Going to order a new mold, need to decide on gas check vs plain base

[jamesp81]

Still pretty new to casting, but enjoying it.

I have a revolver and a bolt action rifle chambered in 357 magnum. I'm intending to cast 158 semi wadcutters for both. These boolits are going to get pushed hard. Thinking 1300 fps range out of the revolver and 1600 fps, maybe even a bit more if I find a load that is safe, out of the rifle.

Would I be better off getting a GC mold or is it realistic to wring out that kind of velocity from plain base bullets? My goal 1.5" groups at 50 yards from the rifle, though 1" would be nice and, of course, no leading. Currently the only alloy I have onhand is about 11 BHN, but I'm happy to step up to harder alloy if needed.

[MyFlatline]

Considering what you have just stated, you don't need a gascheck but I would go gas check. For the pistol you could probably do without. I run some on up in the carbine, so use a GC

[wgg]

Plain base gas checks may be an option for you.

[Harter66]

I had a Sec6 6" and an 18" Marlin . Load for load the rifle was 400 fps faster the 1100 fps I shot with Unique and a 358-158 RF Lee was 1500 fps in the rifle .

[Crusty Deary Ol'Coot]

James,

If I were you, I would do two things, #1 not use a Semi-wad cutter style and #2 go with a gas check.

For most of my .38/.357 use, I use a plain base bullet and what few .357 loads I shot, I don't worry about it. Making sure your bullets are not undersized goes a long ways to prevent leading.

But for the rifle, I would want the gas check.

My son has a RUGER 77/357, and as I recall, the semi-wad cutter didn't feed all that well.

I cast a Wide Flat Nose type from an Accurate Mold for the son's rifle.

I use a WFN style in my 77/44 also from an Accurate Mold. About 275gr and I have tested loads to a touch over 1900fps.

Clip on wheel Weights are a good alloy to start with as they will be plenty hard and they can be water quenched as they fall from the mold for more hardness.

Forget buying and adding more tin, the WW alloy casts just fine and has been used for millions of bullets without the expense of additional tin.

I am not. NOT a fan of lee molds, but their cheap 6 cavity plain base molds will cast a lot of banger bullets. their non-gas check styles are many times a bevel base which is not to my likeing, but they are OK for .38 bangers.

I have shot lots of semi-wad cutters in the .38/.357, but that was before use in a rifle with different feeding issues.

By the way, if your using a RUGER 77/357, you might check on a Volquertson after market sear kit. Oh my what a difference it made in both my and my son's rifles. I also shimmed the bolt on my rifle.

I would like better groups, and may find them, but my 77/44 is already a 100yd deer gun.

I can check my files for images of the bullet I'm casting for the son, or make some images if needed. Just let me know if that would help.

Crusty Deary Ol'Coot

[dubber123]

I agree, I would rethink the SWC. While some shoot very well, a good RF design does better for me most times. They also feed much better in a repeater.

[JimP.]

I shoot a lot of cast bullets in straight wall revolver or rifle cases. I use puf-lon casefiller with just a bout all of them, follow the directions and it doesn't matter if the bullet is bevel base or plain based. The barrel stays cleaner too. If I cast them, I don't size them and lube with LLA. Works for me. Don't shoot cast in bottle neck cartridges except for my 45-75 Win, then I leave out the puf-lon filler. JimP.

[runfiverun]

meh 2400 should get you there.
it does in the bigger calibers with a plain base.
I would also suggest you not use the swc but a rnfp or squared off version [wfn] of one.
gas checks hurt nothing and can help accuracy some [shrug]

[mnewcomb59]

I am shooting the Lee 158-rf at 1970 fps and under 3 MOA accuracy for 20 rounds straight. 50 yard groups are right under and inch for 5 shots. 20 shot groups are still in 3" @ 100 yards. I was sick of bench shooting it that day and shot the rest freehand like a lever is meant to be shot!

I bet it woud be 2 MOA for careful 3 shot groups with a scope, but I'm using a 3 MOA red dot and a spray painted paper plate and sand bags as a rest. Bullet diameter is key, not so much alloy IMO. 4% antimony, powder coated, .3595 and water dropped after PC.

Last year for deer I was shooting 2 MOA (with a scout scope) at 1900 fps with water dropped WW unsized .359 with 2 coats of alox. Also that fall I was shooting 1 MOA at 1800 fps But wanted a little more juice for deer. All loads with Lil Gun.

My rossi has a 30" twist though, so that is probably helping me. Your ruger still has a slower twist than your average 357 pistol, meaning good hunting alloys would probably shoot fine at magnum speed. I have heard of accuracy issues with the Rugers with even jacketed bullets, so if I were you I wouldn't expect plain base MOA if it only shoots 5 MOA with accurate jacketed ammo.

