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Old 12-09-2013, 12:23 PM   #71 (permalink)
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Originally Posted by Trinity View Post
To answer your question, I firmly believe that no barrel can be inaccurate at short range and get more accurate at long range.
Yes and no. The phenomenon is described in McCoy's Modern External Ballistics (the very expensive bible of professional ballistics analysis) but basically, under normal conditions the angle of dispersion that a given barrel and ammo produces is constant. So the group size grows linearly with trajectoric arc length or flight time (depending on who you talk to).

However in some combinations, and without getting into descriptions of the physical phenomena*, the forces acting on the bullet make it so that the angle of dispersion can be larger at short ranges than it is at larger ranges. The irony being that the actual group size never gets smaller with distance, its just larger than it should be at shorter ranges.

I have an article clipped in my Evernote about it from back in the day - if there's interest in a more technical description I'll hunt it down and put it up.

* I'm not McCoy but if your interested I touched on one of the phenomena earlier in this thread - precession
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Old 12-09-2013, 01:18 PM   #72 (permalink)
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Originally Posted by Trinity View Post
I tested the Carmatech barrel on CCM 's SR1 alongside the "14 Hammerhead Mojo and it wasn't even a close call. The Hammerhead was far more accurate on that platform.
Trinity which hammer was are you referring to? The carmatech 20 in HH. or the 14 in mojo HH?
I didn't see this test anywhere. Is it on your blog?
Was it with FS or PB's?
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Old 12-09-2013, 03:56 PM   #73 (permalink)
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Here's what I know about barrels in lengths up to 16" at 75ft:

9" LAPCO .690 Smoothbore: +/- 9.86" (68%)*
16" LAPCO .690 Smoothbore: +/- 8.45" (68%)*
9" LAPCO/Tiberius .683 Rifled: +/- 4.80" (68%)*
16" LAPCO/Tiberius .683 Rifled: +/- 2.50" (68%)*
14" Hammerhead .688 Rifled: +/- 2.78" (68%)*
* These are radius values, double them for spread diameter, double them again to show the area containing 95% of your shots.

The 16" LAPCO/Tiberius barrel performed essentially the same (the difference is statistically insignificant) as the Hammerhead 14". However, they both performed significantly better than the 9" LAPCO/Tiberius.

Both barrels employ the same twist rate. The tighter bore does not appear to lend any benefit to accuracy. However, during the testing, it was found that the rifled barrel required a significant increase in operating pressure, which translates to worse efficiency.

Carmatech's 20" Rifled Barrel is produced by Hammerhead and differs from the regular hammerhead barrels in that it doesn't use a sizer and, it's longer. The rifling pattern is identical.

I've not seen any data pertaining to indoor testing of the Hammerhead 20" barrels. I see indoor testing as critical given how suceptible these rounds are to air currents.

The .688, and even the .683 rifled barrels appear to allow the rounds to slip rotationally as they move down the length of the barrel- based on the fact that the rounds don't appear to rotate at the same rate as the rifling when they exit the barrel (as seen on high speed video). This in itself may allow for a longer barrel to better impart the appropriate spin. If this is true, then a 20" hammerhead barrel could, perform better than the 14".

As far as rounds deviating more or less at range- In the very early testing of First Strike rounds out of smoothbore barrels, they may have performed a bit more accurately at longer range than at close range. I can't review the data myself to confirm however, this doesn't really apply to the differences between rifled barrels of different lengths. I know that at 100-150ft ranges, the deviation is linear, at least from smoothbore barrels.
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Old 12-09-2013, 11:17 PM   #74 (permalink)
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Originally Posted by Whiskey Hammer View Post
Yes and no. The phenomenon is described in McCoy's Modern External Ballistics (the very expensive bible of professional ballistics analysis) but basically, under normal conditions the angle of dispersion that a given barrel and ammo produces is constant. So the group size grows linearly with trajectoric arc length or flight time (depending on who you talk to).

However in some combinations, and without getting into descriptions of the physical phenomena*, the forces acting on the bullet make it so that the angle of dispersion can be larger at short ranges than it is at larger ranges. The irony being that the actual group size never gets smaller with distance, its just larger than it should be at shorter ranges.

