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Posted: 10/22/2012 5:47:42 PM EDT
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Remington R25
Fulton Armory .308/7.62 Medium weight 18.5" 1/10"twist SS Barrel JP Enterprises adjustable gas block CMC Trigger Tactical Ergo grip Omega 30 Suppressor 34mm 20moa ADM Recon Mount Bushnell 3.5-21x50mm G2DMR Reticle I just finished it and i'm doing my first unknown distance match this weekend. I'll update how that goes. http://sphotos-a.xx.fbcdn.net/hphotos-ash3/522825_10151204912563211_166616744_n.jpg http://sphotos-a.xx.fbcdn.net/hphotos-ash3/541078_10151204912653211_209820398_n.jpg http://sphotos-b.xx.fbcdn.net/hphotos-prn1/156460_10151204912473211_382322286_n.jpg Federal Gold Medal 168gr smk 10 shot group at a 100yds on the left. |
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That actually looks pretty sweet. The ADM mounts seem to need settling, unlike LaRue, I've noticed. I have both, and I have to give it up to La Rue for making a true return-to-zero QD mount. I have the LT-112 on my .260 Rem GAP, built on DPMS receivers.
That Criterion barrel from Fulton is a shooter, which is customary from them. |
| I haven't done a return to zero test so I don't know how it does. I'll be using 178gr hornady superformance ammo for the "sniper shoot" because the 168gr smk federal gm goes sub-sonic before 1000yds and doesn't do well going trans-sonic and the 178gr hpbt stays super-sonic to 1200yds which is the limit of the match. |
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I haven't done a return to zero test so I don't know how it does. I'll be using 178gr hornady superformance ammo for the "sniper shoot" because the 168gr smk federal gm goes sub-sonic before 1000yds and doesn't do well going trans-sonic and the 178gr hpbt stays super-sonic to 1200yds which is the limit of the match. Nooooooooooooo! Everyone to-date has had serious pressure issues with the Hornady Superformance .308 in gas guns. That load is meant for bolt guns only. Trust me. Especially in a suppressed gas gun, you will have issues. There have been quite a few threads about this here and on Sniper's Hide, all with the same conclusion. I'm guessing that case in the picture is of 178gr Superformance? If you want a really good load for the AR in .308, the 155gr Lapua Scenar or 155gr Berger is the way I would go, and have gone before when I ran a .308 AR built by GAP. In all seriousness, the .308 is really more of a 600-700yd gun in wind conditions of 10mph or more. That is why I went to the .260 Rem. I spent a lot of my career in the Army behind M24's, and have been shooting competitively ever since I got out, and I beat my head against the wall with .308 until I realized I was pushing it as far as practically possible, but wasn't as competitive as I could be against 6.5mm's, 7mm's, and .338 of course. If you do want to push it, get a bunch of Lapua Palma .308 brass with the Small Rifle Primers. That brass is a high pressure brass that can take a beating in the AR and deliver bolt gun velocities without the pressure signs you would see, like the ones the Superformance will show you if you drop the hammer on them. (They will thrash your brass, blow primers, violently smash the recoiling parts into your shoulder, etc.) |
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I haven't done a return to zero test so I don't know how it does. I'll be using 178gr hornady superformance ammo for the "sniper shoot" because the 168gr smk federal gm goes sub-sonic before 1000yds and doesn't do well going trans-sonic and the 178gr hpbt stays super-sonic to 1200yds which is the limit of the match. Nooooooooooooo! Everyone to-date has had serious pressure issues with the Hornady Superformance .308 in gas guns. That load is meant for bolt guns only. Trust me. Especially in a suppressed gas gun, you will have issues. There have been quite a few threads about this here and on Sniper's Hide, all with the same conclusion. I tuned my jp gas block. I've shot about 40 rds of it through my gun with no problems, but we will see i guess. |
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How does it cycle, and what does the brass look like afterwards? That's probably the best way to approach warmer loads in the AR. Have you chronographed that Superformance load?
The chrono is your first indicator of erratic behavior. If you have really wide Extreme Spread, you know you're in a bad place, pressure-wise. That said, the AR10 bolt and barrel extension will take the abuse and ask for more, unlike an AR15, but the timing of the gas system is where it bites you in the rear. If yours runs well suppressed with that load, I would just chrono it and take it from there. You might also consider the JP Silent Captured Spring for the AR10, to help keep the bolt locked longer. |
Here's the dope on that assuming a 2.9" Scope height. Yours should be within .4" of that I think. When I run dope on a load, I look for my 1 Mil wind drift threshold to get an idea of where my practical effective range is for a 10mph full value wind for 1st-round hit probability. You're getting pretty dang good velocity for that barrel length and a gas gun, with that bullet weight. You would get excellent speeds with the 155gr VLD-style projectiles, but drive-on with what you've got for the weekend if your gas system is tamed to be able to run that load. You aren't piercing primers or blowing primers, are you? 2650fps is what 150gr usually runs out of 18" guns with a hot load.
