New 7mm Wildcat....7mm Rogue

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by TMR, Jul 29, 2012.

  1. TMR

    TMR Well-Known Member

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    Been working on this project since February and finally getting it all where I want it. I have played with just about all the 7mm Wildcats trying to find the best balance between performance, barrel life, powder consuption, ect. I wanted a cartridge that would fit into a standard magnum action and that could be fed from a detachable magazine if needed. Over the years, I have tested the following and kept records of performance:

    7 Rem Mag
    7 STW
    7 Allen Mag
    7 RUM
    7/338 Norma Imp
    7mm Super Mashburn
    7-300WM
    7mm Practical

    The 7AM, 7/338 Norma and 7 RUM were all a little larger than I wanted to go with and usually need a super slow powder to get the performance. Most of the time its not a "extreme" powder. I like them, but just wanted to try something different.

    The 7-300 WM had a short neck, although it didn't affect accuracy, it just didn't look right. I noticed with it and the Practical, bullets liked to jump. Seemed like there was a capacity cap where a little bullet jump came into play to get good accuracy. Reading Broz's post, this seem to confirm my thoughts as well. Wasn't a big deal, but I did want something forgiving. I tried to neck down the 375 Ruger case next, but it was a pain, so I abandoned it after ruining several cases in the process.

    My 7 Rem Mag reamer that I developed is very forgiving and doesn't seem to matter what the load is, it just shoots. I had been doing alot of reading and research on the 7mm Super Mashburn and they were getting great velocity out of them back in the 60's with mil sulplus powder, so I thought, lets give it a try. It performed well and wasn't finicky at all. In a 26" barrel it was running right at 3100fps with top end loads using 180 Bergers. I almost just stayed with it, then a customer decided he couldn't live without it, so off it went. I had a theory based on today's recent accuracy cartridges, so I started drawing up a print based on my theory. I have a special throat design that I have tried on a couple of 6mm's, so I included that on this reamer as well. While the reamer was being made, I sent off the print to Hornady to get 3 sets of dies. Once the reamer showed up, I barreled up my test rifle with a 27" broughton between customer builds. I had great success with H1000 in the Mashburn, but this case had more capacity, so I started with Retumbo, which is what I use the 7RM. I added a few more grains than the 7RM, added a 180 Hybrid .010" off, and off to the hills to break in. When the first few rounds went into .482" CTC, I was pretty happy. Speed wasn't to bad at 3100, and I was still forming the cases. I ran up to 76gr of Retumbo before hitting pressue signs, great velocity...3240fps, but accuracy wasn't what I wanted and was getting sticky on the bolt. So, I grabbed some H1000 and started the test again.

    73gr: 3117fps
    74gr: 3160fps
    75gr: 3193fps
    76gr: 3216fps

    75gr was shooting well under 1/2 moa, so that was the load I was going to run. Time to shoot it at distance and check it out. Everything performed perfectly and the cases lasted 9 firings before primer pockets were starting to loosen up. (This is using Winchester brand brass. Domestic brass is the only thing that will work with this case design. During the necking down forming process, RWS brass developed a hell of a donut and would require inside neck reaming. )

    Time to put together the real rifle now. A few late nights in the shop after customer builds and she was finished up. Still awaiting on a new stock design from Manners, but bear season is approaching, so I dropped her in a A-3 I had on the shelf.

    R Bros Rogue Action
    Broughton R Bros contour, 27" fluted, 1-9 twist
    McMillan A3
    DE Muzzle Brake
    DE Cheek Piece
    PTG Alum Bottom Metal
    Jewell Trigger
    NF 5.5x22-50mm w/UL Rings

    weight w/o bipod: 10.5lbs

    This barrel is a little quicker, probably due to being a new barrel vs the old take off test barrel. The same 73gr forming load runs 3140fps. I haven't run any hot load through it yet, starting over with new brass to keep track of barrel life. Still shoots well under 1/2moa. Shot a nice sub 3" group at 675 and is boringly consistent. Here are some pics:
    [​IMG]

    [​IMG]

    7mm Rogue (left) vs 7 Rem Mag (right)
    [​IMG]


    Now, since this has been asked before. The reamer is proprietary to R Bros and I will not post a pic of the print. At this time we are continuing to test it out and will start doing builds with this chambering this winter. There will be a few of them out there for testing this fall. If all continues to go well, then we will continue.

