Threw this one out over on 24hourcampfire, thought I'd see what I get here:

I'm as accustomed to not getting "book" velocities as I am to not shooting "book" deer but this rifle's really got me scratching my head.

Rifle is a brand new Ruger 77 Mk. II in .280. Stainless/synthetic with a 22" barrel. Mounted a well proven Leupold Vari-X III 2.5-8x36. Even lapped the rings. (Returned *exactly* to zero after taking it off to add a Timney trigger.) I know the barrel's shorter than most or all of the test barrels but I figure it's still not accounting for the discrepancy; I should lose about 50 fps for the 2" shorter, I believe.

I've played with several non-premium bullets to try and find a good powder. According to various manuals and the writings of Rifle magazine's finest authors, RL-19 and H4831 (I confess that I used the "SC" variety) ought to be good. I also tried H4350 because I have a whole bunch of it on hand. All loads used new or once-fired Remington brass, sorted for neck thickness, and WLR primers, and all bullets were seated .030" from the lands.

Results so far:

145-gr. Speer SP/H4350. Good accuracy and consistent velocities at all charge levels. But velocity at 53 gr. (half a grain over the max load in the Speer manual) averaged 2762 fps. Speer lists 2950.

150-gr. Sierra MatchKing/H4831(SC). Poor accuracy aside, average velocity with 57.0 gr. (half a grain over Sierra's max load) is 2774 fps. Sierra lists 2900 at max load.

Figured I got good accuracy with the Speer and better velocities with H4831(SC) so I tried those together. Went two grains over their book's max load to get close to book velocity, 2826 fps with good accuracy. Book max load gave me 2746 fps. Though this isn't supposed to be a temperature-sensitive powder, I was shooting at 35 deg. F. Not sure I want to push it this far on my August pronghorn hunt.

Thought I'd try a heavier bullet, the 154-gr. Hornady Spire Point, again with H4831(SC). Got so-so accuracy-- and noticed that either at, or a grain over, Hornady's max load, I had leaky primer pockets. Since then I've not worried so much about this because I've noticed it with much lower loads and suspect the Winchester primers just seat a little loose, which I've noticed in other cartridges.

Scratched my head some more and studied the manuals some more. RL-19 gets high marks so I tried that. First I tried the 139-gr. Hornady Spire Point (since Mule Deer says nice things about it in the current Handloader). Hornady, Lyman and Alliant all say a max load of 57 -58 gr. should push, though not exceed, 3000 fps. I got 2854 fps with 58.0 gr. and accuracy was nothing to write home about at any charge level.

For comparison I tried the same bullet with H4831(SC). The maximum load of 58.0 gr. (Hornady and Lyman agree) was much more accurate than 56 or 57, one group at 1" and one at .44" Velocity was 2837 fps, actually close enough to chalk it up to barrel length. I would be pretty skeptical of reaching the 3100 fps Mule Deer reports with a 60 gr. charge, though his was in a custom rifle, probably tighter chambered.

Finally I tried RL-19 with the proven 145-gr. Speer. Accuracy was inconsistent and so was velocity. While a 56.0 gr. charge gave an ES of 7 for 3 shots, I got a 101 fps spread with a 57.0 gr. charge, and primers (I know, I know, but a clue is a clue) varied from utterly normal to pancake-flat.

If you've gotten this far, here are my questions:

1. Would you try a different powder? I think I've exhausted this part of the burn rate chart but I do have a bunch of RL-22.

2. What would be the first premium bullet you would try? I've been thinking of the 140-gr. Fail Safe, 140-gr. Barnes XLC, or 150-gr. Nosler Partition.

John

That's just the nature of the beast, every .280 I've had was hard to find an accurate full power load. I sold my last .280, and bought another .270, glad I did. H4831 with the 139gr Hornady was my favorite load though.

John,
I have always had good results with 140gr Nosler Ballistic Tips and IMR4350. This load will usually shoot around 1moa 5shot groups, in my Ruger M77 MKII.

Rem. 222

John,
I use the 150 grain partition with imr 4350. I started out at 52.5 grains and worked up from there it shoots good, but like you I can't seem to get the velocity the books say with any load I've tried.
My gun is a browning a-bolt stainless stalker, and even with the 139 grain light magnum loads I only get about 2900 fps, the box says 3100 .So I just decided to find a load that shoots good and not worry about the velocity.
JT

Try some 150-154 grain bullets (preferably Sierra 150's) with RL-25 from 54.4 grains to 58.5 grains and Remington 9-1/2 primers.

Insofar as velocity is concerned I have a similar gun in .358 Win. A Ruger 77. I think the issue is a slightly oversize chamber coupled with an undersized bore. Did a Cerro Safe cast and found the groove diameter at .3565".

