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jwtharpe

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Reply with quote  #101 
Quote:
Originally Posted by helix6
That is pretty nice performance and a lot better than I'm getting out of my 20" BHW 6x45 with 87 gr. V-Max. I'm averaging about 2650 with the 6x45 and that bullet due to backing the load off for seating depth.

Helix, what was your load data for these? 
I used hornadys data for the 6x45 to get a starting point with BLC2, I ended up 1.5gr. over their stated max, but their max was at 50kpsi. I am sure I was over 50 with these. 
I will take a few pictures tomorrow to try to explain how this case can be better than the 6x45 for velocity, even though its much shorter. 
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jwtharpe

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Reply with quote  #102 
Here are a couple of pics and some data to illustrate the differences between the Mongoose, and the 6x45.

When you take a look at both of these cases you might ask yourself why? They are very similar, and both shoot the same size bullet.    

mongoose vs 6x45-2.jpg 

I pulled both of these cases out of a batch of weight sorted LC-96's I selected two that were within .1 grain of each other. I formed one of them with the mongoose die and shot it. Then I resized it and trimmed it to 1.680" to fit the new 20" barrels chamber. 
The other case was resized to fit my 223 barrel, and the neck was expanded to 6mm in order to replicate a 6x45 case. Its case length was 1.745 and didn't need trimming. I then checked both cases water capacity. The 6x45 measured 29.4 grains of water. The mongoose case measured 30.7 grains of water. The mongoose holds 1.3 grains more water than the 6x45 based on my test. 

Now for the meat and potatoes. 



mongoose vs 6x452.jpg 

Both of these cases have 87 V-max in them. (Pic didn't pick up the red tip) Both of these are loaded to 2.255". If you look at the case on the right, you can clearly see that the ogive is inside the neck. Most of you hand loaders know what kinds of problems this will cause, so I wont go into it. The OAL length to the lands with this bullet in the mongoose is right around 2.30" and should be GTG for load development. No special mags needed, just use a P-mag, or your favorite 223 mag and go on with it. I have been using a 10 round pmag, and it has been running 100% so far. 

I then tested them for water capacity with the 87 V-max seated to 2.255". The 6x45 measured 24.3 grains of water. The mongoose checked in at 25.8 grains of water. The mongoose now has 1.5 grains more capacity with any bullet seated at the same OAL as the 6x45. 

Case- LC-96
Primer- 450
Bullet- 87 V-max
Trim- 1.680"
Powder- BL-C(2)
Barrel- 20" 4 groove 8 twist
OAL- 2.255"

27.5gr These shot like the 90FMJ's .6" group
1-2754-av-2752
2-2749-es-5
3-2754-sd-2

28.0gr.
1-2812-av-2792
2-2788-es-29
3-2783-sd-16

28.5gr.
1-2855-av-2856
2-2836-es-43
3-2879-sd-21

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talonxracer

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Reply with quote  #103 
Some very nice improvements in the case design over the 6x45 to match the caliber to the platform.

How can that little beauty not get ya excited!

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helix6

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Reply with quote  #104 
JW, I settled on 24.8 gr. of Benchmark under the 87 gr. V-Max. I started getting pressure signs after that (though not necessarily uncomfortable like my extra hopped up H110/277WLV loads) and decided to stay there - it was also the most accurate load during development (though I was already experiencing some weird accuracy issues even at 100 yards). That's still a lot lighter than the 26.2 max load Hodgdon has in their manual for the 85 gr. Speer and had much better velocity than H4895.

My real disappointment with the 6x45 came when I took it out to shoot a meager 500 yards and had really poor accuracy despite using a quality BHW barrel. My Ruger American Ranch in .223 can ring steel with the 75 gr. Hornady BTHP with ease at that range but I was really struggling with the 6x45. I think it is the large jump into the lands. I have put together a few rounds to test that are loaded longer to minimize the jump but haven't had a chance to shoot them.

All this happened in August and I haven't picked up the 6x45 since. Then I stumbled onto this alternative and I've been looking for a 20" .223 barrel to put on that 6x45 (as a placeholder) ever since. I think I just need to take it apart and sell off the dies and barrel now so I can jump on this as soon as barrels are ready.

