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Posted: 12/27/2025 7:30:34 PM EDT
[Last Edit: txsgar15a2][Edited]
| I took it out this afternoon for its first range session. I fired 10 total rounds during the session. I used an unmodified GI style 30 round allum magazine. I fired in three different times. I loaded three rounds then two rounds, and then tried my luck with five rounds. All fired ejected and fed the next round. The bolt locked back on each firing session. I also hit what I aimed for at around 25 meters. The big surprise was the monster mule kick it gave me on the first shot. OMG it did not hurt too bad, but it certainly made me hold the stock into my shoulder better for the subsequent rounds. I watched my son shoot it it and I could feel the shockwave. I call this an OUTSTANDING experience. |
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I built one about 4 years ago,heard all kinds of horror stories about FTE,FTF etc. Mine, has been 100% reliable with old GI 20rnd, lancer 20rnd, and DPMS 450bm mags shooting Hornady black. Recoil has been reduced with a Tromix radial brake.I didn't notice it being excessive prior though. Good luck with it,it is for sure a "thumper" as a large 10pnt E Tn buck found out |
| When the box for the ammo says for deer hogs and bear, the name "Bear Spray" came to mind. A new lower with a solid stock seems to be the correct way for me to go from here. I do not hunt often. The idea of the .450 Cartridge intrigued me that an AR15 platform Rifle could accommodate and safely fire it. The solution to the T-Rex problem is solved with this one weird trick. Polar and Grizzly Bears are not around these parts, however, if the bears or Jurassic Park's finest start going through my garbage then I am well equipped. |
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Originally Posted By majg1234: I built one about 4 years ago,heard all kinds of horror stories about FTE,FTF etc. Mine, has been 100% reliable with old GI 20rnd, lancer 20rnd, and DPMS 450bm mags shooting Hornady black. Recoil has been reduced with a Tromix radial brake.I didn't notice it being excessive prior though. Good luck with it,it is for sure a "thumper" as a large 10pnt E Tn buck found out How many rounds are you getting into the GI 20 round mags? |
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| I bought 2 Bear Creek 458 SOCOM uppers,one in semi, the other a bolt action. I’ve shot 25 rounds through the semi, worked great, no failures. Just doing a quick “get the scope sighted in before dark” session. Haven’t shot the bolt action yet, but working it without ammo isn’t the smoothest. Recoil wise, I didn’t think it was any worse than my 308. Big hole in the target was cool. |
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| Can you run the bear creek side chargers without gas as a straight pull bolt action? I have a 450bm SBR that I think would be cool as a straight pull. |
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Originally Posted By ScottyPotty: Can you run the bear creek side chargers without gas as a straight pull bolt action? I have a 450bm SBR that I think would be cool as a straight pull. Yes you can. I'm right handed, and I shoot this one using my left hand to operate the bolt. 300 Blackout with a can. It takes some getting used to, but it can work well.  " />
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Originally Posted By ELittlefield: Hell yeah! I love Bear Creek, and I love big bores. Here's my Bear Creek upper 450. Side charging uppers are awesome. https://i.imgur.com/o7kO5H5.jpeg" target="_blank">https://i.imgur.com/o7kO5H5.jpeg Nice looking rig, What suppressor is that? I’d like to suppress my 458 Socom, as well as a 1911, but I don’t think I can do it with the same suppressor…pistol suppressor too light for a rifle, and a rifle suppressor would be to heavy for the 1911. |
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Originally Posted By RobRat: Nice looking rig, What suppressor is that? I’d like to suppress my 458 Socom, as well as a 1911, but I don’t think I can do it with the same suppressor…pistol suppressor too light for a rifle, and a rifle suppressor would be to heavy for the 1911. Originally Posted By RobRat: Originally Posted By ELittlefield: Hell yeah! I love Bear Creek, and I love big bores. Here's my Bear Creek upper 450. Side charging uppers are awesome. https://i.imgur.com/o7kO5H5.jpeg" target="_blank">https://i.imgur.com/o7kO5H5.jpeg Nice looking rig, What suppressor is that? I’d like to suppress my 458 Socom, as well as a 1911, but I don’t think I can do it with the same suppressor…pistol suppressor too light for a rifle, and a rifle suppressor would be to heavy for the 1911. SilencerCo Hybrid 46. If I were to pick one silencer out of my collection of 10 to keep, it would be this one. Now SilencerCo advertises that it can work on pistols, but I have not tried it. I would not try to repeatedly switch it between rifles and pistols. To be frank, the notches at the base which allow a wrench to grab on, and thread in new HUB mounts, are extremely shallow, and I don't think they're up to repeatedly tightening and loosening a rifle mount and a piston (pistol) mount. I've tried a few different HUB mounts in there, and the notches are getting pretty chewed up. I currently have a YHM SRX mount in that silencer, and that's the way it's going to stay. |
