20" Specialized Dynamics 204 w/ 32gr Nosler Varmint & Reloader 10x

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PowellSixO

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I just put an order in with Scott at Specialized Dynamics for a 20" Ar-15 chambered in 204 ruger. This will be my first AR, and the first one I've ever reloaded for. I was wondering if anyone has some experience reloading for an AR, and if there was anything I should look out for. I've done some research and found a decent starting point, I'm hoping. I just picked up some stuff that I have available to me, that's still on the shelves in the stores near me. I picked up a RCBS FL Die Set, #10 case holder, 204 case cutter, 100 32gr Nosler Varmint bullets, 1 lb of Reloader 10x, and 100 CCI BR-4 primers. I realize that primer seating depth is probably going to be very important for a semi auto rifle. Are there any other things you guys could help me out with? Can I use the same starting point for bolt gun load data, and work my way up? Or do I need to start higher or lower? Will high pressure signs be the same or are there other things to look for? Does anyone have any load data for a simalar load that they have used in an AR rifle? Thanks for your time guys. Any help is much appreciated.
 
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I've had a custom built .204 AR since about 2006 and while it was produced by a different builder (DTech and Spec Dynics was unknown at the time), my builder queried me about the bullets I intended to shoot, since the Berger 50gr had just come out and if I intended to shoot them, the chamber would have to be cut a little differently...My chamber was specifically cut for the 39 & 40 gr bullets..

I have found that with a custom cut chamber, full length sizing is always required and, in my case, bumping the shoulder back slightly is also required for reliable seating in the chambering process..

I have only used Winchester 748 powder with my 39gr Sierra Blitz King bullets and still working on some Nosler 32gr loads...Below is a 100 yard target with the 39gr SBKs and W-748...I have never found a reason to change it..


Mike Mili turns out some excellent work and here is a target from one of his .223 AR uppers that he built for me several years ago using a light weight bullet and Ramshot's X-Terminator powder..(just a slightly faster burn rate than the W-748)


You should really enjoy the .204 in the AR platform...Take your time finding the right load for it and remember that a .1gr difference in powder charge can make a big difference in your results...I've tried both regular and magnum primers and that can make a difference as well, depending on the bullet and powder used....204s tend to like a little 'jump' to the lands, and with the AR magazines, you may be restricted to Over All Length of the cartridge, but don't be afraid to try a slightly deeper seat if you are having problems finding that "Sweet Spot"...
 
Originally Posted By: OldTurtleI've had a custom built .204 AR since about 2006 and while it was produced by a different builder (DTech and Spec Dynics was unknown at the time), my builder queried me about the bullets I intended to shoot, since the Berger 50gr had just come out and if I intended to shoot them, the chamber would have to be cut a little differently...My chamber was specifically cut for the 39 & 40 gr bullets..

I have found that with a custom cut chamber, full length sizing is always required and, in my case, bumping the shoulder back slightly is also required for reliable seating in the chambering process..

I have only used Winchester 748 powder with my 39gr Sierra Blitz King bullets and still working on some Nosler 32gr loads...Below is a 100 yard target with the 39gr SBKs and W-748...I have never found a reason to change it..


Mike Mili turns out some excellent work and here is a target from one of his .223 AR uppers that he built for me several years ago using a light weight bullet and Ramshot's X-Terminator powder..(just a slightly faster burn rate than the W-748)


You should really enjoy the .204 in the AR platform...Take your time finding the right load for it and remember that a .1gr difference in powder charge can make a big difference in your results...I've tried both regular and magnum primers and that can make a difference as well, depending on the bullet and powder used....204s tend to like a little 'jump' to the lands, and with the AR magazines, you may be restricted to Over All Length of the cartridge, but don't be afraid to try a slightly deeper seat if you are having problems finding that "Sweet Spot"...

Thanks for your input, I really appreciate it. Yeah when I discussed the build with Scott he asked me what bullet I planned on using. I told him I wanted to go fast and flat, and that I planned on using the 32gr Nosler bullet. He said it was a good choice, and he's putting the appropriate twist barrel on to best suit my needs. I've read good things about the Reloader 10x, and I'm hoping I'll have some good luck with it. I can find it relatively easy. But we shall see. I'm going to use this for coyotes most of the time, and most shots are 300 or closer. I've been using my 243, and it works great, but I've been wanting an AR for a very long time. With everything going on in the media, I figured I better do it now or never.
 
