Range Report on .375 x .284 Win

Started by gitano, October 15, 2008, 11:03:09 PM

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gitano

Finally got the gun to a field-ready condition and got to the range. AS I said before, the rifle isn't finished yet, needing bluing and a wooden stock, but it is ready for hunting. SO... I needed to get it sighted in and find a good, precise load. One outta two ain't bad for a start I guess...
 
After considerable work with QuickLoad I settled on a powder - AA 2495, a bullet - the Accubond 260, Optimal Barrel Timing theory node - 5, and calculated a range of charges - from -1% down from node charge to -3% down from node charge. That range turned out to be from 49.50 grains to 48.50 grains. Divided into 5 increments of 0.25 grains each, I loaded four rounds each of five loads. I also loaded 6 rounds with the Speer 235-grain round-nosed, flat-based bullet for getting 'on paper'.
 
Getting on paper was quick and easy and the 235s shot well at 25 yds. After 3 shots, I moved the target to 100 yds. I shot the bullets "round robin" in order to minimize any effects fue to shot string order. In other words, I shot one bullet from each of the five loads; waited for the barrel to cool off; shot the next set of five shots of one each from each charge group.
 
The temperature when I arrived at the range was 34F (1C) and when I left it was 35F(2C). there was a steady wind from the 9 o'clock position of about 10 mph.
 
Shooting the rifle was a real pleasure. Even from a bench on a cold day, it wasn't unpleasant. Mush better than my .3338 WM, even though the ME for the .375 was a bit more than it is for my .338 WM loads. The .375's extra weight makes all the difference.
 
As you can see, it ain't great. I really don't know why. The simple points to consider are that the barrel was brand new and these were the first 26 shots out of it. Of course there's the obvious one, being the "nut behind the butt". Possible, but later shots would render that expalanation unlikely. Operator error (again me) in the manufacture of the finished rifle - probably the most likely cause. Could also be that the gun doesn't "like" the 260 Accubond - it is after all, a boat-tail. Could be the charges were wrong. I simply don't know, but I wasn't exactly 'proud' of the groups. There is one subtlety that renders the results not quite so bad though.
 
If you examine the group in the upper left (the 48.50-grain group), and the group at center bottom (the 49.5-grain group), three of four of the shots are at least "OK". What's important, is that the outlier in both was the first shot from a cold barrel - on a cold day.
 
Removing the outlier (first shot) from the 48.50-grain group (the lowest (-3%) charge), renders a 3-shot groups with dimensions of 0.804" x 1.300". That's not "bad".
 
Removing the outlier (first shot) from the 49.50 grain group (the highest (-1%) charge), renders a 3-shot groups with dimensions of 1.745" x 1.530". That's not great, but it is 'tolerable' for the time being.
 
None of the remaining three groups have outliers whose removal (with justification of being the first shot from a cold barrel), makes any real difference in groups size.
 
The little verticel 3-shot group at about 4:30 o'clock, is a 0.500" x 1.200" group from the MAI.
 
From lowest to highest, the average MVs for each four-shot charge were: 2417, 2429, 2440, 2452, and 2463 f/s. Even though the best 3-shot group's MV is the lowest (2417 f/s), it still delivers 2020 ft-lbs to 300 yds. Therefore, I will "work" with that charge and see if I can't tune it a bit and make sure it can consistently deliver about 1 MOA.
 
I'll have some more thorough statistics for each group sometime tomorrow.
 
Oh yeah, the target says that the range of charges goes from 45.5 to 49.5. That's wrong. WHat I stated above - 48.5 to 49.5 - is the correct charge range.
 
Paul
Be nicer than necessary.

22hornet

It might not be great but its a start.
 
Thats what I like about load development, trying different things untill it all comes together.
 
Any other projectile choices in the works?
"Belief:" faith in something taught, as opposed to "knowledge:" which is awareness borne of experience.

subsonic

Was the brass fire-formed for these loads?
 
That could be part of it.... although if I had "made that" as you had, I'd still be proud!
 
It's accurate enough to "make things die", and that's what it's all about!

gitano

#3
Any other projectile choices in the works?
I was pretty 'sold' on the 260, because of it's great BC - .473.
 
Nosler is supposed to have a 300-grain Accubond out, but nobody has it on their shelves yet. That is my second choice. After that, it's any and all comers. The six 235-grain Speers looked like they might be shooting straight, but I only shot 3 at 25 and 3 at 100. The results are far from 'conclusive'.
 
