Over Pressure Problems, I got 'em

[PinesAndProjectiles]

Heres my story.

Last year I shot the 6.5x47 with Lapua Brass, CCI 450 Primers, Varget and 130 Grain Berger Hybrids with a suppressor off the end of a 22 inch, 8 twist barrel which is a prefit by Shilen.

I bought the barreled Savage action used.

I loaded up some rounds and found that without the can, 36.9 grains shot well.

The can came in and continued shooting the same load.

Loaded up a bunch and shot them up until December of last year.

While doing load development, they shot best jammed.

After shooting a few local matches, I decided that shooting jammed wasn't a good idea.

December came and I decided that it was time to have the barreled action Cerakoted. Brought it to the Cerakoter, and got it back in January. I spoke to them last week, and the guy that did the Cerakote no longer works there, but they don't see a reason that he would have removed the barrel to do the job. (I thought maybe I had a headspace issue.)

Started developing a new load after getting my rifle back.

I started at 36.6 grains, this being lower than what I shot last year, and was showing pressure signs as there were ejector marks on the brass.

OK. Do another test, this time starting at 35.7 grains. Still showing pressure. Primers are still rounded on the edges. The primers do crater, but that's normal for this sloppy Savage and I should have the firing pin hole bushed, but would rather put that money towards a new action. But that will have to wait until funds are available.

Fired a few of the rounds of the 36.9 grains that I had loaded last year, and those showed pressure signs also.

Ordered a set of go, and no go gauges. Everything checks out. I can close the bolt on the go gauge, and the bolt will not close up while trying with the no go gauge.

I seated a bullet into a dummy round, colored the bullet with a Sharpie, and loaded it into the chamber. I can tell that I'm way too long. After removing the dummy round from the chamber, I get a ring all the way around the bullet.

Here is a picture of it.

I am no pro when it comes to reloading, but I've been doing it for a few years so I'm no beginner either. But, this isn't what I expected to see.

I would think that if a bullet is seated too long, I would see a few distinct marks, one from each of the riflings, not a ring all the way around the
bullet.

I did some research and thought that maybe I have a carbon ring inside the chamber. So, yesterday I brought the rifle to the local smith and had him check it out with a bore scope.

He found nothing.

Not sure what to do.

I've thought about loading rounds with some virgin brass and trying again. Ive got plenty on hand, but am reluctant to try them as they are expensive and I don't want to kill them on their first loading.

Berger book shows to load the 130s starting with 32 grains of Varget, and the max load is 35.8 grains. I know that I am well over max recommended charge weights, but also know that Berger data is pretty conservative.

After reading tons of info about the 6.5x47, it seems like 37 grains of Varget is pretty typical in this round and some guys are running closer to 38 grains.

Hopefully my post isn't confusing.

Any insight would be greatly appreciated.



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[PinesAndProjectiles]

I do want to add that I did not chrony any of these loads. I only have a Magnetospeed and it will alter group sizes so I dont check speeds until I find something that looks promising.

Typically, I load five rounds of each charge weight. Not all five rounds would exhibit the pressure signs. Sometimes it is one of the 5, sometimes 2 or 3.

And here is a pic of some ejector marks. They are very subtle, but sill there. Its hard to see, but it is between the "a" on Lapua and the Lapua logo.

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[MachoKing]

Can you catch the mark with a fingernail? No? Load and go. Yes? You have pressure signs.

 

[PinesAndProjectiles]

I can't catch them with a fingernail, but I have a tough time thinking that ejector marks are ok.

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[MachoKing]

If it's just a shiny circle then there's no issue. It's when the brass actually flows into the ejector hole that you know you have an issue. Get a micrometer and measure your unfired cases with your fired cases. There are tutorials on how to do this (I think Hornady has one). This will tell you more of the story and if you are actually over pressure.

 

[djarecke]

That sure looks like a carbon ring to me. Despite what your smith said, I'd have a go at that with some cleaner and a brush. This happened to my brother's 6.5 Creedmoor barrel and it was toast. It formerly shot well and then developed pressure issues with the same load. The carbon ring was the issue, and couldn't be cleaned out.

