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Discussion Starter · #1 · (Edited)
16" LMT 6.8SPC DI:
1. Brief Description:
16" Chrome Lined Barrel with a 1:10" Twist/6-Groove/SAAMI Chamber (Converted to SPCII Chamber). Carbine Length Gas System.

2. Break-in:
The first thing I did was convert the SAAMI Chamber to the SPCII Chamber. I also polished up the Bore with some Remington cleaner. I broke in the barrel with the Tubbs Final Finish Bullets (Sierra 135 Gr. SMK Bullets). I had no failure to feeds of any sort during break-in.

3. Accuracy Results:
Support Used: Harris Bi-pod and rear sandbag.
Optic: Swarovski Z6i 1x6 scope set on 6x.
Trigger: WOA Tuned RRA with Superior Shooting Springs.
Range: 100 Yards.
Shot Groups: 2 10 round shot groups.

Sierra 90 Gr. HP:
Brass: SSA.
Primer: CCI#41.
Crimp: Lee FCD.
OAL: 2.260".
Temp: 80.

28.6 Gr. of H4198:
Avg: 2885 fps, Lo: 2867 fps, Hi: 2898 fps, ES: 31, SD: 13

27.6 Gr. of AA1680:
Avg: 2769 fps, Lo: 2754 fps, Hi: 2783 fps, ES: 29, SD: 14
28.1 Gr. of AA1680:
Avg: 2827 fps, Lo: 2812 fps, Hi: 2842 fps, ES: 30, SD: 21

33.5 Gr. of TAC:
Avg: 2632 fps, Lo: 2619 fps, Hi: 2661 fps, ES: 42, SD: 18

Speer 90 Gr. TNT:
Brass: SSA.
Primer: Wolf Smal Rifle Magnum.
Crimp: Lee FCD.
OAL: 2.270".
Temp: 60.

28.1 Gr. of H4198:
ACCURACY: 1.286"
28.6 Gr. of H4198:
ACCURACY: 1.065"
29.1 Gr. of H4198:
ACCURACY: 1.058"
29.6 Gr. of H4198:
ACCURACY: 1.180"

31 Gr. of H322:
ACCURACY: 1.225"

Hornady 110 Gr. BTHP:
Brass: SSA.
Primer: Wolf Smal Rifle Magnum.
Crimp: Lee FCD.
OAL: 2.245".
Temp: 60.

25.3 Gr. of H4198: (5 rounds)
ACCURACY: 2.201"

29 Gr. of H322:
ACCURACY: 2.207"
29.5 Gr. of H322:
ACCURACY: 2.632"

29.5 Gr. of X-Terminator:
ACCURACY: 3.518"

Hornady 110 Gr. V-Max:
Brass: SSA.
Primer: Wolf Smal Rifle Magnum.
Crimp: Lee FCD.
OAL: 2.270".
Temp: 60.

25.3 Gr. of H4198: (5 rounds)
ACCURACY: 1.233"

28.5 Gr. of H322:
ACCURACY: 1.739"
29 Gr. of H322:
ACCURACY: 1.667"
29.5 Gr. of H322:
ACCURACY: 1.956"

29.5 Gr. of X-Terminator:
ACCURACY: 2.595"

Hornady 110 Gr. V-Max:
Brass: SSA.
Primer: CC#41.
Crimp: Lee FCD.
OAL: 2.260".
Temp: 80.

30.5 Gr. of TAC:
Avg: 2438 fps, Lo: 2437 fps, Hi: 2442 fps, ES: 5, SD: 2
ACCURACY: 2.050"

25.3 Gr. of H4198:
Avg: 2482 fps, Lo: 2469 fps, Hi: 2492 fps, ES: 23, SD: 12

Sierra 110 Gr. Pro-Hunters:
Brass: SSA.
Primer: Wolf Smal Rifle Magnum.
Crimp: Lee FCD.
OAL: 2.270".
Temp: 60.

