As some of you may recall, I've been trying to get this thing 'to shoot' for some time. It was a disappointment for the elk hunt last fall. In fairness, there have been "mitigating circumstances". Bad scope bases. Bad scope. Wierd stock problems. So, I decided to go back to zero and start over.
 
So I loaded up 20 rounds of 260 Accubonds. Five each with 46.06, 46.40, 47.00, and 47.35 grains of I3031.
 
Here are the results. I got "confused" when I first started shooting, so group 1 only has 3 shots, group 2 and 3 have 4 shots, and group 5 has 5 shots.
 
Here's the whole target:

 
Here are the groups for 46.40 (I know it says 47.4, but remember I said I got 'confused') and 47.0 grains.

 
Average velocity was 2324 f/s for the 46.4 grain charge, and 2350 f/s for the 47.0 grain charge.
Group size is 0.898" windage, and 0.643 elevation for the 46.4 grain group, and 0.973" windage, and 0.327" elevation for the 47.00.
 
Here is the 46.06 grain group:

 
Average velocity was 2310 f/s.
Group size is 1.065" windage, and 0.383" elevation.
 
Here is the 47.35 grain group:

 
Average velocity was 2365 f/s.
Group size is 1.798" windage, and 0.925" elevation.
 
I'm satisfied with these. I think I'll work around the 46.40 charge.
 
Oh yeah, don't get too excited about these groups, they were shot at 50 yds.
 
Paul

Nothing to scoff at Paul. If you recall, I have a .223 that shoots better groups "farther out". At 200 yards it might surprise you

Do you think you came up with the answer to your problem in the loose scope mounts etc?

RJ

Are you using 3031 because of available case size? I would think a slow burning powder might produce better groups? I say that because my 6.5-284 loved RL22 and H4831SSC. I might also try some Varget as it's not temperature sensitive and has a good mid range burn rate. Just my .02. Regards, Rick.

QuoteDo you think you came up with the answer to your problem in the loose scope mounts etc?

Actually, the 'scope and 'scope mounts were more frustrating than cause of poor precision. They just caused me to waste time and resources. The stock issue was a legitimate precision problem.

As far as synthetic stocks go, I like the Hogue stocks, a lot. However, they make two models. One has an internal aluminum frame, the other doesn't. The framed one costs ~$200 the unframed one about $100. I didn't realize how wimpy the unframed one was 'til I had bought the second one. (In my defense, the first one I used was on the .338 MAI, and that rifle shot well from the getgo. However, in retrospect, I recall that occassionally it would exhibit 'lapses' in its precision.) It's easy to use one finger and pull the foream tip at least half an inch off the barrel in the unframed version. Now when I shoot from a rest, the rifle sits on the rest at the action, and not in front of it.

QuoteAre you using 3031 because of available case size?

In large part, Rick. Run the numbers through QL and you'll see that I3031 is almost always the powder that gives the highest velocity for the lowest pressure in LOTS of cases. For this cartridge, 4831 - in all its forms - requires about 120% of case capacity to get 2000 ft-lbs to 300 yds, (a MV of 2350 f/s). RL-22 is off the chart. As for Varget's "temperature insensitivity"... I bought some for that very reason. I have not found actual practice to live up to the hype in this regard. In fact, I do not find Varget AS temperature insensitive as 4831 or H414, the two powders I have compared it to. I've looked all over for some combination of bullet weight, seating depth and powder to come up with the "best" load. So far, what you see above is the best I have been able to come up with.

This rifle has a 26" barrel. I am suspicious that "long" barrels are more difficult to get to shoot straight. It may be a matter of barrel timing or just amplification of movement. Whatever it is, I may cut this one back to 24, and maybe even 22. The reason I haven't so far is that I am trying to get the max MV to get that 2000 ft-lbs out to 300 yds. I may have to sacrifice that spec in order to get the best precision.

One final issue is the bullet. Those 260 Accubonds are very "pretty". They just look like killers. The 300 Accubonds and 300 Hornadys do too. HOWEVER, they're ALL boat-tails, and you guys know how I feel about boat-tails. The problem is, once you move into flat-based bullets you lose the BC that gets you the 2000 ft-lbs at 300 yds without having to crank up the MV to the point that recoil becomes unpleasant. I've got some SPeer 235 flat-based bullets, but they're ballistic 'pigs' - 0.301.

