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delbertmccord
I have a question about head-space in a 308. I am loading Starline brass for my AR-10 and will be loading for my M1A soon. My children purchased me this AT-10 (Sig 718 I think) and its a beautiful rifle and shoots great. I do not want to do anything to hurt it.
I am working with a batch of 20 pieces of Starline brass (new when I started) I have fired them 4 times so far. My fired cases show me 1.628 and the M1A show me 1.631 head-space. From what I read I do not want a lot of extra head-space and I am using RCBS Small Base Dies for semi autos. When I size my brass I clean off the lube and measure it and the head-space is all over the place. Most are around 1.625 which is fine but some are as low as 1.620 (threw that one away) and as high as 1.627.
Is this normal? am I just worrying to much? After this firing I annealed them and cut 2 of them open to check the condition of the cases and they were fine no case head separation (Looked bran new).
I know I can not come up to the head-space that the brass is at after firing but how low can it go safely? I want my brass to last but I really do not want to blow up the rifles (or me).
If anyone has the time to educate me I would be thankful I have received some good advice on what bullet to use with what gun over the years and I have read enough post here to think there are some real wise people here.
delbertmccord-
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Mike B.
Ok Lets see where we can start to answer your questions. First of all you noted that you are using a SMALL BASE DIE SET. The Small base die sets are basically designed to size the cartridge case down to insure that the loaded cartridge case will fully chamber into any Semi Auto. That is most probably a whole lot more sizing on the individual cartridge case each time that you use that particular set of sizing dies than might be needed for your individual rifle. They in itself are in addition to resizing the base of the cartridge are most probably moving the shoulder of the fired cartridge case back more than is needed to insure that the loaded cartridge case will fully chamber in any Semi Auto.
SO… How much is needed to insure that the cartridge case is sufficiently sized to insure that your cartridge will basically chamber in any 308 Winchester in the world? For that you can go to the SAAMI specifications and download the pdf of the Rifle Cartridges. You will I believe find the 308 Win Cartridge and Chamber specs on page 122 of that document.
Here is the link to the SAAMI website : https://saami.org/technical-information/cartridge-chamber-drawings/The 308 Win head spaces on the cartridge shoulder which according to the SAAMI specifications is listed as 1.634-007. From that SAAMI dimension drawing one would assume that one has a range from (1.634 to 1.627).
For your Convenience I have attached the scan of page 122 from that document. That should be enough for now to answer the portion of your question on cartridge sizing without going into a doctoral dissertation on the whole loading process…
Thank You for taking the time to reply with all this good information and even links to the drawings. I printed it and saved it. I have a set of Lee Dies I may try them and see what I get. I really do not understand why each case I resize does not have the same head space its all over the place. I just watched a video from a man called the Hornady Reloader and he said the Hornady Comparator is just that its not exact head space figures it just lets you compare it to something else. I have fired over 150 reloads in this rifle so far and no problems but I need to understand what I am doing and not just be lucky.
Thank You again for your great information and your time !
In resizing your 308 Win brass you will I believe want to move the shoulder as little as possible in resizing the cartridge case. Most all of the reloading die instructions state that one must run the sizing die down until the press just cams over the ram. That will give you the maximum amount of sizing that the particular sizing can deliver.
One of the ways to adjust the resizing settings is to back the sizing die off just a bit so that the cartridge case is resized a tiny bit less and then see if the resized cartridge case will chamber. A standard business card is around .005 in thickness. If you back the sizing die off by inserting a business card in between the shell holder & the bottom of the sizing die gently… you will be sizing and moving the cartridge case shoulder that much less.
SAAMI says that the 308 Win has a .007 tolerance window on the shoulder dimension, and your fired but unsized case dimensions apparently measure within the SAAMI tolerance window… as per your original query statement dimensions.
Doing this type of a Go — No Go resizing check in a bolt gun it is easier than in a semi auto. You might have to sacrifice a case or two by making up a dummy cartridge (sans primer) to see if the action will truly go into battery with slightly less sizing. Unfortunately this is the case neck on a resized (Partially resized case… In this instance) may hang up when moving from the magazine in to the chamber on the empty cartridge case neck. (Without a bullet to help guide it into the chamber).
