casting .308 bullets

[Maven]

tucker joy, I have several suggestions, which may be at odds with some of the above. First, the quick & dirty measure of cast bullet fit is to take #311332, as cast, and insert it gently into the muzzle of your rifle. If it drops in up to the drive bands of its own weight, you will not get match grade accuracy from it. Second, if -332 fits your bbl., you'll still need to slug your bore or do a pound cast of its throat. You can then determine the correct diameter to size your CB to. Third, rather than spend lots of $$$ on bushing dies, try the Lee Collet Die (more information about it here http://castboolits.gunloads.com/showthread.php?392156-Lee-collet-neck-size-die). Lastly, once you get this stuff sorted out, try something like 18 - 20gr. 5744 or 19 -20gr. IMR 4198 as your test loads: you can always work up (or down) as needed. Hope this helps!

P.S. Is there a chance your new bore is rough and could be broken in/smoothed via firing several hundred jacketed bullets through it? If you opt for this, look up C.E. Harris' method for doing so.

 

[fiver]

the LEE collet die is what I use in my AR-15 to set the neck tension.
yeah neck sizing fire-formed after annealed cases for a semi-auto rifle.

 

[Winelover]

I can tell you right now that 18-20 grains of AA5744 won't even come close to cycling the action of a AR 10. With a 180-200 grain bullet, 25 grains will just start to cycle the action............by then it's shotgun patterns. I just consulted my binder of AR10 targets flops.

 

[Winelover]

I just use RCBS standard .308 seating die. Rick even brought over his concentricity tester and was surprised at the results.

 

[Maven]

I didn't realize tucker joy's rifle was a semi-automatic, Winelover. You're right the loads I mentioned won't operate the action, but may be good for working up accurate loads. Moreover, given that it's a SA action, I think a collet die will work in the short run, but a good FL die should be on hand for the long term.

 

[fiver]

yes.
the collet die is for the final setting of the cases.
you can't work the semi cases like a bolt rifle so you have to give and get.
the idea is to gain in small increments while still having 100% function.
I fire-form with jacketed bullets at full pressure, then make sure I can re-chamber the case,, just chamber the case.
then set the neck tension for cast using the squeeze die, and put my load in.
slight gain, slight gain, slight gain,,, there ya go.
then you have to start over re-setting the cases just because of the nature of how the rifle operates.
you basically have to do the same with the bullet.
match it to the throat but just a hair short on oal, use an alloy that will take the brute forces of the feed ramp and the rifling once the round is fired.
a long nose that is looking for the rifling on all 4 lands is probably gonna be a fail pretty quickly, especially when combined with an alloy that will move and flow under stress.
conversely.
a tapered nose shape that allows the nose to gradually take up the rifling while being supported by the alloy and the case neck will be a lot more successful.
think about putting this = into this > and you'll see where you have all kinds of room for things to go wrong.

 

[tuckerjoy]

I’m going tonight to start and order some dies etc to see if I can get this thing to shoot . I guess the worst thing to happen is shoot jacketed Bullets and that is a money pit if you are shooting paper or metal

 

[Ian]

I'd advise against buying stuff until you know what you need. You can buy an RCBS full length neck bushing die for about twice what a Lee collet die costs but have a lot more control over neck size....if you also know what bushings to buy along with it. The RCBS universal cast bullet expanding die body, mandrel, and interchangeable spuds like what Winelover mentioned are excellent...but you need to know what size your rifle and brass will require. You can guess and get close, maybe close enough, but you can also measure things and get a lot closer. The Lee collet neck die does provide some adjustability if you go a little beyond the instructions, but it is only as consistent as your press flex, handle stops, and amount of pressure put on the handle.

It's always good to have plenty of ullet sizing options when it comes to loading .30-caliber cast bullets. Alloy strength and age of bullets both affect sized diameter so at least having a .309" and .310" on hand is a minimum. You will likely want a .311" too, but .308s typically don't like bullets that big unless the rifle has a NATO chamber and is well worn in the throat entrance area.

Some bullets are better suited to the semi-autos than others. I never had much luck pushing the two-diameter bullets fast, they just don't have the support they need to stay straight in the barrel no matter how hard you make them. Hardness isn't the answer, bullet shape and how you set it up is. There are a couple of good ways to cheat on the bullet fit and one of the simplest is to use any one of some designs already well proven to work for virtually any .30-caliber semi-auto, regardless of throat shape:

• MP Molds 30 silhouette
• NOE 311-165 "XCB"
• NOE 30 Hunter (311-195?)
• Lyman 311644
• Lyman 311679 "Ardito"
• Lee C312-160 Ed Harris SKS bullet.