Running the pressure up to my personal max of 56,565 PSI, I can get that 235 bullet up to 2668 f/s at the muzzle. Even at that MV, the delivered energy at 300 is only 1816 ft-lbs, and the muzzle energy is 3711 ft-lbs.

In contrast, the 200 Accubond with its 0.473 BC can be going only 2350 at the muzzle, and still deliver 2000 ft-lbs to 300 yds with a muzzle energy of only 3194 ft-lbs. 500 ft-lbs is a big difference in perceived recoil.

The 300s - whether Accubond or Hornady - can deliver 2000 ft-lbs to 300 yds with a MV of 2217 f/s and a ME of only 3273 ft-lbs.

Now imaging cutting 2 to 4 inches off that barrel...

There is also a practical matter. These cases are necked up from holding a .284" bullet to holding a .375" bullet. As such, the neck walls are kinda thin. They don't grab the bullets very tightly. What that means, is that it is difficult to load charges that exceed 100% of case capacity because the powder pushes the bullet back out the neck. THAT means that getting precision seating depths is nigh on to impossible with charges that are much in excess of 100% of case capacity. This is not an insurmountable problem, just one that takes extra effort to mitigate.

Such is the nature of wildcats. To quote the Rolling Stones, "You can't always get what you want". Trying to get 2000 ft-lbs deliverd to 300 yds and keep ME below 3400 ft-lbs may simply not be possible in this case. Troof is, I'd settle for 1500 ft-lbs out to 300 yds. I wouldn't be happy exactly, but I wouldn't be unhappy either. It would still be an excellent cartridge in my opinon.
 

Paul

If I were trying to get 400 hp out'n the Mustang engine and had to settle for 389 because of "altitude" ??! I'd be as happy as a colt in clover. If I were trying ot get "2000 lbft of energy at 300 yards" and could only achieve 1816 lbft I don't think I'd be to upset either..

As for the stock issues? Does one of your girls need a new canoe paddle? Or maybe you should save it for one of  those times when you're up the creek in need of one. :grin: Brings to mind the stock that came on my newest .223. Light weight, flimsy, plastic, flimsy, pretty nice to look at but did I mention it's flimsy? The barrel channel/fore end is so flimsy that I've been contemplating filling it with bondo or fiberglass resin to add some stiffness and give it some heft. The H.S. Prescision stock that came on my 300RUM isn't all it's cracked up to be either, but it's better than the POS that came on the .223. The black/grey mottled spiderweb pattern makes it look accurate but at times I think I'd rather have a nice piece of walnut.

It's been a concern of mine that these newfangled plastic
"wonder-stocks" may not be as good  as first thought. (Not the carbon fiber/fiberglass/laminate ones) Seems like they'd tend to do what plastic does when it gets hot or cold. Get softer when it gets hot and get brittle when it gets cold. Now the Houges may not be that suseptible to cold as others bein's as how they're kinda rubbery, but it seems that if it were say 104* (like it can be on a good pdog hunting day here in NW CO, when you lean your rifle against the doorjamb or rear tire to cool and it gets HOTTER!!!) that they would tend to soften and flex that much easier. That is unless of course they had the internal aluminum frame.

As far as the case necks not "holding a bullet at over at over 100% case capacity"  here's a thought and mind you I'm just thinkin' outloud here but. Brass being the wierd freak of nature that it is could you "reverse anneal" the necks? You know, heat them up red hot and not quench them? I've done tha same thing with .270 brass in necking it up to .358 to build some 35 Whelen brass, almost the same as necking up from .284 to .375. I didn't anneal before or after and they seem to be holding a bullet at about 105 or so percent of case capacity.

Just throwing things out there. You've probably hit on all them but maybe not.

RJ

QuoteIf I were trying ot get "2000 lbft of energy at 300 yards" and could only achieve 1816 lbft I don't think I'd be to upset.

Well... I said I wouldn't be unhappy... :)
 
As for the stock, I tried to stiffen it by filling it with bedding epoxy. That helped, but surprisingily little actually. I think the only solution for the Hogues is the aluminum bedding block. I was liking these stocks as good temporary stocks to use while I worked the kinks out. Once everythig was 'settled', I would switch to the final walnut stock, and in the case of this rifle, open sights. Now, it appears that this stock is throwing a monkey wrench into the work-up sessions.
 
