This is my first post here, so I hope this is the right place to put this article. The project is several years old, but enough people have asked me about it that I finally wrote an article about it for a web site. I figured it could be put here too.

The 510 WSM (BMG on a budget)



The .50 BMG is pretty much the ultimate human portable rifle, but it has some drawbacks for the typical gun enthusiast. For me, its primary drawback is cost (though strangely enough, not its impracticality...). The BMG rifles are expensive, the ammunition is expensive, the reloading components are expensive, most of the normal equipment can't be used and BMG specific equipment is, you guessed it, expensive. The high ballistic coefficient .510 diameter bullets are a big part of what makes the BMG appealing for me, and they can actually be had at a reasonable price from military surplus dealers. So, what if we could somehow launch these tips using a normal rifle and assemble rounds using normal reloading components and equipment?

Few common cartridge cases are made with a large enough diameter hold a .510 bullet and those that are usually fall into the "elephant" gun category; the likes of which are often more expensive than BMG brass anyway. There is one relatively recent exception to this, the WSM and ultramag series of cases. These cases are supposedly based on the 404 Jeffery, but their larger production volume makes them a fraction of the price. If you take any WSM and cut it back to the shoulder, you'll end up with a nearly straight wall case that looks like it's ready made for a .510 bullet--hello 510 WSM. When loaded it looks like a big 9mm auto with a pointy bullet. The WSM case is also a modern high pressure design, so there is no worry about pushing the limits of some old big-bore black powder case like a 50-70.




With a BMG bullet seated, case capacity ends up around 30-40 grains--almost an order of magnitude less than the BMG. So, we're clearly not going to get BMG muzzle velocity, but what kind of velocity is possible with only 40 grains of powder? The 510 Whisper is a similar concept to this one but it uses elephant gun brass with proprietary modifications. It's often loaded subsonic but the data available online suggests a similar case capacity, with charges around 35 grains and muzzle velocities from mach 1 to 1500fps. So, it looks like we could expect to get around half of the velocity of a 50 BMG using roughly a tenth of the powder, standard/readily available rifle actions, brass, primers, and reloading equipment. Seems worth a try.

The first step for this project, after setting a BMG tip next to a WSM case and thinking "Hey," was getting a barrel. Back before ebay was big enough to move their servers to the people's republic of california, I found a chambered 50BMG blank for $99. The blank was just a heavy cylinder of steel about 30" long, presumably from some kind of military surplus deal. With that in hand, firmly, a call to Pacific Tool and I had a reamer made to my specifications within half a year for around $250. Trying to stick to the affordable theme for this experiment, I spent that time looking for an inexpensive rifle action, or a used gun chambered for any WSM (or WSSM) round to take apart and mate with the barrel. I looked online, at local gun shops, in the newspaper, I looked at the local gun show, and I even went to wally world hoping for a closeout deal--all without any luck. The few specimens I saw were all either the same price as retail, or else well used for about 5 bucks less. When the reamer arrived, I gave in and just went to Sportsman's Warehouse and bought an XR-100 chambered for 223. I figured if I had to pay for a new gun it might as well be one I liked, and actually new. Plus I figured the 22 barrel from the XR could be put to use on an aging Swift. The 223 bolt face also leaves plenty of material to work with when adapting it to the WSM case. The XR comes with a decent adjustable trigger and I like the relatively short action, which is loosely based on the XP-100 pistol.

