Home Forums Reloading Big Game Rifles .257 Roberts fav's

Finally, I have a Bob. Winchester 70 bull barrel stainless in a super Grade LA stock (???) Anyhow, UPS snapped the stock and I have a used standard stock in LA coming off Ebay. No Idea of the history but it shot two minimum load rounds just fine -- 40 grains H4831 SC and a 117-grain Hornady BTSP. Drilled out stock at break, inserted long eyebolt, JB Weld 5-minute epoxy and sawed excess off after cure begun. Finishing up in safe next to GoldenRod. Buehler mounts re-installed with Leupold 3-9x. Everything cleaned up good, including the bore.

Any favorite loads or suggestions?

H4350 with about any good 100 gr bullet. Most data is fairly low pressure, check out JBs "loads that work" article or Gun Gack book for more updated stuff. Should be able to go well over 3k with the 100s

My Model 70 featherweight loves the 90 gr. Barnes X-bullet (no longer made) and a max charge of IMR 4350. Same goes for the 100 grain Nosler Ballistic Tip. I"ve got some old factory Hornady Light Magnum 117 gr. BTSP that shoot pretty well in my rifle as well, but it's factory stuff and not near as much fun!

H-100V is the velocity champ in the Roberts. Not as temp stable as H-4350, just faster.

My Brux barreled, LA .257R shoots near one hole groups with the 100 TTSX over H-100V at 3,250 fps.

And, it's a killer.

What's not to like.

Check COAL, too long for SA, fine in a LA 700.

DF

A few.

1) Sierra 75 grain HP, 44 grains of IMR 4064, WW +P brass or Remington brass, Fed 210M
2) As above, but 41 grains of 4064 and 90 grain Sierra BTHP
3) 100 grain ballistic tip or partition, WW +P or Nosler +P brass, Fed 210M, 48 grains of H4831SC. Note that one gun shot both very well, the other only shot the ballistic tip load well. In the first gun, 5 shots were going under 0.25 inch C2C at 100 yards.
4) 120 grain partition, WW+P brass, Fed 215 primer, 43.0 grains H414.

One thing I found .. .257s can be twitchy. I've had a couple that would shoot the 75 and the 120 well but wouldn't shoot any of the 85-117 grain bullets I tried with any decent accuracy.

Tom

The target isn't much to look at, but the rifle sure is...

Offhand?

I bought a rifle from Mule Deer, and used the 46.0 gr of H4350 'neath a 100 TTSX that he recommended, and woujda believe that it worked?





I know, RIGHT???!!!!

FC

Along these lines, one of Cookie's photographer friends has an heirloom pre-64 in 257 and is on hard times. His local Cabelas offer was $1,700. I'd like to help him out, but just dropped a large sum on a travel trailer. If someone has interest, shoot me a PM, and I'll look at linking the parties up.

Here's my .257, built by Ron Lampert, MN using a Brux barrel. It's LA, but one of the smoothest feeding bolt guns I own regardless where the round is placed in the box mag. Ron did a great job, tweaked the Walker trigger to perfection.

I fitted it in the Ti take off stock, converting ADL to BDL, glassing and free floating.

Pictured with different scopes, currently wearing the Conquest.

DF

Wow! Maybe I'll post pics of my Bubba fix. Need to inlet the used stock some, then bed it. Still figuring out what I have. Thanks!

Twins. The 75 grain V-Max are very accurate in both with 42-43 grains H4895, 3325 - 3350 fps. 115 grain Nosler Partitions are my favorite for Mule and Whitetail deer. 43-44 grains H4350 2845 - 2860 fps. Checked a new batch the other day and clocked in at 2875 fps.

Tag

[img]https://i.imgur.com/XfNNIkI.jpg?1[/img]
Eyebolt from under grip cap to half-an-inch before rear action screw; drilled out first.

[img]https://i.imgur.com/RjEEHg7.jpg?1[/img]
JB Weld / 5-min epoxy surrounding eyebolt and oozing out shattered grip.

[img]https://i.imgur.com/iesAlNB.jpg?1[/img]
We'll see how she shoots factory next.

Believe she'll shoot!

[img]https://i.imgur.com/L81UuLK.jpg?2[/img]

My Model 70 pre-64 likes 115gr Nosler partitions, second is 110gr Accubonds. I get over 3100 fps with several powders all slow burning. RL23,
Norma MRP, RL26, all gave over 3100 fps. Plus good accuracy . RL22 will get you over 3000fps. I,m sure there are others. My model has a fast barrel
buy the way.