 

[PinesAndProjectiles]

Which part of the case am I measuring?

1x Fired brass is measuring 1.469 using the Hornady C375 comparator. New brass is 1.466

2x brass is also 1.469



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[MachoKing]

http://www.hodgdonreloading.com/rel...-trick-monitoring-pressure-your-rifle-reloads

 

[BRU15]

An ejector mark by itself is not necessarily an indicator of an overpressure condition, I see absolutely nothing wrong with any of the brass pictured above and would continue to look for a load.

 

[birddogsx3]

Primers flow, primers being "flat", ejector marks are not really a good way to determine over pressure. If the bolt lift is "sticky" or "heavy" then you know you are getting pressure sings. Your head space seems fine if your measurements are correct from above new brass is typically a touch smaller than SAMMI spec. So three thousandths growth is fine. The rings on the bullet is odd and I would have to agree with the above that it's carbon or something else. You should have rifling marks on that not a ring. If you have some blade micrometers you can measure the web of the case and check for expansion there. Find the SAMMI specs for the 6.5x47 or measure several of your fired and resized cases and look for growth there. That is the definitive pressure sign case web growth is no good.

 

[birddogsx3]

I should also include that you have to have mics that will measure a half a thousandth anything above that is to hot.

 

[PinesAndProjectiles]

Thanks Birddog. I am using a Mitutoyo caliper that reads down to .0005"

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[SONIC SAAMI]

As far as the carbon ring goes this is easy to check out. Take a fired case and see if you can drop a bullet through the neck of the case. If you can drop a bullet through a fired case the issue is not a carbon ring.

Carbon ring becomes an issue when the build up of carbon is so great the neck of the case no longer has room to expand. The neck will literally stick the bullet in the case as the cartridges is fired.

 

[birddogsx3]

No problem a tenths mic is far better just depends on how comfortable you are with what you are showing I would be to concerned with that level of pressure. I typically like to keep web growth around 3/10ths. I am also not a speed chaser I miss left to right far more than I miss top to bottom.

 

[PinesAndProjectiles]

As far as the carbon ring goes this is easy to check out. Take a fired case and see if you can drop a bullet through the neck of the case. If you can drop a bullet through a fired case the issue is not a carbon ring.

Carbon ring becomes an issue when the build up of carbon is so great the neck of the case no longer has room to expand. The neck will literally stick the bullet in the case as the cartridges is fired.

I can drop a new bullet in a fired case with no issues.

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[lash]

An ejector mark by itself is not necessarily an indicator of an overpressure condition, I see absolutely nothing wrong with any of the brass pictured above and would continue to look for a load.

^This^

First, to address your light swipe, Check your shoulder to base of cartridge measurement. It looks to me that you are neck sizing only, which is not a bad thing, but eventually all brass needs to have the shoulder bumped back about 0.002" from that of a fired case. Otherwise, you can get that swipe mark while loading and bringing the bolt down into battery. I've especially noticed that issue with my Savage if I haven't full length sized. It does not create nor necessarily mean that you have pressure. The primers are not flattened at all and I would bet that if/when you measure the diameter of a loaded vs. fired case, that you will not see pressure signs there either.

If this were my situation, I would most definitely be looking into the cause of that round ring mark on the projectile though.

On a slightly different note, I think that it would behoove more people to pay attention to what is happening with their cases while they do load development. The fact that you are concerned at least shows that you are paying attention, unlike whoever it was that shot these rounds that I saw in the brass bucket at the local range yesterday:



Now THAT is some ejector swipe, along with brass extrusion into the ejector hole and case rim damage where the ejector ripped through and the case probably had to be manually removed. Yet, this dough-head obviously kept shooting the same load up to 5 times with the same results each time. I'm just glad that I wasn't there in case he kept going. This guy was obviously seeing (or not seeing) pressure long before he got to this load of 43.5 grains of whatever. I'm sure that his bolt face looks like the craters of the moon after this session.

Another pic, showing the case head damage:

 

[birddogsx3]

^^^^^^^ That load is insanely to hot. When you have to use a hammer to open your bolt and eject a case might want to reconsider your load development practice. It might just be the light but they all definitely look like they have some web expansion. If you can visually see that you are damn lucky they didn't separate. If you see that fellow again be sure to head the other direction and get your phone out for video.

