Building 257 Roberts on Browning Safari Sako. Wondering if I can seat bullets out farther that 2.800 inches. I will modify mag box if it will work. Thinking copper bullets. Hammers etc
257 Roberts Seating depth
- Thread starter MooseHunter
- Start date
Seat a bullet so the boattail is about even with the neck/shoulder junction then see how it fits magazine and how much you will have to alter mag. Keep in mind monolith bullets can be much longer so rifle barrel twist must be able to stabilize that longer length.
I am working with Sako basically a 579. The 90 gr Hammer was on my list. Barrel I am using is 9 twist. According to hammer 10T will work. Wondering how much I should mess with mag box. The gunsmith will figure this out as he will have the reamer and the box in hand. I may send him some dummies seated long and he can adjust COAl/box to reamer.
Does anyone run 62,000 PSI in .257 Roberts these days? Dont see how it would be a problem in modern action but figgered I would ask.
Does anyone run 62,000 PSI in .257 Roberts these days? Dont see how it would be a problem in modern action but figgered I would ask.
If both cartridge's are run at 62,000 what is the velocity gain of the AI?
Good question. I've no pressure test equipment. Haven't worked with a standard Roberts for a few years, but about 7-10% seems about right. With my latest 257 Ackley; long action 700, 9 twist, OAL pushing 3", I'm knocking on factory listed 25-06 speeds with 100s & 115s from a 24" barrel. Brass life is good, primer edges are round, & bolt lift is normal. Re: copper... So far it seems to like the Barnes 80s & 100 TTSX pushed hard, but more testing is needed.
Case life is quite often better with improved cases, but am thinking it depends on brass, chamber, & die dimensions jiving happily. My 06 Ackley doesn't seem to agree with Lapua 06 brass as it's a bit larger at the .200 line than 90s era WW brass. Between my chamber & the Forster FL die, the WW brass goes many firings w/o trimming, the Lapua needs trim every other firing. Correlation isn't necessarily causation but is how I'm seeing this situation until proven otherwise.
I have a Ruger ultra-light from the 80's in .257 Roberts. I tested a lot of different lead-free bullets in it from 80 to 100 grains, different depth settings, etc. One of Barnes' recommended powders (Hunter) worked best (I use 43.2 grains) along with the 100 grain TSX. This was with Remington cases and CCI BR2 primers. Get just under 1/2" MOA, not bad for a pencil barrel. Those Barnes (and most all lead-free bullets) really show improvement in all of my rifles (I use them in about 8 different calibers) when the bullet is allowed to jump. So, I think you might be disappointed when you try them close to or into the lands. If they shoot terribly, just try backing them out. Mine were loaded at 2.780" OAL, as ironically recommended by Barnes. They test at these depths and sometimes that translates well in other rifles. It did for me. They shot like crap further out. I'm not bothered by single-feeding when hunting, but the load has to work well enough to warrant doing it.
If I were going only after average-sized white tails or smaller, I'd probably look at the newer 85 grain bullet which wasn't available when I did my testing. In my 7 MM Rem Mag, I started out with pretty heavy, working down to 150, 140, then settled on the 120 for the hunting I now do. The 120 knocks pigs down with great authority, so I feel pretty good about the penetration - and they do open up quick.
If I were going only after average-sized white tails or smaller, I'd probably look at the newer 85 grain bullet which wasn't available when I did my testing. In my 7 MM Rem Mag, I started out with pretty heavy, working down to 150, 140, then settled on the 120 for the hunting I now do. The 120 knocks pigs down with great authority, so I feel pretty good about the penetration - and they do open up quick.
Last edited:
Simply running a cartridge with less powder volume at the same pressure is not the answer. The Ackley with more powder volume produces more velocity with that additional powder volume while at similar pressure. You still need to add more powder to produce more velocity.
True. I just wonder what pressure people run the Roberts at these days. The + P is specd at 58 000. Seems mild in modern rifle
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.