Range Report 6.5 Creedmoor Velocity/Ballistics Conundrum

[Pusher591]

This is in regards to a new gun, two different chrono's and two different dope cards.

These are the things that are a constant:

Gun- 6.5 Creedmoor SAC built 23'' melonited barrel 93 rounds down barrel
Scope- Leupold Mk6 in ADM mount with a 1.8'' height over bore
Ammo- 140 Amax Factory Lot# 3121293

1st RANGE TRIP:

My first outing I was using a "middle of the road" type chrono I've used in the past with consistent and accurate readings. I got averages of 2920 fps using said chrono. At that time I didn't believe it so I changed the battery in the chrono and repeated string. Again, It avergaed low 2900's. I thought, lets see what it will do at 600 on 10" plates. I plugged everything in to the app I've used the last several years (Bullet Flight L2) and it gave me a ballistics of 3.2 mils for 600. It was an overcast day with tempratures in the high 50's. I began shooting and wind was some what trouble some to get hits but I could see my misses and elevation appeared to be good. On the 3th shot I found my target and continued to make consistent hits using the 2920 dope info. I actually backed it down to 3.1 mils after hitting slightly high on the plates.

2nd RANGE TRIP:

Fast forward to yesterday and a buddy and I went to the 100 yard range just to chrono his build and get it zero'd. I borrowed a buddies Magneto V2 chrono to get our velocities. He shot first and he was seeing the velocoties he should from a 21" 308 with 44 grains of varget under a 178 bthp so in theory it should be reading correctly.

I set the Magneto up on my gun. I used the same ammo as I chronoed with last time and for a 10 shot average I got a 2720 velocity average, which is more realistic then the 2920 I got from the other chrono. I plugged in the data to my ballisitc app and with everything being the same except the velocity changed to 2720 it gave me a 3.9 mil hold. That's a .8 mil diffrence from the last time I shot. If my math is correct, would that not be a 17.28" difference at 600 yards then my last dope?

I don't understand how I could making hits on 10" plates consistently with that kind of a difference? Nothing is in the bore, and gun only has 93 rounds total so its not so dirty its lost 200 fps. Trying to figure out if I'm over looking something. Weather for 2nd range trip was rainy and 40 degrees but that shouldn't constitute a 200 fps loss.

Thoughts please.

 

[Pusher591]

I also plug in all my specifications into bullet flight, I don't use thier BC's. BC I used was Litz BC for the 140 Amax which is .584

 

[bornhunter04]

Well a 140gr @ 2920 from a 23" barrel doesn't quite pass the smell test. I think i'd tend to believe the magnetospeed. 2700 sounds like a more realistic number with that short barrel. As to how you were making hits @ 600 with that dope, that's a good question. Maybe the plate wasn't exactly @ 600? Idk, that's crazy though.

 

[Pusher591]

Well a 140gr @ 2920 from a 23" barrel doesn't quite pass the smell test. I think i'd tend to believe the magnetospeed. 2700 sounds like a more realistic number with that short barrel. As to how you were making hits @ 600 with that dope, that's a good question. Maybe the plate wasn't exactly @ 600? Idk, that's crazy though.

I do have a buddy who runs 140's out of a 26'' barrel and he gets 2900's (confirmed on chrono and dope) but they are reloads. I believe they are 43.1 grains of H4350 but this lot of factory 140's is averaging 42.4 grains from the ones I've pulled. I wouldn't think 3'' of barrel would cost me 200 fps. I agree, the 2920 is very unrealistic and I didn't believe it either but the dope worked. I smacked 10" plates and 2/3 IPSC torso's all day at that distance. Anything I missed on that first range session that day was due to wind. We have a red clay berm behind those targets, with it being an overcast day it was extremely easy to see splash. Any splash I saw that day was left or right not high or low. After shooting for a while I still couldnt believe it so I ran a dope card for 2800 fps (which is a realistic number for that barrel length) and I was shooting high according to spotter and witnessing splash myself.

This is my home range, its a private range that belongs to my FFL and all distances on the range are GPS'd and ranged with multiple different range finders. We've trained at this range for several years and I'm possitive of all distances on it, that's definantly not the issue.

 

[bornhunter04]

Yeah i wouldn't think 3" would equal 200fps difference either. Do you happen to have any other 140's from a differant lot? Maybe crono both lots same day, with both crono's? Dope seems to be on, it's just strange. There's got to be an explanation somewhere, maybe someone smarter than me can chime in and figure it out....

