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Author
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Topic: Need opinions on accuracy velocity point
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Frank
CAN START A FIRE WITH A BUCK KNIFE AND A ROCK
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posted March 25, 2014 05:50 AM
Here's a graph depicting load data developed so far. Still have more to go as can be seen by the "0.0" in the Velocity column. Maybe the remaining rounds will be shot this weekend? This is a REM 700 in 7mmSTW with a light weight barrel. I'm thinking the oscillations in group size(bottom graph) are because of the light 26" barrel. The green trace is for 5 shot groups, red is showing one flyer removed for four shots, and blue is for best 3 shot group size out of the 5 shot groups. This eliminates flyers that happened for whatever reason. The top graph shows the velocity increase per 0.5gr increment. The data which generated the traces is shown in the spreadsheet. The goal is as 120gr Nosler V-Max bullet going somewhere around 3700 (maybe higher). Can this be achieved given the data already shown? Where do you think the accuracy point is going to be on the velocity scale?
This is a first loading of virgin brass (Hornady select) so nothing is optimized yet.
Just as a point of reference, The rifle shot a factory Hornady 140gr Partition at 3593 with a 2.5" group size........all rounds were cronographed.
[ March 25, 2014, 02:08 PM: Message edited by: Frank ]
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Leonard
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posted March 25, 2014 08:32 AM
Frank, I think you need to explain your data, a bit more?
Another thing, you need to define your question a little more precisely.
And, while we are at it, what's your mission?
Good hunting. El Bee
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Fur_n_Dirt
So. Ariz. Zone Tech. Expert
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posted March 25, 2014 04:07 PM
So the velocity column is the average of five shots?
The best 3rd, 4th, etc.. Is taking the closest ctc group of 3 , 4, etc shots?
So, 83 or 84.5 provides the smallest groups, eh? Sorry, but your gun doesn't like this load combo for high velocity
[ March 25, 2014, 05:05 PM: Message edited by: Fur_n_Dirt ]
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Leonard
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posted March 25, 2014 04:42 PM
Yeah, what I get out of it, thus far, you should be trying maybe R22, possibly R25, or using a more suitable bullet, i.e.: heavier.
But, we don't know what you are trying to accomplish? Based on the 120 grain bullet, I assume long range work is out of the question. But, if that's the case, why have you not identified the barrel twist?
I don't know why you want to throw out fliers? That's data. Negative data deserves consideration. Instead, consider shooting only 3 shot groups until things start to take shape. It will save barrel life and with a cartridge like you have, you can't afford too much load development.
That's why you should seek every source on the web for suitable powders and bullets before you begin. Looks like you have already burned 100 rounds of guilt edge accuracy. Somebody out there has done the legwork for you, find it and drastically shorten the learning curve.
Good hunting. El Bee
PS Nice graphs.
Good hunting. LB
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Frank
CAN START A FIRE WITH A BUCK KNIFE AND A ROCK
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posted March 25, 2014 04:44 PM
Well, I spruced up the description of what is going on a little better. Maybe that will help.
I'm suspecting accuracy like I want (say sub .5") isn't achievable given what I'm seeing in the trace on group size (bottom graph). From the look of it accuracy is trending worse and I only have a little more to go before reaching max with this powder (Ramshot Magnum).
Given all the high and low points in the accuracy trace I'd say the barrel is pretty whippy....just a few grains of powder one way or another leads to a big opening up of group size.....and the accuracy points aren't occurring where I want them to occur....at the higher velocities.
I'm going to try H4831 next and see what happens. But I have a sneaky suspicion I may need a heavier barrel.
As for throwing out flyers, that's because this is new brass. I don't really trust new brass to be consistant. That, and I knew a few were my fault. The stock trigger was "really bad" so I installed a 40X trigger about 1/2 way thru the load work. That's two days worth of shooting in the chart above.
The barrel just may like a heavier bullet, that's why I'm beginning to think a heavier barrel may bring an accuracy node into the range where I can get the lighter bullet to shoot.
OH, goal is to poleaxe bigger varmints at long range with speeds that'll frange the bullet......all 120grs of it ![[Smile]](smile.gif)
[ March 25, 2014, 04:51 PM: Message edited by: Frank ]
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DAA
Utah/Promoted WESTERN REGIONAL Hunt Director
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posted March 25, 2014 04:49 PM
quote:
The green trace is for 5 shot groups, red is showing one flyer removed for four shots, and blue is for best 3 shot group size out of the 5 shot groups. This eliminates flyers that happened for whatever reason.
I've heard plenty of good reasons for using 3 shot groups. And this rifle would seem a good candidate.