Can't complain about the accuracy though as it digests anything for no more than 1.25" groups. 225 Nosler BT's have shot as small as .221"(3 shots).

I post this with some concern, but here it is anyway.

In my own rifles, I note that the current handbooks are useful only to find starting loads. There is evidently much more worry about being sued than in the past. I can understand that. Also, each rifle is a law unto itself.

Some of my rifles require several grains more powder to get the velocities that should be attainable in those cartridges. They do this with normal pressure as far as I can tell.

I start with the recommended starting charges and test for pressure, and velocity. If the extraction is easy and there are no obvious signs of too high pressure I increase the charges until I do find a stiff bolt lift. Then I reduce the load at least one grain. At that point I usually find that the rifle gives approximately max velocities normally associated with the cartridge. I do use the chronograph, and if I find that with the recommended loads that the velocity is significantly below "normal", and the pressure signs are OK then I increase the charge regardless of the handbooks.
I do not recomend anyone else do this, as I also don't want to be sued.

Handbooks of 20 or so years ago were much better as far as max loads are concerned.

I might add that I have had a few rifles than never quite reached the expected norms. I also had one M721 Rem .270 that would not show signs that I expected, and would blow primners with max handbook loads. I never was able to get the velocities I wanted and sold it.

I have a couple of pounds of old H 4831 that was made shortly after the original batch ran out, and it was marked "Newly Manufactured". I recently bought a pound of H4831 SC. The new powder needs from 1/2 to one grain more powder to reach the same velocities as the old powder at seemingly the same pressures.

Some will disagree with my method, but it works for me and has for about 45 years.

Start at handbook recommendations and work up carefully. I personally doubt that one could blow up a good factory rifle in the 280 category using slow powders such as H 4831 unless he used the bullets for a larger caliber. You should experience a sticking bolt far in advance of any catastrophic failure.

Jerry

Try the RE22. I have gotten some super results in a 7X57mm with it and 175-grain Nosler Partition bullets. You might also try Norma MRP.

John

I really don't see much of a problem. I think your estimate of velocity loss is way too low for a cartridge in the 280 class, for one thing. The Speer manual I have used a 24" barrel to get data. I doubt it is the same manual you have since the data doesn't match. Their max load with H4350 was 2760fps. They used a Ruger with a 24" barrel. In this class of cartridge, with a slow burning powder, I would expect at least 50fps/inch and maybe 75 fps/inch loss. That would be a difference of 100-150fps from a 24" to 22". There is always some difference in chambers, and there is actually a lot of difference in case volume from one case manufacturer to another. The other source of error can be the chronograph. My guess is theirs is more accurate than theirs, no insult intended. The data you have may be for 26" barrels. All things considered, I don't think there is an anomaly. I think your gun is shooting just as expected.

I have the Speer #12...

All of the charges you list are over max in Speer #12. Maybe you have a different volume.

Examples: Speer lists a MAX of 54.0 grains of RL19 for their 145 grain bullet, and it flew at 2849 fps from their 24" test barrel. Knock 50 fps off of that, and you should be seeing somewhere around 2800 fps.

Speer lists a max of 51.0 grains of H4350 with their 145's, and that gave a velocity of 2763 from their 24" test barrel. You would likely have seen around 2700 fps from the 22" tube. Bumping up to 53.0 grains would take you back up a little, which is what you noted (2762 fps with 53 grains of H4350).

I don't believe there is anything wrong with your rifle.

If you want to work with the 145 grain Speer bullet, try this:

Do OCW load development (see instructions for the method in the link at the bottom of this post) using IMR 4831 in these charge weights: 55.3, 55.8, 56.3, 56.8, and 57.3 grains. You'll find the OCW for IMR 4831 with the 145 grain bullet somewhere in that range.

I would ditch the WLR primers, and get some Remington 9 1/2's or some Federal 210's. CCI 200's are more consistent that the WLR's as well...

If you don't have the IMR 4831, you can go with the Hodgdon, just drop the first increment of 55.3, and tack on 57.8 to the end of the sequence if using the H4831.

Fire three shots at 53, 54, and 55 grains for pressure testing before you begin the round robin sequence with the 4831.

I think 4831 is going to do you a better job here than some of the faster powders will.

Your velocities are fine, as far as I can see. You just need to identify the optimal charge weight for the load.

The 4831 charge should get the 145 grain bullet to about 2925 fps, or there about. Excellent velocity...

If you're leaning toward another bullet and powder, post back and let us know.

