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Let's understand that this is just one test; the next test could be better or worse. What I hoped to do here is corroborate previous test results, to wit, the accuracy of a BCM 16" Light Weight Enhanced barrel with an AA piston kit. If there is any truth to pencil barrels and/or piston systems being less accurate than more conventional configurations, this pencil barrel and piston combination should be convincing. However, and here's the link to the test, it showed that a pencil barrel with a piston can be very accurate.

[video]http://www.defensivecarry.com/forum/defensive-rifles-shotgun-discussion/305937-been-running-some-tests-week-accuracy-assessment-di-gp-vid.html[/video]

Encouraged by that test, I decided to test a 18" DD DI against a BCM 16" + AA piston. The results of the 18" DD DI are posted here:

http://www.defensivecarry.com/forum...onger-barrel-may-bit-slower-but-accuracy.html

All accuracy, and actually it's precision testing since I'm only considering group size capability of the guns, is performed at 100 yards and I started with some targets that are not easy to see distinctly even with a good scope. But once I started I was stuck with the targets. Also, bear in mind that as shooters, bowlers, golfers, whatevers, we have good days and, well, frustrating days and everything in between. What I'm saying is small differences could be more reflective of the kind of day I was having, the brightness of the day, the angle the sun was with relation to the targets, etc., etc., etc. That is to say there are variables we have loose control of.

Having said that ( I like to say that don't I :tongue: ), this is the accuracy test for the BCM 16" SS410 1:8 twist ion bonded barrel. There are two targets and I did a no-no in that I didn't use the same scope in subsequent tests. I've been having trouble with a Vortex Viper PST 2.5-10x scope holding zero - that really - well I shouldn't elaborate on that. So I remounted the scope in an Aero Precision super light extended scope mount. And I've replaced several of my American Defense Recon mounts with the AP mounts, although I like the SPR version. better than the extended version.

This first target was shot with the Vortex on 10x - it held zero! Bear in mind that I'm shooting for groups and making minor tweaks on the zero as I go so groups can be close to the point of aim, or just a click or two away, but I'm not worried about accuracy right now, just group size.

As you look at these two targets realize that I'm trying to see what the gun will do if I don't mess it up. So, if I pulled a shot, and I knew I did, I re-shot that one shot - more carefully. Remember this is about what the gun is capable of if I don't get in the way.



Not bad for a non-bench gun and a non-bench scope. Now that I'm both pleased and relieved about the Vortex holding zero, I pondered what might happen if I changed to a more powerful scope. So I mounted and partially zeroed a Burris XTR II 3-15x and shot another 100 yard target.

Before we go much further, a guy had a LWRC .308 piston gun at the range and invited me to shoot it. So I aimed at the center of the big diamond. I had been shooting a 2.5 lb Geissele National Match trigger, and his trigger was a far cry from that so I had to adjust. Still all in all, first time shooting the gun, and in .308 - not bad. That one shot outside the circle was the first shot. I had a better feel for the trigger after that shot and did a little better. OK, back to my gun.

It is interesting to see that moving from a 10x scope to a 15x scope only produced 0.09 MOA better accuracy! That 0.09 represents an improvement of about 18%. I'm not sure we can make much out of that - the day might have been brighter when I shot the 10x - just too many things that can make a difference to draw too much from this.

But, one thing we can draw from this is the gun, equipped with an AA piston system, shot a multi-group average of 0.6 and 0.51 MOA - not sure we could claim better accuracy if we had been using a DI system. Nothing wrong with DI, but there is a claim that DIs are more accurate. From the repeated tests I've run, I'm not seeing it.



BTW, just for comparison, the average group for the DD 18" DI ( http://www.defensivecarry.com/forum...onger-barrel-may-bit-slower-but-accuracy.html ) was 0.65 MOA. The BMC + AA piston actually out shot the 18" DD DI with about 8% more accuracy.

These are comparable profile barrels, the BCM is 1:8 the DD 1:7. The scope on the BCM had about 11% more power (10x vs 9x). But again I would caution against drawing too much from this; there are just too many variables that come into play. But, this is the third comparison test I've run and even with a pencil barrel I see no accuracy advantage in DI over piston - for what ever that is worth.
 

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Tangle, I always (ALL WAYS) appreciate your threads, observations & copious persnickety. Yet less than one tenth of ONE minute-of-angle?!? Do the words "obsessive" and "compulsive"...ring any bells? :biggrin2:
 
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Tangle, I always (ALL WAYS) appreciate your threads, observations & copious persnickety. Yet less than one tenth of ONE minute-of-angle?!? Do the words "obsessive" and "compulsive"...ring any bells? :biggrin2:
Thanks for the kind words!!!

LOL, well somebody has to be obsessive/compulsive!

