Caliber Choice for Long Range

[rsterne]

There have been a few groups posted, some good, some bad.... some good ones right here in the last few posts, in fact.... Everyone has a different idea of what "accurate" is.... I have never achieved 1 MOA at 100 yards with ANY air rifle bullet OR pellet.... so for me, anything that can do that would be great.... I wouldn't care if it was pellet, FB, GC, or boattail.... I'd be tickled pink....

Carl, not so much.... he wants aspirin size groups at 100 yards.... I've never done that for 5 shots even with handloads in a .222 Rem.... 

None of this has ANYTHING to do with the purpose of this post, however.... If you want to start a thread about long range accuracy, why not DO that.... Even better, shoot the NUAH target, and qualify as a Master....  .... There are currently only 9 guys on the GTA that have done that, and none of them at over 100 M.... https://www.gatewaytoairguns.org/GTA/index.php?topic=119449.0 .... We have a spot just waiting for the first guy to do it at 300 yds....

Here are the rules for "Master".... https://www.gatewaytoairguns.org/GTA/index.php?topic=100865.0 .... 5 shots in a 1 MOA group, and all inside or touching the 2 MOA ring.... 100 yard minimum, but same rules apply further out, if that isn't challenging enough... Maybe Carl can be the first NUAH Master at 1000 yards?.... only 5 shots allowed, though, all to score....

Bob

[WesBob]

Bob, just want to say thanks for all the sharing of information you do, and as the most voted for man on the GTA person of the year, I think you realize you are greatly appreciated. I think big bore threads tend to be the most testy ones on the GTA, seems like the bigger the bore the bigger the egos get! And perhaps rightfully so, a lot of big bore guys have something to be proud about. Anyway just wanted to say thanks, I am not a big bore guy but still find myself reading because it is always interesting reading your threads and trying to wrap my brain around them.
Thanks, and don't quit even if it would be less headache!
Enough said and I'm sure unnecessary, lol😊

[rifle50]

I'm not quite sure where this thread went off the rails (well I am, thank you Carl).... but it has turned from an informative thread about caliber choice into a "lets bash Bob's Boattails" thread....
Bob

Thanks BOB, You carefully forget I DID GIVE AN ANSWER to this threads TOPIC, 2nd paragraph, of my initial response on page 2. Stating that having shot .257 and .457 to OVER 1000 yds and UP NORTH AIRGUNNER doing same with a .357, it didn't matter what caliber was used. Shooter just needs to decide what SIZE was best for their needs....

YOU added the comment, and do it over and over about the EBR WINNING BULLET YOU DESIGNED, showing the drawings etc, as if it was something special. IT DID NOT place shots on target at that match better than an RCBS .308 standard bullet, and ONLY WON because another shooters ERROR resulted in a 20 point subtraction, and then he was in 3rd place by I believe 7 points. Bullet ONLY WAS STABLE BARELY on HELIUM. Yes it won but a better bullet, not hardly. AND NEVER shot in competition again.Then to prove it was a great bullet, you scaled DOWN that BBT to .257 and built a SPECIAL 7.5" twist rate barreled rifle to stabilize. How did that work out BOB? Not very well.

You think I am bashing BBT........You keep bringing it up and posting that long 200+ gr .308, and after so many times hearing the EBR THING, I consider it bragging from your side I have heard it and seen it posted so many times. All I am doing is giving another point of view on that specific bullet to readers who are unaware or not heard another slant on that subject. And yes you brought it up in the initial post, so FAIR to have a view that doesn't agree with how good the bullet is or isn't, in this thread. YOU provided the ammunition, so to speak. Specifically that EBR LONG .308 and same  design scaled to .257.

We have hashed this  out before. But you keep implying it was such a great bullet, flack or dissenting opinions will flow from me. Bob if you design a bullet that is better consistently than any of my SAECO molds deliver in .45, or Arsenal in .257, I and others will be all over it....Until then

Also having an opinion and stating additional information you don't want to remember or hear, isn't bashing.......It is called a disagreement..........And in CIVIL DISCOURSE, allowable............

Cheers.........Carl

[rsterne]

you scaled DOWN that BBT to .257 and built a SPECIAL 7.5" twist rate barreled rifle to stabilize. How did that work out BOB? Not very well.