    I know I could have just gone with a standard case design, but everyone know what happens when gun guys get a theory in there head. I had to try it out and wasn't dissapointed at all. Might not be for everyone, but I am happy with it and I think it will be another good 7mm option.
     
  2. Broz

    Broz Well-Known Member

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    Thanks for the write up. Looks like you have a winner in the 7mm department here. Our thoughts and experiences are almost identical. I haven't seen the donut wth RWS brass in the necked down 300 win I do, Maybe that is something to do with the dies and necks length? But I sure seen the need to drop the charge in RWS brass due to its thick case and lower case volume. Takes about 3 gr less and velocity is still good.

    My next one I will be digging into my brass stash and using some of my 300 win Lapua brass. Or even better I have heard that maybe Lapua will be offering 300 win again?? Time will tell, but I have a hunch the Lapua brass will add a little to this chambering and I want to test it out.

    Glad to see someone move forward like you did with this. I see it as the perfect 7mm and a barrel life I can live with. Plus I don't really feel I am giving up a thing as the velocity is plenty good. So this is definatly the 7mm I want to hunt with and shoot.

    Jeff
     

  3. TMR

    TMR Well-Known Member

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    Because the shoulder is reformed and pushed way back vs the 300wm, that is where I was getting the donuts. Just necking down to make 7-300wm cases won't cause any issues. The 300wm shoulder becomes part of the neck with this case design. I will try to get a pick of the parent case vs a formed case.
     
  4. elkaholic

    elkaholic Well-Known Member

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    Very interesting and good writeup! Isn't wildcatting fun:D. I ran into the same issue using 6.5x65 RWS brass to form my 6.5 Sherman cases becasue the neck material was originally part of the (Thicker) shoulder portion of the RWS case. Once you get that cured, it is a heck of a case. I'm curious as to where you had so much problem with the Ruger case? That is the parent for my 30/375 S.I. and even though there are a couple of steps, the cases form very nicely. Good luck and keep the data coming......Rich
     
  5. pyroducksx3

    pyroducksx3 Well-Known Member

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    I cant wait to shoot out my 7RM and get my rifle back to you.
     
  6. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Very interesting. In your original post however I would like to point one thing out about the super magnums in the 7mm family. As you mentioned and I would agree, they are not needed for alot of big game hunting, no arguments there but they sure are nice when you need the extra power.

    Anyway, you mentioned that you had to step up to the ultra slow powders for this class of chambering. When I started development of the 7mm Allen Magnum I had just got finished developing my 257, 6.5mm and 270 Allen Magnum and with these there was no choice, you simply HAD to use the ultra slow burning ball powder such as WC-872 and WC-860 surplus powders and also US-869 from Hodgdon. As you correctly stated, they tend to be more sensitive to temp changes and can be a bit off as far as velocity consistancy.

    When I started developing the 7mm Allen Magnum I simply deduced that it would be a waste of time trying the stick powders and went right to WC-872. Well over the years I had to develope loads with the 140, 160, 175 and 180 gr bullet weights and decided to try Hodgdons Retumbo and to put it simply, its a perfect powder for the super 7mms. I have used Retumbo in my 26.5" 7mm AM to drive the 140 gr Accubond to 3625 fps, the 160 gr Accubond to 3475 fps, 175 gr SMK to 3410 fps and the 180 gr Berger to 3390 fps with consistant velocity, no powder bridging issues at all and consistantly fine accuracy.

    Just wanted to let guys know that Retumbo has been working extremely well with the 7mm AM and that is now my recommended powder for that wildcat. For smaller calibers with large capacities, yes, the surplus or ultra slow ball powder are perfect.

    Sorry for the hijack, back to your wildcat. I used the 7mm Rem Mag for many years and loved it and built several 7mm-300 Win Mags for guys that shot GREAT as well but the 7mm STW kind of made it unpractical EXCEPT for those that wanted to use a true standard length receiver.

    My biggest complaint about ANY belted magnum chambering, standard or wildcat is the variation in belt thickness, IE headspace measurement. I have measured pretty much all brands of brass and every one has had lot to lot belt thickness variations that were large enough that I could not chamber my barrels to a true zero headspace setting. The best brass generally had less then 0.005" variation but some US commerical brass had variation up to 0.020" and that was from a US brass maker that touts its amazing quality in brass. In reality it was terrible.