I tried RL-26 in my Roberts, burned dirty, left granules of unburned powder in the chamber, couldn't chamber the next round. Shook'em out, chambered easily.

I think it's too slow to be optimal for that round.

H-100V is the fastest Roberts powder, IME.

H-4350 works great with heavies, just slower.

DF

Never had any of those problems, but RL26 was least accurate. Norma MRP was my favorite and RL23 was a close second.
I used RL22 for a while, but found the MRP was better, you have to use about one more grain of powder. Plus it likes heavier
bullets better than the RL22. I used a lot of MRP in my 270 with 150gr partitions and RL 23 with 140gr. Also MRP in my 7mm Mag
With 160gr Accubonds or Trophy Bonded Tipped.

MRP is claimed by some to be the same as RL-22, maybe made to a higher standard.

There can be lot to lot variation, maybe more with RL-22 than MRP. Even if they are nearly the same, there can be slight differences in burn rate and data.

RL-23 is said to better than ‘22. I have a big jug of MRP, some RL-23, doubt I’ll buy any more RL-22.

Don’t think RL-26 is an optimal Roberts choice. Too slow. Great in 7RM and such.

DF

115 BT with IMR 4831 in Nosler cases. Several finicky Bobs would shoot it quite well.

[img]https://i.imgur.com/vR8ns90.jpg?4[/img]

Mo bettah!!

its getting to be kinda sad these days with the common American rifle manufactures don`t even offer a 257 Roberts in their rifle selections anymore for me to stock ,this fine cartridge and now ammo for 257 Roberts selection is poor and many times what ammo is for sale from warehouses 257 Roberts it is out of stock too. so much for a very fine cartridge and that is very sad !

I don,t think RL22 and MRP are the same. If I make to loads just the same RL2 will be faster, but I will have to stop adding powder to
the RL22 load as it gets over pressure. With the MRP after I get about one more grain of powder it starts to exceed velocity of RL22,
and I can keep going a little. Also I get more velocity from heavy bullets in the 270 win. Have started to use a lot of RL23 in the 270 with 140gr
bullets, also works good in 270 WSM. But not so good in small case, you can not get enough in.

Early start at the range at 70 degrees. Went back after noon at 83 degrees, having cleaned the barrel and loaded some more. Not bedded, and I doubt I will. Anyhow, here's the result.
[img]https://i.imgur.com/LeRGy3n.jpg?2[/img]

Ooops.
[img]https://i.imgur.com/qbcXabM.jpg?1[/img]

Are you going to replace the vented recoil pad?

What are you planning to shoot with it?

There are 4 bullets that I have loaded extensively in a variety of 0.257" bore rifles:

I've shot a tall stack of pdogs with the 75 grain VMax and Sierra HP over 44.0 grains of H4895.

I've shot a gross of predators and a dozen or so deer with the 90 grain Sierra BTHP over 42.0 grains of H4895.

i've settled on the 110 grain AB for shooting medium game with my 0.257" bore rifles and like 38.0 grains of H4895 in my 2 favorite 257 Roberts rifles, a Remington 700 parts gun and a Ruger 77 RSI parts gun.

The slip-on pad and ammo sleeve are to get me to my LOP. Just wanted to have a rifle in the caliber I shot my first two deer with (late '80s.)
Shooting paper mostly, and I'll play with bullet weights, etc. Safari hunting with .300's is more my "style", and I have a long 7 mm Weatherby to also play with.
H 4831 SC and IMR 4350 look good so far with 117's. If I get REALLY bored, I can bed the .257 Roberts, but the barrel is fully floated ahead of the action already.

Thanks a bunch for the recommends!

Barry

IMR 4350 with 100 grain Sierra's was good at 44 grains. Gonna try H4895 next, as recommended.

I have the exact mate to that one here except my bbl was made by the late Bevan King in BC.

I'm not sure why I bother tinkering with other WT rifles this is the only one that goes out now. I got the donor gun online when a fellow advertised it with the bolt "stuck" in the receiver. It was sold "as is" for a stupid low price. Removal of an extra long weaver screw was all it took to get the bolt out.

