.308 VLD-ULD pressures and volocities

[Glock119]

On another thread was the below post, as i did not want to highjack thread I thought i might start a new one.

Posted was:
shadowman,
>>Where do you get teh VLD and ULD bullets???
>>Well, for lower velocity rounds, under 3200 fps in most occasions, Bergers VLD bullets are very quality bullets. In fast twist barrels they just tend to not like things much over 3200 fps in a 1-8 to 1-9 twist barrel.
>>Hornadies A-Max bullets are much the same way as the Bergers but I call these a semi-VLD bullets. They just do not quite run with a true VLD bullet ballistically. THey do however have better on game performance at long range because their polymer tip initiates expansion better then the HP match bullets.
>>Again, for over 3200 fps there are better bullets.
>>Now another semi-VLD design is the Sierra Matchking. Again I call them Semi because some of their designs do not offer true VLD ballistics. Others such as the 240 gr .308 and 300 gr .338 are VLD designs.
>>The Sierra Matchkings have a thicker jacket then the Bergers or A-Max bullets and will generally accept velocities 200 to 300 fps higher then these other two match bullets.
>>Personally, from what I have seen testing the Wildcat Bullets, I would use these for any VLD or ULD design. These bullets offer extreme ballistic performance in the ULD family of bullets. One example is the 156 gr Rebated Boattail in .257" that I use in my 257 Allen Mag. This bullet over 500 yards has a B.C. of .810 with a muzzle velocity in the 3100 to 3300 fps range.
>>Wildcat bullets offers bullet options that I have yet to find from anywhere else. YOu can get +.800 B.C. numbers but in a bullet built with a heavy tapered jacket to perform like a premium big game bullet.
>>Here is my contact informtion for Wildcat Bullets: [email protected] This is where I shop!!!
Good shooting,

Kirby Allen(50)
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Well, Kirby thanks for the info. I contacted Richard at wildcat bullets and he said he had the 169.5 gr. rebated boatail ULD being the lightest and the heaviest was a 225gr. rbbtuld. All are built on j-4 jackets and that bullets heavier than 225 can be built on a harrfield jacket.

He said that twists rates for them seem to be equivalent to comparable bullet weights, the secret with the ULD's appears to be seating depth and pushing them hard, as you stated above. He said that in fact they seem to shoot better as pressure goes up and that usually a max load produces the best accuracy.

Now heres my many questions:
1: in a .308 the 1 in 12 twist rate would stabilize how much lead in your opinion? in the wildcat ULD's. 169.5gr or more?
2: with max loads how long before barrel failure or fatigue with my 700 LTR? Don't worry just looking for your opinion based on your use.
3: How high or what type of velocities do you think are realistic and are the ULD's of benefit in this round?
4: When you use these ULD's, what type of seating depth do you find works best? Just touching or just off or something different?

Many Thanks, /ubbthreads/images/graemlins/laugh.gif
Ben

 

[Fiftydriver]

Shadowman,

Well, I would say that with a 1-12 twist, you will be able to shoot Richards 169.5 gr ULDs with good results. They may be pushing the limits of the 1-12 twist but I would bet they will shoot well. I agree that teh top pressures will produce tighter groups. THis is a personality trait of Wildcat Bullets. Kind of refreshing compared to most bullets that perform best short of max.

Even with full tilt max loads, your 308 will last quite a while. Getting well over 3000 rounds of accurate barrel life in a 308 is not uncommon at all. Throats last longer with a match chamber as well, yours will soon have one of these.

The 308 should be able to get in teh 2650 to 2700 fps range with the 169.5 gr ULD. This is plenty of velocity to perform well at long range. If your looking for flat trajectories, this is the wrong cartridge to use, if you want consistancy at long range this is a great choice.

I feel teh ULD bullets are always an advantage at long range as long and your rifle will stabilize them. Their higher B.C. cuts wind drift considerably and in my opinion this is their best performance feature. The 308 generates plenty of velocity to make these bullets very useful.

Different VLD and ULD bullets prefer different seating depths in relation to the rifling origins.

In a fast twist barrel, say, 1-7 to 1-9, I like to develope loads seating the bullet well into the rifling. Especially if it is a cartridge that will generate substanital velocity. This starts the bullet rotating as soon as it starts traveling down the bore.

If the bullet is allowed to gain velocity in a static state, when it engages teh rifling, the bullet is severely strained, just like wringing out a wet towel. This will weaken the core/jacket bond and accuracy will suffer.

Even in slower twist barrels this system generally works the best with the Berger, Hornady and even Sierra match bullets.

I have not found this to be the case with the Wildcat ULD bullets. I have seated them into the rifling and as far as 0.150" off the lands and they preform in a similiar manor either way. The only exception would be the J-4 jacketed Wildcat Bullets. These are a thin jacketed match bullet and they should be seated to touch the lands and develope loads accordingly.

Most of the Wildcat ULD bullets I use are designed with very heavy jackets designed to survive teh launch speeds of my Allen Magnums. These heavy jackets solve the problem with thin jacketed match bullets.

Hope this helps some,

Kirby Allen(50)

 

[Glock119]

Thanks for the reponse and info /ubbthreads/images/graemlins/laugh.gif

Ben