28.5 Gr. of H322:
ACCURACY: 1.422"

Sierra 115 Gr. SMK:
Brass: SSA.
Primer: Wolf Smal Rifle Magnum.
Crimp: Lee FCD.
OAL: 2.270".
Temp: 60.

24 Gr. of H4198: (5 rounds)
ACCURACY: 1.076"

28 Gr. of H322:
ACCURACY: 1.033"
28.5 Gr. of H322:
ACCURACY: 1.549"

29 Gr. of X-Terminator:
ACCURACY: 1.964"

Sierra 115 Gr. SMK:
Brass: SSA.
Primer: CCI#41.
Crimp: Lee FCD.
OAL: 2.260".
Temp: 80.

30 Gr. of TAC:
Avg: 2361 fps, Lo: 2347 fps, Hi: 2385 fps, ES: 38, SD: 20
ACCURACY: 1.693"

24 Gr. of H4198:
Avg: 2322 fps, Lo: 2298 fps, Hi: 2347 fps, ES: 49, SD: 24
------------------------------------------------------

Factory ammo:

SSA 90 Gr. HP Tactical Load:
Avg: 2937 fps, Lo: 2904 fps, 2969 Hi: fps, ES: 65, SD: 21
ACCURACY: 1.536"

SSA 110 Gr. Pro-Hunter Commercial Load:
Avg: 2443 fps, Lo: 2415 fps, Hi: 2469 fps, ES: 54, SD: 19
ACCURACY: 1.555"

SSA 115 Gr. Enhanced SMK Commercial Load:
Avg: 2465 fps, Lo: 2450 fps, Hi: 2473 fps, ES: 23, SD: 7
ACCURACY: 1.860"

4. Conclusion:
1-3-09: So far, I have only had zero failures, but I only fired 80 rounds. I tested the SSA 115 Gr. SMK Tactical Loads and I didn't have any pressure signs of any sort. The brass is ejecting at the 1 O'Clock Position wih all of the ammo I tested, which is not good. I even switched to the H2 Buffer and it only helped out a little bit. I checked the headspace with the No-Go Gauge and the bolt closed, which is not supposed to. So either it is seriously over gassed, or there is a headspace issue.

1-5-09: I spoke with LMT today about the brass ejecting forward and I was told that it should eject from the 1-3 O'clock position. I also told them about the no-go gauge closing and I was told to check out the accuracy. If it is bad, they will replace the barrel.

2-11-09: I did send the LMT 6.8SPC barrel back to LMT and they replaced it. Turn-around time was approximately 1 week. I Reamed the barrel to the SPCII Chamber using the Michiguns SPCII Reamer and all of the ammo that I tested had no pressure signs. Today, I finally got the chance to finish test loading the 6.8SPC MRP Barrel. I can honestly say I am pleasantly surprised with the accuracy of the barrel. Even the Hornady 110 Gr. V-Max shot under 2MOA at 100 Yards. The winners were definitely the Speer 90 Gr. TNT with H4198 (no surprise), and the Sierra 115 Gr. SMK with H322. The only bullet that sucked ass was the Hornady 110 Gr. BTHP, which is very disappointing because I was hoping that it would be the most accurate. All of the other bullets were all under 2MOA, with the TNT and SMK right at 1MOA.
The only negative was that this barrel and most of the LMT 6.8SPC barrels are seriously over gassed. Even with the H3 buffer, most of the brass was ejecting at the 2 o'clock position. LMT uses the Hornady ammo as their test ammo, which is pretty weak compared to the SSA ammo, so that is most likely why their barrels are over gassed.

3-25-09: I recently sent my barrel to Harrison to get cut down to 14" and have the FSC30 permanently attached. This was mainly one to try to get the brass to eject at the 3-4 o'clock position since this barrel was so over-gassed. I recently got the barrel back and I went to the range today where I tested it out. With the H3 buffer, the brass was ejecting at the 3-4 o'clock position and the recoil was much less. I also tried some more loads with the H4198 (Hornady 110 Gr. BTHP, Hornady 110 Gr. V-Max, and the Sierra 115 Gr. SMK) and the accuracy was great. I only chronoed the Speer 90 Gr. TNT with 28.8 Gr. of H4198 (2872 FPS), which is the load I am taking to the class in April. I'm officially a happy camper. H, I love you man. (No ****).
 