I have a milsurp M-48 stock that I sacrificed as a work-up stock for a rifle I made on an M-48 action. (.257 Robterts with bull bbl. It's a real sweetheart shooter.) This involves ruining the stock's historical originality as I have to cut off the bayonette fitting and hog out the barrel channel to handle the civilian barrels I use. That's why I was hoping the Hogues would work. Looks like it's probably going to be necessary to sacrifice a Turk '38 stock too. That's not heart-breaking, but I was just hoping the Hogues would work.
 
Spending the $200 on the aluminum bedded Hogue is out of the question. I'd just buy a wooden one for a lot less.
 
As for the "reverse" annealing... that's a thought. It may turn out that the 7.5x55 Swiss brass will give better 'grab' because it's being enlarged from .308" instead of .284".
 
Paul

As for the "reverse" annealing... that's a thought. It may turn out that the 7.5x55 Swiss brass will give better 'grab' because it's being enlarged from .308" instead of .284".
 
Paul[/SIZE][/QUOTE]

Or the 7.7-58 Japanese........think about it. I have some Hornady brass if you want to try...Might be a bit long but you could trim.  Regards, Rick.

Rick, Is the 7.5x58 the right size? Recall that the head on the .284 Win is about 0.501". Is the jap case that big?
 
Paul

Quote from: gitano;96085Rick, Is the 7.5x58 the right size? Recall that the head on the .284 Win is about 0.501". Is the jap case that big?
 
Paul

It's a 7.7-58. I'm pretty sure they are the same as many folks make brass out of 30-'06 cartridges. The rim of the 284 is .4728 and the rim on the 7.5-58 is identical....I just measured it. Regards, Rick.

That's what I thought, and it won't work. The spiffy thing about the .284 Win case is that it has the .473" rim with a 0.501 head. "Standard" .308/.30-06/X57 cases don't have the head diameter, and you can't really blow the web out to the larger diametere
 
Thanks.
 
Paul

Quote from: gitano;96117That's what I thought, and it won't work. The spiffy thing about the .284 Win case is that it has the .473" rim with a 0.501 head. "Standard" .308/.30-06/X57 cases don't have the head diameter, and you can't really blow the web out to the larger diametere
 
Thanks.
 
Paul

Oh well, a good try. I forgot about that 284 Win having a large head. Regards, Rick.

Hmmm.... some rifles just don't want to follow the rules.

One of my thoughts is that maybe the rifle just doesn't like that 260gn Accubond. If everything else, scope bases mounts and bedding are OK then I would be inclined to try a much lighter projectile, such as Speers 235gn. Not to use it necessarily, but to see if your rifle "likes" it. If it shoot well then working around that projectile weight could be an option.

Quote from: 22hornet;96151Hmmm.... some rifles just don't want to follow the rules.

One of my thoughts is that maybe the rifle just doesn't like that 260gn Accubond. If everything else, scope bases mounts and bedding are OK then I would be inclined to try a much lighter projectile, such as Speers 235gn. Not to use it necessarily, but to see if your rifle "likes" it. If it shoot well then working around that projectile weight could be an option.

My experience with Accubonds is that they are the most accurate bullet I've ever fired in a variety of rifles and calibers. But, you're right.....some rifles don't want to follow the rules. That said, remember Paul's E criteria.......not sure the lighter bullet would produce the energy he's looking for. Regards, Rick.

You're both right on track, and I'm doing two things:
 
1) Looking at other bullets, and
2) Coming to the conclusion that I might not be able to realize the 2000 ft-lbs at 300 yds in this cartridge.
 
I haven't quite given up on #2, but I'm moving in that direction. As to # 1, the next bullet on the docket is the 235 Speer. I have had them from the beginning, because they are inexpensive, and I thought I might use them for testing. Hornady makes a 225 Spitzer. Its BC is .320, compared to the 235's .312. I'm going to 'run some numbers' through QUickLoad and compare them at 300. I'll let you know what the results are.
 
Paul

Here's the 235 Speer's trajectory:
 

 
And here's the 225 Hornay's:
 

 
Note the difference in muzzle energies. In order to get the 235 up to the 225's numbers, I had to increase ME from 3556 to 3637. THat would be detectable at the shoulder.
 
Anyway, in the case of these two, it would simply be a matter of which shot the straightest. Isn't it always...
 
Paul