Range Velocity Energy Trajectory TOF Drift |
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Here's the dope on that assuming a 2.9" Scope height. Yours should be within .4" of that I think. When I run dope on a load, I look for my 1 Mil wind drift threshold to get an idea of where my practical effective range is for a 10mph full value wind for 1st-round hit probability. You're getting pretty dang good velocity for that barrel length and a gas gun, with that bullet weight. You would get excellent speeds with the 155gr VLD-style projectiles, but drive-on with what you've got for the weekend if your gas system is tamed to be able to run that load. You aren't piercing primers or blowing primers, are you? 2650fps is what 150gr usually runs out of 18" guns with a hot load. Range Velocity Energy Trajectory TOF Drift (yards) (fps) (ft-lb) (MILS) (sec) (MILS) 0 2654 2784 0.00 0.0000 0.00 100 2473 2417 0.00 0.1171 -0.20 200 2299 2089 -0.39 0.2429 -0.41 300 2132 1797 -1.13 0.3784 -0.64 400 1973 1538 -2.03 0.5247 -0.89 500 1821 1310 -3.07 0.6830 -1.15 600 1677 1112 -4.25 0.8546 -1.44 700 1543 941 -5.58 1.0412 -1.75 800 1420 797 -7.09 1.2439 -2.08 900 1309 677 -8.79 1.4641 -2.43 1000 1213 582 -10.72 1.7024 -2.80 1100 1134 508 -12.90 1.9585 -3.18 1200 1070 452 -15.34 2.2314 -3.57 Very close.... No blown or pierced primers. I'm thinking one of the reasons i'm not getting really high pressure is because of the barrel its self. It's a very smooth lapped 4 groove that shows no signs of copper fouling when cleaning after 40+ rounds. I'm thinking that helps keep the pressure down run it with this info 308. 178gr BC: .53 MV: 2654 Scope Height: 2.8 Temp: 62*f Alt: 628 Pressure: 30.09 250 yd zero |
| When I checked the BC on Hornady's website, it was .495 for G1 model. Hornady Data on 178gr AMAX |
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That is a good load. Just keep in mind your 1 Mil wind drift threshold is just under 500 yards, and you said the match will be UKD. Are you allowed to use LRF's, or do you have to Mil your targets out?
All the competitions I attend overseas are UKD, with a need to Mil them out. We make sure we know the dimensions of the width of the silhouettes. You should get dimensions before the match in the brief if possible. One thing that will kill your time in these events is if you use a data book while shooting. The best method for having your dope is with turret decals, followed by a dope chart attached to the scope, followed by a dope card laminated to the stock. You can run all your simplified ballistic charts into excel, then power point in a sideways graph with a 1:1 scale based on the circumference of your turret diameters. Print on high quality paper with a laser printer, and laminate them to the turrets for waterproofing. 
Range Velocity Energy Trajectory TOF Drift I take this data and simplify it into clickable form, so 13.72 Mils of drop becomes 13.7 Mils, 3.26 Mils becomes 3.3 Mils, etc. I cut out the flight time and use it for the leads for movers on another chart, which has to be memorized. Uisng the 250yd zero, you will want your 100yd POI data to fall back on, because the matches usually have some paper stage with faces, colored circles, etc. |
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Here is the link to the match: http://events.r20.constantcontact.com/register/event?oeidk=a07e6cmd0dqdb551eba
This is the second match they have held so they are still figuring stuff out. I use Shooter and Strelok ballistic programs for android phones. Shooter uses your gps to get the current weather from your closest weather station and automaticly adjusts your corrections which is nice if you can use it. I also have fixed ballistic charts and mil measurement charts for 18", 9", 4.5" targets. |
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Plus, i'm using the G2DMR reticle which has .1 mil measurement marks which is nice.
http://dscdaily.com/wp-content/uploads/2012/09/Screen-Shot-2012-09-04-at-7.22.17-PM.png |
| Well I shot the match and the rifle did really good. Me on the other hand did ok at best. I hit 12 out of 20 targets and my longest hit was 969yds and the farthest target was 1070(+ or -)yds. This was my first match and I caught myself making mistakes like not watching my bubble level, bad shooting positions, and not making wind calls. The rifle had no problems other than some blow back from the suppressor making the ammo dirty which didn't effect anything really. 1st stage I hit 2 of 5 targets, 2nd stage I hit 2 of 5, 3rd stage I hit 4 of 5, 4th stage i hit 4 of 5. As you can tell once I started to settle down I made more hits. |
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Those Fulton barrels are Criterion, which is basically Krieger, only button-rifled. Did your elevation dope end up being dead-on? Could you put up a link to the match, or give a brief match description? Sounds like you do have a shooter. The dope was damn close! Probably would have had more hits if I hadn't made some simple mistakes. I put the link up earlier but I think it's off their site now. |
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