The "not very well" is purely your opinion.... I posted a group back in the spring, during initial Chrony testing, and until I get the time to properly test the Monocoque (after the Motel closes in 2021) I may very well not get back to shooting it.... The large black square is 2", so that group, at 100 yards, is just a whisker over 1".... pretty much the best I have ever shot at 100 yards with any airgun.... first time out with that gun and bullet....



As far as the special 7.5" twist barrel, it was actually a 7" twist, which is what the calculations told me was the correct twist for a .257 cal bullet of that length with that boattail.... and the holes look perfectly round to me.... Compared to that target you keep posting with the aspirin sized group it's terrible.... Did you get that group the very first time out with that gun and bullet?.... Somehow I doubt it.... 

You keep doing what you do well, shooting at targets at long range, using big bullets that kick up a big cloud of dust so you can see the impacts better until you finally get on target.... It's entertaining, and shows how far a bullet from an airgun can carry.... Your accomplishments are legendary, just hitting anything at that distance is impressive.... I'll keep plugging along, trying to develop a bullet that is accurate enough that even you might try it.... while having the superior aerodynamics that only a boattail can provide, and the inherently lower wind drift that goes along with that.... I don't care how well I can shoot.... I'm just trying to help the sport improve to the best of my limited ability.... All the snipers in the world can't have it wrong....

Now can we get this thread back on topic, please?....

Bob

[rifle50]

you scaled DOWN that BBT to .257 and built a SPECIAL 7.5" twist rate barreled rifle to stabilize. How did that work out BOB? Not very well.

The "not very well" is purely your opinion.... I posted a group back in the spring, during initial Chrony testing, and until I get the time to properly test the Monocoque (after the Motel closes in 2021) I may very well not get back to shooting it.... The large black square is 2", so that group, at 100 yards, is just a whisker over 1".... pretty much the best I have ever shot at 100 yards with any airgun.... first time out with that gun and bullet....

Bob

I remember you posting that......The 3 shots aren't bad, and you said it was best group and also posted a couple 5 shots, the best you said of 5 shot groups and weren't  good, your  admission. So the ones that weren't as good as the couple of 5 shot groups and not shown were even worse??

And yes with my rebuilt .257's, and 85 gr and 92 gr Arsenal molds, 5 shot groups were better than 1" first time out, and a lot were .5"...........I showed Aspirin comparisons just to show sometimes it all comes together and I consider 1 moa as very acceptable accuracy for airgun.  Over counter powder rifle, stock same but custom and hand loads, even 1/2 moa to me is not acceptable, As you mentioned, accuracy means different things to different people........

I am done.................Carl   

[Sbak]

Carl, would you mind posting your caliber, mold, muzzle velocity, and barrel twist rates that you have achieved what you would consider good accuracy with? It's been my suspicion that the subsonic stability factor models we have been using are close, but not quite right (just in the same way our drag models cannot quite predict accurate BC numbers for pellets). I am trying to compile a field experience vs calculated chart to compare theoretical s factor optimums vs what people are actually getting good groups with

Edit: I would also need your approximate elevation above sea level.
Also, thank you to both bob and Carl, for both innovating in your areas of passion. Remember, without disagreement there will no longer be innovation

[rsterne]

Good idea, Shane.... perhaps start a thread for that?.... Others may have input as well....

Bob

[Relentless Holiday]

Wow Bob. i actually kept up with that. Awesome explanation! 

[bluethunder]