I opted for a heavy gun considering that it would be launching a BMG bullet at half the BMG velocity, thus producing half the recoil momentum but without benefit of the muzzle brakes universally found on BMG's. It's not like I was planning to carry this thing around on hunting trips anyway. Even with a 7kg rifle, the recoil was expected to be stiff. The 30" barrel blank was already chambered for 50BMG, so after cutting off the chamber that left a little over 26" to work with. A full bull contour was used to retain as much weight as possible and it was also simple to do on a lathe. And when I say "full bull" I mean receiver diameter the whooole way. So the blank was centered on the bore, turned down, chambered, crowned, and fitted to the receiver. I've never built a rifle to this extent before, but it was all pretty straight forward using the removed barrel as a guide. A muzzle brake was not used due to the relatively small quantity of powder being burned and the already nose heavy barrel. The Remington tolerances were not very impressive, so some truing of parts was involved and the new barrel ended up tighter and better fitting in a couple different ways. One difference is that the entrance to the chamber needed a little bit of a chamfer so the case mouth wouldn't hang up when chambering a round. The bolt face was opened up for the WSM case on the lathe and a Tubb 2000 extractor was fitted on the mill. To handle the full bull barrel, I took a hacksaw and palm sander to the laminated stock. The result is a bit odd looking, but I think it's an aesthetic improvement over the quasi-vented thumb hole that the XR came with. There's no need for a sling, so the studs were removed and their holes filled with epoxy. I didn't want to mess with fitting rounds in a magazine and the XR-100 solid bottom single shot takes care of that problem. The case is half as long coming out as going in, which means ejecting cases is no problem either. To un-chamber a live round with a long bullet though, the bolt stop is released.



Next was the scope mount. "Easy," right? I wanted to use a weaver style base so that I could reuse a scope with quick release rings that bounces between a few different rifles and Contender barrels. The only base I could find like this was a cheap extruded aluminum one. Well "no problem," I thought; I work at a machine shop so I'll just get the dimensions and make what I need. Well, after a few phone calls to Remington, it was pretty clear that my brand new XR-100 target rifle with no built-in sights is not intended to have any kind of optical sight mounted to it, ever. I asked Remington for dimensions, even very rudimentary dimensions, specifically scope base interface dimensions, like you'd expect to see on a typical interface drawing--and you'd think I was asking for the full blueprints to a nuclear submarine. That was a very disappointing experience, but it was too late to go with a different receiver brand. Leopold was actually pretty helpful over the phone even though I was not planning to use one of their bases. I did borrow and test fit a 1 piece steel base made for an XP-100 and noticed a significant gap at the rear. Reportedly, the precision interface between a Remington receiver and a machined scope base is often finished by hand using a belt sander, so plus or minus half a millimeter is normal on a Remington and shims and/or glue and/or lapping scope rings is the typical solution. I thought the rifle industry invented interchangeable parts?!? So I got some help with a Faro Arm (a coordinate measurement machine) to measure and reverse engineer my particular XR to make a custom, receiver specific, base. I also learned that the rifle industry likes to use 6-48 screws, (which are about as standard as the popular 7-51 screws that are used nowhere) so I had to order the custom screws and a tap for good measure.



Any normal WSM die can size the case body, but new brass is under size a bit to begin with and a simple neck sizer was turned on the lathe and used for subsequent loadings. The chamber reamer was used to make a seater die out of aluminum. Because seating depth has a significant impact on case capacity with this round, the reamer was specified with a pretty long throat. For some reason the 7mm WSM is a bit longer to the shoulder, so using those cases exclusively could net a bit more case capacity, but I already had a bunch of 270 and 300 range brass. Using these, cartridge overall length with surplus BMG tips ended up around 3.350" with a little gap left to the lands. The chamber was cut to 1.670" and cases were trimmed to 1.665. The idea was to have the round headspace on the case mouth like a straight wall pistol round, but when neck sizing fired brass there's enough taper to take out any slop on a chambered round. Initial testing used surplus pulled 645 grain M8 API projectiles and surplus WC297 powder, which is slightly slower than 296. Some of the other dozen or so rounds like the 500 S&W, the 50 Beowulf, the 50 Rhode Island, etc. provided some hints for starting loads. Working up some loads was pretty straightforward with no surprises. I find it interesting that this round uses the same powders as the 22 Hornet, which I also reload. I did have to get some new bore brushes and patches though.