I have an article clipped in my Evernote about it from back in the day - if there's interest in a more technical description I'll hunt it down and put it up.

* I'm not McCoy but if your interested I touched on one of the phenomena earlier in this thread - precession
Actually I am aware of McCoy's book and the theory you're talking about, but let me be clear - I didn't read his book. That would take somebody like UV Halo or someone with an engineering background to really appreciate it. I know about the concept because I was was trained to shoot at long range and because I happen to hang around a lot of real-steel forums where that kind of ballistics discussion takes place. There is so much math and theory involved that it makes my eyes glaze over. I have said it before and I will say it once more here. Ballistics is not my deal. I am just a trigger puller.

I have been shooting real-steel at long range just a bit over 40 years. I was trained by some very capable shooters and part of that training involved lots and lots of shooting with a variety of very good weapons at everything from short range to the maximum effective range of whatever I was pulling the trigger on. I have been shooting first strikes through a variety of guns since they were introduced. Tiberius actually sponsored me at that point. I have lost track of the number of rounds and barrel combinations I have tested. That includes different bore sizes, different barrel lengths, different rifling styles, and no end of smooth bore rifles. I still shoot at long range nearly every weekend just because I like pulling the trigger to see just how accurate first strikes can be and because it takes a lot of practice to become familiar with how wind will alter the path of a first strike at a variety of ranges.

Is it theoretically possible to find an combination of round/barrel that results in the kind of accuracy variable discussed by McCoy? Sure. Have I ever personally seen it happen with any weapon I have used? Nope. Not even close.

Remember, our chances in the paintball world of finding such a combination should be much, much higher because unlike real steel, we don't have an unlimited variety of rounds, calibers, and barrels to choose from. We have just first strikes and a limited number of barrels to put them through. If someone has actually found a real-life example of such a combination, I would love to test it. I tip my hat to theoretical possibility, but until I actually pull the trigger and see it happen, my opinion (and it's only that) remains the same.

One last note in response to UV Halo's post. My recollection is that the Carmatech barrel actually did have a fin, or at least mine came with one. I no longer remember what size it was but the barrel is now in the hands of my playing partner DJMatt who uses it on his Dye Dam. He checks in here occasionally and may be able to fill in that information.
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Old 12-09-2013, 11:30 PM   #75 (permalink)
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Originally Posted by tangus999 View Post
Trinity which hammer was are you referring to? The carmatech 20 in HH. or the 14 in mojo HH?
I didn't see this test anywhere. Is it on your blog?
Was it with FS or PB's?
Boy was that a badly written sentence Sorry about that. The Hammerhead Mojo very clearly outperformed the Carmatech Hammerhead on my SR1. I think the test results were on my Blog.

At the time of those tests I was desperately trying to settle on a final barrel configuration because I like eliminating variables as much as possible. I wanted to start doing some serious long-range shooting and once I started I wanted my SR1 in a steady state. In other words, I wanted my rifle, from the Nikon M223 scope down to the Harris bipod, to be the best combination of components I could put together so that I could forget about swapping out equipment and just learn how to extract the very best accuracy from it.
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Old 12-09-2013, 11:59 PM   #76 (permalink)
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I just meant that first strikes in general never gave me great groups under 40 yards, no matter what I shot them through. I have to test this CF Mofo as soon as possible. I really want a short barrel, and after much research between the sharktooth and FSR barrel, I chose the latter. If I get the testing with the Mofo done now, it'll be easier to turn the reg up to test the FSR barrel later.

I do remember after checking the barrel for fouling, I didn't always get great groups with the Hammerheads I have shot first strikes through though, which is what led me to pay attention to the difference between the way the Dye UL barrel and FSR performed. I seem to remember the Hammerhead shooting better than my CP .689 smoothbore, but the results he got between the two barrels on the DAM makes me wonder if I ever got ball on ball accuracy like he did with the FSR. I did see the vertical variance FSR users have noted but that's still a pretty good group.
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Old 12-10-2013, 03:31 AM   #77 (permalink)
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Originally Posted by Rover Lead View Post
I just meant that first strikes in general never gave me great groups under 40 yards, no matter what I shot them through. I have to test this CF Mofo as soon as possible. I really want a short barrel, and after much research between the sharktooth and FSR barrel, I chose the latter. If I get the testing with the Mofo done now, it'll be easier to turn the reg up to test the FSR barrel later.

