Range Report More Load testing with my Larue Stealth

355sigfan

355sigfan

Sergeant
Full Member
Minuteman
Apr 12, 2004
328
5
Alaska
#1
10-11-10 Chrono testing and accuracy with Vitavory N140.

(I have wanted this powder for a while but its made from unobtainium meaning I could never find it in stock until a few days ago at the Sportsmans warehouse. They only had 1 pound)

Gun Larue Stealth
Laruedesc.jpg

24.1 grains (Sierra recommended Accuracy load)

1. 2574
2. 2589
3. 2613
4. 2613
5. 2599
Average 2597
Spread 39
Accuracy .568 Best 4 All 5 groups .73

N140accuracyload.jpg


24.5 grains (max load)

1. 2634
2. 2611
3. 2676
4. 2692
5. 2688
Average 2660
Spread 81

Accuracy .90

N140maxcharge.jpg


I like this load the best its 100 fps faster than my accuracy loads with N135, Varget, and H335 and its still very accurate.

Best loads to date in my Larue Stealth. (all with Sierra 77 grain SMK)
BEST LOADS in Larue Stealth with 77 grain SMK bullets

24.1 grains (Sierra recommended Accuracy load)

6. 2574
7. 2589
8. 2613
9. 2613
10. 2599
Average 2597
Spread 39
Accuracy .568 Best 4 All 5 groups .73 (one called flier ruined average)


Load 23.8 grains of Varget Remington Match primers 77 grain SMK

1. 2455
2. 2480
3. 2538
4. 2495
5. 2530
Average 2500 Spread 83
Average 5 shot group .66

N135 21.8 grains 77 grain SMK

1. 2448
2. 2545
3. 2534
4. 2519
5. 2459
Average 2501
Average 5 shot group .65

22.6 grains of H335

1. 2524
2. 2505
3. 2483
4. 2529
5. 2521
Average 2512 Spread 46
Average 5 shot group size .72
 
#2
Re: More Load testing with my Larue Stealth

Keep the good info coming! I'm building an SPR off a Larue Stealth platform myself, so this is an interesting thread to me.
 
#3
Re: More Load testing with my Larue Stealth

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Alaskapopo</div><div class="ubbcode-body">
22.6 grains of H335

1. 2524
2. 2505
3. 2483
4. 2529
5. 2521
Average 2512 Spread 46
Average 5 shot group size .72 </div></div>


Speed this load up a bit. I run 25.0 grains of H335 with 77gr SMK... 20" Larue stealth upper... this load is the cats ass for my gun.. just sayin...
 
#4
Re: More Load testing with my Larue Stealth

To the OP, I've been getting very consistent accuracy with 24.0 grs of TAC with 77SMKs in both Win and LC09 brass in my 18" Larue Stealth SPR(ish). Its a bit slow at 2640 fps, but it shoots lights out to 500m.

And the beauty is TAC is one of the cheapest and most available powders out there.
 
#7
Re: More Load testing with my Larue Stealth

Very nice post! Also, very impressive groups, particularly with the 24.1gr load. That LaRue is sweet. I'm curious as to your intended use for these loads, and whether you have tested the accuracy of any of them yet at longer ranges (200-600 yd)?

The reason I ask is that it seems like 2500-2660 fps is rather slow to be pushing an SMK 77gr if you have any intention of going out to 600yd. If you don't, well there's my answer. But with that MV, you're looking at a drop of over 10 feet (5.6 mil) at 600yd. Is it not possible to push the SMK 77s any faster (ie. unsafe pressure), or does the accuracy suffer too much if you do?

I recently ran some Hornady 5.56 Superformance 75gr BTHP and 5.56 SSA 77gr OTM through a 21" (1 in 10" twist) just to see what they would do. The Superformance averaged over 2900 fps and the SSA came in at over 2800 fps. Now, I'm in no way trying to compare accuracy/quality of these commercial loads to your handloads. I'm just curious about what you think a handload with a higher MV, say in the 2800-2900 fps range, might (or to be fair, might not) buy in the accuracy dept. at a longer range?
 
#8
Re: More Load testing with my Larue Stealth

The furthest I can shoot is 600 yards. You would think Alaska would have longer ranges but that is the max I have available to me and that one is 90 miles away.

Every time I have pushed the velocity my accuracy has suffered. N140 has given me the best velocity with good accuracy so far.

My Larue barrel is a little slow for a 20 incher. Its only 100 fps faster than my 14.5 inch Noveske carbine barrel.
Pat
 
#9
Re: More Load testing with my Larue Stealth

Thanks for your response! I was guessing that might be the case. I had a discovery along the lines you just mentioned this past weekend. I was testing a (factory) 45gr .223 varmint load in my Sig 556 DMR (21", 1 in 10" twist). I have pushed a lot of different factory loads through this weapon and strangely enough, the best shooters are FGMM and Black Hills .77gr. Go figure. Anyhow, the DMR, which is a piston gun, has an adjustable gas valve that allows you to close off the port and prevent cycling. My understanding is that this was intended enable to allow single shot mode to improve the accuracy.

The average muzzle for the FGMM and BH 77gr loads is about 2525 +/- 50 fps and in my hands, there was no statistically significant difference in accuracy using the heavier (longer) loads in single shot mode. However, I found that with the 45gr varmint load (MV = ~3200-3250 fps), the single shot mode made marked difference in accuracy (better). Further, the standard deviation of the muzzle velocity (10 shot strings) went from ~50-60 fps down to less than 20 fps. So I'm guessing that pressure fluctuation during cycling was playing some role in the decreased accuracy during semi-auto firing.

Does your LaRue have the option of shutting the gas system off? If so, you might see some improvement in the accuracy of your hotter/faster loads. For me, the single shot gas valve setting is somewhat of a pain in the ass and it defeats the purpose of having a semi-auto for full time use, but it's nice to know I can get some improvement in accuracy with certain loads using it.

Anyhow, I've been interested one of the LaRue 556s, so it's great to see your reports on it, thanks!
 
#12
Re: More Load testing with my Larue Stealth

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Alaskapopo</div><div class="ubbcode-body">The furthest I can shoot is 600 yards. You would think Alaska would have longer ranges but that is the max I have available to me and that one is 90 miles away.

Every time I have pushed the velocity my accuracy has suffered. N140 has given me the best velocity with good accuracy so far.

My Larue barrel is a little slow for a 20 incher. Its only 100 fps faster than my 14.5 inch Noveske carbine barrel.
Pat</div></div> Sorry to get off topic, but where do you go to shoot 600 yds?
 
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