357 rifle chambers were designed by idiots, and therefore you need really oversized plain base cast to shoot accurate and have no throat leading. They are funnel shaped from the case mouth to the barrel, rather than having a shoulder like a proper chamber. This allows gas to easily blow by the bullet before it plugs the bore. .359-.360 is where most people find top accuracy in rifles.

I also want to add that the gas check Lee SWC was less accurate at 50 and 100 yards. Near 2000 fps it was more like 5-6 MOA. Never tried it last year with the lighter loads. My ranch dog 135-rf gas check Is very accurate at 2100 fps so, from my experience RF bullets are more accurate than SWC.

[Hick]

I'd go with GC for the mold. Bullets designed for a gas check can also be used without the gas check. So, I buy the mold that is designed for the check, then load some with a check, some without, depending on how hard I plan to push them.

[Bigslug]

I would second that a LFN/WFN mold would probably give you fewer feeding headaches in the bolt gun.

I would probably NOT get a gas check mold for what you're doing, though I would suggest an alloy change for your intended speeds. My accuracy load for a modified .32-20 Martini Cadet ended up being a 130 grain plain base at 1530 fps, but the load experimenting took it to over 1700 in a cartridge with less of a base to spread the pressure load over than your .357's. This was with an alloy akin to water-quenched wheel weights in the low to mid 20 BHN range. Good fit in the bore and good lube (Ben's Red) - leading not a factor and accuracy in the 2-3" range for 100 yards. Expect bedding the barrel channel to improve things somewhat. In short, the cartridge maxed out before the bullet/lube did.

Gas checks can do some nice things with regards to locking the bullet to the bore (which can also be accomplished to a degree with good fit and harder alloy), and they can therefore be an accuracy enhancer, but I think your rifle goals can be met without them. Fitting the revolver might be a little trickier with variables of throat, forcing cone, potential for frame thread crush constriction. If that gun tends to lead up, I would suggest deciphering the "WHY?" before going to checks as the fix.

[MT Gianni]

NOE often offers pb and gc in the same block. I would go for a 4 cavity with 2 of each version. Put a small punch mark, no more than a small dot in the two cavities for gc and it is easy to sort rifle ammo. I have pushed pb to over 1600 fps but it gets into fit and lube at those speeds, gc are much easier to group with.

[gwpercle]

My rule of thumb is 1000 fps. If I'm at or above that , gas check it. The GC just makes life much more simple at those velocities especially a 357 in a rifle.
Gary

[dragon813gt]

NOE often offers pb and gc in the same block. I would go for a 4 cavity with 2 of each version.

Almost all of my recent purchases have been these molds. Even when they're pistol molds. It's the best of both worlds. I don't shoot high volumes of rifle bullets and the decreased production is negligible. I don't worry about checks until around 1800 FPS. I haven't found a need for them out of a Marlin 1894C let along a revolver.

[jamesp81]

Interesting info here, especially on the bullet style. I had initially leaned towards SWC because my revolver (GP100 4") grouped commercial 158gr SWCs very nicely. I didn't think about feeding problems in a 77/357 however, but it makes sense.

I'll look into the WFN style molds instead. I probably will use Lee just because cost is a factor here.

[paul h]

There is no magic velocity at which a gas check is needed. The real issue is one of the rifling sheering the bullet and that is based on the twist rate of the rifling, the pressure the load operates at and the hardness of the bullet.

I haven't chronoed the load but based on others chrono results I'm pretty sure I'm pushing the Mihec 359640 plain base ~1500 fps out of my 357 Blackhawk and those are air cooled COWW's so bhn ~13. I've had excellent accuracy and no appreciable leading. I've shot 1000's of plain base cast bullets at 1200 fps out of my 480 and they should be in the 40,000 psi range, again no appreciable leading.

The Lee 158 rf is a great bullet design. I would suggest using a .358" reamer to remove the bevel base.

[jamesp81]

Is there any issue with shooting GC boolits without gas checks installed, should they not be needed for a particular application?

[OBIII]

Not really, unless there is leading you shouldn't need one. As Hick said, it's easier to put a gas check on a gc boolit than a plain base. You could also try PC'ing some and see how they work w/o the gas check.
OB

[c1skout]

My stainless GP100 has a pretty hefty constriction at the frame, so anything over 1100fps leaded pretty heavily. I just started using the Lee 158 swc gas checked boolit and that cleared up the leading for me. Now I have a proper magnum again.

[paul h]

Is there any issue with shooting GC boolits without gas checks installed, should they not be needed for a particular application?

A gas check bullet without the check will have less bearing length than the same bullet design with a plain base and may be less accurate. Also typically the area between the gas check and next band holds lube so less lube capacity.

Gas checks don't hurt anything, but the added expense and time to install them gets to be a pain after awhile. I prefer my day in day out cast pistol bullets to be plain base designs.