BC of 200g wildcat??

[remingtonman_25_06]

ss7mm What rough BC can you give me? I am curious because I would like to punch it in with the 7 WSM. I am looking at either the 180g vld or 200g wildcat. I want the highest BC bullet available though, and its obviously gonna be the 200g WC. Am curious as to what your guys thoughts on velocity might be with a 200g out of a 26", maybe 2850fps? Let me know what you guys think.

 

[lerch]

at those speeds i would guess very high .8 to .9 . hopefully Richard will come out with the 250gr ULD soon and we can break the 7mm into the full digit zone!!!

I would have never thought the J4 jacket could hold up to elk sized animals but you cant argue with the results SS7MM has shown us!!!

This bug 7mm bullet seems to draw a lot of flak at times but is a hoss no less!!!

take it easy
steve

 

[Ernie]

with a 2700 MV I would put it in the .800 - .840 range.
I was at a elevation of just over 2000 ft., and the temps were cool.

 

[Ballistic64]

I would think a 200 gr bullet at 2850 in the 7 WSM would be pretty optimistic,but then Ive never owned one.The 7 Ultramag would probably be better at attaining those velocities with a bullet that heavy.

 

[reed mosser]

Having a good bit of experience with 7 wsm I would have to say the 200 grain wildcat is to much bullet for that case. 3000 fps is top for that case with 180's. I'd say with the 200's at max , pretty stiff load 2800 fps. I think you would be much better off shooting bullets in the 160 to 180 grain range in that case.

 

[Fiftydriver]

RemMan,

First off, at the velocity potential of the 7mm WSM I do not know if the standard 1-9 or 1-9.5 twist will stabilize this bullet. A 1-8 would and a 1-7 certainly would.

At +3000 fps, the 1-9 will start to work well and at +3100 fps they really start to shoot well. At the +3200 fps potential of the 7mm AM a 1-9 twist will accurately handle this bullet in most cases but thats with alot of velocity.

If you get a fast twist barrel and use this bullet as a single shot mode it would probably work very well.

Most do not realize that the 200 gr ULD RBBT has nearly identical baring surface as a 160 gr Accubond so the extra weight will not be a major issue to increasing pressures. The main problem is length and for a repeater it would not be a good choice in the WSM.

As far as BC is concerned. No idea what the true BC of this bullet is. What I can tell you is that I use a BC value of 0.910 in my Exbal program to match my 7mm AMs actual bullet flight out to well past 1000 yards.

Keep in mind this is at about 3500 ft elevation as well and at a velocity of 3200 fps.

Realistically, I would say you would top out at around 2750 to 2775 fps with this bullet in a 26" barrel out of the WSM. I do not think you would break 2800 fps comfortably in that barrel length with that bullet. This does not mean it will not perform at extreme range because it certainly will at those velocities.

Kirby Allen(50)

 

[daveosok]

250 grain 7mm? If the 200 requires a 1:8 twist where would you get a 1:6 for the 250 grain? You'd need at least a 1:6 would'nt you?

 

[remingtonman_25_06]

Well I ran these numbers. A 180g vld at 3000fps with a BC of .684 has 1788fps and 1278 ft lbs at 1000 yards. It drifts 52.5 inches @10mph, and drops 229 in. from a 200 yard zero.
A 200g WC with a BC of say .850 at 2750fps would be going 1801fps and have 1441 ft lbs at 1000 yards. It would drift 45.5 inches@10mph, and drops 252 inches.

Hopefully I can seat the bullets out in the magazine and use it as a repearter. I should have enough room to use it as so. I can load my 300 RUM shells out to 3.8". A 7 wsm with a 180 or 200g shouldn't be longer then 3.8" would it? I am leaning more towards this 7 wsm and either of these bullets. To me, it will work very nice for its intended application. Pretty much duplicate my 300 RUM performance, while burning 25g less powder. Just gotta start saving.

 

[bailey1474]

Kirby and Richard seem to think we are going to be able to get away w/the 7" twist on the 250. We shall see!!!!

 

[Fiftydriver]

Rem Man,

Just one suggestion, If you have a RUM length receiver have you ever considered using the 7mm Dakota case? Only 2.5" in length but would get you to that 2900 fps velocity area much easier with only a bit more powder.

Only reason I mention this is because really short cases generally do not feed well in a long action rifle. The feed rails will often release the case to soon before the bullet is contained in the breech of the rifle and at times will pop out. Long loaded this would not be as big of an issue but may still happen at time.

The Dakota would solve this problem and be much more user friendly then say a 7mm RUM.

Kirby Allen(50)

 

[Fiftydriver]

Dave,

When Richard and I were playing around designing the 7mm AM we knew from the start that we would be trying some extremely heavy bullets in the 225 to 250 gr wright range. As such, we designed the barrels with Dan Lilja to hopefully handle bullets from 200 up to 250 gr and as such we went with the 1-7 twist to hopefully cover everything.

This is generally not the best way to do things but I could not afford tooling for two different twist rates at that time.

It has been proven that the 200 gr ULD RBBT will stabilize in a 1-9 twist at velocities over 3100 fps. In fact the 1-7 actually will limit the top velocity of this bullet because it tears it apart in rounds such as the 7mm AM. This produces a velocity ceiling of around 3200-3225 fps, typical of any J-4 bullet in a fast twist barrel.

My personal 7mm AM that I am getting ready to build will have a 1-9 twist 6 groove barrel which I plan to use with the 200 gr ULD RBBT.

With the new 250 gr ULD RBBT, the velocity level will be significantly lower then anything that can be produced by the 200 gr ULD RBBT. As such we will not have to worry about the high RPMs like we do with the 200 gr ULD RBBT in the 1-7 twist barrel.

The 1-7 will also be MUCH more appropriate for this length of bullet as well.

In all honesty, I am looking for a 2900-2950 fps velocity range with this bullet and the BC should push 1.000 pretty easily from what I have seen. If we hit that and the bullets stay together, ballistically it will offer the same BC as the best 50 cal match bullets but with a 300 fps velocity advantage.

We are not really looking at bullet drop here to improve on. More interested in wind drift or limiting it as much as possible and retaining as much velocity as possible for 2 mile shooting.

Will it work. How knows!!! We will soon when bullets start to fly!! If it does not at least we proved it did not work instead of just thinking it was not a good idea. If it does work, we will open up a whole new relm of ballistic performance for sub 338 cal cartridges.

Kirby Allen(50)

 

[youarenotcrazy]

A 250 grain 7 mm!!!?? I just drooled all over my clean shirt... /ubbthreads/images/graemlins/tongue.gif

 

[remingtonman_25_06]

Kirby, are you talking about 2900fps with the 200g Wildcat? If so, and what you say about the WSM cases in a long action, that might just be the ticket. Are they your AX magnum? How much powder do they burn?

 

[Fiftydriver]

No I was talking about getting 2900 fps with the 250 gr ULD RBBT in my 7mm AM.

My AX rounds are wuite a bit larger then the WSM case capacities as they are based on the 300 Dakota case which has slightly more capacity then an STW case.

Kirby Allen(50)