I'd kinda like a light-for-caliber bullet like the 235, but it's both a round-nose and a flat-base. As such it's BC - .248 (IIRC) - makes it difficult to achieve my terminal performance goal of 2000 ft-lbs to 300 yds. The poorer the BC, the higher the MV has to be to deliver energy 'out there'. Then of course, the higher the MV, the greater the recoil.
 
Was the brass fire-formed for these loads?
The brasss was already fire-formed before these cases were loaded.
 
It's accurate enough to "make things die", and that's what it's all about!
That's true. However, my attitude toward 'custom guns' is that they should always perform AT LEAST as good as "factory-made" arms. The maker - in this case, me - has all the time they need to 'get it right'... Time a commercial manufacturer cannot afford. Personally, I'd return a new "factory-made" arm that couldn't shoot any better than this. Also, you may have noticed that I can be a bit of a 'hard task-master' with folks that "make things" commercially. You'll have to take my word for it when I say I hold myself to even higher standards.
 
although if I had "made that" as you had, I'd still be proud!
I appreciate the complement, truly.
 
Paul
Be nicer than necessary.

Nelsdou

Wow, that looks just like the results of my 9.3x57 that doesn't seem to jive with any OBT prediction either.

Paul you mentioned to me in the past about adjusting the QL weighting factor from .5 to .7 for large bore to case diameter.  Would that be the case for the .375x284 as well?

H'mmmm I wouldn't think a new bore would make that much influence unless it was extremely rough.  Assuming bullet runout is ok, I think I try a different primer or a different powder (maybe IMR3031) as a simple change and check results.  My thinking is obtaining a quicker pressure rise on ignition than 2495 might get that BT launched more squarely into the lands.  Dunno if it would change barrel residence time enough to affect nodes.  Another quick change might be just to crimp some of your present loads and see what happens.

Good luck and post more pics.

Nels

Put it into perspective; we live on a rock hurtling through space, what could be scarier than that?

gitano

As you might imagine, I've been chewing on this all day Nels, and I have come to some of the same conclusions as you. One was the weighting factor you mentioned. I forgot all about that when I was doing the QL work-up.
 
I agree that a "new" bore shouldn't cause this much variation.
 
I'm thinking about a different powder too, but I'm shy of I3031 because of the likely temperature differential between here and Colorado and what I've read about its temperature sensitivity. I'm gonna try X4064 first. If it doesn't help, I'll go to I3031. Load density is better with I3031.
 
I hadn't thought about crimping.
 
I think one good candidate for cause is seating depth. I have always had great luck seating bullets with cannelures, to the cannelure. The 260 Accubond has a cannelure, so I decided that was as good a place as any for a 'start'. In retrospect, maybe it wasn't. The cannleure seating depth probably works great for the .375 H&H, but there's no reason to believe it would work for a .375 wildcat. More importantly, seating to the cannelure, puts the bullet about .200" back of the lands. I think that could be a real problem. In the 8mm SLT, the 220 Sierra is just off the lands about 0.010".
 
Speaking of the 8mm 220, it is a very heavy/long bullet for the 8mm caliber, yet it is shooting great. I'm thinking the .375x.284 Win might "like" a long/heavy bullet too - like a 300. That would automatically put it closer to the lands, (mitigating that issue), even if the seating depth was kept the same. Trouble is, I don't think I can get any 300s before I head to Colorado.
 
Finally, I am thinking teh 26" bbl may be a factor. I'm considering cutting it back to at least 24", and maybe even as short as 22". I'm also considering "choking" it. More about that later.
 
I'm gonna call RSI tomorrow and ask about the "weighting factor" for the .375x.284 Win. I gotta think it's greater than 0.53.
 
What would you like to see pictures of?
 
Paul
Be nicer than necessary.

sakorick

Hello Paul. Were it me I would......

1. Switch to a slower burning powder....slower than 3031.
2. Get that bullet seated 0.020 off the lands and...
3. Consider a slower burning powder. Don't know what X4064 is but IMR 4064 would be my #1 choice

The new barrel effects accuracy to the tune of about zero.
0.200 off the lands is very Weatherbyish and could be part of the problem. I don't think the bullet is the problem.

Finally, your shooting sequence puzzles me.:undecided:  Why not simplify things at first and just shoot 3 shot groups using consistant loads then move on? Good luck and keep us posted as this is bound to get interesting! Regards, Rick.
Talk to yourself. There are times you need expert advice.

gitano

#7
I already responded to you once Rick, but in one of those "vanished into the vapor" incidents, it 'went away'.
 
So.. Do you really think I need to go to a slower powder? I just wanted to make sure since you mentioned twice. ;)
 
I agree that a new barrel shouldn't cause this kind of variability.
 
