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 Post subject: PSD or 10.5" upper?
PostPosted: Sun Dec 27, 2009 5:35 pm 
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I'm planning an SBR build, and really want to go with an LWRC upper (unless I just can't save up enough, then I might build a standard upper, but I want to go with an LWRC).

I was looking around at prices and for the most part, given the same caliber, the PSD uppers are much more expensive. Is there anything more to the PSD than just 2" less barrel than the 10.5"? Aren't the other parts the same? While a 8.5" would be nice with a suppressor, for the money, I have a hard time justifying the extra cash needed. Any info on the difference would be great!

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PostPosted: Mon Dec 28, 2009 2:37 pm 
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I'm certainly not the expert here, but this topic has been discussed a little in the past. If you're shooting 5.56 and/or supressed I think the consensus has pretty much been to go no less than 10.5". If I remember correctly it's because most companies don't guarantee/recommend going under 10.5" with their supressors because of the concern for baffel strikes. As well 10.5" was a better length for getting decent velocities out of a 5.56, unless you're looking at the PSD for extreme close quarters work and the 2" will give you more benefit then the added velocity, I'd say go 10.5".

If you're planning to shoot 6.8 I think their were some guys that got excellent results out of the PSD's which in my opinion would make it the chosen caliber for shorter lengths. As it's been said, mission drives equipment so I'd think about exactly what you need out of the SBR and make your decisions based on those facts. My suggestion would be to stay with the 10.5", but again I'm not an expert and it's just an opinion. I'm sure some of the other more knowledgable guys will chime in.

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PostPosted: Mon Dec 28, 2009 3:13 pm 
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I would go with the 10.5 as well. For all the same reasons. 8" is cool, but pretty much a novelty item. For 5.56 go with the 10.5, and save that $200 for your tax stamp.


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 Post subject:
PostPosted: Mon Dec 28, 2009 7:49 pm 
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I have both the 10.3" in 5.56 and the 8.5" in 6.8. Both are great guns. The 6.8 is better for short barrels, it was designed to be used in 16" and under barrels where the 5.56 was designed for 20" barrels. IMO the 10.3 is plenty short enough for most applications. If you want more energy on target, better penetration against inetermediate barriers, and better performing bullets at lower velocities then 6.8 is excellent. The 5.56 in the 10.3 inch barrel with the right ammunition is nothing to dismiss either. Darren has a list of ammunition that has good terminal performance out of the PSD in 5.56 but he still needs to list that information.

The average velocity difference per inch of barrel (depending on ammunition) is about 40 to 50 fps, so you will lose about 100 fps going from 10.3 to 8.5. Also, the shorter the barrel, the more muzzle blast you will get.

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 Post subject:
PostPosted: Mon Dec 28, 2009 8:25 pm 
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Not Darren, but here is the date he intended to post:

At 50 yards (bare gel),

SSA Barnes 45 gr. TSX: MV 2395 penetration 14.5", expansion 0.42", retained wt. 44.7 gr.
Federal 55 gr. Tactical Bonded: MV 2424 pen. 14.75", exp. 0.47", ret. wt. 54.8 gr.
Speer 64 gr. Gold Dot: MV 2216 pen. 13.5", exp. 0.50", ret. wt. 63.8 gr.
SSA Barnes 70 gr. TSX: MV 2306 pen. 23.5", exp 0.38", ret. wt. 69.9 gr.

At 100 yards (bare gel),

SSA Barnes 45 gr. TSX: pen. 16.8", exp. 0.34", ret. wt. 45 gr.
Federal 55 gr. Tactical Bonded: pen. 16.8", exp. 0.43", ret. wt. 55 gr.
Speer 64 gr. Gold Dot: pen. 16.2", exp. 0.45", ret. wt. 61 gr.

At 100 yards (Auto glass & gel),

Federal 55 gr. Tactical Bonded: pen. 11.5", exp. 0.32, ret. wt. 29 gr.
Speer 64 gr. Gold Dot: pen. 13.7", exp. 0.31", ret. wt. 35 gr.

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 Post subject:
PostPosted: Mon Dec 28, 2009 8:47 pm 
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Thanks 300LW. Those tests fall within the FBI's recommended 12 to 18 inches of penetration except for the 70 grain TSX which is a beast and gets 23.5".

I'm biased but I would still take a 6.8 in the PSD, ALOT more energy. The 70 grain TSX at 2306 from the 5.56 PSD gets you 826 pounds of energy. The 6.8 PSD using the 85 grain TSX at 2600 fps (new tactical loading from SSA) gets you 1275 pounds. The SSA Tactical 115 grain OTM is chronographing from my PSD at about 2160 average for 1191 pounds.

I need to look at my chronographing data (not with me at the time of this posting) but my LWRC 10.3" 5.56 pushes the Federal Tactical 62 grain BSP to about 2500 fps for 860 pounds per square inch. I think I chronographed the 64 grain Gold Dot from my 10.3 last year so I need to see what that did for comparison. My M6A1 10.3" is an original Leitner Wise upper, 2006 - 2007 that I ordered from Darren, and has been a fanatastic performer. That old chrome lined bore chrono's fast, as fast as our Colt Commandos with 11.5" barrels. Anyway, I'll post some velocities when I get them.

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 Post subject:
PostPosted: Mon Dec 28, 2009 8:50 pm 
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Awesome guys, thanks for the help! I think I've settled on a 10.5" upper once I get my lower delivered and my BAFTE paperwork settled. Still have to decide on 5.56 or 6.8. If I didn't ALREADY have a 5.56 rifle, I'd go with 6.8 without reservation. Since I have a 5.56 though, it'd be nice to not have to buy new magazines and different ammo for the shortie. I'd still really really really like it in 6.8 though. Guess we'll see what's out there if/when I get things approved.

I was really thinking of just going with an M6 standard upper since I really want a MOE handguard on it (I know I'd have to modify it somewhat to work), but I'm not sure if anyone out there has an M6 10.5" in either 5.56 or 6.8. Even if they've got them now, who knows what'll be around in 3-5 months when I get the paperwork back.

Again, big thanks for the help!

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 Post subject:
PostPosted: Mon Dec 28, 2009 9:28 pm 
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The 5.56 with 10.3" barrel is good all around carbine. I found my chronographing data for the Speer 64 grain Gold Dot and Federal 64 grain TRU from my 10.3" barrel.

Gold Dot - 2483 fps - 876 energy
TRU - 2578 fps - 944 energy

Like I said, this barrel chronographs high, always has.

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