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Trailblazer
06-11-2005, 10:29 PM
I have a 444 Win 94 that i don't use, so I thought I would cook up a more useful combination for my purposes. In the interest of science I scrounged up a Rem SS 7mm RM barrel and cut it off and threaded it for the Big Bore Winchester. The goal was to have a 2.04 " case length which would enable me to use FN bullets designed for the 7-30 Waters and crimp in the cannelure. The case is the one with the 120 Sierra stuck in the mouth.
http://www.hunt101.com/img/295657.jpg (http://www.hunt101.com/?p=295657&c=556&z=1)
This lineup includes the 7-30 Waters, 7mm-08 Rem, 7mm Mauser, my shortened 7mag and the 284 Winchester arranged in order of increasing case capacity. The short 7mag lies midway between the 7 Mauser and the 284. Based on the info in a case forming handbook belonging to a friend the capacity is about the same as the 7mm Mauser AI.

This is one nifty little cartridge. My initial load testing is with 120 Sierras. 53 gr. WC852 gave 2660 fps. 53 gr. H450 gave 2909 fps. 51 gr. H4350 gave 2855 fps. 50 gr. W760 gave 2918 fps. 42 gr. Varget yielded 2749 fps. and 45 gr. IMR 7383 delivered 2599 fps. Primers are round with only a hint of a flat center in the higher velocity loads. E.S.'s are low and accuracy is fair. Groups ran between 1" and 2" and increased with velocity.

The only fly in the ointment is the platform I built this cartridge on. It really takes a good bit of pressure to open the action after firing one of the higher velocity loads. I am getting to much bolt thrust with the large base diameter.

Next step is to polish the bearing surfaces on the locking bolt to see if it will make it easier to open the action. Then I am going to work up a little more with WC852, IMR7383 and try some H4831. After that I will start playing with cast bullets. I have the Lyman 287346 and the Saeco 071. The Lyman may work better since the 7mag has a throat and the Lyman has a longer bearing surface. This case, with the reduced capacity, ought to be a little more cooperative than the full size 7mag.

Case forming is laborious. The easiest to work with is 6.5 RM brass. Base diameter runs from .505" to .506" in the batch I bought-just about perfect. I turn the belt and rim off with a lathe and then bump the shoulder back about 1/8". I am using a cutoff 338 WM die to bump the shoulder and then a shortened 7 mag die. This process has to be done in steps with a relube between steps to prevent wrinkles in the shoulder.

I can tinker with this one for a long time!

Buckshot
06-13-2005, 03:25 AM
..............Trailblazer, first of all welcome to the board! Another tinkerer/casemasher aboard. That looks like a real neat conversion. I wonder if the chamber is polished or very smooth, and it's letting the case ease back a bit too much? Then again those are some impressive ballistics. I never did a bunch of work with my 7x57's and lighter slugs, although I did shoot some, but this was in mostly 29" barrels.

This is my own personal feeling, but if the action operated smoothly without undue effort with the 444 Marlin, which is a 42K (ish) cartridge, I'd sure try and stay in that area. I'd let lever operation tell me when I was getting outside that pressure region. Getting 7x57 ballistics from a lever action would be a neat accomplishment in any regard. That larger case would let you do it at a lower pressure, too.

................Buckshot

C A Plater
06-13-2005, 08:10 AM
To ease some of your conversion pain ($$$$), I suggest you take a look at a wildcat based on the .444 necked to 7mm. I believe you could use 7-08 dies as I have seen this done in T/C Contenders in .30 and .35 calibers using .308 and .358 dies so I am certain a 7mm version is not a problem.

Whatever path you take, good luck.

45nut
06-13-2005, 08:50 AM
To ease some of your conversion pain ($$$$), I suggest you take a look at a wildcat based on the .444 necked to 7mm. I believe you could use 7-08 dies as I have seen this done in T/C Contenders in .30 and .35 calibers using .308 and .358 dies so I am certain a 7mm version is not a problem.

Whatever path you take, good luck.
C.A

I did just that when I kept having issues with cases sticking in my 7mm INTR TC .
I sent my barrel off to OTT,[On Target Technologies] and had him EDM a new chamber to a 444 case run right up a 7-08 die. No Changes to the die,case ,just a teeny bit of imperial sizing wax and a few bumps later I have a case. Haven't dont much real work with it lately but nearly full of 4350 they just dropped right out. Much nicer than the old grab a stick and beat the cases out ordeal the previous chamber had.
YMMV of course.

StarMetal
06-13-2005, 08:53 AM
Most the time factory advertised velocities are never realized in reality, but in the case of the 7-30 Waters it definately achieves the 2700 fps in the 94 Winchester and that's with a 20 inch barrel. In my honest opinion your creation is too much labor for not enough gain and if you have to do it, Platers suggestion of using the 444 Marlin case is a far superior and easier conversion to do.