I personall have used all of these to good effect at velocities adequate to cycle an AR-10, M1, and M1A rifles using powder ranging from Reloder 7 to 4831.

 

[fiver]

powder selection is fairly straight forward too.
you need port pressure, and gas volume.
20grs of anything will not provide that, 30-35 will/well, should.
25-30 might [rolling my head back and forth, making a grimace type face] maybe.

 

[Ian]

Here are some of the tools I use. There are MANY other tools and brands that do similar things and many that do not do what needs doing.

Size die is an RCBS GMM FL neck die with a .333" bushing set to bump the shoulder 1.5 thousandths back from my rifle's headspace dimension and size the necks of WCC military brass (unturned) to hold a .3095" bullet with 1.5 thousandths of interference fit. I do not anneal military necks, for several reasons. The expander is a powder-through type I made from scratch. All it does is true the neck ID slightly but does not exceed the elastic limit of the brass, if I remember right it's about .310" diameter and has a "VLD" type, long taper. I sleeved the Lee PTE rifle charging die body to support a sized .308 case. The seating die is a Firster Benchrest micrometer seating die with the nose punch honed for short-ogive bullets. The internal sleeve works with cast bullets provided the bulket is absolutely no larger than .310", otherwise the neck of the support sleeve must be honed out slightly to accommodate the slight case mouth bell. As Winelover pointed out, the standard RCBS seating die is adequate, but it is subject to how good your expanding die is, how tight your necks are, how straight you place the bullet, and how square and aligned your press ram is. Since I use a non-crimping seating die, I do a light crimp with a Lee FCD that I modified to do a taper crimp with lathe and tool post grinder. RCBS roll crimp seating dies are plenty good for this, as are Redding and some others. The Lee seating dies stink.



My current favorite high-velocity .30-caliber bullet design is this MP 30 Silhouette. The main reason I like this one is it shoots equally well in four different .308/7.62 NATO rifles, each having dramatically different throat sizes and shapes. Powder-coated and sized .3095-8" and cast of straight wheelweight alloy, air cooled, it is accurate to the oressure limits of the cartridge...at 12.5 BHN. It needs to be a lot tougher and sized to .310" if using ordinary lube, and not pushed quite as fast. I size the bullet nose-first in a special form die I made which keeps the nose, body, and base absolutely concentric with each other and the base square.






A 100-yard target:



A 200-yard target:

 

[Ian]

I'm typically running bullets at 2460 fps from an 18" barrel with midlength gas system, suppressed, and have to cut the gas way, way back with a Superlative Arms gas block to keep from cracking the end out of the buffer tube. More target photos. The LR-308 is a PSA bone stock lightweight upper (except gas block) and a James Madison plastic lower. Everything about it is low to medium $$ and low weight, it doesn't take super-expensive stuff to have fun and work really well, nor is there only one way to do this. There are, however, innumerable ways to fail dismally if you don't get certain things that we've been talking about correct. HOW you get them correct...well, none of us here use quite the same tool combinations or even techniques. Note I use a tattletrap Lee turret press....the forced alignment of the custom expanding die and Forster seating die make up for a lot.

The Lee bullet, four sighters and four for a group.
35.5 grains Reloder 7 gets 2460 fps and single-digit SD consistently from the 18" LR-308:






The M1A at 75, note the speed:



M1A at 100:



More groups from the LR308 and my Savage bolt rifle with a custom Rock Creek 5R gain-twist barrel and a looooong, skinny, tight Bisley throat....shooting the same load built for the sloppy semi-auto chambers:

 

[Ian]

Custom powder-thru-expander that helps make this happen:



There is a tapered leade, parallel sizing portion, and a slight, gentle belling portion and a positive stop shoulder to work the measure. I detest the stepped, Lyman and NOE "M"-type expanding dies unless they are modified tobthe correct dimension and taper for the job needed.

I'm not putting this blitz of photos and information up to brag, 1.5 MOA average for 10 repeated dozens of times over a long period won't win any matches or impress a target shooter, but the LR-308 is my 300-yard pig rifle and I wanted to demonstrate what CAN be done with cast bullets in a semi-auto at near full power, IF you get the principles correct.

 

[Ian]

Took me a while to find this again, but this is one of our members WACO, shooting high-velocity cast bullets from a bolt-action, without powder coating. The same bullet he's using works well in the semi-autos too.

