Bought a CVA/BPI Apex single shot in .35 Whelen last year for our so-called "primitive weapon" season here in Mississippi, which is ridiculous but now legal (single shot, exposed hammer, any caliber .35 or larger).

Mounted a Zeiss Conquest 3x9x40, bought some of the new Hornady Superformance loads, 200 gr. psp @ 2850 fps, which is one hell of a powerful pill out of the '06 case, amazing.

Didn't really expect this load and gun combination to stack bullets, but thought anything under 2" would be fine for the occasional deer or hog.

The gun won't shoot this load or Hornady's new Custom load, a 175 gr. psp @ 2900 fps. 4" groups with both loads is the best it will do.

The CVA tech guy first suggested a heavier bullet (250 gr.), to which I said absolutely no due to recoil and being totally unnecessary for my use. He then said he thought it might be a problem with the scope base that came with the gun, saying there has been some problems with bad tolerances where the rings clamp on. I was highly skeptical this was the problem, but they wanted to send me, at no charge, one of their Durasight one-piece base scope mounts (http://www.durasight.com/), which I said was fine. Then...

I put my old rifleman's cap on and asked what the rate of twist is on this caliber in the Apex. He told me 1 in 14, which I immediately thought is too slow to stabilize these bullets. Would have figured at least 1 in 12 for this cartridge would have been more appropriate. Do I have it backwards, a slower rate for lighter bullets? Have I got a rifle that I can't use with 200 gr. or lighter bullets. Not going to start back reloading, and only Remington loads a 250 gr. slug @ 2400 fps.

Whatchall think?
JR

For a given caliber, the lighter & shorter the bullet the slower the twist rate required to stablize it. The heavier & longer the bullet the faster the twist rate needs to be.

1 in 16" or 1 in 14" are the normal twist rates for .35 caliber rifles using bullet weights of approximately 200 to 250 grains.

I would think your problem is not the 1 in 14" twist rate.

Thanks Brittany. After I posted, I figured out the twist rule. But something definitely is wrong somewhere for this gun to shoot this badly.
JR

Go to the basics...forend, bedding, trigger.

I found one guy that had a mount that was flexing (?). Another suggested the headspace was a little deep and neck sizing was the way to go.

You may never find a satisfactory commercial load.

After crawling around on the world wide web a little, I think I may have discovered what's going on:

http://www.bellmtcs.com/store/index.php?cid=597

Obviously there is a market for these, so others have had the same problem. Got one of each ordered; what the heck, it's less than a box of ammo for both with shipping.
JR

Going to try some Remington 200 gr. also. Trial and error, mostly error.
JR

My Rem. M30 in .35Rem. has a 1 in 16 twist but that was designed for 200 grain bullets. I am told it will probably be fine if I rechamber to .35Whelen and stay with 225 grains but I might have trouble at 250 grains. Remington also used 1 in 16" for their 700 Classic .35 some years back and also their pump Whelens.

But most guys starting out a build these days will go 1 in 12".

Twist rates are tied to density (wt/volume), length & velocity of the bullet. It takes a faster twist to stabalize a spire point than a round nose even though they are the same weight & of the same density. The .35 Whelen pushing the 200 grain bullet to 2800fps could use a slightly longer bullet than a .35 Rem @ 2200fps.

If you made an aluminum bullet having the same length as the 200 grain jacketed lead bullet it would require a faster twist to stablize due to its lower density even though of a much lighter wt. Thus just stating a given twist will stabalize some weight of bulet, does't take all factors into consideration.

As long as one is speaking of only conventional jacketed lead bullets then the old Greenhill formula will virtually always work. It was based on velocities down around 1300 fps as I recall, thus somewhat on the conservative side for modern calibers. At the higher velocities of modern loads bullets slightly outside its parameters are often quite well stabalized. As mentioned I seriously doubt bullet stabalization is your problem

UPDATE!

CVA sent me free of charge one of their Durasight scope mounts and I installed a Mike Bellm 2X oversize hinge pin (http://www.bellmtcs.com/store/index.php?cid=597). Result: cloverleafs @ 100 yds. with Hornady 175 gr. ctgs! Get this: the Hornady Superformance 200 gr. shot into one ragged hole with the 175's! Wow. Tickled shitless.
JR