The new creation is definitely a "niche" rifle, but overall I'd call the experiment a resounding success. The total cost ended up around $1200, and could be replicated for much less if you can borrow a reamer and/or start with a WSM rifle. However, if I were to do it over, I'd start with something like a Pierce action instead of buying a new rifle to take apart and reverse engineer. Accuracy so far is roughly MOA, which is acceptable considering the price and condition of the pulled military surplus bullets. Apart from meeting the budget and velocity targets, recoil is not too tremendous, the round is pretty efficient by making over 3000 ft-lbs of muzzle energy on 40 grains of powder, and it's just plain fun to shoot. It might not be BMG class fun, but I think it's an effective compromise at less than a quarter per shot. It looks odd enough that it attracts plenty of attention at the range, particularly when people see either the loaded rounds or the size of the hole at the muzzle. Also, BMG projectiles are pretty interesting in and of themselves. Plinking rocks at long range in the desert with incendiary rounds was a new and thoroughly enjoyable experience--two booms per trigger pull! They don't go through 3 inches of steel like they will at BMG velocity, but they'll go through a lot more than most other common rounds. You probably wouldn't get invited back if you took it to a silhouette shoot with AP rounds, but I wouldn't be surprised if you could take down multiple targets with one round. Things definitely happen when those bullets make it down range. The impressive BC means that even at only 1500fps muzzle velocity they're still supersonic at 1000 yards. This round does exhibit quite a lot of drop at long ranges though (think artillery trajectory). Predicting this while plinking is also kind of fun and quite a change from the varmint rounds I'm used to. A 220 swift is just point and click, but the 510 requires a little more planning. A scope base with some built-in angle is pretty useful. At a distance, the relatively lengthy time of flight also allows you to recover your sight picture to see impacts, or just look up and watch for the basketball sized flash of light and subsequent cloud of dust and white smoke. For spotters this makes things easy at long ranges and harder up close--the reverse of what I'm used to.

The next phase of this project will probably be casting some lighter bullets to try with this rifle, or maybe trying to excavate some prairie dogs. The lighter bullets also allow more room for powder, up to around 60 grains with a flat bottom bullet seated out. I'd also like to try some nice bullets like the Hornady A-Max to see what kind of accuracy is possible with the discount barrel. The prices these days are getting hard to swallow though, kinda like paying more for gasoline than you did for the car. Sorting my existing stock of surplus bullets by weight, bearing length, etc. might help accuracy quite a bit, so I'll probably try that first. Also, the reamer was made long so the option exists of running the reamer further down the bore and switching over to ultramag brass for more case capacity. With cast bullets, this round could be loaded to the equivalent of a 45-70 and used for hunting; call it a modern 50-70 maybe.

Example load data:

645 grain M8 API, WLR, 29 grains WC297 1050fps
645 grain M8 API, WLR, 40 grains WC297 1550fps
425 grain cast solid, WLR, 42 grains WC297 2200fps

Well, I think you're in the right place. It might take folks a while to read all that...I had to take a couple of breaks myself. So far it looks like a good 50 Cal. dual-purpose round, both sub and super sonic that is. The fact that it is done on a normal sized action and in turn lighter (except for that barrel lol) rifle is certainly woth something. Are you considering turnig the barrel down? in anything short of 20MM I would. LOL
Looks like an interesting project so far.

Pretty cool round, and a good read!
the great big bmg bullets are pretty darn HUGE .. got a chamber/case drawing? i would love to know how long you made the throat? I did it VERY long on the 500 AR, to be able to seat the 645 and 700gr milsurps out very long.

i am impressed .. ballistics like the 500 whisper, which is pretty GREAT ..

You can go a bit longer if you cut off RUM cases at the shoulder
jeffe

Oh that is COOL! I can't wait to hear some more results from cast bullet testing.

If you're interested in some data for lighter bullets 325-500 grains, I'll send you what I've got.

Only .050" difference in case length, shouldn't be too much of an issue.

Any chance I could buy a dummy with the longest bullet you have seated way out there? I like collecting weird shaped cartridges...

To answer a few questions:

No, there are no plans to lighten the rifle. There is really no intention of carrying it around much and I usually go through a couple hundred rounds in an outing (between a few different guns). So in this application heavy means less recoil, which makes it easy to shoot more.

The throat was specified long to preserve case capacity. I think it's around 3/8" or so, and you can see in the pictures that the cannelure is not used. The reamer was also specified long to allow chamber lengths up to around 2.4" which, as you say, would require ultramag or 404 brass. The WSM neck walls measure around 0.015" thick, so the chamber neck diameter was set at around 0.545" to obviate neck turning/reaming when forming new cases. There is no shoulder or belt, so the head space is determined by the case mouth, or basic case length. This is similar to various auto loading pistol rounds.


fireball168: Yes, I am interested in your data. michael458 also has a similar wildcat (50 vs 51 cal), and he kindly sent me some of his load info for "lighter" bullets. Have you posted other information on your version of this round?