Joe

Buckshot
06-13-2005, 10:14 PM
............Oh Joe! You tactfull sonuvagun :D !

..............Buckshot

Trailblazer
06-14-2005, 10:07 AM
My goal was to exceed 3000 fps with the 120 gr. in the Winchester 94. The cartridge is certainly up to it. I stopped adding powder at 2900 fps because it was getting to hard to open the action. The case will hold about 58 grains of ball powder to the base of the neck. Based on published and pressure tested data for the 7x57 my pressures should still be below 45000 cup. It may be that the short fat case develops a higher peak pressure than the 7x57 though-I don't know. Another problem is that the firing pin is not supported with the rebounding hammer in this model 94. The primers started extruding into the firing pin hole in the hotter loads. I never fired any max loads in the 444 so I don't know how the rifle handles it. I will probably screw the 444 barrel back on and load it up to see how it behaves with max loads.

For the next test I am going to polish the locking bolt, replace the rebounding hammer with the earlier style ignition system and make sure the chamber and cases are completely grease free. I am also working on a way to resize the cases to get a better fit in the chamber as the die I am using sizes the case down a lot more than it needs.

The case forming wouldn't be that bad with a proper set of forming dies. Turning the rim and belt off only takes a minute or two per case once the setup is done. In fact if the cartridge worked out in the levergun I would open the bolt face to fit the .532" rim and dispense with the lathe work.

It was a cheap and interesting experiment. The dies and barrel were free and I have $30 + shipping from Midway in brass. I really like the cartridge. It is what my 7mm-08 should be!

35remington
06-14-2005, 09:59 PM
I guess I'd have to ditto Buckshot and Starmetal's comments that if you have to go to extreme measures to prevent the lever from being hard to open, you are pushing things too far. What if cases get slick on a hunt? It happens. You can't swab the chamber with brake cleaner all the time. Polishing the bolt or the locking surfaces? Yes, it might make it have less friction and open easier if the cartridge pressure set it back some, but you're still talking about cumulative effects that will bite you in the rear at some time in the future. Most likely with short case life and possibly increasing the headspace. Rear locking lever guns have a pressure limit; sticky extraction is a warning notice best heeded rather than avoided.

You also ought to reload a single case repeatedly and see how long they last before imminent head separation becomes apparent (be careful!). Check with a sharpened wire, or look into the case while shining a strong light into the mouth. The RCBS Case Master can also dectect thinning at the web. In my opinion, if you can't get around a dozen loadings before they are about to separate you are definitely pushing it past 42,000. Cases that last these dozen firings in, say, a .35 Remington NEVER stick, and they are noticeably more enthusiastic than factory load levels, which may show case life in excess of 25 firings. I'd guess your pressures are way past even +P levels for a Model 94. My guess is your cases will go maybe 4 to 5 shots before separating if you're sticking the lever, and that's not good for you or the gun.

Leverguns have crappy gas handling characteristics if pressure problems occur, probably another reason not to push it.

I agree that 7mm leverguns are cool though, and I also agree the 7-30 Waters can get over 2700 fps with 120's in a 20 inch barrel. I've done this with a friend's Model 94 using several different handloads published by a number of powder suppliers and data books.

bdoyle
06-15-2005, 10:37 AM
Layne Simpson was able to run 2910fps with the 7mm Shooting Times Easterner in a 94 and 336. He based the cartridge on the 307. There is data available. I thought is was a neat concept but I don't recall pressure issues wht the provided data. Bit short of your goal but is 100fps short really a failure?

Brian

Four Fingers of Death
06-17-2005, 07:08 AM
Layne Simpson was able to run 2910fps with the 7mm Shooting Times Easterner in a 94 and 336. He based the cartridge on the 307. There is data available. I thought is was a neat concept but I don't recall pressure issues wht the provided data. Bit short of your goal but is 100fps short really a failure?

Brian

Wasn't the 94 Layne used a Winchester Big Bore? These are substantially heavier in the action where it counts. The 307 and 357 or whatever they were called were no slouches.
Mick.

bdoyle
06-17-2005, 09:55 AM
The articles I was able to search up just said 94 or 336. I'd have to look at home for the actual magazine articles. That's all the info I gots at the moment

Brian

Trailblazer
06-17-2005, 11:48 AM
2900 fps is good! Trouble is the rifle is not really useable because its to hard to open the action. I AM using the Big Bore action which was chambered for cartridges that are SAAMI rated at 52,000 cup. I don't know why my rifle isn't working.

