How far is too far?

[Banshee]

My 270 WSM has been a challenge to bring to acceptable group sizes. By accident, I loaded some 130 gr BT with the die set for a different bullet and didn't notice until several were loaded 0.153" from the lands. They were moderate loads so I decided to shoot them instead of pulling the bullet and starting over.

Big surprise, they shot very well. Best groups I have yet obtained from this rifle. I loaded several more to confirm. Again under an inch. I've tried shorter jumps (0.125 and 0.100) and both opened the groups.

Can I go even longer in jump? What is the limiting factor?

 

[JD338]

Banshee

Most rifles will actually have a couple sweet spots, one close to the lands and one farther away. The limiting factor for you is the bullets ogive.

JD338

 

[Guest]

JD is right on the money, and what you've discovered is a trick few handloaders seem to find on purpose. I load very few rounds close to the lands, as it seems I've not been able to find good accuracy there, for the most part. In many instances, it's been a necessity to load shorter to feed correctly or as in the case of the Weatherby rounds, you just can't load to the lands, no matter what you do. I've had excellent accuracy all the same, just as you've discovered. Congrats on getting it shooting well.

To answer the question you asked, you are only limited by the length of the bullet and neck as to how short you can go. Obviously you don't want to get so short that the bearing surface of the bullet is below the top of the neck (because it looks silly, won't feed reliably, and can spike pressures if the neck gets bent in) but other than that, shorten it up as much as you like. You're already onto the biggest issue, which is to drop back to a moderate load and then play with COL, and then work back up if you so desire, watching for pressure signs.

Happy loading!

 

[jmad_81]

Could a guy load up a moderate load and then do some sort of a ladder test with AOL. Shoot them at 200 yards and have .010" increments? Mark every shot and see if you get any that group close to try to find the sweet spot.

 

[JD338]

Could a guy load up a moderate load and then do some sort of a ladder test with AOL. Shoot them at 200 yards and have .010" increments? Mark every shot and see if you get any that group close to try to find the sweet spot.

I would first find the load and then play with COL.

JD338

 

[Guest]

I'm with JD on finding the load first. The earlier post I made indicated something of the opposite, so let me clarify. Within normal limits, pressures won't spike much with bottleneck rifle cases as you shorten the COL, as the heel of the bullet doesn't take up a large enough percentage of the case volume to make a difference. Now, if you play with small cases (like 223Rem, or 6mmPPC, or such) you may actually be able to impact case volume enough to cause significant pressure increases. If you shoot pistol rounds, you most certainly can (especially high intensity, small case stuff like 40S&W). Additionally, if you sink a 150gr Barnes TSX as deeply as you can into a 270WSM case, you might impact pressures, due to the overly long bullet shank on the all copper Barnes TSX. Thus my caution above about watching pressures.

Under normal circumstances, I'd work up a load at least .030" off the lands, and then play with COL, being very careful if I got any closer to the lands, but not worrying much if I shortened up to .150" off the lands, as long as the case was one that had at least the volume of something like a 30-06 case versus the bullet volume protruding reward into the case.

I wonder if a 308Win shooting ultra short COL 180gr rounds might have the potential to pressure spike? Anybody got a 308Win and experience with such an eventuality?