It’s also basically why a lot of the serious accuracy shooters only tend to neck size… and leave the cartridge case shoulder as close as possible to where it is for that particular rifle & dedicate the use of that reload to that rifle only…
That is the down side to most neck sizing applications… Those shooters are also normally shooting their neck sized reloaded cartridges in bolt guns which have a greater cam over force when closing the bolt to put the rifle into battery.
Semi Autos unfortunately only have the force of the carrier slamming back forward to strip the cartridge from the magazine and to fully chamber the round by going into battery.
One way to do this is to size a case the case just enough to allow the reloads to chamber in both rifles…
You will be resizing the cartridge case a bit more… but you won’t necessarily have to dedicate your limited amount of cartridge cases to one rifle or the other.What you also have to being to look at is what the loads are doing to the individual cartridge cases. A hotter load will tend to stretch the case more than a milder one. Also the bullet weight comes into play.
Do you know which of the cartridge cases were fired with what load combination?
Also what was the bullet weight that was used in each of those four sets of reloads…?One might surmise that the original case whose measured shoulder was shorter after sizing might possibly have been fired with a milder load or possibly a lighter bullet in doing your shooting events.
Also in an AR & the M1A action, I believe that you may find that the action may actually begin to unlock and begin to remove the fired cartridge from the chamber before the bullet actually leaves the barrel… depending on where the gas port is on the barrel and the powder power curve at the instant that the fired bullet passes the gas port and a portion of that gas is bled off to cycle the action either by direct impingement of the gas into the rifle chamber or by piston cycling… depending on your individual firearm. ARs were originally direct impingement and lately come in a piston version also. The M1A is a piston driven action…
In shooting different loads in a Semi Auto you have to basically also take into account that you probably want the rifle to cycle and load the next round… automatically… Unless you are satisfied with shooting the rifle as a single shot to try to get a bit more accuracy & then recharging the rifle chamber by cycling the carrier by hand to extract and load the next round. Thus you have a much narrower range of loads that will cycle the firearm…
Also did you use more than one type of powder in those four sets of reloads? Or worked up accuracy loads with incrementally larger charges? All this Intel is necessary to try to properly & completely give you a more quantitative answer your original question.
Finally… You have to in your mind decide if the round in question besides being somewhat accurate is meant to go bang each and every time in a Semi Auto… Factory Loads, & or possibly limit your reloading spectrum to reloads that tend to duplicate the factory loads. They will be the safest ones that have been tested so as not to damage your firearms. The major US powder manufacturers each have on their websites links to their load data…
I would recommend using that load data Intel, & bookmarking those websites… the websites also allow one to print your selections out for later reference. Anything else… Please check the Intel against the published reloading manuals that are out there. One can never have enough of those manual on hand to use a reference material.
Last but not least… Annealing your cartridge cases will tend to greatly lengthen the life of your cartridge cases.
Doing that properly is another lesson in cartridge reloading…. Starting to sound at all… Like a Doctoral Dissertation yet?Take Care & Stay Safe…
Travis Franklin
Regarding your statement: “I really do not understand why each case I resize does not have the same head space its all over the place”
Annealing…if your brass is not annealed, it can “bounce back” when you size the case…the better annealed the brass, the less bounce back you have…there are other factors like the quality of the brass, thickness, etc, but I have found that once I anneal the brass, that extreme spread on the headspace goes down like 90%…and it also makes your brass a ton longer…
And even “hand annealing” is better than no annealing…imho…
Hope that helps!
RascalT
You might also find down the line that you can actually over anneal the cartridge case brass…
At that point the brass itself will no longer spring back at all.. and can from all reports back to me never be work hardened again…
No matter how often it is resized… afterwards…
This might possibly be a cause of the sizing issues that you are observing… and the velocities variance due to the differences in neck thickness and bullet crimping will be for not.