 

[Pusher591]

Don't know why I didn't think to do this but had someone suggest last night I shoot on paper at distance to see exactly where I'm hitting and tune/true dope and velocity based on that. Hopefully I can do that this coming week and report back but if anyone has any suggestion or theories I'm still all ears.

 

[Pusher591]

Well, shot today on steel and paper to try to figure this out. Results were surprising.

I shot the same lot of ammo and positions were gps'd and ranged to double check. Since I chrono'd last and got 2720 I decided to shoot first with that dope. I began shooting my group on paper at 600 and spotter calls first three shots high 12"-14" into the berm. I also see the splash in the berm.

I decided to re-dope gun to my original 2900 dope and begin a string. I was about 3"/4" left and a little low of center. I'm good with it so we set out the small Mcree steel. Its 9" wide by 16" tall.

The first pic below shows the whole target. Wind was light today so I inserted a 10rd mag and preceded to put round after round center mass (mostly)

After that I decided to try some head shots. All five shots hit target in head/neck area. At 600 yards my dope is still 3.1 mils with a 100 yard zero and a 1.8" HOB for scope.

That last pic is of the same small Mcree but flipped around. We moved back to 860 and I put 5rds on it using 6.3 mils.

Again, I don't know why its working but it is, I guess that's all that matters but it still has me scratching my head.


9" wide x 16" tall Mcree Steel

5rds head shots @ 600

10rds @ 600 center mass

5rds @ 860 (9" wide steel)

 

[LawnMM]

If it helps, my Creedmoor went from about 2720 up to over 3000 and settled at 2925 with 123gr Scenars out of a 22" barrel in the first 250 rounds. The barrels seem to pick up speed as they break in.

 

[shamir]

Could be that your scope tracking is off to. Have you box-tested or confirmed the scope's tracking in some other way?

 

[Aimsmall55]

That's pretty confusing.... I'll bet you that if it isn't something mechanical, or the ammo, it'll get better the more rounds you shoot. But 2720 sounds right to me. As I'm shooting the 312*** lots at 2815 out of a 27" GAP. Maybe pull a round and have your buddy weigh the powder charge and post a pic of the powder. That'll tel me alot really quick. It's not the 312 lots, but the 313 lots that hornady has been using h100v and a Reloader powder instead of h4350. SHITTY AS HELL ammo. But every 312 lot I ever shot was FANTASTIC. But possibly it could be a late 312 lot when things started going crappy??

 

[Killswitch Engage]

man that velocity out of a 23" barrel just doesnt seem possible with factory load. i shot some of the 312 factory and it was 2850ish out of my 26" barrel.

 

[jbailey]

Do a simple tracking test on your scope. Put out a big piece of paper at 100yds (make 100% sure its 100). Make sure the paper is level and square to the world. Setup your rifle, also making sure its level and square to the world. Shoot a zeroed group at a target. Turn up the scope to 3.1mils, shoot a second group, aiming at the same point of aim as the first group. POI should be ~11.20" high (3.1mils * 3.6"/mil at 100yds). If its not, your scope isn't tracking with the mils your ballistics program is telling you to come up.

Good luck!

 

[lte82]

I'm running 2980 fps out of my 24" with the 123's, and 2750 with 140 amax hand loads. 2900+ fps with a 23" is definitely feasible, but only with the 120-123gr. With the 140's anything over 2800-2850 would be suspect without pressure signs. A couple of days ago I actually got the 139 scenars up to a legitimate 2950 fps, but blew every primer. I'll be damned if it wasn't accurate though lol.

FWIW, my magnetospeed reads within a few FPS of my buddies expensive chrono, and my dope matches perfectly with it. My cheap Chrony would read accurate if in the absolute perfect lighting, but would read a consistent 5-10% faster when light conditions were poor, never slower for some reason.

 

[flounderv2]

Scope Tracking
Atmospheric Conditions may have been off
Scope Height
Powder Temp
Etc.

Its pretty apparent that your not getting 2900 with the 140's so that means you have an issue most likely in your ballistics setup or scope.

 

[flounderv2]

Scope Tracking
Atmospheric Conditions may have been off
Scope Height
Powder Temp
Etc.

Its pretty apparent that your not getting 2900 with the 140's so that means you have an issue most likely in your ballistics setup or scope.

 

[Ring]

That's a .8 mil diffrence from the last time I shot. If my math is correct, would that not be a 17.28" difference at 600 yards then my last dope?

I don't understand how I could making hits on 10" plates consistently with that kind of a difference? Nothing is in the bore, and gun only has 93 rounds total so its not so dirty its lost 200 fps. Trying to figure out if I'm over looking something. Weather for 2nd range trip was rainy and 40 degrees but that shouldn't constitute a 200 fps loss.