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That is good accuracy wise... cant wait to see how she does as you continue to shoot her... are you planing on doing any courses with it?
 

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I am getting 3 o'clock with a H3 buffer in my MRP with Hornady and Remington ammo.
I tried Slash's HSS buffer which is even heavier at 6.5 ounces and noticed no change from the H3.

As soon as I receive my Michiguns reamer and have the SPC II chamber I will try some SSA ammo and see what happens.

Slash also makes a XH buffer that is 8 ounces, do you think that would be worth a try?

:cool:
 

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Discussion Starter · #4 ·
BillBond said:
I am getting 3 o'clock with a H3 buffer in my MRP with Hornady and Remington ammo.
I tried Slash's HSS buffer which is even heavier at 6.5 ounces and noticed no change from the H3.

As soon as I receive my Michiguns reamer and have the SPC II chamber I will try some SSA ammo and see what happens.

Slash also makes a XH buffer that is 8 ounces, do you think that would be worth a try?

8)
It is worth a try. I noticed a difference from the H2 to the H3. I also ordered the heavier bolt carrier from LMT, but that is on backorder.
 

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Discussion Starter · #5 ·
marinesg1012 said:
That is good accuracy wise... cant wait to see how she does as you continue to shoot her... are you planing on doing any courses with it?
For a 16" Medium profile chrome lined barrel, I am very happy with it. I plan on taking the 6.8SPC course in April down in Carolina that J.Boyette is having. I'l either use the Speer TNT load or the Sierra 115 Gr. SMK Load.
 

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Let us know how she runs during extended shooting sessions.... I plan on running my Xtreme through a course in july just to get the 6.8 out there...
 

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Discussion Starter · #7 ·
The weather today was 60 and at the end I shot off over 100 rounds in rapid succession with no pressure signs. Half of those rounds rounds were loaded hot, so I don't think I'll have a problem with the hotter loads in the summer.
Out of the 5 SPC barrels that I've had this one and my 16" Cardinal Armory have been the two most accurate ones.

I also sent LMT an E-Mail with the results of this testing. I doubt they'll change anything, but it will be worth it.
 

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outstanding data logging.... I am jealous
 

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My 556 MRP has been perfect right out of the box! Ejects at 3:00 consistantly and has not had a single failure.

It would be nice to find some 6.8 so I can test out my 6.8 MRP!!!!! :evil: If ammo doesn't start to loosen up I am going to dump a brand new 6.8 MRP! Which is really dissapointing as I had high hopes for the platform. The ammo situation is laughable and embarrasing to the ammo companies. I can go out and buy almost any other ammo on demand, yet I cant find a single round of 6.8 for sale. I have some on order but so far I have been waiting a month!!!!!

I believe the current ammo situation if it continues will kill the 6.8 as having any viable marketshare. The platform is useless without ammo! I would rather shoot .308 than have a boat anchor in the safe.
 

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Discussion Starter · #10 ·
d90king said:
My 556 MRP has been perfect right out of the box! Ejects at 3:00 consistantly and has not had a single failure.

It would be nice to find some 6.8 so I can test out my 6.8 MRP!!!!! :evil: If ammo doesn't start to loosen up I am going to dump a brand new 6.8 MRP! Which is really dissapointing as I had high hopes for the platform. The ammo situation is laughable and embarrasing to the ammo companies. I can go out and buy almost any other ammo on demand, yet I cant find a single round of 6.8 for sale. I have some on order but so far I have been waiting a month!!!!!

I believe the current ammo situation if it continues will kill the 6.8 as having any viable marketshare. The platform is useless without ammo! I would rather shoot .308 than have a boat anchor in the safe.
Have you tried ordering from SSA? They usually have ammo in stock.
 

