Multiple questions on .308 Brass

[character26]

So I’ve been reloading a bit but have just started on .308/7.62 loads. Reloading for a IWI Tavor 7. Already worked out basic loads but I have some concerns and not even sure if I should be concerned about it.

First concern is my brass. There is a big variety on the cases I have. I have a majority of mixed military brass. There is a big difference in case weights which in turn causes internal case size differences. Most of the military is 175-179 grn. But some weigh as much as 185, mostly IVI headstamps. And then I have a small batch of BHS Match that weighs 172.

Because most manuals are listing max loads as compressed for .308 does this play more into safety issues. Should I be sorting my brass by weight with this much differences in case weights. What are signs of over pressurized loads to be watchful for.

I’ll be using either 4064 or mostly Varget and 150 or 168 grn bullets. I’m looking for a consistent load that can be accurate, but can also be reloaded in quantity for safety. What should my goal fps be on an average load?

Might be over thinking this. What are your thoughts. Thanks for any help.

 

[sirhrmechanic]

First, you aren’t looking at loading a precision rifle here… so mixed brass is not going to really affect you.

Second, the last thing you want to be doing is going to Max loads. Especially for a semi.

What you seem to want to do is get a reliable and reasonably accurate shooter. Which you can do with mixed brass and should ideally be done with a load well below max.

Your main concern should be in sizing. Full length and ideally small base die for semi. Pick (or work up to) a load that cycles the gun reliably. It will be nowhere near max.

And pick a bullet weight that will be happy with your barrel twist.

I do t know if Tavor has adjustable gas system, but that can help with cycling on a load you choose.

If you want to really wring all the accuracy out of it… you probably want to buy 500 or 1000 same lot cases. And there is a lot of info here on loading for best result in semi-auto.

But for “plinking” and getting to know your Tavor and making some inexpensive rounds for both… mixed brass is not a massive issue if you do your case prep right. Clean cases. Good sizing. Right OAL. Right (not near max) load for cycling. Right bullet for twist rate.

You will be fine.

Cheers, Sirhr

 

[diggler1833]

So I’ve been reloading a bit but have just started on .308/7.62 loads. Reloading for a IWI Tavor 7. Already worked out basic loads but I have some concerns and not even sure if I should be concerned about it.

First concern is my brass. There is a big variety on the cases I have. I have a majority of mixed military brass. There is a big difference in case weights which in turn causes internal case size differences. Most of the military is 175-179 grn. But some weigh as much as 185, mostly IVI headstamps. And then I have a small batch of BHS Match that weighs 172.

Because most manuals are listing max loads as compressed for .308 does this play more into safety issues. Should I be sorting my brass by weight with this much differences in case weights. What are signs of over pressurized loads to be watchful for.

I’ll be using either 4064 or mostly Varget and 150 or 168 grn bullets. I’m looking for a consistent load that can be accurate, but can also be reloaded in quantity for safety. What should my goal fps be on an average load?

Might be over thinking this. What are your thoughts. Thanks for any help.

I'll second the position on not loading to near max charges on military brass...that stuff is generally very thick. Actually, I'd start much closer to the minimum starting charge, as I know from my experience that IMR-4064 started to show pressure really quickly with my LC military brass myself.

I would definitely sort by headstamp to reduce variation in capacity, not weight.

There is no real correlation between brass weight and internal capacity. Just because you're seeing 4gr difference in case weight doesn't mean that you'll see 4gr difference in capacity etc... When I was doing my H2O capacity test on my 'good' LC LR '12 brass a few years ago I had 3 of the 20 random cases weight about 2gr higher than the others. However their capacity was right in the middle of the sample, not lower like you'd expect. LC LR brass isn't all that good I found out that day too.

For blasting ammo out of a blasting rifle, don't worry about a goal in velocity. We worry about that stuff way too much. It becomes necessary for things like NRL hunter or maybe F-class, but for the average dude is unimportant and much less necessary than having a safe and accurate load. Look for pressure instead. When you see it, reduce by at least a half grain and make that your max that you never go over again.

 

[918v]

There is no real correlation between brass weight and internal capacity. Just because you're seeing 4gr difference in case weight doesn't mean that you'll see 4gr difference in capacity etc...

But there is a difference in capacity. It might not be 1:1 but it’s there and will affect pressure. You can’t load the same charge into a 185 grain case as well as a 172gr case and call it good.

 

[Old Corps 8541]

OP, for peace of mind , I would suggest the following ;
1. Do a search for 1X fired 308 brass and as sirhrmechanic stated above get 500 to 1000 cases. Sizing & trimming makes for a MA winter project. While LC 308 brass will be less expensive, you will probably have problems FL sizing these cases plus you will have to remove the primer crimp. Look for LCLR , FGMM, or other factory brass.
2. Get a case gauge , this will let you know if your FL sizing process is sufficient , or do you need a SB die.
3. go to the "new and improved POS " Hodgdon web site and look at 308 Win.Service Rifle load data , even their MAX data is well below the listed MAX pressure listing for the 308.

