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Posted: 10/1/2007 8:27:51 PM EDT
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What a great gun! I went out on Sunday and went through 45 rounds. Now I admit I'm a bit of a recoil wimp, but I like to be totally relaxed and not anticipate the round. Well, after the first couple of rounds in the prone I was flinching pretty good. This thing kicks pretty good, but boy did I love it! I was firing the 24” 50DTC upper with a Magpul PRS. I had one home made recoil pad and after the first round another slip on pad. After about 15 rounds I put another piece of foam in there. I had on top a sacrificial BSA 6-24 that I was just abusing for the laugh. Well, the scope held up fine, I guess china's laughing now. I will change it out soon though. I was firing 50 DTC , AP (black tip)“forming” rounds loaded by Mr Kubota from Calguns. The first round didn't fire. Wait 30 sec, cock, reload same round and it fired. Same thing on the second round. I stopped, pulled the hammer out, and bent the spring open a little to make it strike harder. From then on I had no FTF or any functioning problems. The max rate of fire I attempted was about 10 RPM for 5 rounds in the offhand. It got kinda warm doing that. On to issues. I lean in hard on my bipods to get better support, after about 40 rounds, at the end of the day, one of the bipod legs broke and fell off where it was spot welded together. I just fixed that tonight in my shop with my own MIG and I think it will be fine. There is also either an issue with the ammo, brass or headspace. I had about 8 cases that had cracks at the base (see pic). One even seperated entirely. These were not consistent when they occurred, offhand, hot bore, cold, I dunno. I am mailing the brass to Mr Kubota and have a call into Chris. I checked it with the 10 cent no go, headspace gage (a dime on the back of the round) and the bolt wouldn't close so that's a good sign. It could also be bad brass that was initially shot out of a M2 with excessive headspace. I'll post when an answer comes in. I got 3 shot groups at about 1.5-2” at 100 meters. I didn't fire out past that due to starting late, but will next time. Sorry, no pics. Well, I am thoroughly pleased and totally impressed with the product and the service I've received.   
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VEPRguy1 Thanks for the range report. I got your phone call LATE sunday, I was stuck up in LA for the better part of the weekend. he If everyone is ok with it.. I would like to shoot some video as well. |
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Thanks for the response Ben. And the great service. I am sending you a bunch of LC brass so we'll see how it does. If those were "light" loads, I really am a wus. If anyone hsn't been dealing with Ben, he's great. I may not be out again for a month or two, but I'll let you know Nef. I shot lots of video, but don't have the motivation to figure out how to post it. Besides, most of the shots were followed by someone exclaiming F*&K! I still can't believe the BSA held up so well!!! |
Gives me time to stock up on more ammo - Ben needs a mailing list hot |
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Hey VEPR- How did the upper handle the case failures? Did you get a bunch of gas in the face? I noticed that there is a hole in the bottom of the bolt that leads to the mag well on the lower. I assumed that was designed for venting gas, and wondered if it works. Haveing never had ANY case failures on any weapon, I'm pretty nervous about the BMG 
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No issue at all. I didn't even notice until I ejected the case. The one that totally seperated I fired in the offhand with my arm under the mag well. I didn't notice anything at all. THen again having a howitzer go off in your shoulder tends to be distracting. This thing is built like a tank. I still can't believe the BSA stood up. |
I wish! It was prone, but as I said, I was taking a pounding so I was anticipating BAD. I would just get it on target and instead of BRASS, I flexed everything I had to tighten up and YANKED the trigger while whispering profanity. I bet that from the bench would be the best combination of recoil management and stability. |
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Vepr - Thanks for the range report. As we talked on the phone, I think the case seps are from the fireforming as well. I have never had a case split like that (never even seen one). I've seen cracks at the neck but that's to be expected after about 5 reloads with 50BMG As far as fire forming for DTC goes, I use a load of 75 grains of RedDot shotgun powder toped off with cream of wheat. Either drip wax ontop of the case neck or there is a fellow selling rubber discs you can use to plug the neck. This is a cheap, easy and no recoil way to fire form your brass. This method was passed onto me by Matt Tompson (Proud owner of DTC #1) And the fellow that talked me into making DTC's in the first place. Thanks again Chris Rosequist Bohica Arms Corp |