But, best three out of five? Holy fuck! That's a new one!
I don't believe in flyers, though.
I mean, even if you do believe in "flyers", 40%? Really? To me a flyer that you aren't going to count should be called instantly, at the shot, and discarded. Not waiting to see whether it happened to clump together with any two of the others (the other flyers?), better than any other combination.
Your blue line is showing exactly what it is showing - what taking the best 3 out of 5 gives you. Compared to the real accuracy. Given you get to cherry pick the best 60% and throw away a whopping 40%, it's not surprising how much better it is.
But I can't figure out what possible use that information could be? Especially in trying to objectively evaluate load performance?
It strikes me as possibly the most shit house crazy manipulation of load dev data I've ever seen?
- DAA
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"Oh yeah, they're gonna talk to you, and talk to you, and talk to you about individual freedom, but they see a free individual, it's gonna scare 'em." -- George Hanson, Easy Rider, 1969.
Rocky Mountain Varmint Hunter
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Fur_n_Dirt
So. Ariz. Zone Tech. Expert
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posted March 25, 2014 04:57 PM
Ok, so he's a little optimistic..
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Frank
CAN START A FIRE WITH A BUCK KNIFE AND A ROCK
Member # 6
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posted March 25, 2014 05:06 PM
Appreciate that response, DAA. Still, if you look at the data all the traces are a close approximation of the other...just group size is smaller when throwing out the flyers. All I'm really looking for at this point is a trend. That and the 5 shot groups are listed so in a sense I didn't throw out the data.....just smoothed it out a little.
Now that I have a better trigger, the three shot group seems to be a better option....can't argue with that!
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"Truth is no prostitute, that throws herself away upon those who do not desire her; she is rather so coy a beauty that he who sacrifices everything to her cannot even then be sure of her favor".
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TOM64
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posted March 25, 2014 05:25 PM
Being that I love pencil barrels, I assume yours is free floated? If so try stacking a few business cards between the barrel and stock. I've had 4 Remington Mountain rifles that shot better with the barrel bedded.
But cherry picking groups will lead you false hope. Taking the "flyers" into account is the only way to find the sweet spot. And you never know where the next accuracy node will be.
That said I just kiss the lands and work up to pressure and move on.
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Az-Hunter
Hi, I'm Vic WELCOME TO THE U.S. Free baloney sandwiches here
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posted March 25, 2014 05:36 PM
Frank; from what Ive seen, is a technical type of guy. Some gunnies love that kind of stuff ie: graphs,data,BC tables,load development etc. For some guys, that's as fun for them, as the shooting part is for me.
Back in the late 80s I had a semi custom 7STW, typical for the period, long 26" barrel, muzzle brake, good barrel,trigger, all the good stuff. I went straight to the 7STW god himself, Layne Simpson, via his various gun rag articles on the cartridge. He had his cherry picks and they were good then, just as I suppose they are now, 79 grains of RL22 and a Nosler 140 BT , shot like a champ in mine.
Sometimes just a bit of reading, can eliminate a lot of headache,wasted bullets and burnt powder. Although, I do understand, that for some guys, that's the fun part, and I don't want to knock that.
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DAA
Utah/Promoted WESTERN REGIONAL Hunt Director
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posted March 25, 2014 05:46 PM
Along the lines of what Tom just said, if I see I'm just not even in the ballpark of where I expected or wanted to be, in terms of accuracy, I halt load development and go into rifle troubleshooting mode.
I'm not sure where this one falls along those lines, but I like Tom's idea as a quick check.
Frank, I think you'd be better served with two, 3 shot groups per, and count everything - ESPECIALLY the lousy two-and-ones you'll see. They really are telling you something, fairly important. And the average of multiple 3 shot groups (counting every shot) is more relevant data than what you have going above.
I'm always FAR more interested in what the worst groups a rifle shoots are than the best ones. In fact, I tend to look at the best groups as being the "flyers". They are the outliers, the ones that aren't repeatable. The "flukes". So, I tend to not pay them much attention.
The groups on the worse end though, they seem to be quite repeatable ![[Big Grin]](biggrin.gif) . Not what we really want to see maybe, but it's the truth we need to embrace.
- DAA
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"Oh yeah, they're gonna talk to you, and talk to you, and talk to you about individual freedom, but they see a free individual, it's gonna scare 'em." -- George Hanson, Easy Rider, 1969.
Rocky Mountain Varmint Hunter
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Leonard
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posted March 25, 2014 06:04 PM
But, then we can't pick his brain? And, you could be right, Vic? He wants to do it his way.
