20 SCC cartridge (For real this time)

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20 SCC cartridge (For real this time)

Postby RwBeV » Thu Oct 24, 2013 10:57 pm

I had the pleasure to meet Brad from CRT last summer, and a very nice fellow he is. Somewhere in our visit the idea of this cartridge came up, I never gave it much thought after he left. So to my surprise months later he contacted me wanting to know if I could possibly help out. So with a few phone calls and some discussing and cussing we figured out a way to chamber a rifle with what tooling I had. I wont go into all the particulars of how it was chambered but I used a 204 Savage barrel that I had and put it on a Savage Model 10 that I just happen to have laying around being lazy. A whole lot of this cartridge was centered around the new Nosler brass that just came out not to long ago. So Brad sent out a few rounds, and in between Elk hunting trips I went to work (Still haven't found a damn Elk though). The parent case for this cartridge is the 221 Remington Fire Ball, of course necked to 20 caliber, Brad has ordered the reamer with the minimum body taper and a 40 degree shoulder. Yes I know it sounds like a 20 Vartarg improved and it is, at first I didn't think that it would make that much of a difference but I let you decide after you see what I found. For some reason I was thinking IMR4198 probably because that's what I shot in my Vartarg, and it worked ok although with a case almost plumb full it still wasn't showing any pressure. Brad suggested Accurate 2200, I just happen to have a pound collecting dust. What I found is that the SCC case only holds about a 1/2 grain more than the Vartarg, no big deal then. All along we where only concerned with 30 to 35 grain bullets, so I settled on the 32 Vmax for my first tests. Again these are just the first test loads I didn't feel that it was a fair comparison to try and shoot for accuracy with the barrel I had so everything was shot just for velocity for the time being. Always start 10% below starting loads, approach max loads with caution!!

Test #1 IMR4198 32gr Vmax CCI400 primers and Nosler 221FB cases .230 neck bushing.

17.0g IMR4198 3631 fps No pressure at all
18.0g IMR4198 3800 fps No pressure
18.5g IMR4198 3888 fps Case full half way up the neck, still no pressure

Test #2 Accurate 2200 everything else the same

20.0g A2200 3763 fps No pressure
21.0g A2200 3981 fps Still nice round primer no case expansion
22.0g A2200 4154 fps Showing pressure signs probably the max

You be the judge weather it gains anything over the standard Vartarg.

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The left cartridge is a standard Vartarg, the right case is the new SCC cartridge
Image
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Re: 20 SCC cartridge (For real this time)

Postby CRT » Fri Oct 25, 2013 12:00 am

As Bob mentioned in the post above the parent case for the 20 SSC is the 221 Fireball brass made by Nosler.

Based on the data Bob has provided above the 20 SCC is a solid 3,900 plus fps cartridge (with 32 grain bullets) as we had anticipated during the cartridge's design phase. I believe there are a number of powders that will work well in it including: H4198, IMR 4198, Accurate 2200, and even possibly Accurate 1680. With accurate 2200 being the clear winner in the speed department. A big part of the reason that we decided to move forward with this project was due to the high quality Nosler 221 brass hitting the market. I can't mention enough how nice this brass is, it comes right out of the box fully prepped and is much more consistent than the alternative Rem brass. A big Thanks goes out to all the people at Nosler for bringing us this greatly improved 221 FB brass.
I attribute a big portion of the performance boost of the 20 SCC to the ultra efficient 40 degree shoulder as well as the small improvement in case capacity. Add the correct powder into the mix and as evidence posted above great things can happen. This cartridge is knocking on the door of the 204 Ruger with 6 - 8 grains less powder. :o
Our focus was to produce a cartridge for the varmint/target crowd that offered solid performance as well as top level efficiency. I believe we have hit that mark. With powder getting more difficult to come by as well as more expensive efficiency has become the name of the game for many of us.
Many thanks go out to Bob for all his help on the 20 SCC. He is a good friend, a great gunsmith, and just an all around nice guy.
If anyone has questions feel free to post them up, Bob or I will be happy to answer them to the best of our abilities.

Brad
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Re: 20 SCC cartridge (For real this time)

Postby BillK20VT » Fri Oct 25, 2013 9:59 am

It looks interesting, however I wonder why a improved shoulder on the standard 20VT would not do the same. I also wonder about the pressures that are running to gain this amount of velocity, over the standard 20VT and trying to reach the 204 Ruger FPS. Like everything we play with wildcats, for various reasons.. Going to watch this one and see how it goes. I also, would like to see a lower priced set of dies out for it, the one's coming out are a little rich for a lot of guys/gals budget, no matter how good they are. Just a couple of my thoughts. Do not get me wrong, I do have a interest in the increase and cartridge, just going to plug along with my present 20VT and 204's for now. Bill K :)
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Re: 20 SCC cartridge (For real this time)