 

[character26]

That is exactly what I’m looking for. A measure of accuracy with consistency in mind, while staying at a safe operating level of the rifle. I have to get a chrono, it’s on my short list, but I’m already seeing primers pretty flat at 38.5 of 4064 with 147 grn pills. Gun cycles just fine. I did have issues with it, then SB sized all the brass and it runs fine now. So I’m thinking with the manuals I have to reference for Varget powder, I should shoot for 150 grn. pills at around 2700 fps for accuracy and then 168 grn. pills at around 2500 fps for accuracy. Does that sound too conservative? I figure that should allow for variations and minimal risk of MAX loads. Are there any risks associated with compressed loads I should worry about?

 

[character26]

OP, for peace of mind , I would suggest the following ;
1. Do a search for 1X fired 308 brass and as sirhrmechanic stated above get 500 to 1000 cases. Sizing & trimming makes for a MA winter project. While LC 308 brass will be less expensive, you will probably have problems FL sizing these cases plus you will have to remove the primer crimp. Look for LCLR , FGMM, or other factory brass.
2. Get a case gauge , this will let you know if your FL sizing process is sufficient , or do you need a SB die.
3. go to the "new and improved POS " Hodgdon web site and look at 308 Win.Service Rifle load data , even their MAX data is well below the listed MAX pressure listing for the 308.

Will do sir! I have several good sized lots of the same HS. But do have a large lot of mixed I’m a little worried about.

 

[straightshooter1]

I'll second the position on not loading to near max charges on military brass...that stuff is generally very thick. Actually, I'd start much closer to the minimum starting charge, as I know from my experience that IMR-4064 started to show pressure really quickly with my LC military brass myself.

I would definitely sort by headstamp to reduce variation in capacity, not weight.

There is no real correlation between brass weight and internal capacity. Just because you're seeing 4gr difference in case weight doesn't mean that you'll see 4gr difference in capacity etc... When I was doing my H2O capacity test on my 'good' LC LR '12 brass a few years ago I had 3 of the 20 random cases weight about 2gr higher than the others. However their capacity was right in the middle of the sample, not lower like you'd expect. LC LR brass isn't all that good I found out that day too.

For blasting ammo out of a blasting rifle, don't worry about a goal in velocity. We worry about that stuff way too much. It becomes necessary for things like NRL hunter or maybe F-class, but for the average dude is unimportant and much less necessary than having a safe and accurate load. Look for pressure instead. When you see it, reduce by at least a half grain and make that your max that you never go over again.

Sorry . . . to say that "there is no real correlation between brass weight and internal capacity" just isn't exactly true. Compare a batch of heavy brass and for the most part you'll find in general and most often find they'll have less volume than a batch of the lighter brass. BUT. . . it doesn't always hold true as you can see this in some data from Peterson Cartridge Company. The case weight for Winchester brass compared to the weight of ADG or Alpha brass, there's a definite correlation for their difference in internal volumes.

The best thing to do is to measure a sample of the particular lot of a head stamp to see just what volume you're really dealing with.

 

[diggler1833]

Compare a batch of heavy brass and for the most part you'll find in general and most often find they'll have less volume than a batch of the lighter brass. BUT. . . it doesn't always hold true as you can see this in some data from Peterson Cartridge Company.

That's uhhhh...exactly my point.

Thanks.

 

[sirhrmechanic]

And... you don't need a chrono for a Tavor. Keep it well-below the maximums for reliable feeding. Velocity will take care of itself.

You are probably looking for 'Minute of Duck' (old SH folks will get that)... on a Tavor Semi.

The big thing is to get reliable feeding and if you are shooting 1.5 MOA with mixed brass, you are probably doing fine. And that's ok for plinking.

If you want to go full precision... get some matched brass (I like BHM or FGMM... but I "LOVE" LC after I remove crimp, etc.) and make a round tailored to your Tavor.

But a Chrono for a semi like yours is not needed. Work off load data and your results on target.

Cheers,

Sirhr

 

[smoothy8500]

but I’m already seeing primers pretty flat at 38.5 of 4064 with 147 grn pills.

That may actually be a "false-flattened" primer due to excessive sizing of the case. The case is smaller than the chamber and as it's fired the primer gets squished as the case stretches.

Excessive sizing also promotes early case head failure/rupture as the brass thins.

 

[character26]

And... you don't need a chrono for a Tavor. Keep it well-below the maximums for reliable feeding. Velocity will take care of itself.

You are probably looking for 'Minute of Duck' (old SH folks will get that)... on a Tavor Semi.

The big thing is to get reliable feeding and if you are shooting 1.5 MOA with mixed brass, you are probably doing fine. And that's ok for plinking.

If you want to go full precision... get some matched brass (I like BHM or FGMM... but I "LOVE" LC after I remove crimp, etc.) and make a round tailored to your Tavor.

But a Chrono for a semi like yours is not needed. Work off load data and your results on target.

Cheers,

Sirhr

I definitely understand the phase sir. And I’m getting a better picture of what to try and what to look out for. Lots of homework to do.

 

[character26]

Thank you everyone. I definitely have a better picture of how to proceed and what to look for. I’m it will cut down on the learning curve. Thank you.