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garryc
April 14, 2010, 06:24 PM
I'm looking for feedback on a Daniel Defence M4 barrel. It is chrome lined and 1-7 twist.

http://www.brownells.com/.aspx/pid=29320/Product/AR_15_M16_M4_BARREL

Palmetto-Pride
April 14, 2010, 06:30 PM
Did you notice that it has 10 reviews? The people that actually bought it would probably be a good start...........:)

garryc
April 14, 2010, 06:41 PM
I always figure those reviews are filtered. Toss in one bad one just to make it look good.

RT
April 14, 2010, 06:51 PM
DD makes good barrels. That looks like a nice 4150, MPI, 1:7 barrel. Don't know if that's one of their cold hammer forged, but you could do a lot worse.

Palmetto-Pride
April 14, 2010, 06:56 PM
I always figure those reviews are filtered. Toss in one bad one just to make it look good.

I can understand your skepticism, but on the flip side I have seen some products get really bad reviews. I think sites that allow reviews know it can be a double edge sword.

garryc
April 15, 2010, 06:01 AM
So, how does free floating an M4 barrel usually work?

WeedWacker
April 15, 2010, 07:59 AM
Free floating an M4 uses a single piece handguard and no delta ring. It only attaches at the upper receiver and doesn't make contact anywhere along the barrel or gas tube.

Palmetto-Pride
April 15, 2010, 08:20 AM
You will need a low profile gas block and a hand rail or guard that is made to be free floated.

garryc
April 15, 2010, 12:30 PM
No, I know how to do it, what I want to know is how it generally affects accuracy.

Omaha-BeenGlockin
April 15, 2010, 12:41 PM
I have one of those and its been good----says its on back order so good luck getting one any time soon.

moshpit
April 15, 2010, 12:56 PM
No, I know how to do it, what I want to know is how it generally affects accuracy.

Free floating the barrel on it's own does nothing to accuracy. But depending on your method of holding or slinging your rifle, a free floated barrel will not suffer accuracy degradation caused by grip-related barrel flex as much. This issue is VERY small at sub-100 meters, but at ranges out past 100 meters begins to show more and more degradation of accuracy in poor gripping scenarios. I'm not totally conversant on which grip scenarios constitute "poor-grip", per say, but I understand the theory behind it.

MMcfpd
April 15, 2010, 11:10 PM
The barrel linked is not a CHF, rather it's a close out item as DD has gone to all CHF production. There were some initial reports of short stroking attributed to undersize gas ports, but I believe there were few instances of that actually being the case.

I did put together a rifle with one:
http://i150.photobucket.com/albums/s95/MMcfpd/Last_09_AR.jpg

It doesn't have a lot down the pipe yet, but it may become a favorite as it appears to be pretty accurate. So, if you feel like building you'll probably do well with one of those barrels.

ETA - As soon as I posted I started wondering about them being a discontinued item and that Brownells listing shows availability as "Backordered." They may just be all gone.

Bartholomew Roberts
April 16, 2010, 09:36 AM
I keep a shooting log. After I added a KAC free-float rail and Magpul M93 stock to my Bushmaster 16" HBAR (only two mods), 5-shot groups improved by about 0.5" at 100yds using the same ammo.

If you check out some of Molon's posts at AR15.com, he did a similar test of freefloating and happened to arrive at about that same difference (0.5" improvement at 100yds).

moshpit
April 16, 2010, 09:59 AM
Considering even a small stock adjustment could have affected that accuracy, I find a half inch at 100 yards hard to credit to the barrel change. Stock size changes can directly affect shooter comfort and make that 1/2" difference (unless your groupings are already 1" and you just cut it down to 1/2" in which case that IS a huge improvement! But if it was around 2 to 3 inches, that difference is only 25-33% improvement)

Bartholomew Roberts
April 16, 2010, 10:35 AM
Considering even a small stock adjustment could have affected that accuracy, I find a half inch at 100 yards hard to credit to the barrel change.

Based on our previous discussions, I'm going to assume you have some kind of weird firearms dyslexia and consistently use the wrong part name. I am further going to assume you meant "free float handguard" instead of "barrel" in the above quote.

The difference (going from memory) was 1.5" to 2.0" 100yd 5-shot groups with Santa Barbara SS109 ammo. Changing to the Magpul M93 stock and the KAC free-float saw an immediate improvement of 1.0" to 1.5" 100yd 5-shot groups with the same ammo, from the first session out.

As the guy who was actually there and doing the shooting and has a few rounds through this platform, I'm going to credit the free float tube for the improvement. I'll also point out the other experiment I mentioned achieves the same result without messing with the stock.

Palmetto-Pride
April 16, 2010, 01:37 PM
Free floating the barrel on it's own does nothing to accuracy.

This is absolutly untrue free floating a barrel by itsself will improve accuracy. Just on the mere fact that a barrel that rest on a stock or hand guard will change POI from temp change when the barrel gets hot, way more than a free floated barrel.

garryc
April 16, 2010, 07:07 PM
Let's look at another one I'm considering. Bushmaster makes a 16" heavy barrel Dissipater, is that the full length forearm? What would you expect with a free float on that? They don't say what the twist is.

http://www.bushmaster.com/products.asp?cat=7

Bartholomew Roberts
April 16, 2010, 10:55 PM
It is a 1:9 twist. It will be be about as accurate as any other 16" Bushmaster HBAR, though you may do better with irons since you have better sight radius.