Postby CRT » Fri Oct 25, 2013 11:05 am

Bill,

I appreciate your thoughts. To address the pressure concern i would simply say that there is an increase in pressure and always will be when working with fast cartridges. The difference here is that we added a more efficient shoulder, changed the taper of the case, and that in turn increased the internal volume of the case. As Bob mentioned above he took measurements on the case after firing and there was no expansion, in addition the primers were still nice and round. This tells me that pressures are well within a safe zone with the loads we tested and the speed range we were looking to achieve (3,900-4,000 fps). The fact that the cartridge will do well over our intended design speed is a plus, however when people take the cartridge into this speed range (over 4,000 fps) they do so at their own risk. As Bob noted above all load development needs to start low and work up, each rifle will have different characteristics and a load that is safe in one rifle might not work in another. The name of the game is safety first and foremost. We believe that this cartridge will very safely allow speeds of 3,900 fps where the 20 vt typically won't.
We hope to address the die set options next year. I will be working with a die manufacturer to offer a more budget conscious set of dies down the road, however there will be a trade off over the Whidden custom dies we are working with now.

Brad
Last edited by CRT on Fri Oct 25, 2013 11:10 am, edited 1 time in total.
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Re: 20 SCC cartridge (For real this time)

Postby CRT » Fri Oct 25, 2013 11:09 am

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Re: 20 SCC cartridge (For real this time)

Postby BillK20VT » Fri Oct 25, 2013 11:15 am

Appreciate your thoughts Brad.. By the way nice photo of the powder. Other than my stash, have not seen that much powder on any of my dealers shelves in six months. :lol: :lol: Bill K :D
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Re: 20 SCC cartridge (For real this time)

Postby RwBeV » Fri Oct 25, 2013 11:24 am

An improved shoulder on the Vartarg would do exactly the same. I don't think that Brad was trying to reinvent the wheel, just trying to improve on what we have. As far as pressure, Im no rookie. I have doing this stuff for 35 years, wildcatting has always been a best guess at best. None of us has access to pressure guns, or labs so we have to rely on our experience so in my humble opinion I see a substantial gain so far with my testing with no visible signs of excessive pressure. Im not a speed freak, I don't run my guns "balls out" and I don't have a death wish. What I do see is that the improvement in this case has given us the target velocity with safe pressures. At first I wasn't all that impressed with the case capacity so I really didn't have high hopes (not that I would have told Brad that and he still don't know so don't tell him). But what I seen at the Chronograph has peeked my interest, enough to leave the gun together and see what it will do over the long haul. Originally I had left enough shank on the barrel to re-chamber it after I was done with my testing, that's out the window now.

Im in the same boat as a lot of other fellows here, I cant afford that kind of money for dies, but on the other had I can make my own. I know from talking with Brad that he wants to supply the best possible equipment that he can and he has done a great job of finding someone that would build these dies for him. I also know that he plans on finding a less expensive supplier for the dies sometime in the near future depending on how much interest this cartridge brings.

I know right now this little cartridge has my interest and that takes a lot now days. I have a couple dozen 20 caliber rifles so its not doing anything that one of the others wont do, but that's what wildcatting is all about if not we would all be shooting a 22-250 and a 30-06.

Bob
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Re: 20 SCC cartridge (For real this time)

Postby RedMist » Fri Oct 25, 2013 11:29 am

Very nice write-up Bob !! Complete with pics even!! Very cool, I have plenty of 20's but don't own a 20VT. This seems to be the logical progression for the 221 FB case. Should be able to just neck size for a number of firings due to the 40deg shoulder. Would work well for colony varmints, IMO. Makes my 20 Practical look at little plain Jane... :(

Keep us updated, great work. Sharp looking little case!
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Re: 20 SCC cartridge (For real this time)

Postby Waskawood » Fri Oct 25, 2013 1:06 pm

It will be interested to see what 221 Remington brass would do with this shoulder. I have a VT chambered by PacNor that has a longer throat than I would like. This would be a perfect choice to re-chamber to if I didn't have 700 rounds of Remington VT formed brass sitting around.
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Re: 20 SCC cartridge (For real this time)

Postby BillK20VT » Fri Oct 25, 2013 2:28 pm

Do not take my comments wrong Bob. I also have been playing with wildcats and A.I.'s since my first one (30-06 AI) in 1955, since then have and have 22,25,6mm,7mm and 375's in one form of AI or other. May end up with one of the 20 SCC's also, down the road. Seems like we would rechamber a 20VT with 20SCC reamer, and fire form.. I also have been using the 221FB Nosler brass and also LC brass formed into 20VT, stronger and better brass, so accuracy and velocity could/can be boosted.. We all play, learn and have fun with our projects. Know you and Brad will also. Keep us posted, please. Bill K :)
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