    I generally use Win brass for my belted magnum chambered rifles but when I started I would set up my chambers so that there was no more then +0.005" headspace but no less then +0.002" thinking this would be plenty to chamber all belted magnum brass.

    Well, that was not the case. The rifle got to the owner, he tried to chamber his virgin brass and it was not even close to chambering because his brass had belts that were 0.010" thicker then my brass and he was even using Win brass.

    Simply put, I hate dealing with the variation in the brass, yes you simply chamber the barrels so that all possible brass will fit, that means headspace is very loose compared to a non belted case which can have the headspace set at a true zero setting and even if the virgin brass does not chamber easily, its a simple matter to slightly bump the shoulder so it will. That is not possible with the belted magnum, there is no bumping the belt back. Guess you could cut it back but that would be a PITA!!!

    Anyway, Just curious how your setting up your barrels to offer proper chambering with all brass lots, even if same brand or if you have ran into this same issue of belt thickness variation?

    Very interesting and obviously a hell of a good shooting rifle. I have always liked the accuracy of the 7mm Rem Mag and 7mm-300 Win Mag, not surpised your version is stacking them on top of each other!!
     
  7. Franklin

    Franklin Well-Known Member

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    I thought head spacing off the belt was ancient history???
     
  8. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    I am talking about building a rifle, not handloading for a rifle, two totally different things.

    That is why you have to chamber a belted magnum chamber with what would be considered loose headspace so that all brass will chamber properly, then once fired, if you size your brass properly, you will headspace off the shoulder, not the belt.

    Two totally different topics, I am talking BUILDING, your talking reloading.
     
  9. TMR

    TMR Well-Known Member

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    Kirby,

    Hopefully you took no disrespect. When I had one of the 7 AM's, WC872 was the powder of choice. This was before I think you starting using Retumbo. The 7 AM is one of my favorites for sure. I totally agree that more horsepower is better and can get a guy out of a bind. Plus the 7AM cheats wind like no other. I may have to give Retumbo another try and see what happens. It does work well in all the other big 7's for sure.

    I did play with the STW alot. 13 barrels worth to be exact! Brass is difficult to find now a days, and it won't feed out of AI mags for my tactical customers. What I did find, is that this case design comes really close to my STW's speed with less powder. My feeling is that in shorter barrels, they will probably be very close to the same.

    I typically set up belted mags to just drag on the GO gauge and be tight at the bottom of the bolt stroke. Basically zero headspace on the go gauge. I have not had any issue's not being able to chamber any brass, domestic or imported. I do agree that it leaves ALOT of space with virgin cases, but unless a guy is going to stick with one lot of brass, your kinda screwed. There is just to much variance in belt thickness as you said.

    With this wildcat, when forming the cases, one is pushing the should back a fair amount. Basically keep adjusting the die until the bolt will just close on the case. The belt really isn't doing anything at all, and the case isn't stretching. Basically the same concept as you showed me to form 7AM cases. This was one of the things I wanted to eliminate when designing this case...the belt is purely cosmetic in this case and doesn't serve any purpose in regards to headspace. This was one of the reasons I tried the 375 Ruger case in the begining, but it was just to many steps to get it where I wanted it. To form this case, lube up a 300WM case, run it into the FL die. It pushes the shoulder back, necks down, and forms the new shoulder angle. Firing the case blows it out slightly and sharpens everything up.


    Again, I did not mean any disrespect, sway people away or cause any misconception with the Allen Mag. It is the pinacle of 7mm's for sure and ballistically its tough to beat.
     
  10. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    No disrespect taken in any way, I know you much better then that!!!:) Just wanted to point out that with more testing that Retumbo had proven practical for the 7mm AM is the only point I wanted to make, simple as that.

    I agree, for the AI mags, this would be a much better design then the STW and I also agree, that the 7mms based on the 300 Win Mag are damn near equal to the STW and I also agree again, STW brass is really tough to get from time to time.

    Thanks for explaining your chamber set up, makes perfect sense and with you mentioning how you set your brass up to fireform, that also eliminates alot of the problem with the belted magnum.

    Its amazing that with todays technology, the brass makers can not get us belted magnum brass that is consistant.

    Again NO disrespect taken in any way, I just like talking wildcats and rifle building set ups. I think I have mentioned that probably 75% of the customers I have that contact me about a 7mm AM generally get talked out of that wildcat when I find out exactly what they need to accomplish the goals they have for their rifle. I probably build the 7mm WSMs, 7mm Rem Mag, 7mm Dakotas 10 to 1 over my 7mm AM. For most situations, lesser 7mms will do the job easily, but occasionally its nice to have the HorsePower!!!