If you want to try again switch to a magnum primer and use a full bore load and a heavy bullet. Many slow powders are like burning charcoal until you hit the pressure level they were designed for. I have seen this with H870 consistently. A tight neck can help sometimes too. I am not seeing too much crud with R26 and the similar 6mm AI. Bore looks a little dirty but it knocks out with one patch. Some are theorizing the anti coppering agency is what your seeing and is not carbon build up. YMMV

Unburned powder in the chamber can be a sign you are not generating enough pressure for the case to seal itself. Put the hammer down on those loads and they may come around.

Thanks for that info.

I've had such good results with H-100V in the Roberts with 100 gr. TTSX, I'm probably staying there with that round.

I'm going to work up 7RM loads with RL-26 and 160 gr. NAB's for my bud's Africa PG hunt in Aug.

Already got a CDS dial for his VX III 4.5-14x50 LR scope. He loves that scope and it's a proven performer. The gun is a SS Sendero.

I asked him why he packs such a heavy rifle. His response, "I know what it'll do when I get it there". And his track record with a .270 Sendero on WT's and hogs is pretty impressive.

DF

Blew primer at 43 grains H 4895. Bolt sticky at 42, seems fine at 41 and grouped well?

One of my buddies love the Roberts. I think he has 4 or 5 of them. I think his rifles love the Nosler Ballistic Tip in 100 grains. Most of the pics of animals he has killed and sent to me have an old 721 laying next to it.

My current Roberts is a Savage Axis originally in 308. I had Shaw make me a factory contour barrel 24" chambered for the 257 Roberts with a short throat, the same as the 250 Savage barrel I bought on sale from MidwayUSA. I had a gunsmith buddy with a barrel vise screw it on, and now I have the best Roberts rifle I have ever owned (of three). It shoots great, and the rifle weighs 7-1/2 lbs with a 2-7x Burris scope on top.

It shoots about everything very well, as in 10 shots into an inch. My favorite load so far is 44-45 grains of IMR 4831 under a 117 grain Hornady boat tail. Loaded to the cannelure, the bullet is firmly into the lands when a round is chambered. 44 grains of IMR 4831 gives me 2,875 fps and 45 grains gives me just under 3,000 fps. Recoil is modest. If I were to take it hunting for something larger than a NY State buck, I would load up 115 Nosler Partitions to around 2,900 fps. That's 25-06 territory. My first centerfire bolt gun was a Remington 700 in 25-06. Back in the 1980s, I shot a pile of woodchucks and some deer with it. My whitetail load was a 120 grain Hornady HP at around 3,000 fps. This Roberts should be right on its heels.

My first Roberts was a tang-safety Ruger 77 made in 1976. It had a very long throat, but shot well with long bullets. My woodchuck load used Speer 100 grain HPs. The difference in the loads these two rifles would tolerate is vast due to the throating differences.

The third Roberts was a pre-64 Model 70 Winchester. It was somewhere in the middle of the two already mentioned as far as throating is concerned. Like the Ruger, it was also a heavy rifle, so I sold it.

The Savage isn't the prettiest of my Roberts rifles, but is sure is the best shooting and carrying one.

Going against the tide here a little, but the old Sierra 3rd Edition published 38.2 gr of good old 3031 for hundred grainers. Same load listed for both accuracy and hunting. I get around 3000 fps and a little under 1 moa, nothing fancy but it's in a 23 5/8" bbl on a traditional Mauser sporter, set trigger etc. Same load works with 90 gr GMX, 3100 fps. Fed match primer, un prepped Hornady cases. SD runs around 16 fps. May not win at Camp Perry, but it sure is simple.

(Looks like I'll have to bed it.)

[img]https://i.imgur.com/TDZbKbx.jpg?1[/img]

Favorite loads in my Roberts are the ones that shoot well enough to suit me. So far 117-120 grain BTSP's and 42.0 grains of IMR 4350 popped with CCI 250 magnum primers is where my Ruger likes to be. Just ordered some on sale Speer bullets from Midway and just got done testing them. Worked up looking for pressure signs stopping at 43.5 grs. of I4350 with the Speer 120 gr. Grand Slam bullet. Loaded ten with that bullet and put all in 2.5 inches, not good enough. I also ordered some 120 gr. Speer BTSP's to test, loaded ten with 42.0 grs. of I4350 and put them all in just over an inch. Went back to the Grand slam bullet trying the same load and got all ten in just under 2 inches. Still need to do some work with that one. The rifle really likes the 100 gr. Speer hollow point and both Hornady and Sierra 117 gr. BTSP's. Nice day out after the race, might just load ten more up and see what happens.

