RCBS Dies and 308 brass

[Rafael7RM]

I’ve been reloading for a couple of years all self taught. Read a few books and articles here and there but i have no experts that I could turn to for advise. So I turn to you.

I bought this bag of range fired 308 / 762 brass. It was being reloaded and fired without too much trouble thru my friend’s bolt action 308, although we noticed that some rounds required a little more “force” to get the bolt to lock.

Enter a brand new AR10. The thing locked up every other round and we noticed that the bolt was not completely locking on the chamber. I bought a Hornady case gauge, and confirmed the problem, the brass sticks out of the gauge. I haven’t measured how much.

I went back to the dies and tried to re-adjust them on the press. The problem is that the die is bottoming out on the shell plate. The press is a Hornady progressive lock n load.

Which dies can I get or what can be done to the RCBS dies to try to resolve this issue? I’ve got access to a lathe and thought about “shaving” a little off the bottom of the die to get it to sit lower on the press. Any constructive thoughts or input.

thanks in advance.
Rafael

 

[MOA]

Buy small base dies. They reduce the size of the fired case at the base and have fixed all the 308 AR problems all my friends have had.

 

[Dub]

are the over the maximum case length listed in your reloading manual? may need to be trimmed?

 

[Rafael7RM]

Thanks for the replies so far.

1. Cases are trimmed to length according to the books I have. I’m almost sure the problem is at the shoulder.
2. Never heard of a small base die. Could you expand on the subject while I google it.

Thanks

 

[rsmithsr50]

jus do a search on any die maker and buy a 308 sb die. you should only have to use it the first time USED brass is used in a new rifle. most common with gas guns as they have little closing power.

two most common ar 308 and 223/5.56 followed by 30'06

Thanks for the replies so far.

1. Cases are trimmed to length according to the books I have. I’m almost sure the problem is at the shoulder.
2. Never heard of a small base die. Could you expand on the subject while I google it.

Thanks

 

[Rsadams]

Thanks for the replies so far.

1. Cases are trimmed to length according to the books I have. I’m almost sure the problem is at the shoulder.
2. Never heard of a small base die. Could you expand on the subject while I google it.

Thanks

S/B dies size further down the case than standered full length dies... I use them everytime , setup to bump .003 and have never had a problem and my brass lives a long time... Either the action of the gun beats them up or they get lost long before it's time to scrap them... I also don't shoot range pick ups in rifle unless they have a crimped in primer so I know there once fired...

Don't rune your dies by shaving anything , just buy a set of small base dies and be done with it... If it's an automatic I run small base dies just to be sure of function.... All rifle chambers are different so it's not uncommon for brass fired out of one gun to not fit another exactly like the problem your having....

 

[Michael C]

Just an FYI, RCBS seems to make the smallest small base 308 die on the market as far as sizing the base of the case. It’s inexpensive and a sure fire way to help size down unknown brass. Be careful, improperly sized brass in an AR10 can be dangerous.

 

[Zero333]

Small base die is the best solution because even if you over-cam the standard die and are able to size be base of the brass enough to chamber it, it will inevitably bump the shoulder of the brass too much, thus giving the brass very few life cycles.

So a small base die is the proper solution.

You would not of had this issue if you bought new brass.

The range brass can be military and could of been shot in a military chamber, thus overworking it.
Military semi-auto chambers are very generous and expand the brass more than normal.

 

[Rafael7RM]

Thanks for all the input. Small base RCBS dies have been ordered and should be here next week. It’ll be a while until I can fully confirm the cycling on my AR10 as the local range is closed.

Thanks again.
Rafael

 

[D-4297]

Really solid info on this , Rafael . I would suggest that after getting a few cases "re-sized" with the SB Die , clean them off and check them for "Fit" in your chamber . That way , you can make any adjustments to the die , before running a bunch through the process , and having to re-do them a second time . Measure twice ....cut once .

 

[Rafael7RM]

Really solid info on this , Rafael . I would suggest that after getting a few cases "re-sized" with the SB Die , clean them off and check them for "Fit" in your chamber . That way , you can make any adjustments to the die , before running a bunch through the process , and having to re-do them a second time . Measure twice ....cut once .

Thanks. That was my plan.

Rafael

 

[fm1947]

I’ve been reloading for a couple of years all self taught. Read a few books and articles here and there but i have no experts that I could turn to for advise. So I turn to you.

I bought this bag of range fired 308 / 762 brass. It was being reloaded and fired without too much trouble thru my friend’s bolt action 308, although we noticed that some rounds required a little more “force” to get the bolt to lock.