Units, especially small units, can be deceptive that's why I also include percentages. For example, a difference of 0.51 MOA and 0.6 MOA is 0.09 MOA. Sounds obsessive/compulsive alright, but that's a percentage difference of 18% which is quite significant. For example let's suppose you weigh 200 pounds and gain 18%. You would weigh 236 lbs. All of a sudden the same percentage difference, 18%, seems more alarming than obsessive/compulsive.

In a nutshell a change from 0.51 MOA to 0.6 MOA is the same change as 200 lbs to 236 lbs.
 

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Then I've gained about .002 MOA since Christmas. (*you're right, it DOES sound muuuch better.) :biggrin2:
 
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One of these days you will actually get out to something farther than 100.

I think you touched on it before, but 100y is more of a reference point than anything with long guns than an accuracy or precision standpoint.

I believe that the biggest down side to the pencil barrel, regardless of OS, is going to be the at a higher rate of fire, and vertical stringing of shots as the barrel heats, and the Piston system may or may not have an impact on that.

For the "anal-ness" that you are going for here, I put to you other variables that have an impact on your test results.

New barrel, still getting broke in (18"). That girl is still getting faster and will produce better accuracy down the road.

Different temperatures (ammo, chamber, ambient). I am not sure of the difference that this will make at 100, but I know that MV changes can take a stupid accurate barrel ammo combination at 70*, go to complete crap with a 20* change - depending on the sensitivity of the powder to temps (typically factory loads are not that sensitive - this is a home cooking issue). Your change may result in only .02% at your test distance, but you are splitting, split hairs here.

Barometric Pressure on the day you shot the 18" and the 16".

Altitude - did you shoot them at the same range?

All this and more will start to wreak havoc at farther distances. To a hunter, they are acceptable changes - it will still equal a kill on medium game and up, but for small game and targets, it is the difference between a hit and a miss. That .75" flyer at 100 is taking your .51 MOA to a 5" combined group at 400 - missed that prairie rat.

I have a couple 10 shot targets that I am very proud of (16" and RDS) that are sub MOA until I count the two that I shanked (I knew it as soon as I pulled the trigger) that turned that 10 shot group into a 3.5" group.

This is of course all academic here, we are just having fun....well you are. I have not fired a round in almost 2 years now.
 

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Sticks,

Actually I shoot at 200 and 300 yards frequently - that's as far as I can go on my local range. But there is a range I visit about 4-5 times a year and while they are currently maxed at 300 yards, sometime this year they are going to stretch the range to 500 yards! I can't wait! But, around here, 100 yards is a practical distance.

I also shoot in temps from 20° to about 95°.

But, the reason I benchmark at 100 yards is to eliminate some variables and maximize sight picture integrity. At 100 yards wind has less than half the effect on the bullet that it does at 200 yards. The targets look twice as big at 100 yards as 200 yards so I can see the POA more clearly and consistently.

This is about the rifle's ability to shoot tight groups (or not), not long range accuracy. Beyond 100 yards, external variables can mask out the intrinsic accuracy of the rifle. I've even been known to shoot for groups at 50 yards. But at 50, the groups look deceptively small, and it's harder to measure them accurately, and hardly anybody uses 50 yards as a standard.

However, I have repeatedly shot groups at 100 yards, and then with the same rifle, dial in the rifle and ammo info into Strelok in my Galaxy III phone, get the drop for 200 ysrds, and either dial that in to the turrets or use the reticle to adjust the POI. I typically get about the same MOA groups at 200 yards and the POI is pretty close to the bullseye. And I've done the same thing at 300. At 300 the MOA size generally increases some to which I attribute to loss of sight picture resolution as well as variables that come with shooting at 300 yards.

I will certainly continue to shoot the DD 18" - I am quite curious to see if it gets faster - I know it has gotten more accurate. When I first started shooting it, I was so disappointed with its accuracy, I was about to send it to DD for inspection. But as I shot it, it dialed in!

I have a Faxon 18" heavy fluted 1:8 coming in today. I have classes today and tonight but hopefully, tomorrow I'll get the barrel in a Vltor MUR upper and get to the range and chrono it. Should be interesting!
 

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Buy some 77gr ammo when you go for long range with that 18"

I found that my Mk12 does not like the M193 (55gr) that my 16" loves. The accuracy goes to pot past 200.
 

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Buy some 77gr ammo when you go for long range with that 18"

I found that my Mk12 does not like the M193 (55gr) that my 16" loves. The accuracy goes to pot past 200.
Is your 18" a 1:7 twist? If it is, it may be putting too much spin on the M193 because it's leaving the muzzle so fast.

My 18" is 1:7 but I'm shooting a slower 55 gr round than the M193. I'll have to try it at 200 and see what happens.
 