Thoughts please.

scope not tracking right....

 

[Pusher591]

scope not tracking right....

UPDATE***


I've again checked all that has been asked to be checked. Scope tracking test confirmed scope is tracking properly. Another Mk6 was used and it required the same dope. Also, I know all dopes on this range. This range is my home range and private. I've trained on this range for years and dope all my guns here. I'm not winning anything but I've finisher a couple top 10 finishes and placed well in many Woodys events with great hit ratios.

-height over bore confirmed at 1.8"
-same lot of ammo averaged 42.6 grains of H4350
-atmospheric conditions accounted for each outing



I shot this past Sunday and shot from 100-600 and dope is spot on guys. I've had my shooting partner look over my gun and double check everything and everything's correct to him as well.

** Ring, only thing I can think is the melonite has increased the velocity as it as in some other rifles. I know some people have had significant increases in velocity after melonite.

 

[Pusher591]

Scope Tracking
Atmospheric Conditions may have been off
Scope Height
Powder Temp
Etc.

Its pretty apparent that your not getting 2900 with the 140's so that means you have an issue most likely in your ballistics setup or scope.

Updated, everything accounted for and it's all good, I don't know what to say?

 

[LawnMM]

Do you have access to a chronograph??

 

[Pusher591]

Do you have access to a chronograph??

See first update. I've used Magneto, which gave me a realistic velocity but dope did not match. I've used another chrono which gave me unrealistic velocity but dope matched.

 

[LawnMM]

I trust the Magnetospeed, I would check again, I think your barrel is picking up speed and your scope may not be tracking properly. You said you checked the scope, how?

 

[Pusher591]

I trust the Magnetospeed, I would check again, I think your barrel is picking up speed and your scope may not be tracking properly. You said you checked the scope, how?

I've done a box test with it, and even put on another Mk6 that's resides on my Recce. Both scopes, once zero'd shot the same. I know you would just have to see the rifle, check it yourself, dope it yourself, then shoot it to believe but I forcthevlife of me can't think of anything else to check. The thing is, the chrono that gave me the 2900 velocities is the same one my partner and I always use and its always worked for us.

 

[LawnMM]

How big was the box? Were you dialing a solid 10+ mils of travel? More the better, did you verify distance to target with a tape? Did you measure the target itself? 10 mils up should be 36" on the target, etc?

Only asking because that's kinda the likely culprit. Light based chronographs can be misleading. The lighting conditions, angle of trajectory through the screens, can all influence the reading. I doubt very much you arw getting 2900+ with 140gr ammo out of a 23" barrel.

I would check the speed again, I bet even your regular chrono will show a difference. If possible check it against the magnetospeed also.

 

[Pusher591]

How big was the box? Were you dialing a solid 10+ mils of travel? More the better, did you verify distance to target with a tape? Did you measure the target itself? 10 mils up should be 36" on the target, etc?

Only asking because that's kinda the likely culprit. Light based chronographs can be misleading. The lighting conditions, angle of trajectory through the screens, can all influence the reading. I doubt very much you arw getting 2900+ with 140gr ammo out of a 23" barrel.

I would check the speed again, I bet even your regular chrono will show a difference. If possible check it against the magnetospeed also.

Box test wasn't that big but I thought it was large enough to confirm tracking is working. I've also spun turrets all way up and down then back to zero and zero'd. Zero was still on par and running dope to 860 I made hits at all location out to 860.

I don't know if you read above but after using the Magneto I doped my gun for the velocity it was giving me and I was hitting 12-15" high into the berm which to me would indicate the round is traveling a good bit faster. It also matches up with mil correction. If anybody here will be at Woody's in a few weeks, please come double check the rifle and see if you see sonething I mey be missing in the equation. I'm by no means a professional but I feel like I've been doing this long enough that I don't see anything else I could do, except believe I'm very lucky and all the stars have aligned to produce this. I'm about to start reloading soon, so we will see if my hand loads can produce the same results.

 

[LawnMM]

I'm just trying to help you find the answer so please don't be offended by the questions.

That said, you need to fire a group at 100, diallike 10 or 15 mils, and fire another. Then check the distance between them, I'll bet you the math is off. It wouldn't be the first Leopold I've read about with tracking issues.

Dialing up and back down checks how well it returns to zero, not whether its tracking properly. If your app tells you that you need 3.8 mils at 600, that's the correct solution. Math doesn't lie. If you get to 600 in 3.2 mils it COULD mean you have a faster traveling bullet, or a higher BC. That seems unlikely in your case.

