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Posted: 1/17/2011 6:43:57 PM EDT
| Does adding a free float carbine make a difference in accuracy? Id love to add a set of DD omega handguards or something similiar but I dont want the "tacticool" AR, Im trying to get more accuracy out of my gun. |
| Yes it will a little, but it depends on barrel length and quality more than anything.A short barrel is already stiff so it may not show any gain...and your "manufacturer grade" barrel probably isn't much better than 2 moa anyway.Now, if we're talking a REAL match type barrel you will see a difference. |
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Yes it will a little, but it depends on barrel length and quality more than anything.A short barrel is already stiff so it may not show any gain...and your "manufacturer grade" barrel probably isn't much better than 2 moa anyway.Now, if we're talking a REAL match type barrel you will see a difference. Its a bcm 16" m4 upper |
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Does adding a free float carbine make a difference in accuracy? Id love to add a set of DD omega handguards or something similiar but I dont want the "tacticool" AR, Im trying to get more accuracy out of my gun. nothing wrong being 'tacticool' if that's what you want.. own it.. don't let others dictate what you will have on your AR. yes.. Welcome to America. |
| Might make a difference with all variables being constant. I have better luck working on the trigger myself. All my rifles and carbines shoot a little different but all are pretty accurate. Are you going to use match ammo? How does it shoot now? Buy the HG you want, that's what matters and learn to shoot the rifle to it's and your optimum potential. Never seen many AR's that wouldn't shoot better than the shooter. Have you tried dogging it down and seeing how good the rifle really is? |
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Might make a difference with all variables being constant. I have better luck working on the trigger myself. All my rifles and carbines shoot a little different but all are pretty accurate. Are you going to use match ammo? How does it shoot now? Buy the HG you want, that's what matters and learn to shoot the rifle to it's and your optimum potential. Never seen many AR's that wouldn't shoot better than the shooter. Have you tried dogging it down and seeing how good the rifle really is? I went shooting earlier today. Using 55 gr xm193 I was covering a quarter at 25 yards,but at 100 yards using 75 gr prvi I was all over the place. |
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Might make a difference with all variables being constant. I have better luck working on the trigger myself. All my rifles and carbines shoot a little different but all are pretty accurate. Are you going to use match ammo? How does it shoot now? Buy the HG you want, that's what matters and learn to shoot the rifle to it's and your optimum potential. Never seen many AR's that wouldn't shoot better than the shooter. Have you tried dogging it down and seeing how good the rifle really is? I went shooting earlier today. Using 55 gr xm193 I was covering a quarter at 25 yards,but at 100 yards using 75 gr prvi I was all over the place. What is "all over the place"? Figuring you have the CMV chrome-lined BCM barrel rather than the 410 SS variety, you might be shooting better than you think. C/L barrels aren't really made striving for accuracy. 3" - 5" groups aren't shabby for a stock carbine prior to a FF rail and a trigger upgrade. Quality optics are rather important to judge a barrel unless you're already supremely skilled. |
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that also depends, where u standing, kneeling, or prone with a bipod if the last then all over the place is bad if standing well thats a tough one anyways Bench shooting with a sand bag ok then whats all over the place??? and also opics or irons and if optics which? |
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that also depends, where u standing, kneeling, or prone with a bipod if the last then all over the place is bad if standing well thats a tough one anyways Bench shooting with a sand bag ok then whats all over the place??? and also opics or irons and if optics which? I may have been covering a 5" area on a 12" color target. I was using a Nikon prostaff 3-9x scope. |
| Never been a fan of Privi 75 grain myself and have never read a decent review on it either. If that rifle likes 55 gr than that is what I'd use. Did you clean the rifle any? Did you have a scope on it? Did the scope loosen up by chance? Point of impact will definately change with the weight of bullet but this is usually a function of elevation and not windage. Real match ammo has an exact weight bullet with exact measures of powder. This is not something that Privi 75 has. BCM is 1-7 twist correct? It should like heavy stuff but even true marksman can't usually do much with the privi stuff. It's decent plinking ammo as it goes bang everytime but probably a little overpriced for what it is. Federal Lake City Nato XM193 or M855 are really hard to beat for the buck in any twist AR barrel without fine tuning ammo. |
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Free floating will prevent a change in the point of impact from pressure on the barrel, usually from tightly slinging up with a target sling. It will not decrease the size group a particular ammo shoots. This. If you shoot with the sling wrapped around your arm for more tension and you didn't zero your gun with the exact amount of tension on the sling, the POI will be different. |
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Never been a fan of Privi 75 grain myself and have never read a decent review on it either. I just got some in hopes it will be a cheap practice ammo that will mimic Honady 75 gr. TAP. http://www.ar15.com/forums/topic.html?b=3&f=16&t=491816 My main reason for FF is to keep sling pressure off the barrel. Needed, no. Help, yes for precision gun, splitting hairs for defensive gun. It does help me sleep at night tho. 