    Again, I know you would never disrespect me in any way, never took it that way at all. You've been a good friend over the years and I respect your skills in shooting and building, congrats on a find wildcat design. Now its time to get some long range blood on the ground!!!
     
  11. TMR

    TMR Well-Known Member

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    Thanks Kirby,

    Your comments mean alot. I do with brass makers could get things more consistent. I think in this day and age, they are more concerned with production than quality.

    I will be trying to find a bear starting this week to break her in on! Then it will be headed to your neck of the woods for deer and elk later in the year. I will try to swing by on the next trip over to the house and we can catch up. Probably going to run over and hunt archery elk the end of September.
     
  12. midnightmalloy

    midnightmalloy Well-Known Member

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    I dont have anything near kirby allen or tmr but i have read extensively about all the 7mm's in your origional post. Im with kirby that a non-belted case is preferable to a belted one. Also tmr i wanted to fit in an AI mag with long vld's so i wanted to go elkaholics road and neck down the 375 ruger case to 7mm but then found the best solution for me which came from Gunwerks in the form of their 7mm LRM. I will post pics of the case when i get home. No belt, more powder capacity and a very long neck. It is throated that when the berger 195's come out they will work great. The hornady brass looks great and comes with anealled case necks and looks just like lapua brass. I need to get some solid data but the gun needs some more work first. Coal is 3.420 with a 180 gr vld touching the lands. Should get the same velocity as you are with the rouge but no fireforming or sizing issues. Brass isnt bad either at 1.25 a piece. I compared the brass with some 243 lapua brass, 280ai nosler brass and some hornady 375 ruger brass and it was on par with the lapua in quality and with the anealled necks. Im happy.

    Isnt this what you were trying to accomplish? Whats your case oal of your brass?
     
  13. TMR

    TMR Well-Known Member

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    The 7mm LRM is basically a 375 Ruger case necked down. It should perform closely with a little shorter OAL. The 7 Rogue is right at 3.6" oal with a 180 Berger. Still fits in a standard mag box and AI mags as well. At the time, Gunwerks was not going to sell brass separately, not sure if that is the case any more or not. I did do some work with the 375 case, but the number of steps it took to bring down to what I wanted, I knew few folks were not going to want to go through the process. 300WM brass is inexpensive and case forming is easy with the 7 Rogue. Those were 2 of the many things I was looking for. If Gunwerks is selling ready made brass, then their 7 LRM is a great option as well.

    Keep in mind, that what I am running now is a reduced forming load at almost 3150 and shoots well under 1/2moa. Certainly exceptable practice and hunting loads for sure. The belt on this case is purely cosmetic and not even used. I agree and do prefer non belted cases, but in this case, it was a good parent case that was readily available. There really are no sizing issue's, partly due that the dies are setup exactly for the reamer. Wildcatting is fun. Already have a few more in the works that I hope to get running this winter.
     
  14. midnightmalloy

    midnightmalloy Well-Known Member

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    I agree that what your getting in terms of velocity is excellent. Your parent brass is cheaper but not if using the highest quality brass.

    So an update on how the Gunwerks 7mm LRM is doing. They do sell headstamped, and fully formed brass for the 7mm LRM (I just got 200 pieces friday) and they cost $1.25 a piece. This brass comes anealled and seems on par with lapua but we will see if it holds up as well. It seems like gunwerks ordered the brass to their specs so it looks different than the hornady 375 Ruger brass I have.

    One correction to my post: I can easily seat the bullets farther out than 3.6" COAL but the gun is throated so they are seated to 3.43".

    This is actually optimal for my intended purpose which is to shoot the new 195GR berger when it comes out since the nose on this bullet is longer than the 180 VLD.

    What I was asking was the overall length of just the case not a loaded round so I should have been more specific on that sorry. I think for my purposes that what I built will be good for my intentions.

    I also noticed your in Elma and Im in Bellingham so it would be cool to do a shop tour sometime. (of course if thats OK). Here is a picture so you can see a comparison of the cases.

    2012-07-27 20.27.54.jpg

    Left to right:
    375 ruger
    7mm Gunwerks LRM
    7mm Gunwerks LRM with a 180VLD
    30-06 springfield (far right)

    let me know what you guys think