Bought a Mossberg MVP today

Ian

Well-Known Member
#21
Probably a good idea, but chambering in something that won't handle the whole spectrum .223/5.56 pretty much defeats the purpose of a bolt rifle that accepts AR-15 magazines. If I wanted a precision target rifle in a custom chambering I would go a different route entirely and not even bother with the Mossberg action. A 25/45 Sharps might be interesting if I changed the barrel, and different enough I could have a tight-neck reamer and super-long, gentle throat ground for it. But I admit, if I change the barrel, it's probably going to be a 300 BLK.
 

Ian

Well-Known Member
#22
Hmmp. Might not be doing anything to it but shooting cast bullets and having a ball. It took me a week to get all the copper out from the first 56 shots (cleaned in-between every 3-5 shots with brush, patches, and copper solvent, apparently that didn't help much). I decided to try cast and see if it was worth fooling with. The only mould that even comes close to filling up the space is the MP .22 NATO bullet. I had a bunch cast up from ACWW plus about 1% tin, air cooled, which wasn't my alloy of choice for anything supersonic, but they were there so what the heck. I honed a sizing die out to .2255" and checked/lubed/sized a bunch. First batch was over 14 grains of RX-7. First three went into the same hole, then three more opened it up to 3/4" at 75 yards. I chronographed the load at around 2250 fps but the SD was wild and the second group showed it. I bumped the load to 15 grains and shot ten into 1.4", averaging around 2340 fps. That's still better than most of the jaxketed I've shot through it.

Since it looked like this might actually work out, I pulled up QL, matched the data I already had (upped the SSIP to 3K and that dialed it in), and played with powders that would get me over 2500 fps with minimal pressure. 20 grains of IMR 3031 looked good at 28K psi/2580 fps, but it only actually made 2452 average FPS for ten shots. That's a book starting load for the Sierra 63-grain SMK, by the way. The SD was MUCH better at 36 fps, and the second shot cut the first shot's hole even with a 60 fps cold-suppressor boost. Nine went into 3/4" and I rolled the rifle in the bipod for the last shot, dadgummit!!! for a 1-1/8" group at 75 yards.

The only problem so far with doing this is I have to seat the bullet so the entire lube groove and just a titch of the rear driving band extends past the case mouth. There's enough in the neck to be secure during handling, but the cartridges are too long to go in the magazine. I got zero lead in the barrel and almost none on the brake or suppressor from 30 rounds total.

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Ian

Well-Known Member
#25
I would have PC'd them but didn't want to wait for the ACWW metal to re-harden before shooting. Besides, I was curious as to how they'd do the old fashioned way and they seemed to do OK.
 

Ian

Well-Known Member
#26
"Spitzer/semi-spitzer" cast bullets are notorious for theirinaccuracy above1700 fps. Do we really think a .223 cast bullet of such design will do any better?

I have been shooting cast bullets in .223 in bolt actions, SSs and gas guns for 40+ years. This has included ARs with 7, 8, 9, 12 and 14" twists. From my experience none of your designs will shoot accurately above 1600 - 1700 fps in AR of sufficient twist for stabilizing the bullets at that low end velocity level. Function reliability will probably also be a problem. As with any other cast bullet shot at high RPM (as they will be in the faster twists) with any reasonable accuracy a short nose, well supported bore riding nose (if there is one) is needed. The last GB of the heavier bullet is still in the testing phase to see if it is practical at higher velocities in the faster twists. A RN cast bullet feeds fine in most all ARs BTW. The Lovern style 225462 at 58 - 60 gr (fully dressed) has been the best cast bullet so far (40+ years of testing) for the best accuracy above 140,000 RPM. It is capable 2300 2400 fps with M193 accuracy out of 12" twist ARs. The velocity level to maintain that accuracy goes down as the twist increases.
:headscratch::rofl::rofl::rofl:
 

Ian

Well-Known Member
#28
isblyutring in yer eye tends to cause headaches.