I figure, if your gonna run a rail, why not make it a FF? |
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Depends. Shouldered and standing shooting squared-off? No way. Slung up, prone and shooting NM high power style? Yes Bipod deployed or shooting from barrier? Slightly For a regular government profile barrel, non-FF isn't going to change your impact much at all. You would hardly notice the effect of stresses on a non-FF anyways unless you have a more accurate barrel like a SS barrel since your groups would appear more "open" anyways.
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Never been a fan of Privi 75 grain myself and have never read a decent review on it either. Then you haven't looked very hard. 100 Yard Accuracy Evaluation of Prvi Partizan 75 grain Match Ammunition. 
The Prvi Partizan 75 grain match ammunition uses an open-tip-match bullet very similar in configuration to Hornady’s 75 grain BTHP bullet used in Hornady’s TAP line of ammunition and in Black Hills’ 75 grain MHP line of ammunition. The Prvi Partizan (PPU) bullet has a nominal length that runs approximately 0.010” – 0.015” shorter than the Hornady bullet. The PPU 75 grain bullet does not have a cannelure, but the case mouth on this load does have a slight collet crimp on it which puts a slight crease in the bullet. 
The PPU 75 grain match load uses Boxer primed brass cases and is charged with “ball” powder. Neither the primer nor the case mouth have sealant and the primer is not crimped. Previous chronographing of this load through multiple barrel lengths shows it to run an average of 127 fps slower than the Black Hills 75 grain MHP load. 
I have read some statements recently that claim the PPU 75 grain bullet was designed to shoot well through 1:9” twist barrels, yet none of those making these statements have provided any scientific evidence to support this claim. According to the Greenhill formula, the optimal twist for the PPU 75 grain bullet is 1:7.6”. From a 1:9” twist barrel, the PPU 75 grain match bullet has a gyroscopic stability factor (GSF) of less than 1.25 for all velocities. It is generally accepted that a rifle bullet should have a GSF of 1.5 to 2, with 1.25 being the least acceptable GSF. Gyroscopc stability factor from a 1:9" twist barrel. 
Gyroscopic stability factor from a 1:7.7" twist barrel. 
The test-vehicle for this evaluation was an AR-15 with a 24” stainless-steel Kreiger VarMatch barrel, with a 1:7.7” twist, installed on a LaRue Tactical Stealth upper receiver. A Leupold Competition Series Scope was used for sighting. No malfunctions of any kind were experienced during testing. 
Following my usual protocol for accuracy evaluation, shooting was done from a bench-rest at 100 yards. Three 10-shot groups were obtained using the PPU 75 grain match load. Those three groups had extreme spreads that measured: 0.66” 0.92” 1.14” for an average extreme spread of 0.91”. The best 10-shot group from 100 yards. 
The three groups from above were overlayd on each other using RSI Shooting Lab to obtain a 30-shot composite group. The mean radius of this composite group was 0.29”. For comparison, this composite group is pictured below next to a composite group of the Black Hills 75 grain red box MHP load as well as a composite group of one of my handloads. 
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Federal Lake City Nato XM193 or M855 are really hard to beat for the buck in any twist AR barrel without fine tuning ammo. Hardly. The 75 grain Prvi load easily outshots XM193 and XM855. 
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Theoretically, yes.
People are all different. I shoot the same with or without them. For me they just don't make enough difference to justify cost. Maybe if I had a dedicated precision rig & I was shooting high grain $ ammo I might see more of a difference. But I just don't shoot that way. |
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That's about normal for that ammo. I'm a fairly good marksman, and truthfully have never CONSISTENTLY achieved better than about a 6" group at 100yd with a carbine using plinking ammo.
Go get some Black Hills and watch those groups SHRINK. This will have a much greater effect on accuracy than free-floating your barrel ever will. |
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Free floating will prevent a change in the point of impact from pressure on the barrel, usually from tightly slinging up with a target sling. It will not decrease the size group a particular ammo shoots. Actually it does by making the result more consistent. You would have less flyers. |
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Quoted: Quoted: Free floating will prevent a change in the point of impact from pressure on the barrel, usually from tightly slinging up with a target sling. It will not decrease the size group a particular ammo shoots. Actually it does by making the result more consistent. You would have less flyers. Are flyers are not typically user error or a result of a cold barrel? |
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Free floating will prevent a change in the point of impact from pressure on the barrel, usually from tightly slinging up with a target sling. It will not decrease the size group a particular ammo shoots. This. If you shoot with the sling wrapped around your arm for more tension and you didn't zero your gun with the exact amount of tension on the sling, the POI will be different. I dont use a sling. I went to the range again today. My 16" bcm upper shot better with the 69 gr prvi than it did with the 75 gr prvi. I also shot some 55 gr vmax reman'd ammo that I got at a local shop back home and the gun loved it,I did surprisingly well. I would post up my targets but il have to wait until I get back home in a few days. |
| Molon, I'm glad that stuff works for you. I would think that sweet rifle you're using would shoot anything with a little weight better than most. We tried a case of that stuff after your review in six different AR's and it just wasn't up to snuff at $9 a box, granted it's not $20 a box either. The rifles used (2) 1-9 twist, (1) 1-8, and (3) 1-7 twist. OP was covering a quarter with XM193 and not with the Privi 75gr on a bench with a scope. A few in my group had the same results but our groups were better than he posted worse was a little over 3 inch. The rifles we were using easliy shoot under 2in with XM193 or M855 most anyday, any weather. With real hand load match ammo around 1 in or better on a bench, scoped much more than not and only one has free float, but all have worked triggers. I'll stick with what works for me. |
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Molon, a bit off topic but how does the PRVI 75gr match ammo do as far as terminal ballistics? Prvi Partizan 75 grain OTM
Thanks to the efforts of the esteemed Dr. G.K. Roberts, we now have some excellent information on the terminal ballistic properties of the Prvi Partizan 75 grain OTM load. Privi Partizan 75 gr OTM Velocity: 2468 fps from a 16" 1:7” twist barrel penetration in bare ballistic gel: 12.6" neck length: 0.8” maximum temporary cavity: 3.2” at a depth of 4.7” recovered diameter: 0.36” recovered length: 0.15” recovered weight: 30.1gr percentage of fragmentation: 60% The same lot of Prvi Partizan 75 grain OTM ammunition that Dr. Roberts used in testing had a nearly identical velocity when I chronographed it from a 16" Colt barrel. 
