Extractor recess flow?

Proutfoo

Proutfoo

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Need some advice folks.

I got a brand new Savage 10TR, has less than 60 rounds through it so far. I have noticed that the chamber dimensions seem quite tight and am working up a load. At the moment I am at 42.1gn of IMR 4064 for a 168gn projectile, 2.800 OAL. If I go longer than 2.810 I can't close the bolt, so I have stayed to 2.800 which is factory length.

I have shot about 40 rounds of Federal Match 168gn to get some brass, and as you can see from the photo, there is a ever so slightly raised or polished area under where the extractor spring protrudes from the bolt face

recess.jpg




the two on the left are my first reloads, and the one on the right is a factory Federal Match.

I am way under max load, but am worried about pressure based on this. And the fact I see this with factory rounds is not reassuring either. Tips?
 
How is the bolt lift when firing your reloads versus the factory ammo?
Reading pressure signs is a bit of an art rather than a science. The fact that you get extractor marks on both factory and reloads tell me that your loads are likely ok. From what I can see of the primers, your reloads show less flow than the factory ammo and the factory looks fine to me. FC brass is quite soft - perhaps you can try RP or Lakecity which should reduce the marks.

I would use different brass and keep an eye on your primers relative to the factory loads and to your bolt "feel" on extraction. You may just have a quirky rifle but be careful until you get more experience with it.
 
Pr589 said:
How is the bolt lift when firing your reloads versus the factory ammo?
Reading pressure signs is a bit of an art rather than a science. The fact that you get extractor marks on both factory and reloads tell me that your loads are likely ok. From what I can see of the primers, your reloads show less flow than the factory ammo and the factory looks fine to me. FC brass is quite soft - perhaps you can try RP or Lakecity which should reduce the marks.

I would use different brass and keep an eye on your primers relative to the factory loads and to your bolt "feel" on extraction. You may just have a quirky rifle but be careful until you get more experience with it.
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thanks for your help. The interesting thing is that the fired, factory cases that show these marks are harder to close even now than my reloads. If I re-chamber the once-fired case, there is a bit of effort (nothing superhuman...) needed to close the bolt whereas the reloads and a bit of Winchester I have FL resized chamber nicely.

On one occasion, with a factory Federal, I had to tap the bolt back as it was sticky. I set aside that case for FL resizing.
 
I find that when using 1X fired FC I have been surprised by how much the cases stretch on the first few firings. How much relief do the extractor marks have? My thinking is that they may be adding to the cartridge length enough that you can feel the additional "crush".

If this is the case, I'd be concerned from an accuracy perspective i.e. non-flat base causing cartridge alignment issues in the chamber. Maybe save your FC brass for a different rifle or if the rifle is new, send it back for a bolt-head swap. If the extractor/extractor cut-out is too deep, this may cause brass flow even at lower pressures.
 
When you have brass flow "into" the ejector you are over pressure, if you do not have a raised bump you do not have brass flow.

Below is a photo from accurateshooter.com taken by a long range competitive shooter. He stated he increases the load until he has brass flow and then backs off 1 or 2 grains. He did this to find the limits of his brass for long range shooting and Lapua makes very hard brass.

marks_zps63d0459a.jpg


I see similar marks as yours on some of my .223 cases fired in my AR15 rifles. This is because brass varies in hardness between brands and Federal is known for having soft brass. So again if the mark on your cases are not raised above the base of the case it is not a sign of excess pressure.


Simple Trick for Monitoring Pressure of Your Rifle Reloads
http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads

How Hard is Your Brass? 5.56 and .223 Rem Base Hardness Tests
http://bulletin.accurateshooter.com/2014/05/how-hard-is-your-brass-5-56-and-223-rem-base-hardness-tests/

TEST RESULTS
Using Rockwell hardness standards (.062″x100kg, Rockwell “B”), the brass measured as follows:

LC 2008 = 96
Lapua 223 Match = 86
Winchester 223 = 69
Remington “R-P” = 49

Later in the reloading forum CatShooter posted more brass hardness tests and Federal ended up as the softest brass.

95% of the brass below in my scrap brass bucket is factory loaded once fired Federal .223 brass with over sized primer pockets.

193natorejects001_zps87560a0a.jpg


Below a bore scope photo of a custom hand lapped barrel.

custom_zps1da8a9ed.jpg


Below a magnified bore scope photo of a button rifled Savage throat and bore.

Throat-1-C-RS_zps60cef129.jpg


6inchesfrommuzzle-2_zps507846d8.jpg


You might try increasing your bullet jump to lower the pressure until the throat breaks in. The "speed bumps" might be a factor until more rounds go down the barrel.

Below, before and after fire lapping a Savage bore.

beforeandafter_zps0cd22899.jpg


firelap_zps159e74ab.jpg
 
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whew thats a lot of info thanks! if there is a raise it is subtle to none. its more of a flat spot really. And there is a chance my reloads show it only because the first firing had it and I didn't notice.

In any case I am going to have to keep checking. I don't have a lot of throat or freebore in this rifle, I measure it past 2.81x but barely, so I planned to imitate factory spec. I picked up a few boxes of Remington and Winchester to try in the rifle tomorrow to compare.
 
so I shot some Winchester and some Remington and a few Sako rounds yesterday. They pretty much all have to varying degrees, very faint flat spots on all the case heads where the extractor spring rod pushes against the case. Is this normal for a new Savage? Somewhat perplexed.