What's more likely is you are dialing 3.2 and getting 3.8 in movement out of the scope. That's why I'm saying recheck the scope. Check the distance with a tape to the target, not a laser, small inaccuracies add up. Then dial 10 or 15 mils difference and measure the distance between impacts with a ruler and check the math.

If you tweak your muzzle velocity to match your impacts that doesn't necessarily verify the muzzle velocity or make the dope valid. You've just found a way to fudge the numbers so it matches what's happening. I would re check your scope and I'd do it with rings, qd mounts can bring their own issues into the mix.

 

[Pusher591]

I'm just trying to help you find the answer so please don't be offended by the questions.

That said, you need to fire a group at 100, diallike 10 or 15 mils, and fire another. Then check the distance between them, I'll bet you the math is off. It wouldn't be the first Leopold I've read about with tracking issues.

Dialing up and back down checks how well it returns to zero, not whether its tracking properly. If your app tells you that you need 3.8 mils at 600, that's the correct solution. Math doesn't lie. If you get to 600 in 3.2 mils it COULD mean you have a faster traveling bullet, or a higher BC. That seems unlikely in your case.

What's more likely is you are dialing 3.2 and getting 3.8 in movement out of the scope. That's why I'm saying recheck the scope. Check the distance with a tape to the target, not a laser, small inaccuracies add up. Then dial 10 or 15 mils difference and measure the distance between impacts with a ruler and check the math.

If you tweak your muzzle velocity to match your impacts that doesn't necessarily verify the muzzle velocity or make the dope valid. You've just found a way to fudge the numbers so it matches what's happening. I would re check your scope and I'd do it with rings, qd mounts can bring their own issues into the mix.

My ballistics app only tells me I need 3.8/3.9 mils at 600 if I plug in 2720 as my given velocity. But when I try to shoot using 3.8 mils it hits way high into the berm. My scopes also seem to be correct on other guns. I only have 2 Mk6's and move them around depending in what I'm shooting, at least until I can afford another scope.

No worries either, I'm not getting upset or mad, just want you to have all the facts from me so it will allow you to help me.

 

[LawnMM]

The point is, you need to verify that the scope is moving what you are dialing into it.

 

[shoot4fun]

I never got 2800 from factory 6.5CM ammo. And that is with a 26" Bartlien. I do get that and then some with my hand loads of RL17 behind 142SMK. I top the 3000 FPS mark with Berger 130 VLD and H4350.
Try a G7 BC of .299 with the lower velocity reading and see what happens. When I put my 142SMK load data in JBM it gives me 3.7 mils at 600 and 8.6 mil at 1000 yards. That is only a tenth above my real world experience.
I use a V2 and trust it. My PACT has given some screwy readings a couple of times.

 

[Pusher591]

I never got 2800 from factory 6.5CM ammo. And that is with a 26" Bartlien. I do get that and then some with my hand loads of RL17 behind 142SMK. I top the 3000 FPS mark with Berger 130 VLD and H4350.
Try a G7 BC of .299 with the lower velocity reading and see what happens. When I put my 142SMK load data in JBM it gives me 3.7 mils at 600 and 8.6 mil at 1000 yards. That is only a tenth above my real world experience.
I use a V2 and trust it. My PACT has given some screwy readings a couple of times.

I've got 2820 before from factory ammo, as well as several shooting partners but some were slower then others. Most run around 2750-2800 but a few of us see a litle over 2800. I know thier has been some hot lots of H4350 in the past and keep in mind I havent shot this currant lot in anyting hotter then 65 degrees. If this is one the hot lots I may be seeing that speed but when the temps start hitting 80 and above I may start blowing primers, we will see I guess.

As for the BC, my partner runs Applied Ballistics AE and we've run everything through his stuff and results are VERY similar. I have a comp coming up soon and I've been training lately. The training is similar to the courses of fire we may see and all targets are at least MOA. My dope is good on all of them out to 860, so I should at least feel confident in the ballistic table I have for it until I can figure out what the deal is, correct? Ill try to get out this week to do another box test and see if numbers match up.

 

[redneckbmxer24]

I know it doesn't help you much but the first 30 rounds I put through my 26" AI 6.5CM barrel averaged 2828 for all six five shot strings. This was the newer lot with the western H4350 equivalent according to hornadys technical support. It shot about 2moa and had horrible velocity spreads.

Wait until you have about 300 rounds on the gun and chrono it again with the Magnetospeed. Keep in mind a lot of those ballistic apps are way the hell off. I've used several and the only one I've found to be accurate is shooter by Sean Kennedy and not only is it accurate, it's dead nuts on the money with every rifle and load I've plugged into it.