Shot my first .308 loads today

[Truth223]

Was a 70 degree day so I made it to the range to shoot up my first .308 test loads. All shot at 100 yards out of a Remington 700 aac-sd 20" barrel in a bell and Carlson a2 stock. Which of these could I work with? I could have shot better but I wasn't taking my time between shots like I should have. Loads are 168gr smk, federal brass, win LR primer, and varget or imr 4895 powder. There were 3 or 4 rounds that Had a flat spot burned onto the bottom of the case. What would cause this? Here are pics of my targets

Varget loads

IMR 4895 loads

Comments or questions?

 

[Bear24]

Is the "burned flat spot" round? It is most likely an ejector mark from your bolt face and it is yelling at you "too much pressure!!!" Post some pics of your brass.

I'm glad you didn't blow yourself up but run it again without the loads that had ejector marks and take your time and shoot as well as you possibly can. It makes a huge difference in load workup.

 

[Truth223]

Is the "burned flat spot" round? It is most likely an ejector mark from your bolt face and it is yelling at you "too much pressure!!!"

I'm glad you didn't blow yourself up but run it again without the loads that had ejector marks and take your time and shoot as well as you possibly can. It makes a huge difference in load workup.

I have that mark on atleast 1 case on all of my varget loads. 2 at 42.1 gr, 2 at 43.3 gr, 1 at 43.8gr and 1 at 44.4 gr.

 

[Bear24]

I have that mark on atleast 1 case on all of my varget loads. 2 at 42.1 gr, 2 at 43.3 gr, 1 at 43.8gr and 1 at 44.4 gr.

Thats odd, Post some pics of your brass with the marks on them

 

[Truth223]

Thats odd, Post some pics of your brass with the marks on them

 

[Bear24]

Do you know which pieces of bras were from which charge?Some of those are some pretty heavy ejector marks. You really shouldn't be getting those other than maybe on your upper end. 42.1 and 43.3 are fairly light loads under the 168 SMK.

With my rifle (FN SPR) I don't get any pressure signs up to 45.3g varget under a 178g BTHP (just for reference)

 

[bjay]

Its from ejector..but some were from med load..mcgyver in me saying is from somethin else

 

[Truth223]

First 5 shots are 42.1 gr Varget, next 5 are 43.3 gr Varget.

 

[wvlapua]

You definitely should not be in that much pressure with those charges. Whats your coal? How far out or into the lands? Make sure your brass is trimmed to saami trim to length. Check neck tension.

 

[Truth223]

You definitely should not be in that much pressure with those charges. Whats your coal? How far out or into the lands? Make sure your brass is trimmed to saami trim to length. Check neck tension.

col is 2.800" ,brass is trimmed with Lee hand trimmer to 2.010

 

[roggom]

Did you have to "cam" your bolt down when you loaded a round into the chamber? Max for 168 SMK is 45.5C and Varget is 46.0C. All of you loads should be below the limit, but LC brass does have less powder capacity. Does look like some ejector marks going on there.

Might try to seat them out further and try to bump your shoulders back at least .002.

 

[Truth223]

Did you have to "cam" your bolt down when you loaded a round into the chamber? Max for 168 SMK is 45.5C and Varget is 46.0C. All of you loads should be below the limit, but LC brass does have less powder capacity. Does look like some ejector marks going on there.

Might try to seat them out further and try to bump your shoulders back at least .002.

What does that mean to bump the shoulders back?

 

[bcrich]

When you full size your brass you are bumping the shoulders back.... For a bolt gun you should bump it no more than .002 to help the brass last longer but fed brass is pretty soft and doesn't have the capacity win, hornady brass does. You'll run into pressure issues quicker with fed brass if you didn't work the load up slowly.

 

[roggom]

Here is a very good tutorial from Hornady. Internal Ballistics - Hornady Manufacturing, Inc

In a nutshell you have a few things going on. The brass you have was most likely once fired, from another rifle. Also the brass you have is 7.62 nato, so it is a good idea to full length size your brass and set up your die to push the shoulder back .002. You will need something like a Wilson case gage, or RCBS precision mic, to obtain this reading. Although I have heard of some guys using a deep well socket in a pinch.

You size your brass enough to chamber freely, then shoot a few rounds. Take that fired case and take a measurement (from the case head to the datum line) . You will then set up your die to push the shoulder back .002 from that reading.

If you have a neck sizing die, you will not be able to bump the shoulder. You will have to get a full lentgh die or body die first. Once the brass is fireformed to your chamber, you can neck size afterwards.

Hope my explanation made sense.

Here is how to use the case gage, yeah they spell it gage.

http://www.youtube.com/watch?v=RuJYpm-qplQ

 

[Bear24]

Did you have to "cam" your bolt down when you loaded a round into the chamber? Max for 168 SMK is 45.5C and Varget is 46.0C. All of you loads should be below the limit, but LC brass does have less powder capacity. Does look like some ejector marks going on there.

Might try to seat them out further and try to bump your shoulders back at least .002.

If I am not mistaken those are "FC" as in FGMM cases and not LC. I use the FC brass in my reloads and I have zero problems in the range that he loaded up.

