H&K SL8 Caliber Change

Rabid

Rabid

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Hey guys kind of a weird first post I know. Here's my question, is there anybody out there that has attempted a caliber change on their SL8s. I've had a chance to hunt a bit with the .223 and I'm not all that impressed with the balistics of the round. I don't want this to turn into a bash this or that thread but I do know that I would like to turn this gun into a 204 probably go to a 204 tac. I know the bolt face size will remain the same that way also. I have a 204 bolt gun that I hunt with as well and the little 204 flat out rips. I realize that I would have to have a barrel custom made which isn't a big deal but I don't know what kind of pressures the action would take. I would also like to lengthen the barrel to gain some velocity.
I'd like to say that I really like this gun. My first hand loads shot right at 3/4" with 55 blitzkings and I know others say the heavies shoot better out of these guns but the drop balistics are down right awful. I think with a bit of tinkering with the 55s I can get them down to 1/2moa and thats better than I can shoot most days. Anyways sorry for the long first post. Any info on the barrel swap would be great though.

T
 
Rabid said:
Hey guys kind of a weird first post I know. Here's my question, is there anybody out there that has attempted a caliber change on their SL8s. I've had a chance to hunt a bit with the .223 and I'm not all that impressed with the balistics of the round. I don't want this to turn into a bash this or that thread but I do know that I would like to turn this gun into a 204 probably go to a 204 tac. I know the bolt face size will remain the same that way also. I have a 204 bolt gun that I hunt with as well and the little 204 flat out rips. I realize that I would have to have a barrel custom made which isn't a big deal but I don't know what kind of pressures the action would take. I would also like to lengthen the barrel to gain some velocity.
I'd like to say that I really like this gun. My first hand loads shot right at 3/4" with 55 blitzkings and I know others say the heavies shoot better out of these guns but the drop balistics are down right awful. I think with a bit of tinkering with the 55s I can get them down to 1/2moa and thats better than I can shoot most days. Anyways sorry for the long first post. Any info on the barrel swap would be great though.

T
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I've heard of some guys getting stuff like 6.8 SPC, but you'll need to get a new barrel made and installed, which you need special tools for. You're limited pretty much to any of the common AR15 barrel conversions, however getting the custom barrel done will be a little bit expencive.
 
Umm... maybe we've bveen shooting different .223's, but it definitely doesn't have terrible ballistics, you just need to use bullets with a high BC. I've had good luck with Hornady V-Max bullets (relatively mild loads too).

The .204 is a very flat shooting caliber and does drop less than the .223, but we're talking around 5.5" of drop at 300 yards (40gr V-Max, 200 yard zero, .223 Rem) compared to 4.3" with a .204 Ruger (same grain bullet and zero). Theoretically you could rebarrel and SL8 to .204, but it'd likely cost close to $1000 to have the barrel made and installed, and then there might still be feeding/magazine related issues.

What are you planning to do with the rifle, and are the slightly improved ballistics the only motivation?
 
I preditor hunt with it right now. My max shots would be at 500 yards and under. I just ran the balistics on the 204 v 223 with the 39 and 40 grain blitzkings. Even if i could push the 223 as fast as the 204 (3800 FPS cronyd') it would still drop over 10" more at 500, same zero. I know my barrel length is costing me a bit at 20", but evin with the higher BC bullets in the 223 you just can't push them fast enough to make them perform the way I expect my preditor rigs to. No disrespect to the 223 it just doesn't have the legs. Unless you've played with a 204 and the 39 blitzkings the 223 probably seems fine, run the dope at 3800 FPS and a BC of .287 and you'll see what I mean. I think I'll talk to MR. Giallard and see if he can do a 24" tube for me:)
 
I'd try 64gr Berger Match/Varmint bullets. BC of .294, and it'll hit a lot harder than the .204 at 500 yards. I'm actually working up a load for my Swiss Arms using these at the moment. It's well known that the .204 ruger is a very flat shooting round, but IMO the cost and possible issues that may pop up when rebarreling an SL8 to that calibre defeats any real advantages gained in that conversion.

Also, if you think the .223 doesn't have the legs, you should check out some of the guys shooting service rifle at 500, or even 1000 yard target shooting. The accuracy potential is certainly there, you just need to adjust your scope by an extra 2MOA (your aforementioned 10" at 500 yards).
 
Please punch the numbers into a balistic calculator. Out of my fast twist 20" tube 2800-2900 FPS is realistic with the 64s if that. That might seem like an unfair comparison to my long barrel 204 but thats what I have to work with is the 20". Evin with the nice BC# of the 64s that still makes for 49" of drop at 500 VS 25 for the 204 and the 204 is hitting harder 406LBS VS 326 LBS, not to mension the wind drift and time of flight is also better. If your shooting paper at 500 yards you have time to dial your dope, I haven't ran into a preditor hunting situation where that is practicle yet. Holding mills over is what I use, I know I could learn the hold over on the 223 but with those drop numbers the margin of error is way up there. That the 223 is accurate at long range is undisputed. I just want this gun to be a 204.
 
Rabid said:
Please punch the numbers into a balistic calculator. Out of my fast twist 20" tube 2800-2900 FPS is realistic with the 64s if that. That might seem like an unfair comparison to my long barrel 204 but thats what I have to work with is the 20". Evin with the nice BC# of the 64s that still makes for 49" of drop at 500 VS 25 for the 204 and the 204 is hitting harder 406LBS VS 326 LBS, not to mension the wind drift and time of flight is also better. If your shooting paper at 500 yards you have time to dial your dope, I haven't ran into a preditor hunting situation where that is practicle yet. Holding mills over is what I use, I know I could learn the hold over on the 223 but with those drop numbers the margin of error is way up there. That the 223 is accurate at long range is undisputed. I just want this gun to be a 204.
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The numbers I got when I typed everything into my ballistics calculator were less favorable for the .204, and better for the .223. I also hold over for SR out to 500. Also, in terms of the .204 having more ft/lbs of energy at 500 yards, this is true... but there is more than ft/lbs to consider when calculating how hard a round hits. Read a little about the Taylor Index, which integrates momentum and caliber into a relative value to use as a guide for taking game. For what it's worth, the 64gr .223 is 3.2 and the .204 is 2.5 (at 500 yards). Anyways, I just thouht I'd mention that.

If you want your SL8 in .204, go for it. It'll likely be expensive though. I'd contact Herron Arms if you want a custom barrel made, I know several members who have had barrels made by them.
 
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