Here's something that ISN'T isblyutring, 21 grains of IMR 3031 for 2589 fps. That's 207,120 RPM for those counting. 12.5 bhn ACWW alloy wearing nothing but a gas check and some good lube:

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First off, all these were loaded the same. When loading these (4th time on the brass with absolutely zero prep other than FL resize) I noticed the neck tension had gone away on three of them, so I set those aside and shot them first. That's the three on the left. I was worried the 21 grains was too much for the alloy, but the next seven grouped on the right tells me nope. I was struggling with the failing light and the pivot on the bipod letting the rifle twist freely and I called two of the leftmost holes as shooter error, feeling the rifle twist off as the shot broke. I'm unbelievably rusty at bench shooting and it's really showing. Anyway, after shooting the second group I investigated and discovered the friction thimble on the back of the Harris bipod and promptly did a facepalm. I'm not the brightest bulb sometimes.

To hear some others on the internetz go on about it I thought this was going to be really difficult and was expecting another two years and thousands of rounds of frustration before finding anything that would shoot halfway decent at HV. (Yeah, I'm calling sneaking up on midrange jacketed data HV). Neither did I expect ACWW to handle that kind of speed. I'm starting to get excited now!
 
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fiver

Well-Known Member
#30
your about a grain and a half of [a step slower] powder and a couple of BHN points behind where I normally run.
it's impossible is what I was told, I tried it anyway.
 

Ian

Well-Known Member
#31
I'm still shaking my head over all the negative oratory. Can't do this, can't do that, blah blah. Well, Can't never could do anything anyway, but some of us did, including the bullet's designer who would laugh at me only getting MOA groups at near 2600 fps.

3031 looks to have a just little bit of room left before pressures and rate of pressure rise start to really climb, but it's near the edge. I ran RX-7 through QL again and it looks like it might be time to go back to it for a while because at around the same pressures I'm running now with the 3031, RX-7 has a much more gentle pressure rise and a bit more velocity. Hopefully the RX-7 at higher pressures won't show the position-sensitivity/high SD that it did at 14 and 15 grains. Now that I know the bullets can handle 33K psi I have more options before heat treating.
 
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Ian

Well-Known Member
#32
Oh, question: The necks are shot after four reloads and I'm finding that to be about right with any center-fire stuff at HV with cast bullets. Are the results worth the time to anneal and trim .223 brass, or should I just toss it?
 

fiver

Well-Known Member
#33
I usually full length size then neck size after annealing trying to get two cycles out of them before loading them with jacketed bullets to lose out in the desert shooting ground squirrels.
I get everything I can out of them, I absolutely hate processing brass even with all the motorized gizmo's.
 

Ian

Well-Known Member
#34
That's about what I figured. I'm probably going to lay in some fresh brass because most of what I have is loaded commercial or surplus, and the little bit that I empty or scrounge usually gets thrown all in a big bucket and sized neck turned, trimmed, and loaded in bulk with my subsonic, pc heavies.
 

fiver

Well-Known Member
#36
probably best.
it sucks to go through all those gyrations making good cases, then not shoot the rifle for a while and forget where everything is in the cycle.
I'm pretty good about keeping my cases segregated, but poor about notes as to where they are in a cycle.
so when I re-visit I just anneal my cases right off the bat, and try to keep the necks fairly soft throughout the life cycle.
that works for some stuff and not for others.
soft necks and swaged jacketed bullets with a base ring do not get along in an AR type rifle.
I can load them all day long in the bolt gun, but mine doesn't like the weight of those bullets.
I end up with about 6 different piles of this and that for the various rifles until I get frustrated with the whole thing then I toss them all in the bucket and start over.
 

Ian

Well-Known Member
#37
I'm still fighting the segregation thing in several calibers. Putting (and keeping) everything in cartridge boxes and marking them with a sharpie tic mark every time they are reloaded (should be every firing, but it's easier to mark them when I put refills back in) or annealed works for a lot of things, but the autos make it tough when I just want to have three buckets for all of it in each caliber: One fired (who cares how many times), one decapped and cleaned, one ready to shoot. .45 ACP is the worst, too much variance among headstamps for accuracy in the carbines, so I just got the one I had the most of and bulk-load it over and over.

So far I got .38 Special, 300 BLK, and .45 ACP licked. For each I have one load, one bullet, and one huge lot of identical brass that fits and shoots well in all of the guns I have in each chambering. Still working on .45 Colt. .30-30 will never be right because all five of them prefer something different :rolleyes:

I got 500 .223 cases and the MTM flip-top boxes were on sale so I got enough to box it all and keep track of it.
 

fiver

Well-Known Member
#38
I go back and forth between a big bulk pile and the individual boxes.
every time I buy the boxes I can't stop thinking about how much powder/Brass/primers I could have just bought instead.