And what is fire-lapping??
 
The solid brass web of a case flows at around 70,000 psi. The smear mark you are getting is a pressure indicator. Brass varies in hardness (Federal being soft) and rifles vary quite a bit in the pressure they generate.

The reliable way to estimate pressure is to Chrony the factory ammo and use that as a speed limit for your handloads. Velocity comes from pressure.

I use a lot of Savage rifles, and I see marks like yours when my pressures are near max.
 
I wouldn't say that the marks that you are seeing are normal for a Savage or any other rifle in my experience. For some reason you are seeing brass flow into the ejector plunger hole and while this is normally a sign of excess pressure. At the same time I don't see any pressure signs in your primers and you have used commercial ammo and mild reloads. I wonder if your barrel or throat is too tight and creating pressure issues?

I'd consider sending it back to the dealer just so that you are not always wondering.

p.s. fire lapping - shooting special abrasive-coated bullets to polish the bore.
 
Proutfoo said:
polished area under where the extractor spring protrudes from the bolt face
Click to expand...

I think you have said it! I don't see any brass flowing into ejector hole like others say. I see a polished area caused by the ejector standing proud of the bolt face. In my humble uneducated opinion, your cartridges are fine. It's your bolt that's defective.
 
I will likely have to take this to a local gunsmith since this rifle was new but I got it from an individual - he had never used it. I think its from SFRC. The overall consensus is that these bald spots on factory loaded brass is caused by pressure? are factory rounds usually loaded to max?
 
is it possible this is a "feature"? I found this https://www.shootersforum.com/handl...s/48039-ejector-marks-even-factory-loads.html

here is a group shot

recess2.jpg



left side is all factory Federal Match, the right three are factory loaded Sako. The winchester brass has some marks but too faint to get reliably in a photo.

that said, upon close inspection with a magnifying glass, the flat spot appears to be embossed into the brass ; not a raised bump but a worn-down spot. So might not be anything other than easier to mark case heads? Still annoyed because I want to reload for this rifle and can't decide if it has an issue or not. Anyone know of a reliable Montreal area gunsmith or somewhere I could mail this rifle to to check headspace?
 
The overall consensus is that these bald spots on factory loaded brass is caused by pressure? are factory rounds usually loaded to max?
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Factory ammo is loaded to a working pressure and hopefully velocity with tested sample large enough to reasonably assure that only a certain percentage that is considered acceptable will be over pressure and then only by an margin that is considered acceptable. Guns also have a safety margin.

The loads, factory or not are too hot. A combination of a tight chamber, rough barrel, warm load in a particularily soft batch of what is widely regarded as the softest brass around or any combination of the above have conspired to get to a high pressure situation. Believe it or not, this is a sign that the system is working. Despite the unwanted and unlikely situation happening, nothing broke and there was room to spare. Nobody got hurt. The system works. That doesn't mean that you should keep doing what you're doing, just that even when the stars all aligned against you its practically a non event. Most people don't even handload and may not have even noticed. Checking or fixing a gun isn't the end of the world. A different batch of ammo may be completely different and that isn't the end of the world either.
 
I have the same rifle.
These rifles have a very short freebore.
With a 175gr bullet I only have 0.010" of freebore.
The chamber is a bit tight but within spec.
 
another question before I ship this off to get looked at....is it normal or acceptable to have rifling marks on a round that is chambered and ejected? I see about 1-2mm of rifling scratches right at the case mouth on the bullet, on some rounds that I chamber and eject without firing.
 
Proutfoo said:
another question before I ship this off to get looked at....is it normal or acceptable to have rifling marks on a round that is chambered and ejected? I see about 1-2mm of rifling scratches right at the case mouth on the bullet, on some rounds that I chamber and eject without firing.
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Then you must be seating your bullets to jam. I would back off a little and measure each time to see where your ogive length is. Then from there you can bump some more to find out what the rifle likes.
 
PitBull1973 said:
Go get the rifle checked out before you fire it again
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I suggest in order:

1. If you have or have access to headspace gauges, check that first. Headspace an a savage is easy if you are equipped and inclined. If not get a smith to confirm for you.

2. Confirm a few factory rounds all close on the chamber fine, with no gouges/cuts/scrapes on the brass. Also check for marks on the bullets when extracting factory rounds. There should be no scrapes on the jacket when you insert and remove factory ammo.You can also take a felt marker and paint any tight factory rounds to see contact points. You should remove the ejector and extractor and firing pin from your bolt first, so you are not getting any interference. There is a lot of feel in these tests.

3. Once a smithy or you have ok'd it safe to fire, next shot should be chronied as recomended previously.

This should say something. Your ejector marks look medium serious, but tight closing bolts are a real concern. You are probably over pressure.
 
Proutfoo said:
I am talking about factory rounds in this case. The rifling marks are on factory, they measure 2.800
Click to expand...

If you are seeing engraving marks on the bullet of factory loaded ammo, there is an issue with throat length. A chamber cast would show this distinctly.
A good 'smith needs to have a look at your rifle. The signs you see on the fired brass are pressure signs, nothing else.
Dave.
 
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