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Bullet Jump

02 Jul 2017
@ 06:22 am (GMT)

John Smith

I have a 1979 Ruger No. 1A, Serial # 131-51xxx, in caliber 7x57. Not
sure which barrel Ruger used back then. I have reloaded rounds with
a Hornady 162 grain A-Max bullet with a Nosler Reloading Guide
recommended O.A.L. of 3.045". When I measure the bullet jump
with my Hornady Straight O.A.L. Gauge it reads .415". To me this
seems excessive. Using the aperture sight on my 1A I get acceptable
but not great accuracy. What are your thoughts?

Replies

02 Jul 2017
@ 09:37 am (GMT)

Quote this

Nathan Foster

Re: Bullet Jump

Hi John, that is a bit excessive however the throat in this rifle sounds so long (or worn) that it would be impossible to seat close. It may be time to consider reaming to .280 or rebarreling altogether.

You can try seating 7mm into the neck but do keep in mind that this will form a donut in the case neck should you continue to re-use the brass and seat in this manner. The flowed brass donut will only really be a problem if you change bullets and attempt to seat a long bullet past the donut. The donut would then act as a crimp and raise pressures to dangerous levels. Thats about all you have to keep in mind.

You may possibly find that it takes quite a high charge of H4350 or similar to both get up to speed and to keep the pressure wave fairly even through the jump, regardless of OAL.

But above all, ammo concentricity will be the key. If the bullet starts out true, then it has a better chance of hitting the lands true after the space walk.

To all- in my experience based on given versus max COAL's, I find that Nosler (and other manufacturers) aim for 120 thou jump or longer when supplying load data with their bullets.