At least we know he wants to blow the shit out of "varmints" whatever "long range" is, in his mind? As far as I am concerned, the limiting factor at the present time is his accuracy. Which we don't know a hell of a lot, because of the way he is randomly tossing "fliers".
Frank, you can't just decide to keep the three bullets that are closest together, if you are honest with yourself. I think everybody agrees with that assessment.
But, I think the membership here can help you, and guide you in the right direction. These guys know what the hell they are talking about; you can be sure of that. And, the price is right.
Good hunting. El Bee
edit: the definition of what Dave is talking about is called; an aggregate. Aggregates are what wins all the trophies in bench rest.
[ March 25, 2014, 06:10 PM: Message edited by: Leonard ]
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Frank
CAN START A FIRE WITH A BUCK KNIFE AND A ROCK
Member # 6
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posted March 25, 2014 07:38 PM
Allot of good info here in all the posts, thanks.
The pencil barrel is free floated. I suspect Tom may be right in that bedding the barrel full length may increase accuracy. The stock is synthetic so there may be some potential in going that route. Does this give you any ideas on a new lightweight, accurate rifle design?
The worry is in the different thermal coefficient of expansion between the steel of the barrel and the synthetic stock, which is why I believe, all things considered, the free floated barrel is the better choice.
Not that a bedded barrel can't achieve a certain level of accuracy. Truth be known, I'm shootin for one-holers...maybe that can't happen with this barrel but it's a goal i.e. we gotta have sumptin to shoot for
During the shooting there was a thermocouple attached to the barrel. When the temp of the barrel dropped to 100 DegF the next shot would be taken. This was an attempt to eliminate temperature effects from the equation....an attempt at consistency.
Still, there are allot of other variables.... shooter, trigger, sight picture, letoff, heartbeat, sun angle, case, charge weight, powder speed, primer, bullet size, cartridge case temp, powder susceptibility to temp changes, rifle twist (1:9) etc. I'm sure you get the idea.
For example, if you look at the third shot column in the spreadsheet you'll see a load that went over 3700. Why that happened I'm not sure...it's an aberration due to whatever. As DAA said, this is something that could be thrown away but I kept it in the data. Maybe the neck wall thickness was tight on this one? Not sure but something caused a higher velocity than the other rounds in the group of five.
The trick is to control or minimize the variables and that's hard to do...especially this early in the game i.e. new cases, primer type, bullets, etc. I have doubts that the variables can be controlled to the extent where you can make a pencil barrel shoot one holers...maybe that's why we don't see pencil barrels in competition? It's theoretically possible but can we control the variables to the extent necessary for a sweet shooter? I have my doubts this can be done in a cost effective manner.....
This brings out another thought... One of the limiting factors in getting to a certain velocity is overpressure...as measured by pressure signs on the brass case. Just as food for thought, what if we used steel cases instead of brass? I know it's cutting a fine line but maybe there's some potential there?
[ March 25, 2014, 07:45 PM: Message edited by: Frank ]
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"Truth is no prostitute, that throws herself away upon those who do not desire her; she is rather so coy a beauty that he who sacrifices everything to her cannot even then be sure of her favor".
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CrossJ
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posted March 26, 2014 12:30 AM
quote:
Just as food for thought, what if we used steel cases instead of brass? I know it's cutting a fine line but maybe there's some potential there?
Creating more problems than solving here.
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TOM64
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posted March 26, 2014 04:29 AM
I've never had a pencil barrel shoot a one holer group but they will shoot. My gunsmith doesn't like Remington's mountain rifle contour but I've had 4 of them in 3 calibers that all would shoot around 1/2" 5 shot groups except for the 7-08 on the right which I settled on the 120 gr NBT at just under 1". (My SIL wanted this gun so he wound up with it before I messed with it any further).
And here's what the 22-250 will do, not a one holer but close enough.
Light barrels can shoot.
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Frank
CAN START A FIRE WITH A BUCK KNIFE AND A ROCK
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posted March 26, 2014 05:30 AM
I understand what you're saying, Tom. I'm reminded of a time when I was hunting with Rex. He was some young kid at the time, Leonard might remember him. Anyway, his father ran a rifle range somewhere south of Riverside. We'd go there shooting from time to time.
One day Rex's father came up and said "I hear you have a pretty accurate rifle?" I said, yea, it's a 40X Rangemaster in 22-250. He said, "Yea, sure. Lets see if you can shoot this red tack at 100yds". So he goes out and puts the tack in the target. Well, that 40X was so accurate I could literally put the bullet where I wanted. The tack disappeared on the first shot. It was a consistant one holer (ragged one holer to be precise). I loved that rifle. Ol' Painless is what I called her Shot it for years until I wore out the barrel. It had a heavy 26" barrel with a 1:16 twist and preferred the 52gr match from Sierra though it would shoot the 55gr SBT almost as well.
