That's my guess, as I see no evidence anywhere on the rifle that it was military.Originally Posted by vzerone
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That's my guess, as I see no evidence anywhere on the rifle that it was military.
Well, after getting all my brass cut down and annealed, I formed a couple and trimmed them to 2.255". I loaded one up with a 175 gn RN Hornady over 20 gn IMR 4198. My Speer loading book from 1979 was the only one that mentioned a reduced load for old guns. They said 22.0-26.0 of 4198 for the reduced load, and said that should give me 1633-1915 fps. I initially seated the long bullet WAY out, like only about 1/3 down the neck, just to see if it would touch the lands when I chambered it. It did not. I decided to think about bullet jump distance later, and seated it to just short of the cannelure, which was about 80-90% of the way down the neck.
I fired it this morning. The chrony said 1336. All seemed fine, but when I ejected the case, I was surprised that one side of it was all blackened. I've never seen this before, so I really don't know what it means. It certainly appears that gases were going back, but not all the way to the head. It also didn't blow the case out much, as I can still see impressed in the neck how far the bullet was seated. I could add a couple grains of powder, to bring it up to the starting load; I just wanted my first shot to be very conservative.
Before I go any further with this, I'd like to hear your opinions on my observations, especially the blackening. The fact that the charge didn't even fully blow out the neck may be because I started a bit under the starting load. But I don't want to add more powder until I know what's up with the blackening and if it's safe to continue. These cases were all tumbled overnight, and were all shiny and like new before I fired.
Clean side of brass:
Closeup of neck:
Blackened side of case:
Closeup of blackened side of neck:
It's pretty clear how far down the bullet was seated, and it didn't expand the neck at all, other than where the bullet expanded it.
I annealed before forming; should I have also annealed again after forming?
Last edited by brian1; 11-19-2017 at 03:56 PM.
It means one of two things (or both). It is usually a sign of too little pressure and the case isn't sealing in the chamber. It can also be caused by brass that's too hard and might need annealing. I'd up the charge first, as 1336 fps is pretty low for the bottleneck 7x57 cartridge.
Might consider a little faster burning powder also to bump the pressure up.
It's possible that it was used during the long period of 20th century revolution in Mexico.
The brass did not seal against the chamber wall. More powder is needed badly.
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Well, I loaded up a couple more. One with 22 grains of IMR 4198, one with 22 grains of AA 5744. My chrony didn't record the first shot with 4198. It opened up the neck more fully than the last time, but not completely, and there was only a small amount of blackening on the neck. On the second shot, with 5744, I recorded 1650 fps, less blackening than the 4198, and it fully opened up the neck. Maybe another 0.5-1.0 grains.
I am having a hard time understanding the whole low pressure loading thing. We use reduced loads to keep pressures low for old guns. But it appears to me that the reduced loads are done with faster powders, like 4198 and 5744. This doesn't make sense to me. I would think we'd be using much slower powders for reduced loads, not faster ones. All the more so with the long barrels in rifles like the Rem RB. It seems to me that a fast powder is going to produce much more of a shorter, higher pressure spike, that may not even last until the bullet is out of the barrel, than a slow powder that starts off slow, without a quick pressure spike, then continues burning and maintaining pressure as the volume (bullet going down barrel) increases. I suppose there must be some fallacy in this logic, as all the reduced loads I've seen recommended call for small amounts of faster powder, but I just don't see where the error in thinking is.
Here's a simple graph I made of what I'm talking about; blue is a fast powder, red is a slow powder. Wouldn't it happen like this, and if so why wouldn't we be better off with slow powders when we want to reduce pressure, especially in a long barrel?
Last edited by brian1; 11-22-2017 at 03:58 AM.
I wouldn't consider either of those powders as "fast". And if I wanted to shoot reduced loads, I'd look to other powders that truly are fast burning and will generate a quicker rise to the same pressures. Then you could likely have a good seal and even do so at lower velocities.
Powders like Unique, Red Dot, Green Dot, etc. will all seal the case/chamber well and at lower velocities. A load of 12.0 grs. Unique will give around 1500 fps with a 148 gr. bullet and seal great. You might end up 1.0 gr. higher with your heavier bullet.
Perhaps I should have mentioned that I am shooting jacketed bullets in this (cuz I have a bunch of 175gn and 145 gn jacketed and no cast ones), so I am trying to limit PRESSURE due to the perceived limitations of the action steel,and I'm only looking at velocity as an admittedly poor gauge of what's happening inside when I fire it. I'm not really trying to limit velocity. For me, it can have all the velocity it wants, as long as pressure stays low. So that's why I think I want to seek a slower rise to a given pressure, rather than a fast rise. Is this thinking wrong?