As far as pressures, I am probably close to 45,000 cup. For example, Hodgdon lists a load of 51 gr. of H4350 in the 7x57. It yields 2945 fps at 45,800 cup. My cartridge has a little more case capacity than the 7x57 so I expect to get a little less velocity and a little less pressure with 51 gr. H4350. And in fact I got 2855 fps-90 fps less- in the same length barrel so pressure must be a little lower than 45,800.

Pressure doesn't seem to be the problem. Bolt thrust doesn't seem to be either. My cartridge has a head diameter of .506". A magnum case I sectioned has a wall thickness of .035". Using those numbers and 45000 psi I calculated bolt thrust in my cartridge at 6719 lbs. Layne's cartridge has a head diameter of .470" as does the 307 and 356 Winchester. I did not sacrifice a 356 case so I don't know the wall thickness but assuming .035" and 52,000 psi I get bolt thrust of 6535 lbs. If the wall is a little thinner at say .030" I get 6865 lbs. There isn't much difference in bolt thrust between my cartridge at 45,000 psi and the 307 or 356 at 52000 psi. Winchester is now chambering the standard 94 in 450 Marlin and it is rated at 43,500 psi.

There might be something wrong with the rifle. It has been to long since I shot it to remember for sure but it might have been hard to open with the 444 cartridge. I can screw the old barrel back on it and try it to see.

The other question is the shape of the pressure curve. I am basing my prognostications on 7x57 data in CUP. The 7x57 is a relatively long slender cartridge compared to my 7mm, which is a short fat design. It may well be that the pressure peaks higher in my cartridge than it does in the 7x57 with the same powder charge and CUP doesn't measure peak pressure anyway. I haven't done any research in that area but expect there is info out there because of the recent short mag craze and also the short fat bench rest cartridges like the PPC and Remington BR.

I really like the cartridge and will keep tinkering with it. I am thinking about putting it in a bolt gun where I could really wring it out. It would be a fine cartridge in a short action rifle!

felix
06-17-2005, 12:51 PM
TB, I am willing to bet that your particular gun was not heat treated up to spec. Naturally, if it stretches and then compresses on a case tightly, the action will be harder to open. Did you check for any of this? ... felix

35remington
06-17-2005, 06:33 PM
I think some of the problem may lie in the assumption that 52,000 CUP meant 52,000 psi in the .307 and .356, then transferring it over to what you are doing and assuming that you are below a safe pressure level. Nowhere has 52,000 CUP been defined for these rounds, and since this this is the same CUP figure as some high power rounds fired in boltguns (like the .270) lots of users assume this is the same pressure level. I dunno about that.

I've always suspected that 52,000 CUP for the .307 and .356 meant "safe pressure for this type of rifle, and as high as we are willing to go" in SAAMI ballistician jargon. I think the CUP figure was and is still being used because they don't want to be specific about the actual psi produced. I think this is to leave some safety margin for the rear locking guns, and also a reasonable expectation for case life. For most rear locking rifles, such as the SMLE, this was around 46,000 psi. Going much higher than this results in head separations in rear locking rifles after relatively few reloads. The Big Bore design is no stronger than the SMLE.

You also have a rear locking rifle, and you probably ought to figure your pressure levels at around the same figure as absolute maximum. Somewhat less would be better.

Whatever the reason, sticking levers are to be avoided in this type of gun.

Case life will tell you a lot. Since you don't have a pressure gun, then something like long reloading life for your cases is your best option, and it's not a bad one. If cases don't last very long, your pressures are way too high.

Trailblazer
06-18-2005, 11:56 AM
Felix, what you describe is certainly what is happening. I wondered too if it would have been better to use a Chrome Moly barrel instead of the SS as I think SS is more elastic. I had not thought of action hardness but that may well be the problem. I will have to get it tested. According to the 1996 Winchester catalog the Big Bore receiver was forged from 1141 steel, which is a free machining carbon steel. What do you suppose it should measure? Maybe around Rc 35? Thanks!

35Rem, there aren't to many certainties in life and pressure measurements certainly aren't one of them. I will keep all that in mind!

felix
06-18-2005, 01:20 PM
The BR boys are about the only ones who can make real use of these stainless barrels, mainly because their barrels are fat enough to not let the cases become too fat for 65K cup, 80K psi duty. Only few, though, have gone to stainless actions. The best one is the Alan Hall action, as he worked on it for 5 years minimum before he found a satisfactory stainless formulation. Most of these heavy duty actions on the line are still made out of a pure carbon steel formula, at least the bolt is. I have not been keeping up with the new stuff, so probably by now someone has started competing with Alan. I would not worry about the barrel per se, but there is some concern with case integerity. Stainless, if properly treated up front, will give and take at least 4 times longer than the strongest carbon steel before significant cracks appear. That is the positive side of stainless. In other words, you are not going to destroy your gun, but perhaps your cases will be junk in no time. ... felix