Well after trying a couple of different seating depths and shooting the Grand Slams on top of three different amounts of I4350 I got them shooting into 1 1/4 inches. The rifle wanted them seated just off the rifling and did prefer the 42.0 load. This testing took a box of Grand Slams out of general population leaving me with one box to load and shoot a couple hogs with. It seems my Roberts needs a lot of love finding a load that shoots well for some reason.

Should have left it unbedded. Still trying to find a sweet spot.

257 Roberts is a great old cartridge i own 4 now and am in the process of building another one with a real nice Remington 30 express ,7 1/2 twist Brux barrel. its kinda sad how this grand old cartridge is being forgotten , but not by some of us !

I'm down to three I usally find 45-46 grains of H4350 behind a 100 gr pill of your choice seems to work.Right now, I'm shooting 100gr Barnes TSX with 45gr H4350 in the 722 and am getting 3080fps. Shoots really well for me.

5 shot's Kimber 257 Roberts AAA French Select Speer 120gr Grand Slam with RL-22

This has been true for me as well and some burn rate charts show MRP as slightly slower. than R22 What I have read is that the powder starts out the same R22 & MRP but different flame retardents are used on MRP. If you look at the color of both, MRP appears darker to me. I have also heard that R22 is bulk grade which can have +/- 10% lot to lot variation and that MRP is canister grade with a maximum allowable variation of 5%. So R22 can vary as much as twice the burn rate compared to MRP.. This seems true to what I have seen in lot to lot variation, almost none with MRP but some lots of R22 can vary between burn rates from the 4831 range to 7828 or even close to H1000.
I won't stop using R22 but I do want to explore alternate loads with R23 & R16 for the same applications. R16 is very promising being close to H4350 but usually with higher velocities. R16 & R26 are denser so may suit the Roberts well as they have with the 6mm Rem, 243 and the 25-06.

Blowing primers and cracking heads at just 4 reloads with H4895 loads. Either WW brass is junk or those loads are WAY too hot for my post-64.

Bedding didn't help. Might get it pillar bedded. Shoots better in the repaired super Grade stock so far. Time to start over in cooler weather. Sigh...

Tagged.

Any idea what velocity you're getting with those loads? Just FYI, the Hodgdon data shows 38.0 grains as max for the 100 gr. bullet using H4895.

I've always had better luck using IMR 4350 in my Roberts. I had a Browning A-bolt that loved the 100 grain partition and my current Winchester FWT loves the 90 gr Barnes X-bullet (discontinued) and a max charge of 4350. It also loves the 100 gr. Ballistic tip with a max charge of 4350.

42 grains IMR 4350 with 117-grain Hornady = 2850 fps. 100 grain Sierra GK's and 38 grains H 4895 = 3050 fps.

I've been using 44gr of IMR4350 with the 100gr TSX in my old Rem 722. Shoots about 3150 FPS in my rifle and have taken over a dozen critters with that load including Mule and Coues deer and a bunch of antelope. Never lost a critter, never recovered a bullet. Closest shot was 180 yards, longest about 350. Loaned it to a buddy and he killed his pronghorn over at 415.
BUT, based on Mule Deer's recommendation I'm going to give H4350 a try. I'm planning to give the Bob the season off this year in favor of the .270, .243, and .35 Whelen AI, so I have lots of time for loading the Bob.

Cheers,
Rex

Shoots lights out with Hornady factory 117-grain SST load. Box says 2945 fps. I got 3100 with my ProChrony.

That factory load may be the single worst shooting factory load I have ever fired in a center fire rifle. In fact I pulled the bullets and used the brass for reloads with out shooting them first. When the best a factory load does in a rifle is 3.5 inches it is pretty bad.

After lots of work -- mounts (ring screws) shifted enough to throw groups off. Leupold bases and rings now, and I have a good load. Also, that factory load shoots well. So, a sorta skim-bedded replacement stock for the original (broken), fall temps coming soon, it's all good. WW brass is crap, IMR 4831 and H4831SC good with 117-grain Hornady SST's. Hornady brass is better.

For years all I loaded in my Roberts's were 100gn bullets (Hornady SP, Ballistic Tip, Speer HP, Nosler Solid Base) but two years ago I tried some 115gn Ballistic Tips at 2800fps. They performed really well on pigs with very good penetration on going away shots. I load that bullet in my .257 AI now. My two standard Roberts rifles are currently loaded with 100gn Sciroccos and Nosler Solid Bases. When the Solid Bases are gone I'll go back to the 100gn Hornady SP in that rifle as I have 11 or 12 boxes stashed away.

