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Guide

257 Roberts and +P Ammo 2026: Loads From the Makers

By , EditorUpdated How we verifyEditorial standards

We checked 2 current .257 Roberts loads on Remington's and Hornady's own product pages on November 5, 2026: 1 from Remington and 1 from Hornady. The bullet weights, velocities, energy figures, test barrels and statuses below are copied from the maker pages. We don't use retailer prices or third-party ballistics. This is a comparison of popular loads from 2 makers, not every .257 Roberts load sold.

Federal and Remington loads show the usage label each maker prints on its own page, copied as written. Hornady is listed in its own table, because Hornady prints no usage label. The Cartridge column shows the name the maker page uses.

Remington loads

Figures are copied from each maker page. The usage label is the maker’s own wording.

LoadCartridgeItem #BulletMuzzle velocityMuzzle energyTest barrelBoxMaker usage labelMaker status (Nov. 5)
Remington Core-Lokt257 Roberts28335117 gr Core-Lokt Soft Point2,650 fps1,824 ft-lbNot listed on maker page20Big GameAvailable

Hornady loads

Hornady's pages show no usage label and no stock status on our capture, so these loads are listed by product line, such as Superformance. Velocity and energy are the muzzle figures from each page's ballistics table, and the test barrel is the one the table names.

LoadCartridgeItem #BulletMuzzle velocityMuzzle energyTest barrelBoxMaker status (Nov. 5)
Hornady Superformance257 Roberts +P81353117 gr SST® Superformance®2,946 fps2,255 ft-lb24 in20Not listed on maker page

Velocity and energy are the muzzle figures in each maker's ballistics table. Test barrel is the length the maker lists. "Box" is the round count per box. Status is the maker's own wording on its product page, and it changes daily. All pages checked November 5, 2026.

Which bullet weight? What the makers' numbers show

Loads in our tables run from 117 gr to 117 gr. The lightest are Remington Core-Lokt 117 gr (28335) and Hornady Superformance 117 gr (81353), and the heaviest are Remington Core-Lokt 117 gr (28335) and Hornady Superformance 117 gr (81353). The fastest listed muzzle velocity is 2,946 fps, Hornady Superformance 117 gr (81353), tested on a 24 in barrel. The highest listed muzzle energy is 2,255 ft-lb, Hornady Superformance 117 gr (81353), tested on a 24 in barrel. Because test barrels differ or are not listed, compare across makers with care.

The makers label loads for game or for target use. They don't tell you one weight is right for a species. The right choice depends on bullet construction, range and your state's rules. Check your state hunting rules and your state wildlife agency before you buy.

Barrel length matters: the test barrels

Muzzle velocity depends on barrel length, so compare loads tested on the same barrel. Of the 2 loads, 1 list no test barrel, 1 list 24 in. The loads with no test barrel are from Remington. A rifle with a shorter barrel than the maker's test barrel will likely give lower velocities than the box. SAAMI's test barrel for the .257 Roberts is 24 in.

No barrel-length-velocity page exists yet for the .257 Roberts, and we have not charted one. Our barrel length vs velocity data covers other cartridges, so do not read those numbers as .257 Roberts data.

.257 Roberts: what SAAMI lists

SAAMI lists the cartridge as "257 ROBERTS [257 ROB] / 257 ROBERTS +P [257 ROB +P]" in ANSI/SAAMI Z299.4, its centerfire rifle standard (approved Feb. 10, 2025). The cartridge drawing was issued 05/29/1979 and revised on a date the PDF text prints cut off (“05/02/20”), so we do not quote it. SAAMI lists a maximum average pressure of 54,000 psi for the 257 Roberts and 58,000 psi for the 257 Roberts +P, measured by transducer (the table shows 540 and 580 in psi/100). SAAMI lists a crusher maximum average pressure of 45,000 CUP for the 257 Roberts and 50,000 CUP for the 257 Roberts +P (the table shows 450 and 500 in CUP/100). In its proof-pressure table (Section III), SAAMI lists the 257 Roberts as “Obsolete – Use 257 Roberts +P Only.” Cartridge overall length runs from 2.620 in minimum to 2.780 in maximum. Case length is 2.233 in (−.020), and bullet diameter is .258 in (−.003). Bore is .250 in and groove is .256 in, with 6 grooves and a twist of 1 in 10.00 in, right-hand (marked optional). SAAMI reference velocities are Not yet verified, because the PDF text does not clearly pair each bullet weight with its velocity. Read the standard at the SAAMI Z299.4 PDF. Both MAP rows (.257 Roberts and .257 Roberts +P) are also on our SAAMI maximum average pressure table (Z299.4, 54,000 psi / 540 and 58,000 psi / 580 psi/100).

SAAMI says all standard rifle test barrels are 24 in long and that exterior ballistic data for centerfire rifle cartridges is based on that length. Its listed exceptions (7.62x39, 277 Sig Fury, 30 Carbine, 300 AAC Blackout, 300 HAM'R, 350 Legend, 350 Remington Magnum, 360 Buckhammer, 400 Legend and 44 Remington Magnum) do not include the .257 Roberts, so SAAMI measures it on a 24 in barrel.

Not yet verified

These makers and loads are not in the tables.

Rifles for .257 Roberts

The .257 Roberts is a rifle cartridge, and the loads in the tables run from 117 gr to 117 gr. See also new rifle releases and the new hunting rifles of 2026.

Where to buy

We link only to maker pages, listed in the sources below. Federal and Remington show availability on their own product pages. Hornady's pages show none on our capture. We don't track retailer stock or prices. Before you order, check your state's ammunition rules, because some states require a background check or restrict shipping.

For more ammo, see .25-06 Remington ammo, .243 Win ammo, .260 Remington ammo, 7mm-08 Remington ammo, .270 Win ammo, .280 Remington ammo, .30-30 Win ammo, .308 Win ammo, the SAAMI maximum average pressure table, the barrel length vs velocity data, new ammo for 2026 and all ammo releases.

Frequently asked questions

What is the SAAMI maximum pressure for .257 Roberts?
SAAMI lists a maximum average pressure of 54,000 psi for .257 Roberts (and 58,000 psi for the +P), measured by transducer, in ANSI/SAAMI Z299.4 (the table shows 540 and 580 in psi/100).
What grain is .257 Roberts ammo?
In our tables the bullets run from 117 gr to 117 gr. Check your firearm maker's manual for what your rifle is set up to shoot.
How fast is .257 Roberts ammo?
In our tables, listed muzzle velocities run from 2,650 fps to 2,946 fps, and muzzle energies from 1,824 ft-lb to 2,255 ft-lb. Test barrels vary, and some maker pages list none. See the test barrel section of this guide.
What does test barrel mean?
It is the barrel length the maker used to measure the listed velocity. A shorter barrel will likely give lower velocities than the box.
Do you list prices or stock for .257 Roberts ammo?
No. We link only to maker pages. Where a maker page shows a status, such as "Available" or "Currently Unavailable," we copy it as of Nov. 5, 2026. Hornady's pages show none.

Sources

  1. Remington: Remington Core-Lokt .257 Roberts 117 gr Core-Lokt Soft Point, item 28335 (checked Nov. 5, 2026)
  2. Hornady: Hornady Superformance .257 Roberts 117 gr SST® Superformance®, item 81353 (checked Nov. 5, 2026)
  3. SAAMI: ANSI/SAAMI Z299.4 centerfire rifle standard, .257 Roberts drawing (checked Nov. 5, 2026)

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