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Discussion Starter · #1 ·
Below are my results with recently purchased factory ammunition. I am running a 12.5" ARP barrel with liberty mystic multican.

CBB MKZ 105
2640,2625,2635,2650,2638
avg 2637

CBB MKZ 120
2439,2450,2395,2428
avg 2428

hndy 120sst
2395, 2351
avg 2373

S&B 110 FMJ
2509,2528,2476,2468
avg 2495

PPU HP BT
2250,2278,2236, 225
avg 2255
 

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Below are my results with recently purchased factory ammunition. I am running a 12.5" ARP barrel with liberty mystic multican.

CBB MKZ 105
2640,2625,2635,2650,2638
avg 2637

CBB MKZ 120
2439,2450,2395,2428
avg 2428

hndy 120sst
2395, 2351
avg 2373

S&B 110 FMJ
2509,2528,2476,2468
avg 2495

PPU HP BT
2250,2278,2236, 225
avg 2255
Great results from our CBB MKZ ammunition!
Thank you for sharing!
 

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Below are my results with recently purchased factory ammunition. I am running a 12.5" ARP barrel with liberty mystic multican.

CBB MKZ 105
2640,2625,2635,2650,2638
avg 2637

CBB MKZ 120
2439,2450,2395,2428
avg 2428

hndy 120sst
2395, 2351
avg 2373

S&B 110 FMJ
2509,2528,2476,2468
avg 2495

PPU HP BT
2250,2278,2236, 225
avg 2255
Fantastic thanks for the info , I'm definitely going to grab a few boxes of the 105 CBB MKZ for my 12.5" ARP I need to whack a deer this year and pop the 12.5's cherry.
What size groups did you shoot ?
 

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Discussion Starter · #5 ·
Fantastic thanks for the info , I'm definitely going to grab a few boxes of the 105 CBB MKZ for my 12.5" ARP I need to whack a deer this year and pop the 12.5's cherry.
What size groups did you shoot ?
I think it was 1.5” or 1.25. with 1 by 6. was busy breaking it in and getting it setup for hunting.
 

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Below are my results with recently purchased factory ammunition. I am running a 12.5" ARP barrel with liberty mystic multican.

CBB MKZ 105
2640,2625,2635,2650,2638
avg 2637

CBB MKZ 120
2439,2450,2395,2428
avg 2428

hndy 120sst
2395, 2351
avg 2373

S&B 110 FMJ
2509,2528,2476,2468
avg 2495

PPU HP BT
2250,2278,2236, 225
avg 2255
Out of curiosity, do you have any results without a suppressor? I've seen some actual testing on 5.56 ammunition's, particularly M8551 where a suppressor actually netted 90FPS more MV than no suppressor. I'm curious to see if 6.8 SPC benefits from a suppressor or not regarding MV.
 

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Discussion Starter · #7 ·
Interesting. Short answer is no. But will post when I get around to it again. have heard that supressor may bring 20fps more on 6.5 creedmore which runs about 2700 fps on 24” barrel. waa getying snother 12.5 set up for thermal. got crappy 2.5” groups after more than 60 rounds fired in less than 1 hr. took it for another spin and got a 1.5” group with 110 s&b. hiwver was to late and thermal is gonna have to live on 308 for now. A heavy countour 12.5 may be the one. lol.
 

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I have no idea how much 6.8 SPC is affected, I was just curious. And for 5.56, it is probably highly dependent upon the load. But if you read the linked testing from NSWC-Crane, when they were testing mid-length gas ports for reliability in service M4A1's (semi and 3rd burst select fire), they chrono-graphed M855A1 both suppressed and unsuppressed.

What was strange was they picked up about 80 FPS suppressed with that load in 5.56. So I've been curious to see how other calibers benefit for suppressors in terms of MV and if it was particularly only 5.56 M855A1 that saw such large gains.

NSWC-Crane Mid-Length Gas System Testing Shows Increased Performance & Service Life For M4 Carbines - Soldier Systems Daily
 

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I have no idea how much 6.8 SPC is affected, I was just curious. And for 5.56, it is probably highly dependent upon the load. But if you read the linked testing from NSWC-Crane, when they were testing mid-length gas ports for reliability in service M4A1's (semi and 3rd burst select fire), they chrono-graphed M855A1 both suppressed and unsuppressed.

What was strange was they picked up about 80 FPS suppressed with that load in 5.56. So I've been curious to see how other calibers benefit for suppressors in terms of MV and if it was particularly only 5.56 M855A1 that saw such large gains.

NSWC-Crane Mid-Length Gas System Testing Shows Increased Performance & Service Life For M4 Carbines - Soldier Systems Daily
I don't have my notes with me, but a few years back I tested a couple of factory loads suppressed vs non-suppressed with my 12.5" ARP and a Surefire SOCOM-68 and the velocity gain was not much, maybe around 15-25 fps with suppressor as I recall.

Next time I go out I'll try again.

OP; your numbers are right on the mark with mine.
 
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Discussion Starter · #13 ·
That's interesting, it actually ran slower suppressed. Was that on the same day?
A colder day, a different box of ammo bought within a month of others, same barrel. I really should have done a re-shoot with groups of 5 so I could provide some conclusive results.
 

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At this point, it seems to me that there's likely not much difference then as mentioned when taking into account temps. I'll leave it at that. Thanks for the info, I was just curious given the somewhat baffling results of the military testing on 5.56 M855A1 load.
 

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There is always a slight velocity boost when using a can because the gas is still propelling the bullet and there is no friction from rifling. This is referred to as “free bore boost”. I usually see anywhere from 30-50 fps depending on a variety of factors.
 

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I'll add some data here.

XM68GD (90gr) out of a 12.5" ARP suppressed with a Griffin Armament Paladin. Muzzle Velocity readings from MagnetoSpeed

28 degrees F in December here in Washington
2714 2654 2653 2624 2601
Ave: 2649

In a prior August the velocities were almost 100fps faster. Unfortunately, I didn't right down the temperature, but historical data shows an afternoon temp of 73F that day
2763 2715 2751 2757 2753 2759 2754 2730 2710 2728
Ave: 2742

S&B 110gr FMJ 55F
2463 2474 2478
Ave: 2472

SSA 100gr Accubond 55F
2559 2574 2591
Ave: 2575
 
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