I tend any more to strictly use an AMP annealer and sort my brass by manufactures type… and further by mfg lot type if that intel is available…The original AMP annealer even had settings for different lots of mfg brass that had been neck turned in its .001, .002, &
.003 neck thickness variations in its downloadable data base…I tend to believe that the AMP annealer can control the amount of inductive heat annealing that each individual cartridge case gets far better than any flame annealer or any other type of annealer out there that I have ever heard of.
The second version model that has now been out for a while now is even better with more options…
Sorry I did not mean to turn this reply into a plug for an annealer…
But that is just my opinion…AlvinYork
Well, while we’re talking annealers, I use the Giraud. It’s a marvelous annealer. Use a couple of cases to adjust the flame from the propane tank (get an adapter that changes your bbq tank to a 1 pound bottle thread), stack 100 cases in the hopper and sit close to it while you work on something else. I found I can tell when something goes awry by the sound, there’s a break in the rhythm. Of course, never leave the thing running unattended. Frank also has an adapter to hook up an electric annealer which allows you to use the hopper and delivery features of the Giraud. It’s a nice tool.
I looked at the flame annealers, early on, & though a goodly number have bulk feeders, I could never get the precise amount of annealing that I felt was needed with the torch flames to repeat consistently to the level of annealing that I was looking for.
I found that there is a very narrow range in which you actually do what I feel is the proper amount of annealing that I am looking for.
If you hear or see any bit of residual color changes at all in the brass then you most probably annealed the brass a bit too much… with that — those that cartridge case — those cartridge cases most probably lost to the scrap dealer… for any kind of accuracy shooting.
Also I found that one tends to need some of the thermal paint to put on the cartridge case… and spread the sample thermal test lot out throughout the run of brass to give you an indicator of how things are going…
If you are only setup to do one caliber like the 308, & have enough work area to leave it setup then you are most probably pretty consistent in your annealing.
As long as you can monitor the gas pressure in the bottle and a consistent flame and color size from lot to lot…you are most probably ok.
I tend to do around 80 different cartridge calibers — types, so for me the ability to preset up and do the brass consistently from the get go is important to me.
It appeared for me using a flame annealer to be a somewhat less precise method of annealing, especially for those starting out, with the different torches positioning and flame sizes for different cartridge cases.
I applaud you for being able to get your brass annealed via a flame annealer to your satisfaction.
I have found the inductive annealer a bit more precise in allowing me to anneal my brass to a bit more consistent level from lot to lot…
You also basically need a work area that is completely separate from your main living space for a flame annealer.
An inductive annealer can be run without the need for a couple of live flame torches in the particular workspace area setup for annealing and away from any primers or powder…
A pyrex cheesecake baking dish for me serves to collect the annealed brass.
Since I tend also to anneal for others that I shoot with it also means that I have a larger data base of load data & feedback intel to draw on.
Unfortunately the forum is still not allowing me to post photographs, or such or I could show what the annealed shoulders and case necks that one needs to in my opinion do a proper annealing job on a particular lot of cartridge brass…
It all basically boils down to what ever you are comfortable with and are satisfied with as your end product…
The proof of the pudding is on the range, & in consistent measurements on the sized cartridge cases…Take Care, & Stay Safe…
Hey Mike B.
Thanks for the applause! I can tell when the case is annealled, at least to my satisfaction, when it can be sized with a little bit of lube and can be extracted easily. I’ve found unannealed cases seem to stick a lot more even with a lot of lube.
When I was looking for an annealer the electric ones were just starting to become available and they really didn’t have the “oomfff” to actually anneal the case. I’m sure they’re better nowadays.
BTW – you post images (photos or whatever) by purchasing space on imageshack.com, or some such, then use a link from there in your post here.My favorite bullet for the 308 Win is Al’s copy of the 311414. He’s got it in 309 and 311.
The 311414 was designed specifically for the 300 Savage which has a very short neck in comparison to the 30-06 and the final version of the 308 which replaced the 06 as the standard military cartridge after WWII.
