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RangerJoe

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Reply with quote  #1 
The first .20 Viper barrels (20", 24", and 26.5") are made and we will begin beta testing soon.  The .20 Viper is the 3rd of our MONGOOSE line of wildcats (6mm Mongoose, .257 Ocelot, .20 Viper).

It is based on a 5.56x45mm (.223 Rem) parent case, shortened slightly, with a sharp 40-degree shoulder and blown-out sidewalls to increase case capacity.  Just like the 6mm Mongoose, the .20 Viper will require fire-forming to achieve it's final case dimensions and capacity.

We are experimenting now with methods to form the brass for initial firing.  Unlike the 6mm Mongoose which is initially formed in 1 step, the .20 Viper (and likely the .17 Stringer) will require 2 steps to form the initial case.  Setting the shoulder back, changing it to 40-degrees, and necking down from .224 to .204 is too much for 1 process.  We are looking at two different methods; both should work - and then we will recommend/offer the process we think is best.

Our expectations are the Viper will outperform most, if not all, of the .20 caliber .222/.223-based wildcats on the market (e.g., 20 Tactical, 20 Practical, .20 VarTarg Turbo, etc.).  It may even tickle the .204 Ruger, which is based on the larger .222 Rem Magnum case.

We are hoping for MVs in the 4,250+ range with 32-grain bullets from a 24" barrel.  That, my friends, is SMOKING HOT!

Powders that I will initially be testing include:
Alliant Varmint
Win 748
Hodgdon CFE223
Hodgdon BL-C2
Hodgdon H322
Accurate 2520
Ramshot X-Term
Ramshot TAC
Accurate 2460
Accurate 2015
Hodgdon Varget
Alliant 1200-R
Norma 201

Alliant ARCOMP, 10X, and Hodgdon Benchmark are also likely good candidates, but I don't have any in my stash.

As development progresses, we will create a separate ".20 Viper" topic under Mad Dog's Wildcats and post brass forming data, videos, and loading data just like we have for other cartridges.

This should be a WILD RIDE!  Stay tuned for more action to come...

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RIGGS68

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Reply with quote  #2 
Ok, my initial loads were very conservative so the performance may appear lackluster but it gives Joe and Bruce a little more insight- and it reduced the pucker factor for me.
These were all fired using freshly formed brass. After fireforming, the capacity increase, on average, slightly over 1 grain. There were no malfunctions at all charges, the bolt locked back every time, and rounds fed flawlessly. 

24 " SPR
32 NVG tipped
H335   OAL 2.13  
LC mixed   450 primer

25.3

3683
3698    3708    31
3744 

25.6

3741
3735    3741    7
3749

25.9

3808
3757    3781    27
3798

26.2

3831
3833    3830    3
3827

26.5

3925
3894    3920    24
3943

32 NVG HP
8208  OAL  2.08

24.0

3469
3524    3481    38
3450

24.3

3584
3465    3507    66
3472

24.6

3511
3601    3584    66
3640

24.9

3642
3648    3625    34
3585

25.2

3704
3736    3709    24
3689

25.5

3754
3788    3766    19
3756
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RangerJoe

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Reply with quote  #3 
Nice!  Thanks Riggs.  I got my barrel (20") and die this afternoon.  I have the barrel mounted to a trued receiver - will slap on a scope and attempt some loads tomorrow and Saturday.
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RIGGS68

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Reply with quote  #4 
Quote:
Originally Posted by RangerJoe
Nice!  Thanks Riggs.  I got my barrel (20") and die this afternoon.  I have the barrel mounted to a trued receiver - will slap on a scope and attempt some loads tomorrow and Saturday.

Yeah, I am itching to get back out with it again and see what it will do with formed brass. Unfortunately, the weather here went south (temp-wise) so I doubt I will be able to gather more data this weekend.
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RangerJoe

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20" 1:12 Light-weight (M16A1) profile barrel, rifle length gas system.

NEW (non-fire-formed) LC 1x fired brass (RTL), CCI-41, W-748, Nosler 32gr VG HP Flatbase, 2.080" COAL, 5 rounds each:

26.0gr W-748 = 3,565 fps
26.5gr W-748 = 3,665 fps
27.0gr W-748 = 3,720 fps
27.5gr W-748 = 3,788 fps - added 02-FEB.  This is about max load for non-fireformed brass.