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Paul's standards on barrels are amazing. I purchased a BCM EAG upper from Pat Rogers right before he died. I did some accuracy testing and was absolute amazed at the level of accuracy. I asked Pat if that was normal. He said Paul Buffoni would never admit to making a sub MOA rifle but what i was experiencing was pretty much the norm for a BCM rifle.
 

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Paul's standards on barrels are amazing. I purchased a BCM EAG upper from Pat Rogers right before he died. I did some accuracy testing and was absolute amazed at the level of accuracy. I asked Pat if that was normal. He said Paul Buffoni would never admit to making a sub MOA rifle but what i was experiencing was pretty much the norm for a BCM rifle.
Don't know if you saw my comparison of a 18" Daniel Defense to a BCM 16" SS410, but the shorter SS410 not only shot as accurate, or slightly more accurate than the longer DD barrel, but the SS410 produced a higher velocity for a given bullet as well. I like that the 16" SS410 is a 1:8 twist. I don't like the 1:7 in a 16" or longer barrel.
 

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Don't know if you saw my comparison of a 18" Daniel Defense to a BCM 16" SS410, but the shorter SS410 not only shot as accurate, or slightly more accurate than the longer DD barrel, but the SS410 produced a higher velocity for a given bullet as well. I like that the 16" SS410 is a 1:8 twist. I don't like the 1:7 in a 16" or longer barrel.
No I didn't, I would like to, I won a Daniel Defense V7 at the World Shooting Championship with an 18 inch barrel last year. Was the new gun with the M-LOK rail system. Got rid of the 18inch DD barrel and put a 16inch BCM barrel in the DD rifle.
 

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No I didn't, I would like to, I won a Daniel Defense V7 at the World Shooting Championship with an 18 inch barrel last year. Was the new gun with the M-LOK rail system. Got rid of the 18inch DD barrel and put a 16inch BCM barrel in the DD rifle.
Congrats on the win! But, was the 18" length the motivation to change barrels or what?

And which BCM 16" did you go with?

I have a BCM 12.5" LWE, a 14.5" LWE, a 16" LWE, and the 16" SS410. They are ALL impressively accurate except for the 14.5" - not sure what it's problem is but I'm still working on it.

Here's the link to the velocity comparisons. BTW, I was comparing two BCM barrels, a 16" SS410, a 16" Light Weight Enhanced, and the DD 18". You might be surprised who the speed winner is!

http://www.defensivecarry.com/forum...iscussion/324250-when-longer-isnt-faster.html
 

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I put the LWE barrel in same barrel that is in my EAG rifle, for weight reducation. The 18 inch barrel is a PIG. I don't have a picture with the 16 inch barrel, because my Father has taken the rifle from me. I ended up donating the 18 inch barrel and parts to build rifle to a guy stationed down at Fort Benning. His home burned down and he lost 57 guns. including 8 AR's. My EAG has a 14.5 pinned. Here in NOVA we don't shoot very far, if you shoot past 200 yards, you run the risk of hitting a Starbucks.





The white sticker on the magazine well was the control number that was used at the World Shoot.
 

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It was a "PIG"??? Other than the obvious, what's a PIG?

You did good to help out the guy at Ft Benning.

LOL - I'm not sure if hitting a Starbucks would be a good thing or a bad thing :tongue:

Oh, BTW, I see you have a DD stock on the AR in the pic. I have two DD stocks and they both "slip" or jump holes. I've tried them on several buffer tubes and get the same result. It usually doesn't happen with 55 gr rounds, but the heavier rounds, especially 300 blackout (which I despise) collapses the stock instantly. :(
 

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Pig=heavy

https://www.gofundme.com/eric-casey-delong-house

Gentleman was a Captain in the 75th. Least I could do. Dude comes back from war looses everything.

Some of my friends at Magpul donated him a ton of stuff. Everything in his safe melted. Sent me photos very tragic. I asked him if he had any Aimpoints, it was so bad you couldn't tell what optics were on his guns, but Aimpoint was ready to replace everything.
 

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Pig=heavy
Ahhh, by heavy I presume you mean compared to a light weight barrel since the DD 18" has essentially the same profile as a BCM 16" SS410 which wouldn't weigh that much less being only 2" shorter???

https://www.gofundme.com/eric-casey-delong-house

Gentleman was a Captain in the 75th. Least I could do. Dude comes back from war looses everything.
That hurts in so many ways.

...Some of my friends at Magpul donated him a ton of stuff. Everything in his safe melted. Sent me photos very tragic. I asked him if he had any Aimpoints, it was so bad you couldn't tell what optics were on his guns, but Aimpoint was ready to replace everything.
That just warms the soul. I am so glad to hear Magpul and Aimpoint responding so generously!
 

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Plus we do a lot of carbine training here at NRA Building. Everytime I get a AR rifle, I try to set up so if it needs to be loaned out to a student its set up like a typical 16 inch carbine.
 
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