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I just bought ammo and brass direct from SSA - and received my notice that it shipped yesterday. I also bought some from Palmetto a few weeks ago....maybe I've been lucky finding 6.8 ammo without a problem. I just got my dies from Midway so I'll probably focus on reloading for awhile....now all I need is my extreme upper :)
 

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Discussion Starter · #13 ·
I recently sent my barrel to Harrison to get cut down to 14" and have the FSC30 permanently attached. This was mainly one to try to get the brass to eject at the 3-4 o'clock position since this barrel was so over-gassed. I recently got the barrel back and I went to the range today where I tested it out. With the H3 buffer, the brass was ejecting at the 3-4 o'clock position and the recoil was much less. I also tried some more loads with the H4198 (Hornady 110 Gr. BTHP, Hornady 110 Gr. V-Max, and the Sierra 115 Gr. SMK) and the accuracy was great. I only chronoed the Speer 90 Gr. TNT with 28.8 Gr. of H4198 (2872 FPS), which is the load I am taking to the class in April. I'm officially a happy camper. H, I love you man!!! (No ****). :lol: :lol: :lol:
 

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paulosantos said:
I recently sent my barrel to Harrison to get cut down to 14" and have the FSC30 permanently attached. This was mainly one to try to get the brass to eject at the 3-4 o'clock position since this barrel was so over-gassed. I recently got the barrel back and I went to the range today where I tested it out. With the H3 buffer, the brass was ejecting at the 3-4 o'clock position and the recoil was much less. I also tried some more loads with the H4198 (Hornady 110 Gr. BTHP, Hornady 110 Gr. V-Max, and the Sierra 115 Gr. SMK) and the accuracy was great. I only chronoed the Speer 90 Gr. TNT with 28.8 Gr. of H4198 (2872 FPS), which is the load I am taking to the class in April. I'm officially a happy camper. H, I love you man!!! (No ****). :lol: :lol: :lol:
I thought it was mandatory to have pictures with range reports. Whats the deal :lol: :lol:
 

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I love the 14" barrel with the FSC30, my new upper with the DD rail is over at ADDAX for the prevision conversion system, it has a spike's national match m16 carrier the LMT bolt just showed up today, it has the spikes upper and lowers with a cmmg 2 stage trigger, and a FDE UBR for eyes it is getting a T1 on a Larue mount
 

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Discussion Starter · #17 ·
I spoke with Gene from LMT today and he was very receptive. He will be testing the next batch of barrels so that the gas port will be set up properly so it isn't so overgassed. I did ask about the gas piston and they will be making one, but they are very busy with their .308 right now.
 

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Just got my MRP cut down to 14'' by ADCO with the PWS FSC30 pinned. Absolutely love it. Now it is nice and compact. NO problems with short stroking or ejection. It spits em out at 4:00 o'clock right on the money every time. Tested a variety of SSA commercial and combat 110's, and Hornady v-max and BTHP. The setup includes an SSS spring [uncut], enidine buffer, LMT standard AR carrier, and a LMT enhanced bolt.
 
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I've always wanted to get a 6.8 barrel for my MRP. I was always turned off due to the chamber and reports of horrible accuracy. Much like the initial numbers reported from barrel #1 Paulo tested.

Now you have my interest raised again. With handloads can you reasonably expect .5 - .75 range out of a 14-16"? I have a 14.5 CM and a 18" SS that both shoot 5 shot groups in the mentioned range at 100yrds.

Great testing BTW.
 

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Discussion Starter · #20 ·
I've always wanted to get a 6.8 barrel for my MRP. I was always turned off due to the chamber and reports of horrible accuracy. Much like the initial numbers reported from barrel #1 Paulo tested.

Now you have my interest raised again. With handloads can you reasonably expect .5 - .75 range out of a 14-16"? I have a 14.5 CM and a 18" SS that both shoot 5 shot groups in the mentioned range at 100yrds.

Great testing BTW.
The 18" SS barrel should be able to. You might want to either keep it with the SAAMI chamber or get it converted to the DMR chamber. With mine, I can get a couple of bullets to shoot 1MOA at 100 yards (10 rounds.).
 
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