Best of luck,

Dan

Switch to Federal primers

I use 58.5gr RL19 in my Browning with the BOSS so barrel length is really only about 20". I am getting 2900fps and always less than .75 groups for 5 shots with 140gr. BT's

I neck size only

I would recommend the RL22. With this you run out of case capacity usually before pressure gets too high, but it will give some of the higher velocities. I have shot this in a 280 rem. and a 280 Ackley and I regularly got 1/2" groups with 140 grain bullets.
You could also try different primers. I use CCI #200. I would stay away from mag. primers, because they can take away from accuracy in the 280.

Try the Re-19 with some 120's...............

John,
If that rifle came into my shop, the first thing I would do is measure it. Ruger make 7x57 as well as 280 and 7mmRM rifles and technically the bore and groove sizes are different. If they are building all the rifles on the same bore/groove size, some of them are not correct. If they do have different sizes, your 280 might have a 7x57 barrel chambered in 280.

It might be worth your while to check bore and groove diameter as well as the diameter of the case neck area of the chamber and the rate of twist. Until you have those numbers, and have established that they are correct, you are going to be throwing bullets downrange for nothing.

Gerard

I was surprised by your post. Is that statement based on European barrels? In the US, all 7mm barrels are .284 inches. To my knowledge all Rugers and all other guns of US manufacture are of this bore size if they are chambered for any 7mm cartridge, of which the .280 is one, irregardless of its designation. That is the only bore size available when purchasing barrels.

I have best results W/ IMR4831 & H4831 for 139-145gr. For 154-160gr, did better w/ RL22 & IMR 7828. One of the guys was right, you cane expect to loose 35-50fps / inch of bbl. So if you are seeing manula vel. from a 24"bbl. you could br looking @ loosing 150-200fps.
My .280 seems to run best right @ the max. loads for best accuracy.

[ 03-10-2003, 13:26: Message edited by: fredj338 ]

Gerald is technically correct about bore sizes, C.I.P. land/groove dimensions are :
Euro 7 mm : 6,98/7,24 (.275/.285)
U.S. .280 : 7,04/7,21 (.277/.284)
I think it's a moot point though, as my Sauer 202 in 7x64 shoots .284 Sierra and Hornady bullets quite accurately :

I think your problem may be an over-sized chamber. Are you full-length sizing your brass, or are you just neck-sizing? Measure your case at the case head and at the shoulder before and after you fire to see how much the case is expanding when fired. If the case has to expand very much to fill the chamber, then some of the energy that is supposed to be driving the bullet faster is being used to expand the case, so the bullet is slower than it's supposed to be. The pressure barrels used to find the loads in the manuals all have minimum spec chambers, if your rifles' chamber is close to max spec you need to use more powder to get the same velocities. Try to just neck-size cases fired in your chamber and seat the bullets out as far as possible as your magazine and barrel throat will allow. This will prevent the brass from being stretched any more, and by putting the bullet as close to the lands as you can you will minimize the mis-alignment caused by the over-sized chamber. Work up from the starting load again and see if you can get closer to the velocity in the manuals.

All this posting helps me understand why I dislike the 280 so much. In anything less than a 24" barrel life is tough.

In a 270 I can get 3,000 fps with a 150 gr bullets, but can't come close to it in a 280.

If you buy a barrel for a 7mm RM from Lothar Walther for a 7x57 or a 7mm RM, it will be the correct dimensions for the calibre as Andre gave above. Similarly, if you buy a Sako, CZ or Sauer 7mm, the bore will be the correct dimensions for the respective caliber. I may be wrong on this (I am sure someone will tell me if I am ) but I think Ruger is the only USA manufacturer currently offering a rifle in 7x57. I have enquired from them what dimensions they make them at, but had no reply.

CIP specs allow a tolerance on bore/groove sizes and it is +0.030mm on the sizes in Andre's post. The problem now is that no one, except the factory, probably measures the bore/groove of an ill shooting rifle. The only rifles I have ever measured that were under size, were two BSA rifles. One was a .243 at 0.018mm under and a 30-06 at 0.014 under on bore size. Groove dimensions were good on both. Both these rifles reached max speed, according to published load data, at 10% and 5% under start loads. I have learned not to assume that a new barrel is always on spec. We had a .224 barrel in the shop that was over on the bore and under on the groove size brand new. A 30-06 came in with a four groove barrel with the opposing lands and grooves alternatively over and under size. Niether would shoot a group.

I have measured many new rifles that were as much as 0.080mm oversize and they were usually dogs in accuracy and slow as well. The cause is probably bullet distortion as a jacketed lead bullet will expand radially under pressure to try and fill the bore. The harmonics of such a thing must also be pretty diabolical.