 

[Truth223]

If I am not mistaken those are "FC" as in FGMM cases and not LC. I use the FC brass in my reloads and I have zero problems in the range that he loaded up.

Would it be safe for me to throw out the marked cases and use the other cases again?

 

[Bear24]

Yes, but I don't think your problem is with your cases. Something is going way wrong here for you to be getting those marks at the mid level powder charges.

 

[UrbanSi]

Extractor marks do usually indicate higher pressures but that depends on the brass vs the pressure.

Does the bolt lift easy?
Is there any problems with extraction...sticky bolt or bits of brass shavings?
How many reloads before the pockets get loose? (not going to apply toy your loads yet I guess)
Did you change lots of ANY of your components? or try other brass?

I would try different brass and if possible use a chronograph.
If you are pushing 168's with IMR-4895 past 2700 FPS you are in pressure zones around 52,000
The Varget loads should be under 2800 with an extra 10K in pressure

Reading primers and brass can be deceiving. Until a chronograph is introduced its still a process of elimination...

 

[Truth223]

Extractor marks do usually indicate higher pressures but that depends on the brass vs the pressure.

Does the bolt lift easy?
Is there any problems with extraction...sticky bolt or bits of brass shavings?
How many reloads before the pockets get loose? (not going to apply toy your loads yet I guess)
Did you change lots of ANY of your components? or try other brass?

I would try different brass and if possible use a chronograph.
If you are pushing 168's with IMR-4895 past 2700 FPS you are in pressure zones around 52,000
The Varget loads should be under 2800 with an extra 10K in pressure

Reading primers and brass can be deceiving. Until a chronograph is introduced its still a process of elimination...

Bolt lifted easy on every round.
Same component lots on every group. Same jug of powder, same box of bullets, and same sleeve of primers.

I have ppu .308 brass I can switch to. Also have some hornady and LC brass but I don't have a way to remove the primer crimp yet.

 

[roggom]

If I am not mistaken those are "FC" as in FGMM cases and not LC. I use the FC brass in my reloads and I have zero problems in the range that he loaded up.

You are correct I misread that, but my point is that if the case it too long the camming action of closing the bolt can cause excessive neck tension and cause a spike in pressure. This is common when using once fired brass and not correctly sizing, or using the same ammo in two rifles and not properly pushing the shoulders back.


I do agree that those loads should not be getting the type of pressure signs OP is experiencing.

 

[RanchhandTCR]

THE AAC-SD has a 1-10 inch twist and it would shoot the 175-180 grain bullets better than the 168 grains.

 

[Truth223]

THE AAC-SD has a 1-10 inch twist and it would shoot the 175-180 grain bullets better than the 168 grains.

I have a box of 175 smk sitting here. Guess I can work up some test loads with those too.

 

[Truth223]

I also have a hornady headspace guage kit, but not sure how to make use of it.

 

[insight3b]

This thread is precisely why I stopped using varget. One lot was really slow and I had to go over max to achieve target velocity and the next lot needed two full grains less to get the same velocity. Varget just plain sucks in lot-to-lot consistency and it looks like you got a fast lot

 

[scissorhands]

Might be obvious, but I gotta ask. How does it handle factory ammo? I cant remember, but does Rem the put serial number on the bolt and the rifle?

 

[JoshcBoucher]

My Varget load is 44.7, behind a 168, out a Remmy 5R. I'd recheck your Mic on case length, get a guage, for chamber length, and the guage to find the lands, with the ogive of your bullet. I use 2 mic's, just to keep them honest. I don't really trust the electronic one that much, but it's faster. I like to "guage" my guns, before I start. They're all a little different. If you can get your hands on some Viht-135, try 37.3 grns., with a 168. It's a "slower" load, with less pressure. But you need to recheck your dimensions, first. Just my 2c. I'm no expert, but I do alright. Still have all my fingers.

 

[Deadshot2]

Varget is a fantastic powder for .308 and from the targets posted I would use the 43.3 gr load if accuracy is your goal. Notice how there is almost NO vertical spread. The Horizontal spread is most likely "shooter".

As for the "Marking" on the case, this often happens when you set your sizing die according to the die makers instructions and don't use a headspace measuring tool or case gauge to set it for the proper shoulder bump. If you size a case so it has too much headspace the case head gets slammed into the bolt face and the impact leaves a horseshoe shaped ejector hole mark. If the case is only sized short enough so the bolt closes easily that's all that's needed, no more.

Get a case gauge or headspace measuring adapter for your caliper. Adjust the die so it only pushes the shoulder back about .002" from what a fired case (from your rifle) measures.

FWIW, the most accurate load for my .308 is 44.4 gr of Varget. Could go faster but not with the same accuracy.

 

[exx1976]

I have a 700 AAC-SD as well, and I get those marks on damn near everything I feed it, from factory ammo to light reloads to midrange reloads. I think it's just a tight chamber. Odd for a factory 700, I know, but.. ?

If you're going to try to work up something with 175 SMKs, mine prefers 44.0 gr under a 175 seated to 2.800". Book max is 45.0, but as always, work up to it.