What was your favorite powder when shooting the 100gr. bullets in your AI?
I have an AI that I haven't shot in at least 25 + years and a stash of 100gr Barnes X's bullets that I should get up and running again is why I ask..
Thx

I haven't loaded 100gn bullets in my .257 AI yet. I have loaded 110gn Accubonds and 115gn Ballistic Tips with 50gn H4831sc. I have two standard .257 Roberts rifles and load 100gn bullets in them with H4350 (46 - 47 grains). I thought I'd use the AI to try the heavier .25 bullets. My .250 Savage also shoots 100gn bullets so I didn't want four 25s all shooting the same weight bullet. If I was going to load 100s in my AI I'd try H4350, H4831sc and RE19, mainly because that's all we get out here. We don't have the huge range of powders available to us. Basically the ADI and Alliant lines, though Alliant can be hard to get at times as It only comes in every two years, so we usually stick to the locally made ADI stuff which is good powder. There's a rumour that Winchester Australia is stopping the import of the Winchester powders into Australia so there goes another line.

I had a better bob and sold it (kinda regret that) and it shot well w/ 115s & H4831.

I ended up w/ one powder for the better & standard Bobs; Ramshot Hunter is fantastic in both. For 100s in the standard Bob I run 46 GR in 2 and it shots beautifully with Interlocks or ballistic tips. I always use magnum primers.

well i got my 257 Roberts back that i had a Brux barrel 7 1/2 twist on my Remington 30 express with 100 or 115 Nosler B.T. using Reloader 17 this rifle shoots 1/2- 5/8 inch groups at 100 yards with my 1st loadings ever in this new barrel ,thats good enough for hunting for me.

I used to shoot the 120gr Partition at 2,800 with IMR 4831, but I bet many powders would work. Great bullet on game and an easy-to-shoot level of recoil, much like the 120-130gr stuff in the .260 and 6.5CM. Not much difference in the deer woods, and old school can still be cool.

120gr at 2900ish with H4831sc works in several for me. It’s a sweet spot considering trajectory, recoil, and terminal performance. Pretty much matches the ballistics of the Creed at the ranges I need.

[img]https://i.imgur.com/dFR3ohh.jpg?1[/img]

Hornady brass (3rd use)/ CCI 200 / 42 gr IMR 4831 / 117-gr Hornady I-B / COAL 2.905. 5 shots at 70 deg. F

Hunting bud uses RL16 & a 117 Interlock in a basic bob.

You are using the EXACT same bullet/powder/charge that I'm using in my Ruger 77 257 Roberts! I'm getting 3037 fps average out of the 22" factory barreled "1976" Ruger 77 tanger.

Forming R-P 7x57 Mauser brass using .257 Roberts die. Using primer pocket uniform tool and titanium trimmer to uniform length while I'm at it. (Dummy chambers just fine.)

Very nice, SC. Can you tell us the MV you were getting, an a little about the rifle? thanks

Nothing special as a rifle, except it's a favourite. I've been getting 3000fps with that load. Never not worked.

The late Bevan King in BC made and installed the bbl. 22" MR contour into a 700 long action in a TI take-off stock opened up to BDL.



Originally bedded into a walnut MR stock. This little buck looked around a corner with his mouth open and caught it in the back of his throat. DRT.

Thanks. Got a bunch of 100 Hornady’s. May try ‘em with IMR4831!

My Ruger 77RL Bob is shooting 110 ABs pushed by 43 grains of R16 into 3/4".

Have not put thru the chrony, but seems quite adequate and brass holding up well.
Did some loading bench interpolation to come up with that load. Not a lot of data on that.

Also interested in seeing what the de-coppering agent in R16 does for the bore.

Tim

Typical Loony, I swapped the Ti take off, BDL conversion for a Rem factory stock....

I know, I know, maybe not too smart. But, the factory stock has a lower comb and I can use low LW Talley rings. I painted it according to JPro's thread, didn't do as good a job as he does, think I applied too much webbing. Anyway, it doesn't shoot the 100 TTSX/H-100V load as well, but I did shoot sub inch 120 NPT over MRP. It's slower than the TTSX load, like around 2,800, but I do like Partitions.

The hollow butt stock sounded like a drum when thumped, so I left a rag in there to muffle that racket. Works pretty well.

I may sell the Ti take off stock.

