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Jay Andrew
.338 Spectre is a wildcat round for an AR platform that basically scales up the 300 AAC Blackout to shoot 300gr SMK’s at subsonic velocity. SMK’s are expensive and I can’t find a mold that does 300gr bullets in 338 cal, and I’m concerned that a lot of the molds that may do lighter weight 338 cal may not feed from AR mags or chamber in 338 Specter. A can’t easily check this as I do not have a print for the throat dimensions due to the cartridge being a proprietary wildcat and I’m not feeling like pulling my AR apart and doing a chamber cast to figure it out unless I have to.
After conversing with a fellow on one of the Facebook Reloading Forums, I threw together a print loosely based on the 300gr SMK. This is the first cast bullet I’ve tried to design, mold diameter should be somewhere around .340 to .341 and the bullets sized down to .339 despite the drawing saying .338 diameter (I’ll update the dimension on another rev). Ogive profile matches that of a SMK, there is a bore rider portion in front of the first driving band, and all bands after that are at bore diameter (.329). The bullet is set up to accept a gas check, I pulled those dimensions off same cal cast bullets set up for gas checks. I would be planning on hi-tek coating my bullets, so I didn’t worry about real deep lubrication grooves. Open to suggestions.
Since I rarely cast anything in pure lead, weight is based on a 2.5% antimony content and comes out to be about 302gr, obviously that a rough estimate depends on alloy. I’ve attached the PDF below. I know not many people own a 338 Specter but hopefully enough guys own one and want and economical way to shoot it.
Jay Andrew
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Intel6
Full.Lead.Taco
I am in need also of a nice heavy .338 bullet (also for the 338 spectre). If you have the bullet dimensions, I can draw up the bullet. One thing to note about cast bullets and powder coating–long bore rider sections are a bit tricky. If you undersize the bore riding section too much when estimating the powder coat thickness, the bullet will kind of flop around in the barrel. You will have accuracy issues. If you oversize the bore riding section, then you will have feeding/chambering issues. Let’s get the bullet drawn up and tweak it from there.
I attached the original PDF in the original post. I did some more thinking on it last night. I have a revised model and am just updating the print and will post the revised print sometime today. Here’s what I did.
The bore rider diameter is .329″ which is bore diameter. I figure the hi tech coating may add .001-.002″ of thickness to the overall bullet. My plan is after casting and coating to size these Bullets so they are around .339″. There isn’t a significant portion that rides the bore just a little in front. I added a model of the bullet seated in .338 Specter case at max COAL of 2.300. So you can have an idea of the case mouth in relation to the cannelures (lube groves)
I decided to increase the depth of the cannelures, they sit at .320″. The idea being to allow plenty of room if someone wants to lube these Bullets in a more traditional way they can, or if someone like me just powder coats them the lead has some place to displace too as the rifling is being engraved in the shank.
One concern I have is the meplate diameter. Since my plan is to size them, I don’t want to have a meplate so small it will bugger up as a push it through the sizing die and into the base of the previous bullet. Perhaps I’m over thinking it.
I’ve been doing some more thinking on this.
The max COAL for this cartridge is 2.300 which on a 300gr SMK, leaves a significant part of the full diameter shank forward of the case mouth. What I don’t know is how much clearance there is in the throat. If its .3400 or .3410 we would be fine, if it’s .3390 it’s going to give us trouble. SAAMI max chamber drawing is typically puts all diameters at +.002″ and doing a quick search through the SAAMI manual shows that most of the throats of .338 calibers are around (if there is a cylindrical throat at all) .339-.340 (I’m rounding up/down) (For Example 338LM is .3398″ while 338 Federal has a tapered lead in and no throat.)
Based on this I think I’ll need to rev the print again. I need to alter the diameter of the shank that sits ahead of the case mouth to something closer to .330 or .335 as it will allow for more clearance should someone decide to hi-tek coat their bullet, and their rifle has a tight throat. It would also provide a little additional clearance if their cartridge to bullet alignment wasn’t dead nuts on.
Another example of this can be found on the 300 Blackout which can have a throat as small as .309″ which means if this was a 300 Blackout Bullet and we sized the bullet to .001″ over bore diameter, which I think is typical for cast bullets, we can’t have any portion of that full diameter ahead of the case mouth and expect it to chamber in all rifles. Additionally if the bullet is seated just a little cockeyed and has an exposed shank close to the throat diameter, it can be tough to chamber.
Personally, I don’t plan on needing the lube grooves but I figured their might be enough people out there who still lube their bullets that way that this would appeal to them. Same with the gas check, velocity is low enough that I don’t see there being a huge need for the gas check, but I wanted to give the person an option to put on on if they feel they wanted it.
Full.Lead.Taco
After having some offline discussion with Cornmastah. Here is an alternate design based off the Accurate Mold 285gr bullet mold.
I overlaid it on a 300gr Sierra Match King CAD model and the bullet fits within the profile. So I am confident that this bullet will work in a .338 Specter chamber.
Intel6
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