**6 Creedmoor**

[kyotekiller25]

Gotcha! I kinda figured the 107s were a little shorter, thus the shorter OAL length.

I haven't played with mine a whole lot either since getting my custom built 223 wylde and getting it broke in.

I'll probably wait until I have 100 rounds through the 6 creed and get all my brass fireformed before I really start getting serious with my load development. As it is, I feel it's pretty close. Gonna be somewhere around 40-40.2g H4350 at 2.795" or so. I plan to load in .1g increments and shoot at 300 yards to find the right charge, and then see if tweaking the depth a little shorter will change anything. And lastly, trying a couple different primers after I've nailed the charge/seating depth.

 

[Coyote777]

18” 1-8t X-Caliber
88g Berger FBV
CCI 450 Magnum Primer
H4350-45g
BSD-2.130 (.15 jump)
COAL-2.819
Avg FPS-3180

 

[blksno]

26" Proof Prefit
Peterson - CCI 450
RL16 - 115 Dtac
3100 fps

 

[Old Corps 8541]

How much RL 16 ?

 

[diggler1833]

Guess I got it as good as it will go for the 107 SMK / H4350 in this barrel (26", 1:7.25 Bartlein). I had two distinct plateaus in velocity for groups (not a single shot). I usually don't believe in that stuff, but this barrel has shown it enough that I'm starting to drink the "flat spot" kool-aid * in this barrel.

I beat myself about the head and neck trying to get good accuracy out of that slightly higher charge weight. 1/2 - 3/4 MOA...no better or worse.

Loaded back down to the more promising charge weight that gave good results earlier. I did not do as well as last time, but I had more wind today too (excuses, excuses). Loaded one last group and shot it at 300...it held up rather well in the wind. Guess I'm done.

Today's tests:

I tried to move the dime far enough away that somebody wouldn't think I was trying to cover anything.

Whole target:

What I was trying to duplicate and failed:

^ This is 40.0. I ran 39.9 and 40.1 over a chronograph and had an ES and SD average of 25.5 and 8.5 between the two. Velocity is going to be right at 2,950.

 

[TheOfficeT-Rex]

Just dropping a little more N160 data, as I don’t see a lot and VV powders are becoming the cheaper option…

22” suppressed, Lapua cases/CCI 41/N160/105/2.7” OAL

This was shot left column down, then back up the right. The rifle was allowed to “cool” between strings (about as much as you can in with a little shade, no wind, and high temps). The differences in velocity (in red) for 5 shot strings are… something.

I’ve suspected N160 in this cartridge of being a little temp sensitive when it’s hot for a while now. My previous outings with virgin brass at 70*F averaged 2760 on two different 69*F days, same charge with once fired nets about 2823 at 89*F… unless it’s the last group of the day, then the same charge on a hot barrel averages 2865. I haven’t quite wrapped my head around it yet, but I’ll probably be vacuum sealing some rounds to do some temp testing next time out.

It could have been that the barrel was late to speed up (200 rounds then vs 275 now), 40 rounds of fouling, or maybe the difference in sizing/mandrel/the humidity while I was loading – hard to say. I honestly expected a small drop in velocity once everything was fireformed/resized, which is why I added more powder from the baseline of 41/2760.

Considering the total of 40 rounds aggregates under 1” with a .21” mean radius (and the fact I know that I possess neither diggler's oustanding marksmanship nor penmanship), I think I’ve reached the ‘stop messing with it’ phase- I’d just like to have a good temp sensitivity input to load into the kestrel and to add a little more confidence.

Thanks for coming to my ted talk.

 

[TheOfficeT-Rex]

I’ve suspected N160 in this cartridge of being a little temp sensitive when it’s hot for a while now.

A quick follow up: Sometimes I’m wrong.

TL;DR – in my testing, N160 in the 6 creedmoor produced a gain of approx .77 fps per degree F temp increase, in line with the .75fps/1*F I’ve seen listed elsewhere.


I vacuum sealed four 5-round packets and placed half in a thermos with 60*F water, and half in a thermos with 110*F water. They were allowed to normalized for three hours before shooting. I used a food thermometer and recorded the water temp in the thermos. Speeds recorded over a lab radar. While I am certain there is error both in how I estimated round/powder temps, experimental setup, and low round counts, it is in line with what I should have expected. I’m dropping the issue and going back to focusing on basic positional shooting. This was likely the last bit of load development and testing I’ll do in 6CM - this is my last barrel and I don't see myself coming back to the cartridge.