 

[fiver]

maybe a short list of the similarity's of how we get there.
it surely ain't the list of dies or manipulations of them...
buuuut.
bullet design similarity's.
strength of the bullet.
case manipulations especially in the neck area and the consistency of the tension.
alignment and function.
powder selection might be different, but they have similarity's beyond burn speed.
I know a pressure trace or that load data thing would bear out that 3031 or 4064 [probably RL-15] would have quite similar characteristics.
I'm sure I missed something. or two

 

[Brad]

I did t do much testing with my xcb rifle before I unloaded that baggage but did get 1.5-2 MOA groups at 100 with the 30 sil and RE 15. I don’t recall exact velocities but they were north of 2400 FPS.

 

[Ian]

I remember you getting just over 2700 fps and still holding at least 2 MOA. I was getting 1.25 MOA at 100 consistently for five shots from my XCB but never got it to stay together much past 2600. That was with the MP sil bullet as a solid from the first MP run, water-quenched 1.75% Sb/.25 Sn alloy, and soap lube. I think my alloy was giving up before yours.

Some of the similarities:

• NOT using "bore-riding" designs or relying on the tops of the lands to steer the bullet.
• Using fast-medium to slow-medium rifle powder at at least 80% density which has a relatively long pressure rise (IMR 4320 is right in there but spikes up fast and doesn't shoot as fast, as well, as other very similar ones).
• Using a tough but ductile alloy...none of us used more than 6% antimony and most a lot less.
• Tempering our antimony with tin, but not too much tin.
• Using high-quality, consistent castings, and consistent loading techniques and brass prep.
• Paying attention to and tweaking the little things like neck tension, seating depth, and barrel vibration nodes that have the most effect on powder burn, straight and consistent launch, and ultimately group size.

I'm probably missing a lot of stuff too.

 

[fiver]

I got a thread here somewhere [rifle section I'm sure] showing loads and data workups and groups for both the 308 and the XCB which is basically a 308 Ackley improved case without the sharp shoulder.
[Parker would sure be proud of me using that description...LOL]
I probably wouldn't go as far as I did with a gas gun with several of those loads, but the 4064 data and the CFE data would be well worth looking at and using or backing down. [I had to be poking along at or over 2700 fps with those long barrels and a few of the loads]
I don't remember dragging out the chronograph since that wasn't the point of the thread, but the data is valid and there are several descriptors of load details other than powder amounts.

 

[Ian]

I should mention why I use so much Reloder 7 as opposed to any of the suitable, slower-burning powders in my high-velocity .308 loads. It all boils down to keeping muzzle pressure as low as possible to reduce wear and tear on my suppressor. IMR 3031 or 4064 would be preferable in some respects, but I have a silencer on an 18" barrel and the muzzle pressure is ridiculously high with anything slower than RX-7. Anything faster, even just one little jog over to H4198, I get a much faster pressure rise at these near-maximum loading levels and a couple hundred fps less velocity. More than one way to skin the cat, all I had to do to tweak my load for the suppressor was find a powder with just the right burn characteristics and match the alloy to it. The bullet fit stayed the same as with slower powders, as did (in this one instance) the seating depth. With RX-7, an absolute minimum BHN was 13. 12.5 opened groups. 12.5 down to 10 would still shoot great with 3031 at the same mid-2400 fps speeds in the LR-308 and mid 25s with the 22" rifles.

 

[tuckerjoy]

I made a request on how to shoot cast Bullets thru a Ar10 308. I have received numerous reply’s on what to do and what not to do. I am more confused now then when I pulled the trigger the first time on this AR . I guess I’m looking for over the counter Dies or expander or etc. etc. I have no knowledge of modifying dies or making special dies. I can shoot this gun with jacketed Bullets and shoot 1 inch 5 shot groups all day at 100 yards I’m sitting on about 5 tons of good bullet lead and why would you spend 20 cent for a bullet when you can get it for a penny. I will get my throat deminision on this barrel soon and reply then. But if your asking to modify or order some special I don’t have a clue. Hope this makes sense. Ps I don’t mind spending some money to get something that will increase the accuracy.

 

[popper]

Get some 4895, start about 37gr. You probably aren't fast enough to stabilize. If your bore is 307, 310 should work. Does the nose jam loading from long col? ~4% Sb WD should be hard enough. Probably need a 0.308 expander. A lube better than LLA. I've gone to 2100 with BLL. Started with veggie coking oil, dipping the base but it is messy.