I do remember after checking the barrel for fouling, I didn't always get great groups with the Hammerheads I have shot first strikes through though, which is what led me to pay attention to the difference between the way the Dye UL barrel and FSR performed. I seem to remember the Hammerhead shooting better than my CP .689 smoothbore, but the results he got between the two barrels on the DAM makes me wonder if I ever got ball on ball accuracy like he did with the FSR. I did see the vertical variance FSR users have noted but that's still a pretty good group.
Rover Lead ,

Remind me again what gun you are shooting your first strikes through. When you shoot at ranges beyond 40 yards, are you getting the same or tighter groups as you do at shorter ranges. What happens when you go really short like 30 yards? When you say your groups were not that great, how big would you say a group of ten shots would be? Mask size? Bigger? Finally, are you shooting with the rifle benched or supported in some manner or are you shooting off-hand?

I am trying to get a sense of how tight a group you're shooting? While first strikes are not like shooting match-grade .308 rounds through a bull barrel, you should still feel pretty comfortable that you can hit a target the size of a mask or a hopper at 40 yards. For me, holding tighter groups gets to be a real challenge at 70 yards and beyond.
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Old 12-10-2013, 04:16 AM   #78 (permalink)
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Originally Posted by Trinity View Post
Rover Lead ,

Remind me again what gun you are shooting your first strikes through. When you shoot at ranges beyond 40 yards, are you getting the same or tighter groups as you do at shorter ranges. What happens when you go really short like 30 yards? When you say your groups were not that great, how big would you say a group of ten shots would be? Mask size? Bigger? Finally, are you shooting with the rifle benched or supported in some manner or are you shooting off-hand?

I am trying to get a sense of how tight a group you're shooting? While first strikes are not like shooting match-grade .308 rounds through a bull barrel, you should still feel pretty comfortable that you can hit a target the size of a mask or a hopper at 40 yards. For me, holding tighter groups gets to be a real challenge at 70 yards and beyond.
Prone supported, trained shooter, group was bigger than mask size out to 40 meters (my rangefinder doesn't do yards) whereafter out to 60 meters I got some great groups, mask sized with an occasional flier but every so often ball on ball. I was using a Hammer 7 with backbottle HPA tank and 14" Bangstikk Hammerhead barrel. Also a Hawke XB1 SR.

I know the shorter range groups were bigger than mask sized because I had found a paintball shop that sold old used masks and I bought a bunch to start using the rangefinding capability of the scope. Anyway, half of my shots would be on the pole right at the side or front of the mask and the rest actually on opposing side of the mask . Pushing out to 50 meters more of the shots were on the mask. I had a little handheld chrono velcroed on and standard shot to shot deviation was +-5 fps.

I also wonder if the Hawke scope had anything to do with it; once I zeroed it for the recommended 30 meters I found that the reticules for 40, 50 and maybe 60 yards were spot on but the 20, 30, and 70 -100 yard reticule marks were all off where I would have to aim low or high depending. I never shot a lot past 70 yards because of range constraints.

I got kind of sick of it so I got a gen 2 Tiberius adjustable rail and a small rifle scope. I don't have any data to back it up, but once I set the elevation it was near ball on ball at my standard 60 meter board target. I think that may have been because the scope was 6X magnification vs the 3X on the Hawke once it is zeroed.

The reason I found the short range accuracy disturbing was because I knew that having dialed in the scope and shots cases of fs rounds at the 50- 70 yard range, in the fast paced heat of a game, a 20 yard target could suddenly offer me just an elbow, for example.

So I'm looking at putting the adjustable riser on my SR1 when I get it and the Hawke on my tricked DMagged Phenom DMR. I just thinking having a Semi Auto FS mag fed rifle with a Dial in riser rail defeats the purpose for which I built the Phenom, heh.