Tyler: I could send you a dummy round, but it's simple to make; I made one long before I ever got around to building the rifle. Just take any WSM case, trim it down and stick a 50 tip in the end.

Any chance of getting case dimensions? Awhile back Chris Boon reported here on his 458Alpine, an improved, shoulder pushed forward 45cal. I believe at the moment he is testing a 9.3mm version and a 50cal. The 50cal in particular seems similar.
Cheers...
Con

Has anyone necked up the 500 Cyrus another 10 thou?

Nice rifle jpl. The case looks to be a bit smaller than the 510 whisper that is based on the 338 lapua cut down to 1.885". I use 28 grains of surplus WC820 (like H110) to push a 700 grain AP bullet 1050 fps. In my 7.5 pound Encore this results in punishing recoil, especially if I load 950 grain cast bullets.

Any plans to use it with a silencer? I made an all aluminum can on an ATF form 1 that is 2"x18". It sets back on the barrel six inches, but still adds a foot to the length. It is big but makes the gun sound like a car door slamming and really helps on the recoil.

Ranb

Nice write up jpl. Does anyone have any data for a 50 cal (0.510") using the RUM brass at 2.4" versus the WSM jpl used? Just wondering what sort of velocities are possible with the longer case of the RUM.

jpl - What twist does your barrel use? I spoke with Krieger about twist rate and they suggested a 1-14" vs the standard BMG twist of 1-15". The bullet info I gave them to determine what twist to use for my project was Hornady's 750 gr. A-Max bullet which is quite long needing the faster twist at the considerably lower velocities of a 510 RUM compared to the BMG.
Thanks Kevin.

I got a hold of some 750gr amax. What kind of load do you think would work well? I don't have a lot of them to experiment with, so I'd like to start a little closer. Given that they're 100gr heavier (or 15%), I was thinking I'd try about 35gr of 297 (vs. 40gr for the M8's). I also have some 4227, but I have no data at all with that powder. I suppose I could work up a load with 4227 and the plentiful M8's, then back it off some for the amax, but how much?

michael458: I saw your reply in that other thread ( http://forums.accuratereloadin...6521043/m/7031064101 ) and thought I'd respond here to not derail the other thread.

Basically there's not much new to report. The 510 is still a lot of fun to shoot. I did pick up two boxes (only 40!?!) of 750 grain amax bullets. I've been traveling a lot for work though, and haven't tried them out yet. For the cast bullets, I made a flaring tool to slightly flare the case mouth. This stopped the neck from shaving lead off when seating bullets, and it also seems to help keep lube and powder from going backwards around the neck and crudding up the cases and chamber. Oh, one more thing: I've started sizing the cases smaller and a little further down to create a slight constriction behind the bullet. This makes it harder for the bullet to get pushed back into the case when chambered. I think some of my velocity variation was caused by the 0.512" cast bullets or the sized surplus bullets hanging up slightly in the 0.511" throat and getting pushed deeper into the case. The more extensive sizing will probably shorten case life, so I'll keep an eye on that.

Hey JPL

For my 50s (.500) I have not had any luck at all with any cast bullets. Good accuracy to 50 yds, but go past 50 yds and they go to crap. Jacketed bullets are 1 hole at 100 yds. At first I was disappointed, but for the purposes of my rifles in .500 (50 B&M Super SHort--50 B&M Long--50 B&M Alaskan-and 500 MDM) I got over the cast bullet issues.

One reason I thought of you was some of the sample bullets JD has been working with in the 510 Whispers. See with subsonic in all the whispers, terminal bullet performance is always an issue. One of the reasons for the Whispers is animal control. So if they can get bullets that upset, or perform good at subsonic then more damage is done, less issues for animal control officers, double especially those using small 30 caliber and what have you. But JD sent some samples of .510 caliber brass bullets that have big slits in them so that the front petals start to peel back at low velocity in the 510 Whisper. Very interesting bullets. My 50 B&M Super Short and your 510 WSM would both do well at subsonic, although I have never tried it in the 50s. I did make up some shotshells recently-that's a hoot!

