measuring method, it is also my cardinal rule to never have more than one powder out, the one I am using, and only that powder.

[hounddawg]

I don't believe bolt lugs will give enough mechanical advantage to move a shoulder. I have no way to test that, just basing that on experience and common sense

[Joh]

Did you use a factory crimp . I had a problem with that on a 221 fire ball. For me I don't think factory crimp on rifle calibers.

[lugerstew]

No Joh.
These rounds for the 243 for accuracy, I only seat them with about .002 to .005 neck tension. No crimp.

[lugerstew]

My loading bench, doing some berger 95g vld hunting bullets with IMR 4064.

[lugerstew]

Just a quick question, will an AR10 chamber brush work on a remington 700 308 chamber? or will it cause wear or damage?
Bolt action chamber brushes are not that easy to find.