The 311414 was by design made with a very short body diameter length so that when it was seated in the 300 Savage cartridge case, it would not protrude below the .220 cartridge case neck length, and thus tend to contaminate the powder with the bullet lube that was located just above the gas check on the long GC shank that was designed into that cast bullet.
By comparison the 308 Winchester has a cartridge case neck length of .515.
The US government decided that the longer neck that it designed into the 308 would be more applicable than the very short neck on the 300 Savage as a military cartridge as it makes the 308 Winchester far more applicable for longer and heavier bullet designs…I have found that the in the 308 that the 165 grain cast tends to shoot a bit more accurately, & it is most probably for that reason that there is no mention of the 311414 in any of the later reloading manuals for the 30-06 or the 308 as a representative cast bullet model.
I might recommend that if you decide to get the 309 version that you slug your barrel first.
Also you will most probably need to cast the end product with an alloy that is a bit harder than wheel weights to get the most diameter, out of the mould and the least bit of cast bullet shrinkage in the resultant cast bullets due to the increased tin content…A potential alternative to try out in either the 311 or the 309 version is to powder coat the cast product to build up the end body diameter to make the product closer to what your particular rifles bore might be the happiest with…
A whole lot of this depends on the amount of wear in your individual 308’s barrel, & in what floats your boat and works in your end application…
If shooting at a pie plate size gong at 100 yards is what floats your boat, and makes your day… then you should be good to go…
If you are looking for one hole 10 shot groups that you can cover with a quarter at that same distance or further than the process has just begun…It just so happens that the 311414 is the first mould that I bought way back when from NOE.
I had members that had 300 Savage rifles that wanted cast lead product back then.
Purchasing a four cavity 311 diameter version of that mould allowed me to make product quicker than with a single cavity Ideal 311414 mould which did and still does throw a .313 – .314 diameter cast bullet. I used and still use an RCBS 554 TP though the NOE TPs are good too to keep the point on that cast bullet sharp and not rounded off.I tend to think that the 300 Blackout with its relatively short cartridge case length might also be a good candidate for the 311414.
Playing with QuickLoad one can pick and choose a bulk powder like Trail Boss on the low end of the spectrum to get a 100 % burn & keep the 152 gr cast bullet at around 1100 fps which I believe is below supersonic speeds, or step it up as you are doing with the surplus WC 846 powder… with about a 2.102 COAL.
On that note…
WCC844 and WC846 are essentially the same powder. The difference is the amount of Calcium Carbonate in the two powders, the amount was reduced in the WCC 846.Calcium Carbonate is used to reduce the amount of heat a powder produces, thus extending barrel life for the firearm. Downside is, Calcium Carbonate is also Hygroscopic resulting in the burnt powder residue of 844 turning gummy when it absorbed humidity in the air. This was determined to be one of the main reasons for the M-16 failures during the Vietnam war.
It is also a surplus military powder that I tend to believe is no longer available any more…
At least I could not locate any of that particular powder and have not been able to since around 2010.So trying to locate or duplicate that particular load data that you mentioned with the WC 846 for the newer shooters out there is somewhat of an issue without out the velocity generated and other intel parameters that were unfortunately not noted in your reply…
My point was simply that there was and to my knowledge is no current data in any of the recognized reloading manuals or out there for the 311414 mould for the 308 Winchester.
Thus with some comparative load data for powders that appear to be more currently available interest might be developed in the 311414 bullet for what ever purpose one might put it to.
So if the surplus military WC 846 is still commercially available you might want to share where to obtain some and what the chronographic data shows as a velocity in your 308 Win…
Are you using the BLC(2) civilian version of that powder, or the original military surplus powder?That way some comparative data predictions with currently available powders might be generated down the line to help the newer shooters with the 311414.
I am glad your particular 308 prefers the circa 150 – 152 GC cast bullet.
Mine and the other shooters tend to get slightly tighter groups with the 165 gr cast bullets.It all boils down to what your particular 308 likes…
I too can find I believe those same Internet references to WC-846 surplus military powder on the Internet… They all appear to be at least 10 years old and have been updated to show that they are all out of stock on that particular surplus military powder…
The commercial replacement version BLC-2 also appears to have a recall notice against it from circa 2003 in that it is temperature sensitive… with the manufacturer sending out the recall in question.