They don't use slow powders in reduce loads because they need to be a more full load so the powder burns more efficienty. Take for example you can't reduce recommended loads of WW 296 by much at all. I know that's a pistol powder, but one you don't reduce the recommended loads. You can run into a SEE problem.
Top loads I'm seeing for the 4198 powder, which are reduced velocity, is in around 26 grains. It's not a choice powder for standard 7x57 loads. What other powders do you have.
Oh, lots of choices; H CLAYS, Bullseye, Titegroup, SR7625, HP-38, SR4756, 2400, VV N110 (lots), IMR4227, AA5744 (lots), Norma200, IMR4198, H4198, H322, IMR3031, VV N133 (lots), IMR4895, IMR4064, Varget (lots), IMR4320, IMR4350, IMR4831, H50BMG (lots), VV 20N29 (lots)
I was using the 4198 because the only reduced load I could find for 7mm was in my 1979 Hornady book, and it said to use 4198 for reduced loads. Current Hornady book doesn't even mention reduced loads. I also tried 5744 because I have a lot of it and I've heard it's good for reduced loads. I use the 5744 in my muzzleloader
Brian, you could just about use all those powders you listed. What velocity you wanting to shoot? You know that rifle will shoot factory loads. We're not talking about trying to make a 7mm Mag out of it. You can load it up some. Get in your manual and look at data for some of the powders you listed and just load the beginning loads which most often are very mild loads.Oh, lots of choices; H CLAYS, Bullseye, Titegroup, SR7625, HP-38, SR4756, 2400, VV N110 (lots), IMR4227, AA5744 (lots), Norma200, IMR4198, H4198, H322, IMR3031, VV N133 (lots), IMR4895, IMR4064, Varget (lots), IMR4320, IMR4350, IMR4831, H50BMG (lots), VV 20N29 (lots)
I was using the 4198 because the only reduced load I could find for 7mm was in my 1979 Hornady book, and it said to use 4198 for reduced loads. Current Hornady book doesn't even mention reduced loads. I also tried 5744 because I have a lot of it and I've heard it's good for reduced loads. I use the 5744 in my muzzleloader
Oh. I was under the impression I had to use reduced loads because the gun would be damaged by factory loads. I'm really not too concerned about velocity; just pressure. Whatever velocity I get with a load that doesn't harm the gun is fine with me. I'll try a load in the middle of the pack of choices; maybe IMR 4831 or 4350. Thanks for the tips!
Yeah American factory loads are loaded low, although there may be some newer stuff out there that is hotter. You'll be okay with starter load and mid loads for sure. You know too those old 7x57 have generous bores and grooves.
Out of about 150 powders on the burn rate chart 4350 and 4831 are #118 and #123, so not fast powders or middle of the pack either. 4227, H4198, or 2400 would be more "middle of the pack" powders. 2400 has been many shooter's choice for decades for lighter loads. I've used it for decades in reduced loads with good accuracy, and no sealing issues.
The bottom cartridge is a 7x57 loaded for my South American Roller and you can see that the 175 grain semi-spitzer is loaded as far out of the case as is possible with the neck still holding onto it enough so that it won't fall out! (And the bullet is still well off the throat in my rifle ...)
I may have passed my "Best Before" date, but I haven't reached my "Expiry" date!
Interesting. Mine may end up seated way out like that, after I get done setting a load. I did an initial test with mine seated, not quite that far out, and it still wasn't touching the lands. It shoots OK Like that?
What's the top round - 300 BLK?
What sort of starting load in 2400 would you recommend for this 7x57mm? I can't find 2400 listed in anybody's book for 7x57.
thanks,
brian
Brian why don't you stop beating yourself to death over loads and shoot the beginning to medium loads in the books for jacketed 175 grain bullets? The 4898, 4064, 4320, 4350. I think you will be pleasantly surprised.
Yeah, that's what I did earlier today, using 2 of the powders listed in several of my books.
5744 23 gn 1796 fps
4198 24 gn 1662 fps
4350 37 gn 2011 fps
4831 37 gn 1738 fps
The 4350 seemed to be the best result on the brass. Lee manual said to use 37-40 grains. Most of Lee's recommendations are well below others'. Sometimes their "max" load is below others' starting loads. My 1979 Speer book said 44-48 grains, 2015 Nosler book said 43-47, 2016 Hornady book said 35-43. So I went with 37. Now I'll load up several with 4350 and see what the gun likes for accuracy.
That 4350 had the pressure up higher so the brass formed out like you said. I think the LEE loads would suit you. Those should be easy on that rifle. My old Speer manual says 41-45 grains.
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