 

[Cody S]

load data for my last 3 6 creed barrels was split between two loads, the higher of which I advise you not to try because I had a custom chamber and gain twist barrel
all loads with 115 dtacs and Federal 205m and lapua 6 creed srp brass
40.5 H4350 with dtac at 2.8" gives 2977 currently and usually around 2950 for me
41.4 H4350 for 3125fps (and excellent accuracy) at 2.8"
fwiw that is about 20 thou off lands for us.
barrel contours have been M24 or heavy Palma, 28 inch finish with a 8.5 transitioning to 7.5 left hand gain twist.
only downside to 6 creed is the 1000-1500 ish round barrel life

 

[diggler1833]

You aren't kidding about barrel life . I went away from the 6CM because of that, but came back again. It is hard to argue against that midrange trajectory/deflection, along with achieving it with so little recoil.

Was cleaning my latest 6CM barrel and a 6.5x47L this weekend. Stuck a borescope down both tubes to verify that I was back to bare metal. The 6CM barrel with exactly 240 rounds on it had more fire cracking and erosion than my 6.5x47 with 625 rounds on it. Granted, I'm not standing on my x47 barrel (123gr @ 2,815 FPS).

Since I don't shoot comps, and 10 shot strings over 2 minutes is as fast as I'll ever take her, I'm planning on 1,400 rounds before I pull it for good (preemptively). That's about how long my last went.

 

[Cody S]

I should have mentioned we basically only use our 6 creed barrels for comps so pretty much only 10 shot strings in about 20 seconds give or take, then the barrel could down completely before the next stage. and if we go with a normal, "sane" load I expect 1500 before she gets squirrelly or gives up the ghost.

 

[Cody S]

I no longer borescope my barrels, it's too scary.

 

[diggler1833]

I no longer borescope my barrels, it's too scary.

Definitely the #1 source for made up barrel problems .

I still do to check my cleaning and for carbon ring development.

 

[Rob01]

On barrel life - I just screwed on my third 6CM barrel. All run suppressed.
First was a 28", running 105s at 2980 with N160, went about 1500 before it started making comet tails on target.
Second was 22", running 109 at 2840 with N160, went about 2100 before it started dropping shots low and opened up from .23" mean radius (.4-.5" groups, on avg) to .51" MR (group sizes about an inch... ish. Some bigger)

What was that 109 and N160 load? I just got some N160 to try.

 

[TheOfficeT-Rex]

What was that 109 and N160 load? I just got some N160 to try.

Lapua brass, CCI 41, 40.2gn @ +-2.745" COAL.

I'd say a conservative start with N160 and any 105 class bullet is 39gn. I've run all the way up to 43gn but that was tops, tossing them at 3044 out of a suppressed 22" tube (single digit SD over 50 shots tho )

 

[Rob01]

Thanks. I am running them in a 26" barrel with Hornady brass so I will start around 40grns and work up. Just looking to be around 2850fps or so with the 110 ATips.

 

[diggler1833]

Same here, have a box of 109s and 8lbs of N160 for the next 6CM barrel.

Much thanks on the load input.

 

[TheOfficeT-Rex]

IME the 110 ATips (although I only tried a single box of 'seconds') run just a smidge slower than 109s at the same powder - like 10 fps. Right now, 109s are running 2850ish @ 40.2 but it's the heat of summer...

Every barrel/bullet I've tried ended up running comfortably between 40-42 gn of N160. Should be a quick workup if you're only looking for 2850. My lapua brass averaged 51.34 gn H2o. Peterson was a half gn less. I've never seen hornady 6 creed to compare.

 

[Cody S]

why are you running it so slow?
hell I can get 3150 from the 109 using h4350...
you're under book max loads...

 

[Rob01]

why are you running it so slow?
hell I can get 3150 from the 109 using h4350...
you're under book max loads...

No need for velocity for matches. Actually a hinderance as it’s more recoil and burns out barrels faster. The 6 Creed got its “barrel burner” rep back in the beginning of PRS when people ran them at 3180fps and were toasting barrel. Run it slower and barrels last a lot longer.

 

[Cody S]

I forget not everyone does 1k bench rest sometimes.

 

[Rob01]

I forget not everyone does 1k bench rest sometimes.

Why would you need that much speed for 1000 yard BR?

 

[Cody S]

Why would you need that much speed for 1000 yard BR?

because it's a test your limits game where there are no sighters and no wind flags and a huge mountain range so the wind wreaks havoc here in south east kentucky. unpredictable directions with no real cues. a high BC (.32 g7)of the 115 gr dtac at 3125 does great against wind and helps get first round impacts on a roughly 1moa target.
oh plus we have to shoot 300 yards and be able to see out impacts so the 6mm is king of the hill where I'm at.
if you want to win you'll need to at least stay on the 1.5ishmoa (#3 out of 5) target at all ranges and never miss to have a chance and you'll likely have to score at least a few on the 1moa #4 target. Last time I went 4 in a row at the #4 target at 1k.