Michael

To JPL,

just to get this right....
You take a .300WSM and shortened it to the Body/Shoulder Junction ...right??

Best
2RECON

Take any WSM and trim it to 1.665", but the 7mm is easier because the case is longer to the shoulder.

Totally rad dude...

There's at least one 416 WSM, 458 WSM, and 450 Yukon now...I wondered when someone was going to do a 500 or 510 WSM or trimmed RUM...I looked at doing something along the WSM/RUM lines but not very hard...the 500 Whisper kept getting in my face.

Keep posting your results...I'm getting close to finishing my 12GAFH and need another project to start thinking about.

Luck on your project.

I still have not tested the 750 amax, but I was in town long enough to get a few things done at the shop. I made some aluminum blocks to support the action and floating barrel. Here is what they look like after being epoxied into the stock:



This should keep things more stable with the heavy barrel and recoil. Also, for other reasons I ended up machining another BMG blank, which is now extra and for sale if anyone is interested in trying this:



Like the first one, it's straight receiver diameter (1.355") so there's plenty of meat left to contour it, flute it, shorten it, etc. It should fit pretty much any remington action, and maybe some others. I'd say it could just be screwed onto an action without modification or worrying about head space, because the head space can be adjusted slightly by simply trimming cases to the required length.

I should have plenty of time this summer to experiment more.

Tried some cut M17 the other day. These were ~450gr (it depends where you cut them, obviously) and they were going about 2100fps with 47gr of 297. It looked like they could take a lot more too, as there wasn't even enough pressure to iron out the sized necks. Only one lit, so I'm guessing the compound in the very back of the bullet has something to do with igniting the tracer compound. These are pretty cheap too, at $0.15 each.

where did you get your projos at 0.15 cents a piece I would love to get some.

0.15 cents each would really be a good deal! There are a variety of places to get affordable 50 cal bullets from military surplus on the internet. Affordable big bore shooting is what this project was all about! Here is one I found just now. There is also pats, gibrass, etc. Just search around.

http://gunbroker.com/Auction/V...m.asp?Item=131656732

I worked up a load using 680 and got another 100fps (1700fps with the M8). I ran out of room for powder before the pressure got too high.

I found a way to get around the leading problems with cast bullets. I'm still experimenting, but these worked pretty well:

You could try some of these ...

The spare barrel found a home. It got turned down, fluted, and cut short:



business end


A 41gr low-pressure load of W296 behind a 505gr gift-wrapped slug manages ~1715fps and blows confetti like it's New Year's Eve and never leaves any copper fouling! The soft lead has a dramatic effect on jugs of water too. 3800ftlbs of energy stops in just 3' of water and makes pretty mushrooms 1.380" in diameter, nearly 3 times the original size! Heavier loads of slower powder give even more velocity (~1850fps so far) while making a nice flash for good lighting while taking pictures.

BOOM! Can you see the chrony in there? haha


crown afterward


Confetti and result of 3' of water

One pound of lead: (10x 700)



Cheap fun, and a clean bore. Kinda like a giant 22LR. I could get into this casting thing...

I'm interested in making an SBR 510 WSM after seeing this again almost a decade after last commenting. Would be super handy in my bullpup chassis with a suppressor.

Hello jpl, First, I apologize for the off topic questions.

Being fairly new to casting bullets I am very interested in learning about your cast bullet with the multiple grooves.

Please tell me:
- what do you use for lube?
- who made the mold?
- velocity?

Thanks for your help, Brian

Tyler, I've been following your thread on the bullpup chassis. A suppressed SBR would be very fun, however as you're aware the lighter you make the rifle the more these heavy slugs will kick even at subsonic velocities. At 1050fps these have 1710ftlbs of muzzle energy and penetrate an entire 24" box of loose damp earth at 50 yards with my test-load.



Brian, It's a mold from Accurate Molds in Utah. The 'multi-groove' profile works like Lee's Tumble Lube pistol mold designs. I am not heavily invested in casting and I have been using Sno-Seal™ beeswax waterproofing paste for lube since I had a can of the stuff handy. It works well enough for this low-velocity application. I only intend to shoot these 700gr projectiles subsonic, I have other molds for driving bullets faster.