Enter a brand new AR10. The thing locked up every other round and we noticed that the bolt was not completely locking on the chamber. I bought a Hornady case gauge, and confirmed the problem, the brass sticks out of the gauge. I haven’t measured how much.

I went back to the dies and tried to re-adjust them on the press. The problem is that the die is bottoming out on the shell plate. The press is a Hornady progressive lock n load.

Which dies can I get or what can be done to the RCBS dies to try to resolve this issue? I’ve got access to a lathe and thought about “shaving” a little off the bottom of the die to get it to sit lower on the press. Any constructive thoughts or input.

thanks in advance.
Rafael

What MOA said, small base die

 

[nicholst55]

When you get your SB dies, lube your brass and size, allowing the brass some 'dwell' time in the die (a few seconds). Lower the press ram, rotate the brass 180 degrees, and size it again. Some brass has more springback than others, and for whatever reason, this does work. Some people that reuse machine gun brass for their 7.62mm rifles follow this procedure. Your best bet though, is to scrap your range brass and buy new brass. It doesn't have to be Lapua, but it's always best to start with a known quantity, as it were. You have no idea how many times, or in what, that range brass has been fired before it came to you.

 

[searcher]

I think range brass is fine for general shooting IF it can be ascertained the brass is once-fired. Certain brands might have the primer crimped. If evident, at least you are only dealing with different sized chambers and not how many times it may have been loaded or overloaded. Federal, for example, often puts blue dye/primer sealer dot around the primer. If that blue mark is still visible - you know once-fired. In any event, because there is very high probability some of the chambers the brass were fired in were larger than yours - it takes a short-base sizing die to bring the brass back to "unfired" or undersized dimension to ensure you won't run into these types of problems when loading into your "smaller" chamber. You only need to use the short-base die that one time as a rule. All a short-base die is - is that it has smaller interior dimensions than a regular sizing die at the area which sizes the lower portion of the brass case. The use of which simply sizes your brass to a smaller diameter than a regular sizing die. If you are certain your neck is pushed back far enough and your brass trim-to-length is O.K. - this will likely be your problem. If someone gave you a bag of my used brass - your life could be in your hands when trying to reload it. I destroy mine so no one can try. So pays to be very wary of your source.

 

[jonbearman]

Much of the brass we buy second hand from used brass companys gets fired in machine guns with sloppy chambers for functionality reasons. The first thing I do is tumble them in a pin tumbler(Frankford Arsenal Platnum) to get all the filth off then anneal and then small base size each case and inspect for cracks etc. Then you have to trim to length chamfer inside and out lightly then I ream the crimp out of the primer pockets and uniform each pocket. Once I am through they are almost read to reload after 1 more inspection. Little dings and small dents wont hurt a thing in a bolt gun but an AR-10 should be fed premium ammo and or well prepped and perfect handloads. I don't feed a 2000.00 rifle what ever is on sale , they were built around shooting Federal gold medal match . Take it from there but being a novie could cause your AR to disassemble itself and injury is going to happen. One high primer and if it goes off out battery the gun will blow up. Read up on safe service loads. I only shoot commercial brass out of my AR-10 for that very reason. Not trying to scare you but check out the M1A that is on this sight like a just a few days ago and see what it did to it. A total loss.

 

[searcher]

Not trying to scare you but check out the M1A that is on this sight like a just a few days ago and see what it did to it. A total loss.

Those M1's get blown up fairly frequently by guys shooting single shot mode without a device to slow the bolt down. Makes for good slam fires.

 

[kevinbritvec]

I’ve been reloading for a couple of years all self taught. Read a few books and articles here and there but i have no experts that I could turn to for advise. So I turn to you.

I bought this bag of range fired 308 / 762 brass. It was being reloaded and fired without too much trouble thru my friend’s bolt action 308, although we noticed that some rounds required a little more “force” to get the bolt to lock.

Enter a brand new AR10. The thing locked up every other round and we noticed that the bolt was not completely locking on the chamber. I bought a Hornady case gauge, and confirmed the problem, the brass sticks out of the gauge. I haven’t measured how much.

I went back to the dies and tried to re-adjust them on the press. The problem is that the die is bottoming out on the shell plate. The press is a Hornady progressive lock n load.

Which dies can I get or what can be done to the RCBS dies to try to resolve this issue? I’ve got access to a lathe and thought about “shaving” a little off the bottom of the die to get it to sit lower on the press. Any constructive thoughts or input.

thanks in advance.
Rafael

I own small base dies, better never use them. Standard dies, screwed down far enough works 100% of the time for me. I have gages, I set my shoulder bump to SAAMI minimum (go-gage) -.001". Just touching the shell holder is rarely enough sizing for most rifles. I have to turn the die approximately 1/8 turn past just touching to get the clearance I need.