Originally Posted By: SlickerThanSnotthought i read specialized dynamics went out of business. guess not.

Nope they're still in business. My friend has had a 204 and a 6.5 grendel built by them in the last year or so, and has had amazing results with the rifles. Scott is putting on the Arizona Coyote Calling Championship again this year as well in February if anyone is interested in attending. I think there are 55 teams joined up so far. You can go to his website for more information and to get an entry form.
 
Originally Posted By: cedarcreekcoonerI ordered one over 3 years ago. Still waiting for it

I hope you didn't pay up front!
 
Originally Posted By: barkOriginally Posted By: cedarcreekcoonerI ordered one over 3 years ago. Still waiting for it

I hope you didn't pay up front!

Anyone that's been around here for a while is probably laughing
wink.gif


Someone should look up the Old SD threads!!! I don't recall if they were Locked or Deleted though... Just say'in not trying to stir the pot...
 
I'll add my .02 based on experiences with a few ARs in 204.

For starters you picked an accurate bullet to start with IME. I use it over H335. I had terrible luck with the RCBS dies in that caliber; they produced bad runout. Switched to Reddings and my ammo was much improved. But it may have been just that particular set I had.

You will learn all about magazines and what works and what doesn't. Pmags don't work well without modifications. I hear Lancers work well but haven't tried them. I recommend stainless steel mags as they allow a longer oal than aluminum; 2.3" vs 2.26". This gives you a lot more flexibility on seating depth as the 204 round is a tad longer than 223. Two AR's I worked up loads for shot a lot better at the longer length.

I never used 10x so can't help you there, but normal charge weights will work, just like loading for any other rifle.
 
Originally Posted By: reddog964Originally Posted By: barkOriginally Posted By: cedarcreekcoonerI ordered one over 3 years ago. Still waiting for it

I hope you didn't pay up front!

Anyone that's been around here for a while is probably laughing
wink.gif


Someone should look up the Old SD threads!!! I don't recall if they were Locked or Deleted though... Just say'in not trying to stir the pot...

Not sure what you mean by this? I'm hoping I didn't just get taken on the deal. Knowing my luck I probably did. I personally talked to him on the phone and everything sounded legit. I've been known to be taken advantage of though. I'm too trusting.
 
Originally Posted By: 204 ARI'll add my .02 based on experiences with a few ARs in 204.

For starters you picked an accurate bullet to start with IME. I use it over H335. I had terrible luck with the RCBS dies in that caliber; they produced bad runout. Switched to Reddings and my ammo was much improved. But it may have been just that particular set I had.

You will learn all about magazines and what works and what doesn't. Pmags don't work well without modifications. I hear Lancers work well but haven't tried them. I recommend stainless steel mags as they allow a longer oal than aluminum; 2.3" vs 2.26". This gives you a lot more flexibility on seating depth as the 204 round is a tad longer than 223. Two AR's I worked up loads for shot a lot better at the longer length.

I never used 10x so can't help you there, but normal charge weights will work, just like loading for any other rifle.

Sent you a PM..

Good info here and i will add a little.

The 204 really needs a 22" tube to be utilized to it potential.
10X and benchmark along with XBR8208 are also very useful powders.
If your main use is for coyotes I would suggest the 32gr sierra BK/35gr Berger.
 
Well guys, just a little update. I have everything ordered for the rifle, and it should all be here tonight. I've got a tracking number for the upper from Scott, and it should be at the house before I get home. Here's what I've gathered up so far.

204 20" SS Barrel Complete Upper from SD
A2 Buttstock Kit
Lower Receiver Parts kit from SD
3 lb Velocity Trigger
Aero Precision Scope Mount
Vortex Viper 4-12x40 Scope
2- 20 rd Pmags
Reloader 10x Powder
32 gr Nosler Varmint Ballistic Tips
CCI BR-4 Primers
Hornady 204 Ruger Brass
RCBS FL Die Set
Soft Tactical Carrying Case for the rifle

I'll be sure to post some pics tonight or first thing in the morning.
Thanks.
 

Well my wife just texted me a picture of the upper Scott sent. It's here now and I can't wait to get off work. Haha.




Here's a picture of the scope. I'll get some pics later tonight of everything else.

 
I have no experience with a 204 but by all reports I have seen, pmags will not work without modification. I think ive read that lancer mags will as well as metal mags.
 
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I've heard this too. I've heard some have issues and some dont. If I have to modify it, I'm fine with that. We shall see. Fingers crossed.
 
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