Bob,

    I purchased both the 155 gr. and 170 gr. .30 cal. NOE boattail bullets. I have had decent results with these moulds but have struggled with a persistent wobble or yaw which can be seen on target by oblong bullet holes. Most of my testing was at 300 yards.  I have experimented with various alloys from pure lead to half linotype & half pure lead. I have also experimented with various sizing diameters. At first I thought the problem was that I didn't have a fast enough twist rate. I had a 1 in 10" twist rate at the time. So I went through the process and expense of having my 10" twist Shilen barrel removed and replaced it with a 1 in 7" inch twist match grade Shilen. Still the yaw on target was present with both bullets. It is worse with the longer 170 grainer. The best bullet that I have shot so far in my rifle is a RCBS 165 gr. Silhouette bullet that I had the gas check shank removed. My best groups occured with the 10" twist barrel and this modified RCBS flat base bullet. I will retire the NOE boattail bullets. In my rifle they just won't fly without a yaw. And I'm not going to go to the cost of putting an even faster 6" inch twist barrel on it. I will say that groups did improve on the 170 gr. boattail bullet going from a 1 in 10" twist to a 1 in 7" twist barrel. But neither boattail has been able to match the RCBS flat base bullet in the 10" twist barrel. Any new moulds that I purchase in the future will be flat base or have gas check shanks because for what ever reason, they are much easier to stabilize. Also, you'll never get the benefit of the theoretical B.C. advantage of the boattail bullets if they are cork screwing through the air. That's going to cause additional drag on the sides of the bullet. A equally weighted flat base spitzer bullet that flies true will probably have a better BC than a boattail spitzer that's yawing through the air. I do learn a lot from your post. And appreciate your mathmatical prowess. But what sounds good on paper doesn't necessairly work out in the real world. As far as what's the best caliber for long range I think that it's been proven that it really doesn't matter. What ever powerplant that you own that can drive a high BC bullet to 950 fps will work. The real differences in caliber are more a function of practicality. The smaller calibers use less air (that's an advantage) but make smaller holes and kick up less dust and are therefore more difficult to spot at long range (that's a disadvantage). And just the opposite holds true for the big bores which use a lot more air but make bigger holes and kick up more dust.

[AncientSword]

Thanks for your efforts to help in understanding things,  Bob.

Also thanks for being patient and answering questions in PM's. 

[rsterne]

you'll never get the benefit of the theoretical B.C. advantage of the boattail bullets if they are cork screwing through the air. That's going to cause additional drag on the sides of the bullet. A equally weighted flat base spitzer bullet that flies true will probably have a better BC than a boattail spitzer that's yawing through the air.

I agree 100%.... and thanks for your detailed post of your experience with the BBT's.... I have not seen any yaw with my .257 cal 112 gr. in a 7" twist, but have not shot past 100 yards yet, so perhaps that will show up at longer range.... As far as the advantages of larger calibers at long range in punching bigger holes, delivering more energy, or kicking up bigger clouds of dirt on impact (so you can walk your shots onto the target).... I agree 100% on that as well.... However, the original concept of this post was to show the difference in the basic ballistics between calibers from an internal and external ballistics point of view.... Internally, the SD is limited by the barrel length and pressure.... Externally, for a given SD, smaller caliber bullets can have a better BC (this applies to FB or GC as well).... Until you hit the point where the bullet ends up too long to work properly because you either can't make it accurately enough, or get a fast enough twist to stabilze it.... or just plain need more FPE to dispense with your intended game.... IMO smaller calibers have the advantage at long range in airguns.... I just tried to show the reason behind that in this thread.... YMMV of course....

Bob

[AncientSword]

you'll never get the benefit of the theoretical B.C. advantage of the boattail bullets if they are cork screwing through the air. That's going to cause additional drag on the sides of the bullet. A equally weighted flat base spitzer bullet that flies true will probably have a better BC than a boattail spitzer that's yawing through the air.

I agree 100%.... and thanks for your detailed post of your experience with the BBT's.... I have not seen any yaw with my .257 cal 112 gr. in a 7" twist, but have not shot past 100 yards yet, so perhaps that will show up at longer range....

Bob

I would like to point out that Cedric shot your BBT in 7mm out to a very accurate 205 yards,  repeatedly hitting an apple at that distance, in his second 7mm Corsair video. I would call his shots MOA or better from what I saw.

[sixshootertexan]

I shoot the .308 135gr BBT in my home made rifle. It has a 1-20" TJ barrel on it. Is it the most accurate rifle I don't think so. I would not hesitate to shoot a hog at 100yds with it or a coyote at 200yds. I can hit a 8x10 gong all day long at 200yds using shooting sticks no benchrest stuff. On paper I see no signs of yaw. I've tried several bullets that fellow GTA members sent me and different molds I have and so far the BBT is the best out of my rifle.

[rintafile]

Hmmm.. I should try that same bullet on Corsair. Also 1-20" TJ barrel... I've been thinking that it is too long bullet for that twist. Or not enough power to push it....

[oneshot61]

I shoot the 78.6 and 95 grain Bbt out of my Cothran, very good to 100 yards which is as far as I shoot it. Also a tj 1-20 twist. I like the 308 for bigger stuff and have a .257 barrel for it. I find I’m leaning more to calibers 308 and down. Here in Alabama we can hunt deer with .30 and above, coyotes and hogs whatever will take them, so that opens up a lot of longer range calibers, the 224, .257, 7mm etc.