A practical example of how bullet / bore sizes affect accuracy is with Andre's 7x64. The .284 bullet only has to upset 0.030mm to go from 7.21 to 7.24 if the barrel is on spec. Remember that the spec is .285 for a 7x64 and .285 is .284 + 30 micron. Shooting a .284 bullet in an oversize 7x57 or 7x64 will exceed the 30 micron tolerance and will demonstrate why the tolerance is 30 micron and not 40, as accuracy starts deteriorating rapidly above 30 micron.

Matching the bullet to the bore for correct size will always improve accuracy and measuring the rifle will tell you whether you should continue experimenting with components, or give it up and fix the rifle first.

Now the custom 24" 270 I recently acquired ( built in 1948) does about the same as your 280 - at max charges of SC4831, RL19 and 4350 I could never get the velocity I expected and I would have loose primer pockets, after one firing, to show for it. A long time standard load with the 270 (in several manuals and a Jack O'Connor favorite) is 60 gr H4831 with 130 gr and velocity at suppose to be 3150 or so. Well in mine after 58 gr the pressures got unsettling and the velocity barely broke 3000. Then I try RL22 - a new powder to me - and by golly things got interesting. 57.5 gr with a 130 gr = 3160, 56 gr with 150 = 2900 and 55 gr with 160 NP = 2840 fps. All loads demonstrate clover leaf accuracy. Primer in all cases are WLR. Now I think my chamber is fine - post shot factory cases measure right where they should - so maybe the bore is a little tight - whatever - but RL22 did the trick and I shoot these loads in 90 degree Alabama heat - and also at 65 degrees - little velocity change. Good luck

I would try 160 grain Nosler Partitions and 56.5 grains of H4831SC.

lot's of great suggestions so far. curious though, is your ammo cold as you test it for velocity? try keeping the ammo warm until just prior to loading. that method should take the cold temps out of the equation. secondly; i think your hope of losing 50 fps for two inches of barrel is a little unrealistic in this case. 80-100 would be my guess. the Ruger's chamber might be a little sloppy (wouldn't be the first).

finally, if the velocity is that important to you, you may like to try some norma brass. of the calibers that i've had it in, it will be between 1.5 - 2.5 gr. lighter than most of the other brands. that means you can add more gas, the case just has that much extra capacity. none of these factors can do much by themselves, but when added together, they can account for your loss or potential gain in velocity.

gabe

BTW i'd try the partition first. or maybe better yet the Accubond or the Interbond.

gabe

I like RL22 in my .280. 60.0 gr -RL22, 140 gr Nosler Ballistic Tip, Rem brass, WLR primers give 3070 fps from my 24" Rem 700. Accuracy for 5 shot groups is .5moa when I do my part. This powder and bullet combination gave more consistent velocities and smaller groups than many of the other powders I tried (H450, H4831, RL19, H4350, H414, IMR4831) with less pressure.
Hope this helps you out.

You are to velocity oriented and should concentrate on accuracy and shot placement. There are many other powders you have not tried yet. Your rifle may be one of those one bullet weight and one powder only rifles. The Ruger rifle is not my favorite hunitng rifle for many reasons. Ruger rifles are noted for rough bores. If Gerard is correct and the bore is oversized you may as well get rid of that rifle and purchase another before it gets to close to your hunt. You could return the rifle to Ruger for inspection. A select few hunting rifles will never produce what you may have expected in the accuracy department. I would take a Savage over a Ruger any day of the week. In my view a 24" or 26" barrel is better suited for open country hunting. The 22" barrel is much better suited for heavy cover and shots are close with a fast handeling rifle. In some rifles a faster burning powder like IMR-4064 may produce better groups. neck sizing and adjusting seating depth of the bullet should improve accuracy. I like to start with the bullet just touching the lands and adjust seating depth from there. Most hunting rifles will give their best accuracy with the bullet seated up to .030 off the lands. I have owned two Ruger rifles and both were poor grouping copper fouling with lousy triggers and I soon parted with them.

John
If you have been shooting horns, sierras, and speer, I doubt a "premium" bullet is going to make your problems go away. I do not recommend this to anyone but when I get a new rifle, I kinda let it tell me what max is. Thru primer appearence, primer pocket, web measurements and such. And just as you find considerable variance between loads and yields among the several loading books, I have found considerable variance between their info and what I find. I am not suggesting their info is wrong and mine is right. If you have a chrony, that can be one of the best tools you can have to tell you what max is. As you increase the powder charge you will get an increase in velocity. When that yield starts to "flatten out", you are at a operating max with that powder for that rifle.
If the rifle under discussion here will not shoot a good (not best but good) group with 150gr Sierra/horn/speer bullets (you can try both boat tails and flat base, some rifles hate boat tails) and 4350 or 4831, I think I would use it for trade stock toward another rifle.