I guess what I'm trying to say is that this is the standard of accuracy I'm shootin for with the 7STW. Problem is there's a whole lot of things working against this happening....short barrel life, short case life, recoil, etc. It's a challenge for sure.
[ March 26, 2014, 05:41 AM: Message edited by: Frank ]
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"Truth is no prostitute, that throws herself away upon those who do not desire her; she is rather so coy a beauty that he who sacrifices everything to her cannot even then be sure of her favor".
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knockemdown
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posted March 26, 2014 06:39 AM
Frank, you mentioned a "thermocouple" attached to your barrel?
Whatever it is, I'd suggest removing it. Your rifle's barrel is like a 'tuning fork'. Anything contacting the barrel will affect the oscillations of it when fired. And a light contour barrel will likely increase the oscillation...
From your temp readings, you've prolly gotten a good idea of how long it took between shots to 'cool down'. So, SWAG the time, and don't have anything contacting the barrel when accuracy testing!
[ March 26, 2014, 06:40 AM: Message edited by: knockemdown ]
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KaBloomR
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posted March 26, 2014 06:54 AM
As LB stated previously, I would take a look at Nosler's load data. Or is the bullet a Hornady? Nosler shows the most accurate load @ 88 grains.
Step on the gas!
Forgot to add: SAFELY!
[ March 26, 2014, 07:21 AM: Message edited by: KaBloomR ]
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TOM64
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posted March 26, 2014 07:22 AM
With that accuracy requirement, I'd say load and shoot all you want looking for pressure and velocity. Once you burn the barrel out you can replace it with a heavier barrel, I don't think a light barrel will ever do it but at least you'll be well versed in load data.
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Leonard
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posted March 26, 2014 09:01 AM
A whippy 26" pencil barrel into a one holer may be a tall order? The easiest thing to do, which is self defeating as far as reaching your velocity potential is to cut at least three inches off the barrel. That may be 150FPS, but could decrease the "fliers".
You know....there are several hundred versions of what you are trying to do, in many different bore sizes and case capacities. Right now, the 338Lapua is getting a lot of attention among the long range people; for instance?
There are good reasons, Emperical reasons for choosing the 7MM. Same for the 6.5MM.
I spent much range time and a fair amount of money trying to turn my 220Swift into a one holer but it just wasn't in the cards. When realizing that fact, I actually became quite serene about it and forgave myself. Then went on to kill a couple thousand coyotes with excellent performance, but it wasn't a one holer and never would be. If a cartridge says accuracy, I guess a 22PPC is right up there, but would it kill a coyote at 400 yards? You have to identify your mission and accept reality.
Good hunting. El Bee
edit: PS Fred, he can be attaching a thermocouple after the shot, not while actually firing rounds.
[ March 26, 2014, 09:04 AM: Message edited by: Leonard ]
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TOM64
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posted March 26, 2014 09:27 AM
We all have ideas that make up the perfect gun for us and our uses. A light weight one holer gun would be wonderful but like Frank said, not too many pencil barrels in BR matches.
That given, I am totally at ease with a light weight 243ai that I have well past sane ranges for taking critters. I run high BC bullets though and stress long range.
Franks idea seems to be small targets at medium range maybe? If I had a 7mm, I'd be running the 162 Amax with its high BC and possibly a more accurate bullet.
But who am I to choose for someone else, I'm playing with a 22 LR to see how far I can go. It's all part of the fun.
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Leonard
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posted March 26, 2014 09:49 AM
Because he asked. Afterwards, he can't control the direction of the responses.
Tom, give it up! Please! Nothing good can come from dinking with a 22lr.
Good hunting. El Bee
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knockemdown
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posted March 26, 2014 09:53 AM
True dat, Leonard. Have never thermographed anything, was just grabbing at straws for an explanation of groups size.
Just happened across this post on the 'hide, thought it might have some relevance for Frank...
quote:
I had a 7STW before it was factory loaded, necking down 8 rem mag was easy enough. I was pushing 140 ballistic tip at 3600 out of a 27 inch Krieger. Burned the sucker up in 740 rounds, wouldn't worry too much about breaking the barrel in they burn out way too quick.
Accuracy was .3 to .4 MOA with either 79 gr of RL22 or 81 of H1000 topped by the nosler 140 BST, speed was 3595 to 3605 for ten shots, not too shabby.
I know you'll enjoy shooting yours as much as I did mine.
Cheers and congrats
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