I think the 0.200" off the lands is the big culprit. I'm changing that. Plus, simply going to the 300-grainer while keeping seating depth the same will push me closer to the lands.
 
X4064 is Accurate Arms 4064. I'm just too lazy to type Accurate Arms, or even AA.
 
I'm thinking real seriously about shortening the barrel - at least to 23" and maybe to 22.
 
QuoteFinally, your shooting sequence puzzles me.:undecided: Why not simplify things at first and just shoot 3 shot groups using consistant loads then move on?

The sequence is necessary to eliminate any bias induced by "order of firing" between groups. For example: Let's say I shot all the 48.50-grain load first, then the 48.75, then the 49.00, etc. By the time I got to the 49.50 load, the barrel would have a different fouling in it (after 22 rounds) than it did for the 48.50-grain load (after only 6 'get-on-the-paper' shots). By shooting 'round robin', each group gets the same fouling 'treatment'.
 
One might argue that the fouling from those first 16 rounds shouldn't matter. That may well be true - especially for a caliber as large as .375". However, by shooting 'round robin', the possibility of influence of shot-order is completely eliminated.
 
It's really not a big deal operationally. I just set out the 5-shot batch (one of each load). Shoot the first 5-shot batch. Wait for the barrel to cool from that 5-shot batch. (Not too long with the ambient at 35F by the way.) Shoot the next 5-shot batch of one-each of each load, and repeat. In order to minimize the effect of shot order within a 5-shot batch, the second batch starts with the second charge, in this case the 48.75-grain charge. In this way, the 48.50-grain charge wouldn't always be the first one out of a cold barrel - each charge gets one bullet fired that is the first bullet out of a cold barrel.
 
In the alternative, one would shoot a 4-shot group consisting of all one charge as you suggest. Wait for the barrel to cool, and shoot the next 4-shot charge group. This approach eliminates the possibility of having one charge get all of the "first-shot-from-a-cold-barrel" shots, but the 'round robin', done correctly, eliminates both between and within group variability. You have to 'pay attention' a little bit more with the 'round robin' approach, but it's not really a big deal.
 
Paul
Be nicer than necessary.

sakorick

Hello Paul and anyone else interested in my gibber. I see your logic and it makes sense, However, David Tubb is the perennial 1000 yard world champion and he doesn't do anything to his barrel for 300 rounds! Of course he shoots special indexed bullets. I normally shoot at least 50 rounds thru my hunting rifles and haven't noticed any copper build up upwards of 100 rounds. I have also noticed across the board, my rifles don't start shooting the real tight groups until I've shot about 15 to 20 rounds. I normally shoot old obsolete loads to get rid of it before I get serious. This isn't based on any scientific data, just my personal experience.....and I shoot allot since my range is in the "backyard".

I have had 2 "problem" barrels one a Mod 98 Mauser(new barrel) and the other a new Tikka that kept having copper fouling after 10 rounds. The David Tubb final finish system took care of those problems fast.....sure saved allot of wasted ammo!

I am currently running an experiment on Eric's '06 Ackley and haven't cleaned it for 70 rounds....it just keeps shooting lights out so I may shoot about 20 more rounds and clean it. I'll report on copper fouling once the experiment is over. Of course if the groups start to grow I'll stop and clean it immediately.

I was trained by dad to clean after every shooting session....that based on his and my military upbringing. That was a "rule" that has just faded away. David Tubb leaves his rifles alone and so do I. For anyone interested here is Superior Shooting Systems number and they have the best techies around. 806-323-9488.

I kind of got off track but I just had to opine. I think your round robin method has merit but may not be worth the trouble. I would not take anything off the barrel til trying the 4064 then 4350.....and if the groups get better....RL22!!!!

I wait your results with, as Shakespere would say, "bated breath":biggthumpup: Regards, Rick.
Talk to yourself. There are times you need expert advice.

Steve D

I know this is off of the subject, but it brings up a question I have.  If I'm shooting factory ammunition in a factory rifle, and I'm not getting any decent groups, how can I tell if the throat is too long?  I have a 243 and a 280 that both seem to be all over the place.  I'm shooting relatively heavy bullets in both.  (100 gr in 243, 150 gr in 280).  It makes me want to get closer and use a shootsgun.:Banghead:
You\'re just jealous because the voices only talk to me.  :yes:

gitano

I tend to agree with your comments Rick. I was/am just clutching at straws at the moment. I think I'm going to do a "Tubbs exercise" on the .375 bbl. I've got all the stuff I need.
 