I assume the cut for the chamber is different enough from 6x45 to accommodate the heavier bullets without compromising mag length and creating a massive jump into the lands. Your 6x45 round looks a lot like mine - needless to say the issues are clear. 6mm Mongoose looks really sexy. Reminds me of a miniature version of my .280 Ackley.
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jwtharpe

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Reply with quote  #105 
Helix, if I owned your 6x45 barrel, I would see if there was enough meat in front of the extension , and how close to the extension tenon the threads came. based on that I would see if I could set it back enough to rechamber it for the mongoose. We would need to push the extension tenon forward about .100" and reface the breech. You would also need to shorten the gas tube by the same amount. If it could be done, it would be a lot of work. The biggest pain would be re-timing the gas port to the barrel extension. It took me a few hours to do it on the 22-250 barrels that I did. I made those out of 5.56 barrels, I ended up ruining one of them. It was a 8 twist lilja three grove. I almost cried. 
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jwtharpe

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Reply with quote  #106 
Got RJ's 18" middy running today. Still have to make his die, and check gas with some different powders to make sure its right. It ran great with TAC under the pulled 80 federals. 29.0gr. loaded to 2.190" with 450 primers in fresh LC96 was giving 2960fps. 29.2gr was giving 2980, and 29.5gr. was giving 3040. the 29.5 was warm with slight craters, and some extrusion. 


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RangerJoe

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Reply with quote  #107 
Doing the Happy Ranger Dance ...  [rofl]
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jwtharpe

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Reply with quote  #108 
Quote:
Originally Posted by RangerJoe
Doing the Happy Ranger Dance ...  [rofl]

Joe, I think you will be happy with it. It's running the 80's around 100 fps faster than I was expecting. I didn't shoot anything but fresh brass yesterday. No accuracy data due to rain. Your headspace is .005 shorter than the 20" barrel, and .015" shorter than the 26" barrel. Your max case length is 1.680", I trim them to 1.675". You can trim to 1.670" and let them grow to 1.680" if you don't want to trim every time. I use a case to set headspace, it's not as precise as a go gauge. Brass will move a little, the go gauge is solid. Not going to set it back up to get the missing .005"
It's a tad overgassed with TAC, I turned the block down some. I think it will be about right for the faster powders. 
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RangerJoe

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Reply with quote  #109 
Those MVs surprised & impressed the heck out of me!! I have lots of powders to try between the range of A2520, TAC, H-335, BLC2, W748, X-Term, N201, A2015, H332, A2200,LT32, and LT30.  Should find some optimal bullet/powder combination in that mix.
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jwtharpe

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Reply with quote  #110 
Case- LC-96 new, not fireformed
Primer- 450
Bullet- 80 pulled Federal
Trim- 1.675"
Powder-TAC
Barrel- 18" 10 twist mid-gas
OAL- 2.190"

29.0gr.
1-2930-av-2966
2-2962-es-66
3-2976-sd-24
4-2996
5-2969

29.2gr.
1-3003-av-2992
2-2996-es-68
3-2990-sd-25
4-2964
5-2969
6-3003
7-3030
8-3030
9-2962
10-2976

29.5gr. these were a little hotter than I like, brass probably wont last long.
1-3044-av-3049
2-3072-es-63
3-3037-sd-25
4-3079
5-3016

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jwtharpe

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Reply with quote  #111 
I'm done with RJ's upper. it cycles LT-32 with the block open. 


Case- LC-96 fireformed
Primer- 450
Bullet- 68 Barnes Match Burner
Trim- 1.675"
Powder-LT-32
Barrel- 18" 10 twist mid-gas
OAL- 2.280"
Hits lands- 2.305"

Chrono was acting up due to rain/mist and too close to barrel, take readings with grain of salt.


25.7gr
1-3075-av-3065
2-3072-es-14
3-3058-sd-7

26.0gr.
1-3115-av-3117
2-3108-es-21
3-3129-sd-10

26.3gr.
1-3182-av-3137
2-3093-es-89
3-3137-sd-44

26.6gr.
1-3137-av-3149
2-3182-es-53
3-3129-sd-28

26.6gr. again
1-3174-av-3160
2-3144-es-30
3-3144-sd-15
4-3174
5-3167

26.9gr.
1-3205-av-3185
2-3167-es-38
3-3206-sd-19
4-3182
5-3167

It wants to shoot, horizontal dispersion caused by my .5moa shake. Lol.

