I am gonna try to respond to both you guys post at the same time since I am on the wife's lap top and I hate typing on this thing.
As for the throat, this is the reason why we opened up this post, we wanted opinions. I will have to talk to kirby about the throating issue and it does seem like throating for the 200 would leave open a few more options. Hopefully the 250's will be as good as we hope and work out, if so I would like to seat them out so the case would look like how I dream, yes I know that is stupid but I like the looks of a case with the bullet seated out to show the proportions.
I do understand the harshness the 3 groove bbl can put on a bullet and this is something we will have to deal with. It does add some bbl life and God knows with how we are gonna shoot this thing we will need it!! While I would like to get as much velocity as possible from all of the projections we have seen this matters very little at these ranges, it seems that the bc takes over and speed doesnt matter much. I am definantly okay with toning down the fps on this round to minimize SD and ES.
I do think that the BC of the 250 would be amazing. JLK list their 180gr .284 bullet as having a BC of .735, now imagine adding 70gr of length to that!! I know that a bullet this long and with this much bearing surface will present definate issues but could rival .50 cal bullets and the retained energy, prolonged supersonic capability, and sheer wind bucking ability are too hard pass up.
What we will have to see is how these bullets handle the supersonic--subsonic transition. Should be interesting to see.
yes, these are very uncharted waters and to be honest it is exciting to be a part of it. Unfortunatly we both are not recent lottery winners so money is always a issue so it would be great if things would work out great on the first try!! Of course it doesnt work out that way to often!!
I will definantly have to consider the throating issue, we will see what Ol' Montana man has to say.
I am glad you guys posted on this, i was afraid it was gonna be a dead post at first!!
By the way, the range we are actually going after is 3700yds!!!!!!!! Lets just see if it ever happens though!!!
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I know the thought of the BC a 250 grain 7mm could have makes my mouth water! You need to go up to a 300 grain 30 cal to beat that. Good luck with it, I hope it works just the way you want. If it does, my next tube just might have to be a 7mm. [img]/ubbthreads/images/graemlins/wink.gif[/img] The length issues mentioned above concern me as well though. Hopefully it won't be a problem. You know, with the cost of a project like this, maybe some of that money would fund a little developement work by Richard with tungsten powder? Just a thought.
I guess that if nobody tried the new stuff then the new stuff would never get proven would it. Richard and Kirby don't go into this haphazardly and without planing and design work. I have a new barrel on order as we are going to be doing some more testing and experimenting with the 7mm AM in something a little more portable than what you guys are building. When installed, this new barrel will be throated for the 250 Wildcats and I have no doubts that if I want to, I can also use the 200s.
I've been playing recently with some 160 Accubonds and they work just fine. I seat them .020" off the lands and the big Wildcats get seated at the lands. The picture below shows a seated 200 and a seated 160. People wouldn't have any problems giving the nod to a 160 Accubond as being o.k. when it comes to bullet length, bearing surface etc. but if you notice in the second picture, the bearing surface of the 160 Accubond and the 200 grain Wildcat are virtually the same.
I, for one, can't wait to get some of the 250's to try out. I think they'll be fantastic at long range. Hell, life is too short to sit around and think about what you'd like to do, or what "might" work. Just do it and if it doesn't give you the results you want, then make it right and continue to have fun.
Coulda, shoulda, woulda just don't cut it. You're building one hell of a long range gun and I like your approach and the components you're using. If it was me, I'd do the same thing and throat it for the 250s. Hells bells, if it gives you any problems send it back up north and get it set back a little. UPS and FedEX get there overnight. Go for it, or like "crow mag" has in his signature, If you think something is not possible move out of the way so the ones that are doing it can.
You're building a one of a kind rig so go for it, and have fun doing it. [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/smile.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]
I started worrying about that 3 groove recently as well. Oh well, the bbl is a consumable anyway. Problem is, we had to get the tooling for Dan Lilja to make this thing. Not many people are wanting a 40" long 7 twist .284" bbl!!
If it doesn't work, we'll just order a cut rifled 6 or 7 twist. I assume this is possible. Mike Rock, if your out there, can you cut a 40" 5R 7 twist 7mm. If so, we may be calling if this Lilja doesn't work out.