As it turns out, I got my order from Grafs today, so I have the 'scope for the 8mm, and I got some Hornady 300 BTSPs for the .375. I D&T'd the 8mm receiver, and have the new 'scope mounted. I'm going to load some the 300s for the .375 tonight, as well as some more of the 8mm 220s, and hit the range again tomorrow.
 
With the 'scope on the 8mm, I had to change the bolt. The good news is that the .338 MAI bolt works fine in the 8mm SLT. The only 'hangup' will be that the 8mm and the .338 can't go into the field simultaneously while in Colorado. Of course I can't hunt with two guns at once, but HB was going to use one, while I was using the other. So, we'll see how things go at the range tomorrow with a different bolt. The 'new' bolt may throw things completely off. If so, the 8mm prolly won't go to Colorado.
 
"More at 11"
 
Paul
Be nicer than necessary.

gitano

Quotehow can I tell if the throat is too long?

Measure it. ;)
 
The simplest way to get it done is buy a Hornady (formerly Stoney Point) bullet comparator.
 
The second simplest way is to drop your bullet (not cartridge) into the chamber with the muzzle down. Then run a dowel (it'll have to be a quarter-inch or smaller one for the .243) up the barrel 'til it JUST touches the bullet tip. Mark the dowel - precisely. Then, on an empty chamber, close the bolt and run the dowel wup the barrel again and mark it again. The distance between the marks is the absolute MAX length for your rifle with THAT bullet.
 
If your factory ammo is more than about 0.050" off the lands, it MIGHT explain your erratic groups.
 
Paul
Be nicer than necessary.

Nelsdou

Interesting observation on the amount of "jump" from the bullet to the lands.

My 9.3 has a humugous amount of freebore to get to the lands so I decided to measure several bullets to see the differences.

Speer 270 .40"
Privi 285   .41"
Mt Baldy 270 cast lead  .40"
Paper-patched 358 cast lead .35"

All measurements based on seating the respective bullet to the base of the case neck.  

The Privi bullet is the longest but it actually measures .365" in diameter as opposed to the Speer at .366". What's interesting about the PP bullet is that the paper fills the freebore space such that I have to push it in a bit hit the lands. Some of the PP loads have been more accurate than the jacketed but I'd been considering that a fluke.  Now I'm not so sure. Maybe the paper is keeping the bullet centered true into the lands during launch.

Well I'm anxious to see how those 300 Hornadys do in the .375x284 and if reducing the distance to the lands does the trick.

Nels
Put it into perspective; we live on a rock hurtling through space, what could be scarier than that?

sakorick

Quote from: Steve D;84444I know this is off of the subject, but it brings up a question I have. If I'm shooting factory ammunition in a factory rifle, and I'm not getting any decent groups, how can I tell if the throat is too long? I have a 243 and a 280 that both seem to be all over the place. I'm shooting relatively heavy bullets in both. (100 gr in 243, 150 gr in 280). It makes me want to get closer and use a shootsgun.:Banghead:

Hello Steve. Since you don't reload you are pretty much stuck with matching the correct weight bullet to the rifle....it is not a freebore problem.  A good rule of thumb is that the heavier and longer a bullet is, the faster the rifling twist rate needs to be to stabilize it in flight, therefore a lighter shorter bullet needs a slower rifling twist rate to give proper bullet spin for correct flight. The 100 grainer in your 243 is "heavy for caliber and would require a faster rate of twist to stabalize. The 280 150 grainer is middle of the road so you may want to consult with the manufactures of both to find out what twist rate you have. Good luck and regards, Rick.
Talk to yourself. There are times you need expert advice.

Steve D

Paul, thanks.  I guess properly worded my question would be how to measure it.  :smiley: That sounds like a neat trick and I will do that as soon as possible.  I've got some of my guns stored out of my apartment right now (had some exitement a while back and I was afraid someone would break in and steal them; good news, didn't happen and things have calmed down).  I've already started bringing some back.
 
Rick, I do reload, but am not set up for it yet in my apartment.  I have a Lee hand press and could use that, but it's a sloooooow process that way.  :sleeping:   I really want to shoot at least middle if not heavy for caliber as I want to hunt deer with the 243 and larger with the 280.  But, I will try lighter bullets in the meantime.  There has been a lot of controversy about Barnes bullets and their light for caliber.  Even so, if I need lighter bullets I may have to try some in the 243.  I was shooting old (really discounted) 100 gr winchesters.  I have some 90 gr Partitions loaded, but I was unwilling to shoot up expensive bullets until I felt the gun was up to it.  Maybe I should try the more expensive bullets now and see if there is an improvement.  
 
I hope you get that 375 shooting like I know you want it to shoot.
You\'re just jealous because the voices only talk to me.  :yes:

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