Hornady's Lock-N-Load system, RCBS micrometers or my favorite, Mo DeFina's micrometers, will give you cartridge headspace measurements in .001" increments. A standard SAAMI go-gage can help insure you have enough clearance for any rifle.

I find that same headspace brass from the same lot number will resize within +/- .001" over a long run of thousands of cases resized. Different brands of brass will resize to a different spec. with the same die setting. You have to watch and adjust your dies as needed, when needed. You can't mix brass, especially military 7.62x51mm with commercial .308 when reloading. They behave differently through the dies and powder charges need to dropped 2.0 grains when loading Lake City or similar brass that weighs close to 180 grains empty and unprimed.

Some lots of Winchester commercial .308 can weigh as little as 155 grains empty and unprimed. That's a full 25 grains lighter than your typical military brass.

 

[kevinbritvec]

I’ve been reloading for a couple of years all self taught. Read a few books and articles here and there but i have no experts that I could turn to for advise. So I turn to you.

I bought this bag of range fired 308 / 762 brass. It was being reloaded and fired without too much trouble thru my friend’s bolt action 308, although we noticed that some rounds required a little more “force” to get the bolt to lock.

Enter a brand new AR10. The thing locked up every other round and we noticed that the bolt was not completely locking on the chamber. I bought a Hornady case gauge, and confirmed the problem, the brass sticks out of the gauge. I haven’t measured how much.

I went back to the dies and tried to re-adjust them on the press. The problem is that the die is bottoming out on the shell plate. The press is a Hornady progressive lock n load.

Which dies can I get or what can be done to the RCBS dies to try to resolve this issue? I’ve got access to a lathe and thought about “shaving” a little off the bottom of the die to get it to sit lower on the press. Any constructive thoughts or input.

thanks in advance.
Rafael

Removing metal from the top of the shell holder is easier than taking it off the bottom of the die. You only need to remove .001" to .003" to gain the extra shoulder bump you seek. I have a local shop use a surface grinder if I don't feel like using emery paper and elbow grease.

Measure the height of your shell holder with your calipers and use a circular sanding motion on a flat surface to take metal off the top. Take .002" off and try to resize some cases with the die turned down a little more.

 

[Shaggy357]

I buy a lot of military once fired brass. Tried making wildcat brass with moderate success. Always had those chambering issues every few rounds. I ordered the small base dies for each type of brass. Problem solved. .308 match brass makes great 260 and 7-08 cases...just have to size with the 308 die first.

 

[Uncle Ed]

You are using range pickup brass fired and formed for another chamber. The problem is after sizing the brass wants to spring back to its fired size, meaning in diameter and shoulder location. With a standard full length die you can try pausing at the top of the ram stroke for 4 or 5 seconds to reduce the amount of brass spring back. And if this does not work then a small base die might work if you can get bump the shoulder back far enough.

NOTE, dies do vary in size, an example I have a Lee full length .223 die that will reduce the case diameter and set the shoulder back more than my RCBS small base die.

On a semi-auto, the resized case should be .003 to .005 smaller in diameter than its fired diameter. This allows the case to spring back from the chamber walls and extract reliably.

I buy bulk once fired Lake City 5.56 and 7.62 brass and size them first using a small base die. This brings the cases back to approximate SAAMI minimum dimensions.

Below three types of Forster .308 dies.

Below is a "FIRED" Lake City case in a Dillon case gauge and the case diameter is keeping the case from dropping all the way into the gauge.

Below is the same "FIRED" case in a JP Enterprise gauge, and this gauge is closer to SAAMI minimum dimensions. And if a resized case drops all the way into this gauge it will chamber in any rifle. Meaning the average drop in case gauge is closer to maximum SAAMI and mostly used to check shoulder location.

Below is a Hornady cartridge case headspace gauge and it allows you to measure the fired case shoulder location. This allows you do set your die for the proper shoulder set back and not push the shoulder back too far.

Below I'm measuring a "fired" case from my AR15 rifle and then the die is set up for .003 shoulder bump.

The bottom line, if you are going to use range pickup brass the Hornady gauge above and a JP Enterprise drop in case gauges will tell you a lot more. I also use the JP Enterprise gauge to plop check my loaded rounds. This ensures the reloaded rounds will chamber in any rifle I have.