DF

I own the following

(2) Kimber Select Classic - 257 Roberts
(1) Nosler Professional - 257 Roberts
(1) Winchester Custom built by Roger Ferrel
(1) Dakota model 97 - 257 Roberts Ack Imp

What I’ve found is that all of my rifles love a 115gr Nosler BT and H4350 powder. I also use a 110 AB if there is any chance that an elk might come into play.

Just hard to beat a 257 Bob!

I'd BDL the TI take-off. I did exactly that with my 257R and 22-250 faux TIs and like it better than any tupperware offering.

Just sayin'.

I wouldn't do that. A buddy of mine reloads commercially, particularly for rifles he's built for customers. One day I was complaining about accubonds blowing up. He asked .. 110 grain .25 caliber? Yep. He said that is the only Accubond that he has had any complaints about from his customers and there have been quite a few. I've set my 110 grain accubonds aside for coyotes. My .257 shoots 120 grain partitions for game. Honest truth is I would try the 115 grain ballistic tips before I'd use the 110 grain Accubond again, and possibly/maybe even the 100 grain ballistic tip. The results were that bad with the AB. Then again I have my expectations about what a bullet should do, others' mileage probably varies.

Tom

tagging this thread for good data.

[img]https://i.imgur.com/tGzNCOG.jpg?1[/img]

[img]https://i.imgur.com/RXJ2Wu6.jpg?1[/img]

The 100 gr. TTSX is the one bullet answer for big game for the 257 Rbts if your rifle shoots it accurately with respectable velocity

Prepping to load for a new "Bob" and I notice the Hornady 9th manual list Superformance as highest velocity with 100 gr. bullets 3200 fps. Anyone tried Superformance? That's treading on H-100V velocities

Hmmm... I bought a bottle o' Superperformance a while back, & it's just been languishing on the shelf. I'll have to give that a whirl.

And until I saw your post, I was actually thinking about trying some reduced loads for that rifle. I'll probably be working up loads with H4895 at the same time.

FC

FYI...The manual list 49.7 as max load in case you do not have the book

FYI...The manual list 49.7 as max load in case you do not have the book

Thanks. Hornady's 10th also shows 49.7 for the 100 grain Interlock. It's my understanding that the TTSX's I have on-hand have less bearing surface, so I oughta be OK at that powder level.

As always, though, I'll work up to it.

FC

FYI: The new Speer Manual, (Number 15), has some pretty extensive load data for the 257 Roberts. It's the +P data too, not the old lower pressure data.

Great thread with great info. I just prepped up 100 brass cases last night to get my wife's rifle shooting straight. It's a Ruger 77 MKii and I've had some trouble getting good groups from it. I"m determined to get it shooting however. Being here in CA I have to use non-lead, so I"ve got a box of 100 gr TTSX and another box of 90 GMX.

That 90 gr. GMX should be a "killer"... I bet 3200+ fps is possible

It'll be nice if the 90's shoot. Hats off to Hornady for posting the + P data in their reloading manual like Speer is doing.

I think it's possible that part of my problem with accuracy is that I've been sticking to the NON +P published data in the Barnes manual due to using Remington cases, which are NON + P. I've since prepped the Winchester +P cases for reloading, (not that it particularly matters in a Mkii), just to stick with the advice of the reloading manual. I"ll use the Rem cases loaded with lead bullets for my wife to practice shooting at lower pressure levels. I"ve got some Sierra match 100 grainers for her to practice with.

Also, I've taken the Ruger apart and torqued the stock in accordance to what I've read on this forum. The mag hinge plate does close a little easier since I've done this, so hopefully this will help.

When is stops raining here in California, (home of the fruits and nuts), I'll head to the range and do some testing.

I've been shooting IMR 4350 in a Ruger UL 20" 257 Roberts. The standard 46gr IMR 4350 with a Nosler 100 Partition. RP case, BR2 primer, 2.912 OAL, .002 off the lands. Average 3030fps at sea level 40 degrees using a ProChrono Digital chronograph. I'm no target shooter, but can do 1-1 1/4", 3 shots@ 100yards.

Recently changed over to H4350. Same bullet, case, primer and OAL.

3 shot Average fps, @ 35 degrees sea level. Same ProChrono Digital chronograph.

46.5 = 3060 average fps.
47.0 = 3105 average fps
47.5 = 3164 average fps
48.0 = 3171 average fps

Settled on 47.3 @ about 3135fps for the best accuracy that I could do. 5 shots into 1-1/8" @ 100.

Worked up from this data......