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Originally Posted By txsgar15a2: I took it out this afternoon for its first range session. I fired 10 total rounds during the session. I used an unmodified GI style 30 round allum magazine. I fired in three different times. I loaded three rounds then two rounds, and then tried my luck with five rounds. All fired ejected and fed the next round. The bolt locked back on each firing session. I also hit what I aimed for at around 25 meters. The big surprise was the monster mule kick it gave me on the first shot. OMG it did not hurt too bad, but it certainly made me hold the stock into my shoulder better for the subsequent rounds. I watched my son shoot it it and I could feel the shockwave. I call this an OUTSTANDING experience. Glad it went well for the both of you! I really need to swap out the follower on one of my 30rd gi mags with a 450 bushmaster single round follower and give it a try. Thank you for the reminder. |
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| I took my side charging 450bm out today and it wouldn't shoot......pulled the trigger and just got a click. No dimple on the primer, no bang....it was 26 deg this morning, kind of thinking maybe the firing pin froze.....I know my fingers were frozen and didn't want to work. |
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Originally Posted By ScottyPotty: I took my side charging 450bm out today and it wouldn't shoot......pulled the trigger and just got a click. No dimple on the primer, no bang....it was 26 deg this morning, kind of thinking maybe the firing pin froze.....I know my fingers were frozen and didn't want to work. Very possible. Are you pretty confident that the bolt carrier was all the way forward? New BCGs, especially cheaper BCGs, can have stiff gas rings early on, that inhibit the carrier going all the way forward. That's how it would seem to me, if there isn't a dimple on your primer. |
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Originally Posted By ELittlefield: Very possible. Are you pretty confident that the bolt carrier was all the way forward? New BCGs, especially cheaper BCGs, can have stiff gas rings early on, that inhibit the carrier going all the way forward. That's how it would seem to me, if there isn't a dimple on your primer. Mine worked on the 1st outing. I do notice that the bolt carrier needs to be a little broke in as it does not slide as smooth when field stripping and re assembling. |
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Originally Posted By ELittlefield: Very possible. Are you pretty confident that the bolt carrier was all the way forward? New BCGs, especially cheaper BCGs, can have stiff gas rings early on, that inhibit the carrier going all the way forward. That's how it would seem to me, if there isn't a dimple on your primer. Mine isn't new, low round count but has always ran reliable. I did I let the spring slam the BCG forward several times, different rounds.....felt like it was all the way closed. But just a click....I figure Ill look into it this today, I'm curious what happened. One other possibility, is the "crappy ammo"....my hand loads. Ill have to look at my log book, but pretty sure this recipe was tested and found to shoot good enough for me to take deer hunting once sighted in and come up with my dope. |
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Originally Posted By ScottyPotty: Mine isn't new, low round count but has always ran reliable. I did I let the spring slam the BCG forward several times, different rounds.....felt like it was all the way closed. But just a click....I figure Ill look into it this today, I'm curious what happened. One other possibility, is the "crappy ammo"....my hand loads. Ill have to look at my log book, but pretty sure this recipe was tested and found to shoot good enough for me to take deer hunting once sighted in and come up with my dope. Originally Posted By ScottyPotty: Originally Posted By ELittlefield: Very possible. Are you pretty confident that the bolt carrier was all the way forward? New BCGs, especially cheaper BCGs, can have stiff gas rings early on, that inhibit the carrier going all the way forward. That's how it would seem to me, if there isn't a dimple on your primer. Mine isn't new, low round count but has always ran reliable. I did I let the spring slam the BCG forward several times, different rounds.....felt like it was all the way closed. But just a click....I figure Ill look into it this today, I'm curious what happened. One other possibility, is the "crappy ammo"....my hand loads. Ill have to look at my log book, but pretty sure this recipe was tested and found to shoot good enough for me to take deer hunting once sighted in and come up with my dope. Hmm. If you're not seeing a primer strike, it's unlikely to be a handload issue... unless you trimmed the brass back way too far, and the round is sitting far enough forward of the bolt fact that the firing pin can't reach it? It headspaces off the rim, as you know. First thing I'd disassemble your BCG and make sure there's no obstructions in there. Next I'd try factory ammo. |
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It's the ammo.....The overall length seems long, but what I don't understand yet is my log book notes that it should work. *edit* It's not the ammo, it won't fire any ammo. Something else is going on....I'm going hunting will I have to investigate later. Attached File |
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Broken firing pin tip. Attached File |