68-matchburner.jpg 


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RangerJoe

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Reply with quote  #112 
Looking GREAT JW - Thanks!  I wanted to test some loads this weekend, but 30~45 MPH winds and shooting for tiny groups just don't coincide.
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talonxracer

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Reply with quote  #113 
Those are some superb numbers from the 18" barrel
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MDWS

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Reply with quote  #114 
I'm getting pretty excited to see what my 22" is going to do!  'Cause you know, the fancy fluting increases performance and all that [tongue] !
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RangerJoe

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Reply with quote  #115 
Coolness always makes a firearm shoot better!
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gimbel

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Reply with quote  #116 

Quote:
Originally Posted by MDWS
...and 28 grains wins. We are going to have a lot of fun with this. What do you think the best "varmint" bullet will be?

I think you need to load up some 95gr DRT. They are very short for weight freeing up case capacity, have a BC of ~.360, and still enough weight to take medium sized game.

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jwtharpe

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Reply with quote  #117 
Quote:
Originally Posted by gimbel

Quote:
Originally Posted by MDWS
...and 28 grains wins. We are going to have a lot of fun with this. What do you think the best "varmint" bullet will be?

I think you need to load up some 95gr DRT. They are very short for weight freeing up case capacity, have a BC of ~.360, and still enough weight to take medium sized game.


Can shoot whatever you would like as far as hunting bullets go. Everything except the long range match bullets fit in a mag no problem. I'm going to hunt with either accubonds or Barnes, the chamber was made for those to work from a mag.
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helix6

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Reply with quote  #118 
I think I'll just be selling off the BHW 6x45 barrel. I don't want to try to butcher a great barrel that I'm sure someone else could enjoy the heck out of with shorter bullets. The Mongoose seems to have serious potential.
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helix6

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Reply with quote  #119 
Hi JW, I'm sure you are still in the heat of testing your new cartridge and I'm probably putting the cart before the horse... But being impatient to shoot one myself, I wanted to start feeling out purchasing logistics. Are these barrels going to be made by the same guys producing the 277WLV barrels and will they be available through the MDWS store or are they going to be sold through a different outlet? It sounds like you and Mark are working on this together, so I'm hoping it's a joint venture and we can enjoy the great quality and prices we've come to see on 277WLV parts.

By the way, I already missed the boat, but I thought it would have been cool to stick with established naming convention and call this cartridge .243 Mongoose (243MGS?).
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MDWS

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Reply with quote  #120 
Quote:
Originally Posted by helix6
Hi JW, I'm sure you are still in the heat of testing your new cartridge and I'm probably putting the cart before the horse... But being impatient to shoot one myself, I wanted to start feeling out purchasing logistics. Are these barrels going to be made by the same guys producing the 277WLV barrels and will they be available through the MDWS store or are they going to be sold through a different outlet? It sounds like you and Mark are working on this together, so I'm hoping it's a joint venture and we can enjoy the great quality and prices we've come to see on 277WLV parts.

By the way, I already missed the boat, but I thought it would have been cool to stick with established naming convention and call this cartridge .243 Mongoose (243MGS?).


JW is a partner, and yes MDWS will be offering this cartridge. Launch will be soon. Soon...

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jwtharpe

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Reply with quote  #121 
Mark takes care of that stuff. If it were up to me, you all would be SOL.
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helix6

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Reply with quote  #122 
Glad to hear that this cartridge is imminent and will be available from MDWS (as opposed to something like 338 Whisper)... I need to get my Armslist ads emptied out so I can free up a little money. I'm glad you guys are teaming up on this - best for everyone to play to their strengths!

Time to go shoot the last of my loaded 6x45 ammo and get that barrel sold.
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jwtharpe

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Reply with quote  #123 
Mongoose number 1

6Mongoose.jpg 

Mongoose number 2 and 3

24mongoose.jpg 
RangerJoe has number 3. I dont have a pic of it. 


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MDWS

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Reply with quote  #124 
Yee-haw!!
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BIGGDAWG

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Reply with quote  #125 
Sweet, looking good jw.
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