All loads cycled flawlessly... fed, ejected, bolt lock-back, etc.  No pressure signs at all.  Can't tell ejection pattern because I used catcher (can't afford to lose any of these!).

Next loads will push the upper limits a bit...

Note: 1) Edited to correct COAL. 2) These cases will be annealed before next resizing & firing.

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RangerJoe

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Reply with quote  #6 
Currently I have Nosler 32gr VG HP-FB  and 40gr Ballistic Tips to try.  I just ordered Hornady 32gr & 40gr VMAX and Nosler 40gr tipped VGs.  In my x40, the 110gr NVG-tipped is one of the most accurate and fasted bullets I've ever tested.
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RIGGS68

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Reply with quote  #7 
More load development data: (Magnetospeed chrono)

20 Viper 1:8 twist 24" SPR (.090 gas)
LC mixed Fire formed brass
32 NVG -tipped   2.13 OAL
450 primer

10X
23.5    3559
           3506    3566    64
           3635

24.0    3710
           3638    3656    47
           3621 

24.5    3805
           3723    3767    41
           3775 

25.0    3871
           3856    3876    24
           3903

25.5    3887
           3829    3894    32
           3866

Benchmark

25.0    3735
           3766     3764    28
           3791 

25.5    3817
           3803    3799    19
           3778

26.0    3936
           3895    3917    20
           3921

26.5    4025
           4007    4010    12
           4000

Rl7  (Cycled/fed but no BHO on empty mag all loadings)

23.0    3971 
           4019

23.5    4066
           4103    4087    19
           4074

24.0    4095
           4181

24.5    4228
           4238

Note: I ran out of FF brass so this was not 3 shot. Additionally, 24.0 and up had slight cratering of the primers.
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RangerJoe

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Reply with quote  #8 
Congrats - first to break the 4k mark!!  I'm chasing you...  [biggrin]
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RangerJoe

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Reply with quote  #9 
Made ~ 250 more Viper cases this weekend - that should last a few varmint exploding sessions!  I only fire-formed another 15 - added that data to my OP above. 

I've about maxed out with W-748 for new (non-fire-formed) brass.  Will move on to a fast powder next.

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Cabob

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Reply with quote  #10 
Looks like 748 is working based on your speeds, just a little bulky and slow. Based on my experience with a .204 Ruger, 748 was just a little too slow in it as well (Out of a 26 inch tube, nonetheless.) I ended up settling on H335 for 32 gr. Vmax and TAC for 40 gr. Vmax. That factory Ruger will routinely shoot in the .1's with both bullets if I do my part. Out of the powders you have on hand, I think you should try CFE223 and TAC next. Wink, wink!
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RangerJoe

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Reply with quote  #11 
Again - these are only fireforming loads.  The Viper gains a decent amount of capacity once blown out.  My next batch of fireforming loads are being charged with Ramshot X-Term
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RIGGS68

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Reply with quote  #12 
More data...

20 Viper 1:8 twist 42" SPR
LC mixed Fire formed brass
32 NVG tipped   2.13 OAL
450 primer

Benchmark
26.5    3952
           3958    3949    10
           3938

26.8    4007
           3983    3992    13
           3986

27.1    4029
           4082    4046    30
           4028

H335
26.5    3820
           3931    3880    56
           3840

26.8    3983
           3943    3953    25
           3955

27.1    4012
           4065    4018    43
           3978

27.4    4033
           4101    4060    35
           4048

AA2200 (avg)
24.0    3872 
24.3    3872
24.6    3943
25.0    3963

TAC
24.0    3414
           3523    3439    73
           3382

24.5    3596
           3596    3601    9
           3612

25.0    3530
           3656    3609    69
           3685

25.5    3551
           3670    3635    73
           3685

26.0    3747
           3775    3794    58
           3860

26.5    3825
           3832    3818    17
           3798

All loadings cycled properly, locked back on an empty mag, and none exhibited signs of overpressure...onward and upward I guess.
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RangerJoe

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Reply with quote  #13 
Very nice!