atmospheric conditions: Average temperature- 83 degrees F Humidity - 64% Barometric pressure – 30.04 Elevation- 960 feet above sea level |
| No Molon I really wasn't considering yours a review but I did use the terminology . Was really going off of magazine articles mostly Shotgun News as they use the stuff a bunch for comparison when testing most of their AR's. I'm not really big on the lying thing. I knew there was a reason I don't come over to general discussion very ofter. Was just trying to help Op with his problem but I think he answered it for himself. That is a nice rifle you have there, much nicer than any of mine but I honestly won't spend any more of my hard earned cash on Privi unless $5 a box. |
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Free floating will prevent a change in the point of impact from pressure on the barrel, usually from tightly slinging up with a target sling. It will not decrease the size group a particular ammo shoots. Actually it does by making the result more consistent. You would have less flyers. Are flyers are not typically user error or a result of a cold barrel? They can be. But free floating minimizes cold barrel/hot barrel effect. The first thing I do in hunting rifles is to free float. That will ensure that it will group the same day after day after I sight in. No more flyers and wondering groups. |
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Quoted: Quoted: Molon, a bit off topic but how does the PRVI 75gr match ammo do as far as terminal ballistics? Prvi Partizan 75 grain OTM http://www.box.net/shared/static/3o4sakyz9f.jpg Thanks to the efforts of the esteemed Dr. G.K. Roberts, we now have some excellent information on the terminal ballistic properties of the Prvi Partizan 75 grain OTM load. Privi Partizan 75 gr OTM Velocity: 2468 fps from a 16" 1:7” twist barrel penetration in bare ballistic gel: 12.6" neck length: 0.8” maximum temporary cavity: 3.2” at a depth of 4.7” recovered diameter: 0.36” recovered length: 0.15” recovered weight: 30.1gr percentage of fragmentation: 60% The same lot of Prvi Partizan 75 grain OTM ammunition that Dr. Roberts used in testing had a nearly identical velocity when I chronographed it from a 16" Colt barrel. http://www.box.net/shared/static/4j7nxibrlt.jpg atmospheric conditions: Average temperature- 83 degrees F Humidity - 64% Barometric pressure – 30.04 Elevation- 960 feet above sea level It would appear to have less penetration [about an inch or two] (expected) than M193 but much better fragmentation and wounding cavity size. Sounds like what one should expect from a HP. Thanks for the info, Molon. Although, to be fair, I believe the Ammo Oracle terminal ballistics information for M193 was fired from a 20" barrel compared to a 16" barrel for this ammo. So, this ammo is likely far superior in wounding capability based on the fact that its terminal ballistics were measured at a much lower velocity than possible from a longer barrel. Feel free to correct me on any incorrect information... |
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Easy enough to test...
I'm an 0311 in the USMC and I do security. Where I work has a small 'armory' seperate from the main base armory, where there are shotguns and M4's ready to be issued quickly "if something goes down"... Anyway, one day I was tasked with cleaning weapons in this place. I always wondered does FF make a difference, so I was playing around with an M4 and a couple of Eotechs. I put 1 eotech on the upper reciever itself, and one out on the KAC NON-freefloat rail (it clamps to the gas tube, and fits in like a normal 2-peice handguard). I then zeroed them so that I saw 1 reticle. Put a loop sling on, and got in the prone. No matter how I moved my head around I couldn't get the reticles to line up again. Obviously with two holographic sights that close to eachother paralax and other issues come into play, but it's fairly plain to see that everything forward of the upper receiver itself was being skewed to the left and down. Had I had a free float tube, the barrel probably would not have been affected, at least not as much. |
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