The circa 150 grain 30 caliber cast bullet does indeed have its uses in the 308 and other 30 caliber firearms like the 30-06…
Might it not be better to provide a more updated set of load data to go with that particular cast bullet mould to spark interest in the mould design itself with a more recent and currently available powder with said cast bullets given the current run on reloading materials and the apparent lack of load data for that surplus and apparently unavailable powder…
The Military tends to try to recover some of the cost on its old surplus materials by offering it for sale and or breaking it down to salvage the components for sale or recycling… When the Military went from 7.62 to 5.56 the now surplus ammo and the powder from that era was offered to the civilian shooters… at that time…
I tend to believe that every once in a while I still see an advertisement referencing Greek Surplus 308 boxer primed ammo coming back to the US, from when the US was supplying its NATO allies during the start of the Cold War. The ammo in question had apparently been stored for decades in unknown environmental conditions ad infinitum.
That surplus ammo I believe also tends to also be offered with the note that there is no guarantee that it will function properly… and is being offered as materials for salvageable components such as cartridge cases and bullets…
Powder that has been stored for long periods in uncontrolled temperature and environmental conditions should most probably be avoided if at all possible as it most probably has detoriated somewhat since it was manufactured…
The Military and Law Enforcement tend to recycle ammo that other wise may still be good to some shooters to minimize the possibility that said ammo might fail at the wrong moment when push comes to shove…
None of this reply is meant as any kind of a dig on the original load data that notes that apparently obsolete surplus military powder.
Take Care, & Stay Safe…
Attached is a bit of load data for the 308 Winchester from the Hodgdon Powder Rifle Data Base.
Once you have the gotten your headspace correct, and perhaps have decided on a 150 grain cast bullet… This powder may be a good candidate to begin with…
While it may not be pushing a 150 grain cast bullet over 1600 FPS as noted in the attached excerpt attachment… it may be a good candidate powder to get your feet wet with.
Trail Boss is a fairly safe bulk powder for those just starting out in the reloading game especially with cast bullets… It by its bulk nature cannot be double charged as many other of the potential powders potentially applicable for the 308 can potentially be.
If you decide on using one of the other powders then please do double check any data that you find on the Internet with a current version reloading manual such as Lyman, & or the actual powder manufacturers website to confirm what other sources might say or recommend.
While Trail Boss is by no means the fastest powder in terms of velocity it can be basically filled to just below where the cast bullets base will sit when seated to produce the cartridge COAL, & still be a safe load in your rifle.
The only caution that Hodgdon (I believe) notes is that it does not recommend for the reloader to try to compress this bulk powder.
I hope that this bit of load data helps those that are somewhat new to reloading.
Trail Boss is also by nature a very clean burning powder that normally leaves no unburnt powder in the rifle barrel… as Quick Load normally shows a 100% burn factor.
Many of the other powders for the 308 are not necessarily as clean burning… especially in the shorter barrel pistol and carbine versions that one might put together from components, or purchase now days…Take Care, & Stay Safe…
Getting back to the OP, I didn’t see anyone mention trimming.
Every time you fire a rifle cartridge the case will stretch making it longer. This may be where your mismatching headspace comes in. So you need to trim the cases to get them to the correct size, usually 5 to 10 thou below the max length of the case. Not trimming your cases and continuing to fire them could result in a case which is too long. The concern here is the scenario where the brass being pushed into the caliber size bore and held there by the bullet creating a physical lock, giving the mounting pressure no where to go. At that point you are in trouble. The primer will blow out, the case will most likely split and much of the pressure will vent down your magazine slot and back into your face.
So that’s why your cases are different sizes; they are stretching in the chamber, not in your sizing die. And you should trim them to get them below the max size. They will stretch further as you continue to fire them so be sure to measure and trim as needed.
Mike B.
Travis Franklin
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