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I sent Ben the brass and a bunch of other brass so between me and others he is probbably very busy so I will post what he told me to save him some internet time. BLUF, it looks like my brass was soft and slight differences in chambers and shouldes position caused a little too much stretch in the fireforming. Here are the highlights of our email messages. I have to say his service is incredible. I actually feel bad for all the trouble. From Ben: "The PSD brass looks like it was just too soft in many cases. There were a few TZ-79 (Israeli) shells in the first batch as well and they don't show any of the stress that the PSD did. There are a few PSD that look perfect too, though most aren't worth reusing now. It's odd too that the PSD brass shows stretching and tearing mostly on one side of the case. Sort of like bending/snapping a pencil with stretching on one side and compression on the other. Not something I've ever seen before. The cracks that have formed, look to be closer to the case web too. A typical separation in brass fired in an M2HB usually happens a little higher up, with more even stretching around the circumference I'll have to scrounge through my scrap bucket for an example to compare to. When you chambered the ammo, did it go in without any resistance, or a little snug, or tight? (a little snug is what I try for in forming ammo.)" From me: "The rounds dropped right in easy and took no effort to close the breech. The extractor did always catch and the "dime" headspace check passed. It wouldn't close with a dime on it. Thanks again for the great service. I'll continue to do ammo reviews too. The service from you and Chris has been beyond what I expected." From Ben: "John, I've got some of the other PSD ammo coming back, so I'll have some unfired that I can pull down and look at too. I ran a feeler down some of your OK looking returned brass and still didn't feel anything, but this time I also did a visual check and found that even much of the good looking stuff showed the shadow of a stretch at the case head. About 20% of what you returned was fine, 30% showed signs of stress, and the rest had failed. Guess that'll teach me to rely on just the feeler! The stretched area appears to be spread over a bigger area and is lopsided. That's why I believe I couldn't feel them with the probe initially. Too smooth a transition. Coupled with the extra stress of fire-forming, the softer PSD brass just couldn't take it. I'll adjust the case sizer to match the fireformed brass better. Hopefully that give a nice snug fit that should let the new batch form up better. I'll be checking with a light this time too! If you want to send the remaining PSD back, I'll load them back into the newer brass as well." From Me(feeling like a real PITA): "I am comfortable shooting this PSD I have here unless you think it is unsafe. I'll then send you the empties to evaluate." From Ben(still not sick of me!): "There's likely to be some scorching of the back end of the chamber. You'll need to clean and examine that area to determine if any erosion occured as well. Certainly, I've blown my share of cases over the years, but not at the rate this lot's been going. I always want to error on the side of safety, and pulling down the ammo for rebuild is a simple process. I should be able to get at least a hundred new rounds out to you today, so you'll not have to be without." WOW! how can you argue with that! I sent this guy brass that had flaws and he is taking care of me as if it is no big deal. I really apreciate his service and effort. Thanks again Ben and I hope this saves you some time because curious minds want to know. |
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My final take on what I believe went wrong with the PSD based ammo: It turned out to be a good lesson in how we really never know what can go wrong until it does... I think the PSD-04 brass in question was never properly drawn or annealed to provide the proper elasticity to the side walls of the case. After sorting them out appearance wise, I did some measurements and test chambering. The TZ fire-formed brass measured within a few thousandths of both EDM and Serbu sample fire-formed cases. The PSD brass I took to be perfectly formed by appearance, were actually buldged quite a bit near the casehead. They measured .799-.801" where the EDM and Serbu cases measured a nominal .796-.797". Though they 'looked good' the PSD wouldn't chamber into my Serbu while the TZ brass from the same lot of ammo, chambered quite normally. There is apparently no 'spring back' in the casewalls of this PSD brass. That's why there wasn't the typical casehead 'groove' that accompanies excessive headspace. These cases ballooned out, and stayed that way. Thinning over a wider zone in the same general area. In the BMG chamber they held together better as that chamber would be tighter than the deliberately larger DTC chamber the brass was trying to fill on it's second firing. Those that were already borderline blew up like an over inflated balloon starting at the weakest point in it's skin and progressing from there. That's likely why the fractures were so lopsided compared to a typical headspace separation. Anyway, my lesson learned from all this is to add measuring the casehead area of any new lots of brass to see if they are within a reasonable norm, especially if there's no apparent stretch to account for a big reading. I'm going to shorten the recoverd brass and work it into M48 spotter brass for one of my rifles. I'm hoping the extra work hardening in forming it will give some spring back to the brass. If not, I'll at least get one more use of them before they get recycled. //Ben |
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