Max loads, pressure and overall length

[1911 guy]

O.K., here's the skinny. I've got a sweet .308 load that I've been using for a while. 44 grains of Varget over a CCI primer in a milsurp case topped by a Speer 150 grain JSP. Shoots like a champ in my Savage.

Now the problem. I'm going to be out of milsurp brass after a few more reloading cycles. I can get new Winchester brass close to home, but this same load shoots lousy in a Win. case. I'm going with the thought that the slightly thicker brass is giving me a little more pressure and tightening up the groups.

Two solutions I'm thinking of.
One, try bumping up the charge a bit at a time. Pro: Same OAL (2.8 in) Con: More powder used and a lot of monkeying around to get the new measure right.
Two, seat the bullet a few thousandths deeper and try to get the "magic" pressure that way. Pro: Same recipe, slightly different length. Con: This is the biggie. All my manuals say 2.8 is the MIN OAL for this powder. The big question is since I'm not pushing max load (47gr) can I seat 10 or 20 thou more and keep it below unsafe limits?

I know someone out there has a better handle on this than me and I appreciate any responses.

 

[Dave P]

Win cases prolly hold more powder, and therefore need a few tenths more powder to get the same pressure/velocity.

I have case capacity data at home that I can dig up if you want. (measure capacity of fired case by filling with water).

A chrono can be used to compare existing load to new load; load for the same velocity.

Or, plug the data into Quickload, and it can calculate the new load with win cases. Great tool!

Dave

 

[halvey]

Keep adding powder in the Win brass until you get it.

Or, but a Rem 700 and with that combo you have, ANYTHING will shoot great.

 

[Doug b]

Been a long time since I loaded surplus brass. But here goes. Lyman #47 manual says to reduce listed charge data 2gr. for military brass, so by that your load is 1gr. under max. I have to wonder at this point how close to a compressed charge you are as you seem pretty concerned about the seat depth.Vargets max. load with bullet weights from 140 gr. to 155 gr. is 47gr.and is compressed with a win. case. Why not buy the bulk win. brass start at 44gr. and work your way up to a near max. load.A little side note here is the old rule of thumb for loading mil. brass was reduce max.load by 10% and work your way up.That would make you over max.just a little,but the .308 does like it hot right.

 

[halvey]

A little side note here is the old rule of thumb for loading mil. brass was reduce max.load by 10% and work your way up.

Reducing by 10% is for standard brass. You'd need to reduce by 10% of the starting load with mil brass. And, you need to do that on every lot, since mil brass can be a lot different from lot to lot.

 

[Doug b]

I stand corrected,as I said it's been a long time and one should never load from memory.

 

[1911 guy]

Thanks for the responses

It seems the general concensus is to keep the OAL and tinker with the charge. Have to admit I was kinda hoping that would be the case. If anyone is curious, the milsurp brass was all bought in one lot. Spanish or south american origin, 1992 manufacture. Headstamp was "CAVIN" with the "92" 180 degrees from the letters. Been happy with consistancy for a long time, but I'm getting a few no-go's now, so the rest of the lot won't be far behind. Anyway, thanks again. And I learned something else, too. None of my manuals say anything about reducing milsurp brass under starting loads. Makes sense, though.

 

[Ol` Joe]

Changing the charge might get you some improvement, but I think the change in neck tension from military to Winchester has more to do with your accuracy then the pressure of the load. I`ve loads that seem accurate in one brand of brass that just doesn`t seem to measure, up no matter what, when switching to another......JMO

 

[USSR]

O.K., here's the skinny. I've got a sweet .308 load that I've been using for a while. 44 grains of Varget over a CCI primer in a milsurp case topped by a Speer 150 grain JSP. Shoots like a champ in my Savage.

Now the problem. I'm going to be out of milsurp brass after a few more reloading cycles. I can get new Winchester brass close to home, but this same load shoots lousy in a Win. case. I'm going with the thought that the slightly thicker brass is giving me a little more pressure and tightening up the groups.

Two solutions I'm thinking of.
One, try bumping up the charge a bit at a time. Pro: Same OAL (2.8 in) Con: More powder used and a lot of monkeying around to get the new measure right.
Two, seat the bullet a few thousandths deeper and try to get the "magic" pressure that way. Pro: Same recipe, slightly different length. Con: This is the biggie. All my manuals say 2.8 is the MIN OAL for this powder. The big question is since I'm not pushing max load (47gr) can I seat 10 or 20 thou more and keep it below unsafe limits?

I know someone out there has a better handle on this than me and I appreciate any responses.

1911 guy,

You are correct in thinking that you will have to bump up the powder charge when going to Winchester or any other commercial brass. Since Winchester brass is the lightest and has the highest case capacity, it is liable to be 2.0 grains or more. I would start at your milsurp brass powder charge and work your way up. I would discourage you from reducing your COAL. If anything, I would seat the bullet out further to enhance accuracy. I would suggest you get a Stoney Point OAL Guage to determine just how far out your throat is. Chances are, if you have a factory rifle, your magazine length will restrict your COAL well before you reach the throat. With my FN SPR, I seat my bullets to a COAL of 2.845", which feeds thru my magazine and puts the bullet about 0.012" off of the throat. Hope that helps.

Don

 

[MNgoldenbear]

Widener's (www.wideners.com) lists:
UF308WRA
UNFIRED 308CAL MECHANICALLY DEPRIMED WRA67 HEADSTAMP
$ 35.00 PER 500

I assume this is Winchester brass, but should be mil-spec rather than civilian weight.

Also, if you can get hold of some IMI brass, it's also pretty heavy (and consistent). Widener's lists it, but shows they're out.

Regardless of the route you take, changing one of your components will change your results. But hey, isn't that one of the fun thigns about reloading? Time to go search for a new "perfect load". May have to spend hours or days at the range... shooting hundreds of rounds... (sigh) it's a dirty job, and WE GET TO DO IT!! (yay!)

Also just looked on shotgunnews.com under "gun ads" in the "ammunition for sale" category, and they show Cavim loaded ammunition for sale.