 

[lash]

I agree 100% with you. I am not sure if I saw the fellow or not. It may have been one of the two guys leaving when we pulled up to set up steel and targets. I happened to look down into the brass bucket and one of those nasty blown out primer pockets stared back up at me. That got my attention and I pulled out the others because I could hardly believe that someone would continue shooting after anything even close to this came out of the rifle.

I remember when Greg from Primal did some testing to show everyone what pressure signs look like, but I'm pretty sure that even he would never willingly subject his rifle to that kind of abuse. That's why I lined them up and took a picture. I figured it would someday make a good teaching moment without my having to destroy an action of mine to do so.

 

[PinesAndProjectiles]

Thanks lash. I am using a Forster FL die with expander ball. The smith did run a bore scope through the barrel and said he couldn't find anything. I bought a cheap endoscope off of Amazon but it doesnt focus close enough to see whats going on inside the chamber.

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[PinesAndProjectiles]

I found this post and it seems he has the same "ring" on a chambered round. His chamber was cut too short.

Any thoughts?

http://jadeprecision.blogspot.com/2013/04/not-quite-good-day-at-range-problems.html?m=1

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[lash]

The question remains about why this didn't occur before Ceracoating, with your same load and bullet (correct?) Wouldn't a short chamber have showed up already, before you sent off the rifle? Are you using an OAL gage so that you know where you lands are? Reason I ask is that the picture of the round with the marks on the sharpie colored area, does not look seated long at all. I fact, I would consider that seated short as compared to what I load to and others I've seen.

It may well be that you will need to have a gunsmith run that reamer a bit to lengthen the freebore before the lands. But that does not answer why you seemingly had no problem before now.

 

[jwood1284]

I just encountered the same problem shooting 130gr OTM AR hybrids out of my 6.5x47. When I finally realized the bullets were either jamming, or being pushed pack upon chambering I thought it may have been short-chambered. One call to my gunsmith and he confirmed that his 6.5x47 reamer was ground for 130-140gr VLDs and that an OTM would not be able to set out very far, 2.605" COAL to be exact! I now have 500 130gr VLDs on the way and get to start my load development over.

See if you can contact the person that chambered the barrel and get the reamer specs. It will save you a lot of troubleshooting.

 

[PinesAndProjectiles]

Thanks jwood. I bought the rifle used and I believe the barrel was a prefit. Not sure if I will be able to track down that info. I was thinking of doing a chamber cast.

 

[Holliday]

If it's just a shiny circle then there's no issue. It's when the brass actually flows into the ejector hole that you know you have an issue. Get a micrometer and measure your unfired cases with your fired cases. There are tutorials on how to do this (I think Hornady has one). This will tell you more of the story and if you are actually over pressure.

I did not know this! I get occasional shiney marks but nothing else so I have not worried about them......thx!

 

[jsthntn247]

Land marks on the bullet because the bullet is jammed in them and a throat that is too tight are too completely different issues. When finding my lands with a hornady modified case and the stony point tool (now made by hornady) I can feel the bullet pass through the throat then engage in the lands. The throat is just barely bigger than the bullet but tight enough to feel a slight resistance until the bullet passes through then engages the lands. If you are getting a ring around the entire bullet, it's not land marks, your throat (freebore diameter) is too small and your bullet can't get through it to reach the lands. If that's a factory Savage I'd be sending it back for a rebarrel or a new gun. Look at a reamer print and note how small the diameter of the freebore is, if it's off 1/10th of a cunt hair it's too tight and will cause problems like your seeing.

 

[lash]

That still doesn't explain why this issue didn't exist before, using the same load and bullets.

 

[Gerald Stidham]

My first thought on the ring. The bullet is Boeing spun while touching the lands. The spin I would say is from the opening and closing of the bolt. I could be wrong but that would be my first guess.
I had a pressure problem a few years ago with a 30.06 and turned out to be a error in my brass prep. I didn't trim it enough. Lesson learned. Hope this helps.