Last edited by Rover Lead; 12-10-2013 at 04:21 AM.
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Old 12-10-2013, 04:29 PM   #79 (permalink)
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Actually I am aware of McCoy's book and the theory you're talking about, but let me be clear - I didn't read his book. That would take somebody like UV Halo or someone with an engineering background to really appreciate it. I know about the concept because I was was trained to shoot at long range and because I happen to hang around a lot of real-steel forums where that kind of ballistics discussion takes place. There is so much math and theory involved that it makes my eyes glaze over. I have said it before and I will say it once more here. Ballistics is not my deal. I am just a trigger puller.

I have been shooting real-steel at long range just a bit over 40 years. I was trained by some very capable shooters and part of that training involved lots and lots of shooting with a variety of very good weapons at everything from short range to the maximum effective range of whatever I was pulling the trigger on. I have been shooting first strikes through a variety of guns since they were introduced. Tiberius actually sponsored me at that point. I have lost track of the number of rounds and barrel combinations I have tested. That includes different bore sizes, different barrel lengths, different rifling styles, and no end of smooth bore rifles. I still shoot at long range nearly every weekend just because I like pulling the trigger to see just how accurate first strikes can be and because it takes a lot of practice to become familiar with how wind will alter the path of a first strike at a variety of ranges.

Is it theoretically possible to find an combination of round/barrel that results in the kind of accuracy variable discussed by McCoy? Sure. Have I ever personally seen it happen with any weapon I have used? Nope. Not even close.

Remember, our chances in the paintball world of finding such a combination should be much, much higher because unlike real steel, we don't have an unlimited variety of rounds, calibers, and barrels to choose from. We have just first strikes and a limited number of barrels to put them through. If someone has actually found a real-life example of such a combination, I would love to test it. I tip my hat to theoretical possibility, but until I actually pull the trigger and see it happen, my opinion (and it's only that) remains the same...
To be clear, Im not attacking your credibility. Some of your posts get clipped and put up right alongside Bryan Litz's. I point out the technical clarification because the FS community, especially compared to other shooters and forums *cough*PBN*cough*, is one that appreciates technical information and because there is evidence that this kind of dispersion angle deviation is in fact taking place in some smooth bores. We wont be able to prove it conclusively until we mess with the FS darg curve model a bit, but that's part of a larger technical discussion that'll get hashed out later.

And, tangentially related, I cant find the the Carmatech HH 20" vs HH Mojo comparison in the blog either. Your most recent blog post - spetemberish - mentions it at they very bottom of the post but nothing after that.
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Old 12-10-2013, 05:19 PM   #80 (permalink)
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I'm the lucky one who got the 20" HH from Trinity. I messed around with it a little and didn't see much difference between it and my other HH barrels and it is so long, especially with a suppressor in the end that I feel that it's awkwardness is probably not going to make up for any possible gains. I actually just found and ordered a 14" brass mofo to use on the SR1 when they are released. The 20" that I have does have a fin on it but I believe I saw somewhere that they changed it so the new ones are all one piece.

As for the shorter distance grouping, I did notice a lot of wobbling of the FS when shot thru a smoothbore Dye UL barrel on my dam within the first 20 or so yards. After that distance, the fins seemed to stabilize it. Once I switched to a rifled barrel, that problem went away. I don't know if it's the round kind of corkscrewing until the fins spin it up to the right speed to stabalize, but it seems that it could account for the type of problem he's having, although it looks like he's using a rifled barrel so.....

I used the Hawke XB1 and in my testing, I found that at the lowest power, I was only getting about a 7 yard spread between crosshairs. I also zoomed it all the way in and retested and got about 3 yards between crosshairs so I was able to adjust the zoom if needed and just adjust the scale accordingly.

My solution so far is that I got a Bushnell with built in laser rangefinder and mounted it on a HHA Optimizer. I am currently in the process of modifying the Optimizer so that I can get an adjustable range of about 80 yards instead of the stock 35 yards, more to come on that once I get it finished and tested.

I've went thru way to many products testing to get a setup that I'm happy with. I'm almost there, now I just need to have a big sale to recoup some of the expenses....lol.
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