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Posted: 7/12/2003 11:32:00 PM EDT
I'm looking to build an SPR from the ground up and would like to know what details I should pay close attention to in order to squeeze the most accuracy out of the rifle.

I know my way around a bolt gun and what it takes to accurize a Rem 700. But, other than quality components, what can be done to an AR to make it ultra accurate?

I also have a couple of specific questions...

1) Is it common to specify freebore lenght to a barrel maker? Or do they already have set standards which have tighter tolerance than factory?

2) Would it pay to have a matched Lower/Upper set like the one offered by Les Baer?

3) Who makes the best Lowers and/or Uppers?

4) I've seen advertisements for lowers that are cast, forged, etc. Which is the best?

For reference, I have the tools and know-how to work on AR's. I installed a JP Single Stage Trigger and a FF RAS on my first and only AR, a preban Colt with a 16" 1:9 Colt M4 upper. So assembly should not be a problem. This rifle shoots sub MOA with American Eagle 55gr FMJ using an Aimpoint ML2 with 4MOA dot. I've not mounted a scope or handloaded for it yet to test true accuracy.

Thanks!
-Red-
Link Posted: 7/13/2003 5:00:17 AM EDT
[Last Edit: 7/13/2003 5:12:16 AM EDT by Halfcocked]
If you have high quality components, barrel, sites, trigger, assembled competently, there is not much else you can do to make it more accurate. Some barrel smiths will cut the chamber and set the barrel extension to make a close tolerance fit with the bolt. Mike Bykowski, High performance International, is one that does it. He will also chamber it how ever you want (within reason). Most aftermarket barrel smiths will work with you. If you go this route your rifle may be a little finicky on what it will digest reliably. After that hand loading adds the next biggest potential for an increase in accuarcy. I would research bullets first and try to decide on a type and weight range that you want to shoot. Actually this should be done first as this will also determine what twist rate your barrel should be. Some heavey VLD bullets when loaded won't fit in the magazine. Some VLDs that do fit might work best seated into the lands. If you have your thoat cut to accomodate these it may preclude using factory or non VLD ojive bullets. They will be too far into the lands and may cause high pressure problems. You will have to check and perhaps seat the bullets of factory or standard ojive bullets a little deaper into the case. Once you have a good rig there is a lot of work to do with different burn rate powders, seating depths, brass manufacturers, brass prep... Edited to add that forged is generaly considered best. A tight fitting upper an lower is also a good thing but but may be a little over rated. This stems from the practice of glass bedding wood stocked rifles and is not quite as crucial for the AR-15 platform. However, a tight upper to lower fit does tend to instill a bit more confidence in the shooter than a rattle trap.
Link Posted: 7/13/2003 12:42:38 PM EDT
[Last Edit: 7/13/2003 12:47:47 PM EDT by scedward]
First off, I am no expert. I am however, fairly well read on the subject and in the process of the same project you are...just not in SPR configuration. 1. Most smith's with throat a barrel however you want. This is a question to ask your gunsmith... 2. No. Upper to lower fit will not affect accuracy a distinctive amount. If the upper/lower fit is loose and bothers you, get an accuwedge. 3. Take your pick...buy from the tier 1 manufacturers and you can't go wrong. 4. Forged *Edit to add:* My research tells me that the single most important thing that affects accuracy on an AR is the barrel. Free float a good barrel and you should be on your way! -Scott
Link Posted: 7/13/2003 1:26:27 PM EDT
I think most important is the trigger and I can prove it!
Link Posted: 7/13/2003 1:47:38 PM EDT
Key Factors for AR Accuracy? Operator skill. The rest is peripheral, marginal amd merely complimentary to skill. Learn the basics of marksmanship.
Link Posted: 7/13/2003 3:35:45 PM EDT
I'll agree that the nut behind the trigger is the one that needs the most adjustment. Once past that, I would put biggest emphasis on barrel, trigger and ammo (in that order). Upper to lower fit isn't going to matter, but if you are looking for tight, try Oly. I've never seen one that was loose.
Link Posted: 7/13/2003 7:58:25 PM EDT
[Last Edit: 7/13/2003 8:00:23 PM EDT by markmcjunkins]
To build a tack driver, get a Compass Lake barrel and matched bolt, free float the barrel, get a good trigger job, NM sights if you're not going to use any optics. Also good ammo.
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