 

[Rob01]

because it's a test your limits game where there are no sighters and no wind flags and a huge mountain range so the wind wreaks havoc here in south east kentucky. unpredictable directions with no real cues. a high BC (.32 g7)of the 115 gr dtac at 3125 does great against wind and helps get first round impacts on a roughly 1moa target.
oh plus we have to shoot 300 yards and be able to see out impacts so the 6mm is king of the hill where I'm at.

So are you talking about an actual "benchrest" match or just something you guys shoot at your range? BR matches usually have sighters and flags etc. Just wondering as never shot an actual 1000 yard BR but have shot 6mms for 20 years now out past it without issue in heavy winds at less velocity in PRS style matches. Even back when shooting the .243 I only range them at 2990fps when others were running 3150 and did just fine.

 

[Cody S]

So are you talking about an actual "benchrest" match or just something you guys shoot at your range? BR matches usually have sighters and flags etc. Just wondering as never shot an actual 1000 yard BR but have shot 6mms for 20 years now out past it without issue in heavy winds at less velocity in PRS style matches. Even back when shooting the .243 I only range them at 2990fps when others were running 3150 and did just fine.

oh no, I shoot prone, all the old guys shoot off bench. it's not like nra sponsored or anything, we all use brakes or suppressors.
also winner gets 500$, second place gets 250, third gets 50
everybody else just loses their 35$ entry fee.
super fun honestly. if you're in south east kentucky I'll take you to it.

 

[Cody S]

you aren't taking into account you're a talented, practiced shooter. I am not.
I'll take any slight edge I can get baby lol.

 

[Rob01]

oh no, I shoot prone, all the old guys shoot off bench. it's not like nra sponsored or anything, we all use brakes or suppressors.
also winner gets 500$, second place gets 250, third gets 50
everybody else just loses their 35$ entry fee.
super fun honestly. if you're in south east kentucky I'll take you to it.

Thanks for the info. That does look like fun. Always fun to bang steel. Shot a similar match before and had fun.

I'll stick with the lower velocity to keep some longer barrel life. Just looked at my ballistic program and going from the 2930fps where I am now to 3150fps with the 110 Atips is only a .2 mil difference with a full value 10mph wind at 1000.

 

[Cody S]

Thanks for the info. That does look like fun. Always fun to bang steel. Shot a similar match before and had fun.

I'll stick with the lower velocity to keep some longer barrel life. Just looked at my ballistic program and going from the 2930fps where I am now to 3150fps with the 110 Atips is only a .2 mil difference with a full value 10mph wind at 1000.

Try the ballistics with a 115gr dtac (.32 G7) at 3125fps, that's our node.

 

[Rob01]

Try the ballistics with a 115gr dtac (.32 G7) at 3125fps, that's our node.

.2 mil difference between that bullet at 2930 versus 3125fps.

 

[Cody S]

So you're telling me there's a chance!
for real though I got some n555 coming I guess I'll just see where she shoots most consistent.

 

[TheOfficeT-Rex]

My DTACs never trued that high. The BC calc using the labradar tracks was a .296, which shrinks that wind comparison to a .1 mil difference.

My two lots of DTACs also had different lengths and BCs. YMMV.

 

[Cody S]

My DTACs never trued that high. The BC calc using the labradar tracks was a .296, which shrinks that wind comparison to a .1 mil difference.

My two lots of DTACs also had different lengths and BCs. YMMV.

I don't know what to tell you other than me and my dad have went through about 5k ish(at least) of these projos in the last 5 or 6 years and we have bought them in bulk on a hand full of occasions. we true our bc for 3125fps, bartlein 5r rifling, gain twist(not sure if that one matters) and it's been between .311 and .319 g7 consistently through the years but .32 sounds much better than .319 so honestly I embellished a little. I've got a few thousand of a brand new lot that I'll measure against sold old ones and some very old ones to see if anythings changed.
even at .31 bc I love them. I am damn sure at one point the vortex tracked within 1% at any given mil number, practically prefect. I performed a much more crude test on the tt525p and just assumed it was probably close enough. was dead on at 20 mils fwiw..
it's like my mitutoyo calibrated calipers..
calibrated by a calibrated calibrator who calibrates calibrated calibrators for a living so..
probably close enough.
eta oh yes I just finished my drink and now I understand your comment.
yes they're sierras and therefore not as consistent like bergers from lot to lot, I recommend large purchases for slightly easier use..