Holy Cow, you’re doing good work and great pics, a closer, close-up would be better, for a more thorough assessment. Place the cartridges touching each other with the powder weights still visible, then go ahead and zoom on in, let’s have another look at dem-dar beauties, if it will focus… As I can see the shadow ring around the primer, there certainly is no serious flatting of the primer. It’s true, sooting is a function of too little bullet-pull (meaning not enough crimp) or to slow of a powder or not enough of the correct powder (the usual culprit). After you ring out ‘lil gun, my suggestion is to go to H-110 or 296 (their data is interchangeable) and then onto my favorit AA1680. I can’t quite read the speeds, but from the looks of that shooting secession, I sure don’t want you angry at me!
All you guys need to sacrifice a case to find out for yourselves the max internal powder capacity of the case, with the powders and bullets you want to use. The following hints are a real aid in load development and won’t allow you to over fill the case. My method is to drill a 1/4” hole through the primer pocket, cleaning up the burs. Seat and crimp the bullet to the desired depth & OAL, on an empty case. Filling that case with powder through the drilled out primer pocket until the powder is humped up, on the rim face. Now, placing your finger over the full primer hole and the bullet facing the floor, tap the side of the case with a kitchen knife to settle the powder (maybe a dozen or so taps). You’ll see the powder has settled down into the case. Refill with powder again, until the powder is on the top of the rim. After doing this many times and no more powder will go into the case and the primer pocket is completely full and slightly on the rim face, weigh that particular charge. That powder weight represents the perfect compressed load and is the max load you could achieve with the chosen bullet and OAL. Not that-that load is safe, NOT AT ALL, but it is the stopping point, if you make that far in your choices. Some of the powder/bullet/OAL’s choices will allow you to reach that amount of compression without pressure signs and you won’t be wondering if you have too much bullet compression.
Is the bolt holding open on those 43 grainers now? Make sure that you single load with the mag inserted until you get your head around your situation.
I sure do not see any excessive pressure signs at all. I’d, with caution, suggest an increase in powder (h110) watch for excessive pressure signs and you make the call, in relation to safety. I think you’ll end up in the 2500fps+ arena, which is 3500ft/lbs and with a 200yd zero, is 100% hits at 300yds (on a 8″ paper plate), assuming you get the groups down a little. This blows the doors off the other big bore AR’s and you haven’t gotten to AA1680 yet, which will yield 200fps+ more than you are now getting with the same pressures. Note- Someting to consider, in extreme cold weather (zero or lower) the 296 will ignite better.
I plan to call Montana Gold and talk to their engineer and asertain how thick those 250 jackets are, if they are in fact thick enough, these may end up being the new gold standard.
WW296 and H110 are Ball-Powders and their data is interchangeable and not AA1680 (also a ball-powder), which is a much slower powder. As always in matters of reloading you are on your own and anything you read here should be taken with a grain of salt. Your caution is commendable but be very careful with reduced loads. I consider your load with 37grs of 296/110 to be just on the good side of low, you might see speeds in the 2000/2200fps area, but increase the OAL if you can (2.250”). Keep in mind Slash’s 45gr load, according to the picture record he provided for us, had no problem with pressure. 37gr of 1680 is definitely low and possibly dangerous. Watch for sooting down the sides of the case, if you see it the case is not sealing, because pressures are low in the chamber and of course at that moment increased bolt thrust could become a problem. I would definitely start with 45gr of 1680 with your 240gr bullet. Funny thing, RX7 is the next logical slower powder than 1680 and if used in the 450bthe speeds drop off 500fps, you just can’t get enough RX7 in the case. Good luck…t
It’s good you understand the terminal ballistics between bullet types, especially in this High Performance Cartridge. You are miles ahead of some so called experts. There was a highly regarded genius on another board who used a 50b, which primarily uses bullets designed for the 50AE, on a deer this year and posted his shocking pictures, with a pathetic story, that was picked up by PETA, who for a time used him as their Poster-Boy. Needless to say he horribly blew up (nearly off) the shoulder. The deer got away and was later dispatched by another with a 7mm Mag. Our hero thought the bullet just fell out, he had no understanding of what actually happened. A pistol bullet designed to expand on soft targets at range and say maybe 300fps, will blow up into thousands of little specks on big game at 1800fps+, with no penetration into the boiler room. To be sure the same thing can happen with the 450b, so choose bullets that will accomplish your mission properly. The opposite can also happen, bullets that are designed for thick skinned big heavy game and rifle velocities, will not expand at all on thin skinned deer, and are inappropriate for home defense, it is not wise to use some types .458 bullets that will take out elephants or Planes