Thanks jpl, I am going to try one of those "Tumble Lube " style bullet molds in my 500 or 577.

Also interesting about the Sno-Seal. In Canada we use that on everything except our porridge but I never tried it for bullet lube. Thanks again, Brian

quote:

Originally posted by jpl:
Tyler, I've been following your thread on the bullpup chassis. A suppressed SBR would be very fun, however as you're aware the lighter you make the rifle the more these heavy slugs will kick even at subsonic velocities. At 1050fps these have 1710ftlbs of muzzle energy and penetrate an entire 24" box of loose damp earth at 50 yards with my test-load.



Brian, It's a mold from Accurate Molds in Utah. The 'multi-groove' profile works like Lee's Tumble Lube pistol mold designs. I am not heavily invested in casting and I have been using Sno-Seal™ beeswax waterproofing paste for lube since I had a can of the stuff handy. It works well enough for this low-velocity application. I only intend to shoot these 700gr projectiles subsonic, I have other molds for driving bullets faster.

I don't think in an 8-9lb gun suppressed there would be any issue with recoil. Certainly not a 22...but not bad compared to a light 45-70 with high pressure loads.

I'm building a 510 wsm at the moment, just waiting for the suppressor, (not a problem here to have as many as you like )

My 510 Whisper at 7.75 lbs is quite a handful with subsonic 750 Amaxes.

https://www.youtube.com/watch?v=CelM9DsdHos

fancy seeing you here!!

quote:

Would be super handy in my bullpup chassis with a suppressor.

Sort of like this? This is my 510 Whisper on a DTA action with Bowers Vers 50 can. Barrel is now 16" vs 20" in this picture. Makes a quite ragged hole with 750 amaxs.




Bob

quote:

Originally posted by Mikee-NZ:
fancy seeing you here!!

Been here a while now

Hello Kiwi Greg, That's a great video! I am curious. Why are you building a .510WSM if you already have a .510 Whisper? Isn't that a little redundant? I contacted SSK about the .510 Whisper a decade ago but he quoted me $2200 for the smithing work on my own rifle not to include shipping, dies or brass, which is why I went down the wildcat rabbit hole; it was more cost effective for something equivalent.

Omniverous_Bob, I've wanted a DTA for a long long while but can't justify the expense and its all aluminum manufacture makes it quite heavy despite its compact nature. Thanks for posting up, it's a very nice piece of kit you have there.



I had a chance to work up some loads with the .510WSM and these 700gr cast bullets. Around 1450fps they start leading up the bore when lubed with a 50/50 mix of Lee Liquid Alox and Johnson's Paste wax dribbled over the bullets, sized to .511" and loaded with WC297 (slow lot of Win 296). At that threshold they're not terribly accurate but will do for medium sized game and up (~3 MOA). A harder alloy or a slower powder might let me exceed 1400fps and improve accuracy.

On the other hand, I now have a subsonic load that holds about 1.2 MOA to 200 yards. At 120yds they stop at the back side of 24" square cardboard box filled with damp sand, which is handy for reclaiming the projectiles for recasting. It's easy to run though a few pounds of lead per shooting session.

6 on top starting with a cold clean bore, and 5 on the bottom at 120 yds:

quote:

Originally posted by jpl:
Hello Kiwi Greg, That's a great video! I am curious. Why are you building a .510WSM if you already have a .510 Whisper? Isn't that a little redundant?

I have a few rifles

I will sell the Whisper & I wanted a cheaper alternative for my clients.

The WSM brass is much, much easier to make, dies are simple enough, cheaper & better than my C4HD ones, also easier to get a platform to make it on with the standard magnum bolt face.

I'm only really interested in subsonic use, will look into getting some purpose built projectiles, Lehigh etc.

If I want supersonic performance I have other 50cal options



More info here,

http://www.nzhuntingandshootin...nz/f45/50-bmg-28486/

Someone was asking about this so I went back and tried to fix the picture links. It just rained here, so I should try to get a video of the tracers or incendiary rounds. Even a steel plate getting smacked with 700 grains of lead is entertaining.