What load did you select for your fireforming?  I'm still playing with loading ladders to fireform my 250+ cases.  It would be nice to have a reasonable accurate fast plinking load to be able to fireform with.

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RIGGS68

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Reply with quote  #14 
Quote:
Originally Posted by RangerJoe
Very nice!

What load did you select for your fireforming?  I'm still playing with loading ladders to fireform my 250+ cases.  It would be nice to have a reasonable accurate fast plinking load to be able to fireform with.

Right now I am running 26.5 H335, however, I had a "supply" of WC844 and some 34 grain VNE show up recently so I may switch to those. Hopefully, it will result in an inexpensive plinking/varmint load.

Just trying to cover as many powders as possible...I will also transition to the 39 grainers on the next run.
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RangerJoe

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Reply with quote  #15 
VNE  ???  [confused]
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RIGGS68

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Reply with quote  #16 
Quote:
Originally Posted by RangerJoe
VNE  ???  [confused]

Varmint Nightmare Extreme..34 grain HP from Midsouth-they were on sale.

https://www.midsouthshooterssupply.com/item/000042034/varmint-nightmare-x-treme-20-caliber-point204-diameter-34-grain-premium-flat-base-hp-500-count
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RangerJoe

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Reply with quote  #17 
[thumb]
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RangerJoe

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Reply with quote  #18 
Continuing the quest for accurate & fast fire-forming loads, I tested 4 loads with Ramshot X-Term today; still using Nosler 32gr VG-HP at 2.080 COAL and Wolf SRM primers. Temp ~ 60, RH ~ 45%, 7~20 winds at 7:30.

25.0gr X-Term: MVavg=3,710; 1.1" 5-shot group
25.3gr X-Term: MVavg=3,737; 0.95" 5-shot group
25.6gr X-Term: MVavg=3,823; 0.70" 5-shot group 
25.9gr X-Term: MVavg=3,865; 0.95" 5-shot group

All loads functioned perfectly with NO pressure signs.  I'll run another few rungs up the ladder with X-Term as there is plenty of case capacity left, even at 25.9gr.

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Cabob

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Reply with quote  #19 

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RIGGS68

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Reply with quote  #20 
Thanks RJ. This round is WAY more accurate and forgiving than I thought it would be.
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RIGGS68

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Reply with quote  #21 
Hopefully, I covered everything thus far...
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Cabob

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Reply with quote  #22 
Looking good!
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RangerJoe

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Reply with quote  #23 
Nice!  All my brass is LC-06, 1x fired, RTL (back as 5.56) before beginning the conversion to Viper.  BC for the Nosler 32gr VG-HP is .131 (yuk) and VG-tipped is .204. 

I have more X-Term ladders ready to test.

Thanks buddy!

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RIGGS68

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Reply with quote  #24 
Thanks Joe...updated to reflect information.

Load data file moved to a newer post.
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RIGGS68

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Reply with quote  #25 
Data from today's 39 Sierra Blitzking ladders: (all are 3-shot)

20 Viper 24" 1:8 twist (SPR profile)
LC mixed F/formed brass
COAL: 2.215
Primer: 450

H335
25.0    3648    49
25.5    3675    21
26.0    3747   116    **stopped here due to high SD**

Benchmark
24.0    3513    35
24.5    3572    16
25.0    3677    41
25.5    3768    31
26.0    3859    17

TAC
25.0    3540    44
25.5    3604    31
26.0    3703    15
26.5    3772    49
27.0    3841    19

8208
25.0    3621    16
25.5    3702    52
26.0    3754    14
26.5    3814     5
27.0    3935    30    **primer pockets loose**

Additional fireforming data using WC844 - for reference only.

32 NVG-tipped
COAL 2.13
LC-mixed

24.7    3469    51
25.0    3548    23
25.3    3614    24
25.6    3640    0
25.9    3680    14
26.2    3755    6
26.5    3785    9

The Excel load data file has been updated with this information. (Located in the prior post) I will continue to update it with load data that others post here -at least in the interim.
I apologize for not adding any accuracy data, however, I find that a Magnetospeed strapped to the end of a barrel can have an impact on, at minimum POI. Additionally, unless indicated, all loadings were safe in my barrel...but you know the disclaimer. 


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