Buffalo on deer or other targets that may need an expanded bullet or no penetration at all. Which is why I say the 450 Bushmaster is the most versatile, AR-Big Bore on the market. Use pistol bullets when zero penetration is needed, like 180gr-230gr hollow points, which will not penetrate a common house wall reliably, sure don’t want to kill the neighbor’s dog now. Choose fmj’s when penetration is needed and Flat Point FMJ’s when penetration and tissue disruption is most desirable. As a note here, the FP’s disrupts more tissue than an expanded bullet does after it expands and the FMJ-FP penetrates any animal on this planet, killing elephants, Cape Buffalo or deer with equal ease. Keep in mind that 230gr fmj round ball bullets work well in big game too. Think of it this way, though that bullet won’t really expand, 45 cal is already bigger than a 30 cal gets after it expands, so shoot’em if ya got’em! If bigger heavier bullets are desirable, then buy them, they are available or get a Lee lube-sizer die set-up (about $30) and shrink down .458 bullets, we’re only taking them down .003” per side, two and a half times less than a standard human hair. I’ll take a soft lead lubed .458 bullet and use it to lube the die for every 5-10 jacketed bullets or use some Cast Performance .458/500gr bullets to lube that die and then you’ll have some really heavy bullets for plinking in your 450b, not necessary but fun and maybe quite useful. I often use 350gr .458 Hornady bullets, for fun, and do not experience any jacket separation at all in our hydro test or on the reported Buffalo that have been killed with this set up. In other words, it is possible to use .458 bullets in a .451 barrel, but 451-452 bullets in a .458 just does not work well, if hitting the target is the goal.
I can fill volumes with things I’ve been told and I do not know about the 454C problems you discuss (a call Causal might be helpful), but with no forcing cone on an AR and now millions of rounds of fmj’s through the 450b, I’d have less the zero worries about using the fmj’s in the 450b, in fact I recommend them for many applications. However, as stated above, using them in a 458 SOCOM will not work so well, bullet wobble down the barrel is the problem here.
Trim length is 1.700” plus .000”, minus .003”
Concerning your proposed 240gr/1680 starting load, Slash’s last load was 45gr of 296/H110- (their data is interchangeable) with a 240gr bullet, as I remember, as 1680 is going to lower the pressures for the same charge and extending the OAL to 2.250” will also drop the pressures and as 296 and 1680 have the same specific gravity, I’d start at 45gr of 1680 and work up, looking for pressure signs all along and stopping when necessary. But here’s a novel idea. I always like to know the max amount of powder the case is going to take when a compressed load is used, when developing a new load. I sacrifice a single case by drilling a 3/16 hole through the primer pocket. Then seat the desired bullet to the OAL of your dreams. Now, fill the cartridge through the new flash hole, make the powder flush with the base. Plugging the flash hole with your thumb and holding the bullet with your fore finger and pointing the case down, tap the cartridge with a kitchen spoon, many times. When you remove your thumb you’ll see the powder level has gone down. Refill again and repeat the process many times. The last time make sure the powder is again level with the base, now weigh this charge, this represents a slightly compressed load and should be the max the case can hold, with your chosen bullet. With some powders this will be of course way to much powder, but with the slower powders you may well get to this number in your developmental process. I hope I painted the correct picture here. I do this all the time, and as I’m not standing next to you, all bets are off, be careful. But here’s the goal, I wouldn’t by a Corvette to drive 25MPH, if there is performance to get I want it, but of course driving 200MPH has it’s dangers and so does handloading, be careful. One other warning, all powders, but most assuredly ball powders do have high pressure problems if undercharged…t
Keep the OAL’s as long as possible. The magazine will handle 2.260”, so with room for dirt and such, make the max OAL 2.250”, which will easily be achieved with the longer bullets, like with the pointed Barnes 275gr. and many others. Keeping the OAL at max length will lower pressures allowing you to increase powder volume, just don’t get crazy. The loads I’ve seen here for the 275’s are somewhat light, you should be able to up the speeds “at least” 200fps plus quite easily, try AA1680 to do so, which will also lower pressures, compared to H110/WW296 ( which work well for the lighter bullets-btw, the data for these two powders are interchangeable).
If you want to recover real world expanded bullets, use one gallon milk jugs, filled with water. I get mine from a milk bottler, for something in the $.015 area, in bags of 50. Attach three 2X6’s in a “U” fashion and line the jugs up. The 1911 with 45acp Federal Hydro-Shock expands as advertised and eats up four jugs. A 230gr hollow point (450b @2800fps) barely does one jug and explodes into thousands of little pieces, good for home defense. All bullets and pieces are very recoverable and comparable to whatever standard you want to use, let’s say you want to compare your load to a 45-70 or 338mag or whatever, go ahead, shoot them into the jugs, you will be totally surprised at the results.