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Originally Posted By ScottyPotty: Broken firing pin tip. https://www.ar15.com/media/mediaFiles/102712/1000008132_png-3686615.JPG Easy fix! Glad to see you solved it. |
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Glad to hear you guys have had good luck and a fun experience with your Big Bores. I have built up two big bores, both in 12.7x42 (.50 Beowulf). Both are BCA Uppers but in standard configuration with a traditional charging handle. One is a 16" rifle and the other is a 10.5". I use Lancer L5AWM mags with the metal feed lips and have yet to have a malfunction of any type. I have thought about trying the Tromix followers, but everything is working as advertised after a few hundred rounds, so we'll see. |
| I have shot about 200 rounds through my BCA 450 bushmaster upper. Mine does not like soft tip Winchester factory ammo. Had a lot of failures to go into battery and case splits with it. However my reloads with Starline Brass and Hornady flextip bullets worked very well. I am surprised at the accuracy of mine at 50 and 100 yards. I can get five shot groups in less than 2.0 moa with just a red dot. |
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I finished building the dedicated lower receiver yesterday. I will test fire it as soon as I can make it out to the range. We are anticipating snowmageddon this weekend in Texas. On my lower build I installed a full sized A2 rifle stock. This I might mitigate the recoil some. Edited to add: OMG! The full A2 stock was not the pain in the ass other sliding stock assemblies are. I wish someone would design the sliding stock assembly with out the separate end plate. I also have a few slip in 450 followers from Muddy River on the way. |
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I just received the Mag followers from Muddy River. The two metal 30 round mags will feed chamber and eject with the bolt locking back when the bolt is pulled all the way back. This was a dry cycling of the action with store bought rounds. I pulled out some of my old 20 round GI metal mags and installed the 450 BM followers. I am able to comfortably load seven rounds into them. I am thinking that I will purchase some new metal 20 round magazines and dedicate them the the 450 BM rifle. This way the mags will be visually different than the other AR15 mags I use. I tried to load some of the rounds into one of my Magpul magazines. You can load one round. Once you try to depress the 1st round, it is stopped by the raised ridge in the front of the magazine on the projectile. I suppose you could dremel the ridge away if you are that dedicated to it. I will return to this thread and report back the results of live fire. This will test the new lower receiver with A2 stock cycling and the magazines with the Muddy River followers. The reloading of .450 BM will commence as soon as the dies come in. I ordered a set from Amazon, but they were for .45 Colt. I sent them back and am waiting on the right dies. |
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Three new things to report on... 1. Built a dedicated Lower with an A2 Stock. 2. Muddy River Followers in 20 RD alluminum magazines 3. Reloads using 45 ACP Hornady XTPs 1. The dedicated lower worked with the .450 upper. It did mitigate the recoil better. 2. Muddy River Followers in old school Allum Magazines. The follower work ok in the old 20 round magazines. I was able to reliably stuff seven rounds of .450 Bushmaster in them. 3. Reloads with Chrono Results; I reloaded the empty cases with around 37 grains of H110 powder/small rifle primer/230 grain Hornady 45 ACP XTP projectiles. Warning on the reloads. You will need to push the projectiles to a 2.19" OAL or they will not chamber fully. Here are the chrono results. 1st Shot 1962 FPS 2nd Shot 1862 FPS 3rd Shot 1909 FPS 4th Shot 1828 FPS 5th Shot 1825 FPS The store bought Winchester 260 grain soft point round clocked in at 1910 FPS. My reloads recoiled less than the store bought rounds. As stated above I needed to adjust the OAL to 2.19" or they would not chamber fully. The point of impact was around 6" down from the store bought ammo. I still need to work on my marksmanship with this new round/AR variant. I shot targets around 15 yards away. I am still working on function and firing reliability. One of my store bought rounds failed to fire even after three more attempts. The firing pin did dent the primer. Other rounds fired after it, so I am thinking this is something to do with either a primer failure or power issue. One think I noticed is that this is a very dirty weapon. I cleaned it after the last outing. I can see unburned powder in the bore and the casings showed a smoky residue from the reloads. Once I have this set up to 100% reliability, I will use three 20 round allum mags with the Muddy River Followers loaded with seven rounds each for a basic load. |
| I started at the lower end of the recommendation. The reloading manual did not have a match for 230 Grain XTPs meant for . ACP. It did recoil less than the 260 grain store bought ammo. I am curious to know if anyone else tried this. I used the XTPs because that is all that II have at the moment. |
| I will re-check my notes. This was the 1st time I used a dipper that comes with the die set. The conversion was close to 2cc equals around 37 grains. I will be more precise in my next batch. I plan to purchase the recommended .452 “Rifle” projectiles. I think I will save this initial recipe for cheap plinking rounds. |
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