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Old January 25, 2019, 03:28 PM   #26
kilotanker22
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Here is an odd one. This was the Sierra Game Changer 140 grain with 68 grains of H-1000. The first three shots were low, so I adjusted my elevation. This was after shooting the other groups. I have never seen such a POI change at 100 yards using a different charge.. Needless to say, I don't think H-1000 is the powder for this rifle. At least not with 140 grain bullets. with Magpro I was more than 2 inches higher POI.
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Old January 25, 2019, 03:30 PM   #27
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Quote:
Originally Posted by std7mag View Post
Strelok specifies at the oblective lens for your scope height.
What part of the Objective? Center, bottom edge?

The center of the Tube should also be center of the objective for this scope.
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Old January 25, 2019, 04:10 PM   #28
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Quote:
Originally Posted by Jsnake711 View Post
With that sight height, I'm still getting 3275fps
I have spent the time to get a more accurate measurement of scope height. Then using Actual Bullet trajectory at 100, 200 and 300 yards. Along with Bullet specs. 3100 FPS is the value that basically fits the bill to within 1/4 inch at 300 yards on the trajectory. I am gonna set my guess for bullet velocity at 3100. Then get actual readings with my new chronograph in a couple weeks.
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Old January 25, 2019, 06:16 PM   #29
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you know I don't think I have ever changed the scope height when using the JBM calculator I just leave it set the default. I can chrono a round at 100 then run it out to 800 and be within a half MOA just using the programs data. I suppose if I were a precision rifle competitor I would need to be more concerned. Those guys don't get sighters

On the scope dope there is only 1.6 inches of difference at 300 yds going from 2600 FPS to 3000 FPS. Do a come up of 4.25 inches (1 and 1/4 or 1.5 MOA) and shoot for the middle and your group center should be golden on the vertical, or at least within a half MOA if you do your part
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Old January 25, 2019, 06:33 PM   #30
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Hounddawg,

The photos are on the first page at the bottom. I posted several times in a few minutes so I wanted to make sure y'all knew they were already posted.
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Old January 25, 2019, 06:52 PM   #31
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Those are nice groups for a hunting barrel, you can really see where it heated up

better be careful or you will get bit by the long range bug and that's a deep rabbit hole
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Old January 25, 2019, 06:52 PM   #32
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Also I forgot to mention.

The velocity estimation based on bullet trajectory and actual atmospheric conditions at the time of the groups. Was not with the New load I tested today.

It was with the load tested when I first posted this thread. They were tested today as well as last week.

I used the trajectory that I observed last week to compare to today. Making sure that the reaults were comparable. The trajectory that I observed today, was just about Identical to what I observed last week.

The "Trajectory Test" groups were each fired after the barrel had some fouling shots in them. And given just enough time for cooling for the barrel to be close to room temperature between the three groups. Here are the details for the load and conditions.

270 wsm, 22 inch barrel
Nosler 140 grain BT .277 Caliber. G1 BC .456
67.5 Grains of Magpro
cci 250 LRM primer.
COAL 2.757. (.020) from the lands.

Scope height= 1.785 (Rounded to 1.8" for the calculator"
Zero= 200 yards
Zero height= 2.5"
Height at 100 yards= 2.6
height at 300 yards= -2.5

I used the actual Atmospherics for my location at the time the groups were shot.
21 degrees F
Elevation 800 Feet
pressure 30.09"
Humidity 43%
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Old January 26, 2019, 01:53 PM   #33
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Plugging this same info in for a 300 yards zero put me at 3 inches high for 100 yards. So I sighted them 3 inches high at 100. Then fired another group at 100 and a group at 300 to confirm. Again plugging that velocity in with my load. The calculator was right on.

I will post the 100 yards group when I get home. Forgot to bring my 300 yard target off of the range, but all 5 shots landed into about a 2.5 inch group.

Also ran this test with the Sierra Game changer as well as the Sierra 140 grain HPBT Game king. The Game changer had same point of impact as the Nosler BT. The HPBT Gameking was 3 inches lower at 300 yards than the other two bullets. I assume this is because it's not a very streamlined bullet, and the BC is considerably lower.
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Old January 26, 2019, 04:15 PM   #34
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First image is 5 round at 100 to confirm zero height with the Nosler BT and 67.5 grains of Magpro load. Not sure if that one shot was me or coincidence.... Would have been a mighty fine group...

Second photo is the 140 grain HPBT Game King. 68.5 grains of Magpro. As I suspected, I had pressure signs. I will back these off by 1 grain, back to the start of this node. I feel like they will shoot better at 67.5 grains of Magpro. Also by the time I had shot this group I was getting very cold from being on the range. So maaybe I had something to do with the groups windage opening up.
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Old February 5, 2019, 12:49 AM   #35
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I got my Magnetospeed chronograph today so I will be takign both my 6.5 creedmoor and this 270 wsm out to confirm velocity and adjust sight the optic for the velocity I get. then shoot a 300 yard group.
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Old February 5, 2019, 05:07 PM   #36
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So I have a ton of data that I collected today. It will take several posts through the day.. I will begin with the most interesting data of the day.

270 wsm. TC Venture.
Winchester case, CCI 250 primer, COAL 2.737
130 grain Sierra game king
72 grains H-1000
Avg- 3305 fps
Hi- 3325
Low- 3289
SD- 18

71.5 grains H-1000
Avg- 3305
Hi- 3324
Low- 3281
Sd- 16

These numbers near Hodgdons starting data are 140 FPS faster than their listed max charge. I already know that 71, 71.5 and 72 grains of H1000 and that bullet shoot pretty well. Also these were the highest velocities of any of the loads I tested today. Should be an excellent load for deer hunting.
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Old February 5, 2019, 05:15 PM   #37
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Same case, length, primer and bullet but with RL 26
68 grains RL 26
Avg-3220
Hi-3226
Low-3215
Sd-4
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Old February 5, 2019, 05:18 PM   #38
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69 grains RL 26
130 grain Sierra Game king
Avg-3270
Hi-3289
Low-3263
Sd-10
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Old February 5, 2019, 05:19 PM   #39
kilotanker22
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270 wsm. Same cases and primers.
140 grain Sierra Game King BTHP, Coal 2.680
66.5 grains RL 26
Avg-3126
Hi-3137
Low-3121
SD-6
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Old February 5, 2019, 06:17 PM   #40
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That load with Magpro that's shoots really well was slower than I figured.

140 grain Sierra
67.5 grains Magpro.
Avg-2987
Hi-3017
Low-2968
Sd-18

I think with a different 140 grain bullet (that isn't seated so far into the case) and a little more powder I can get the velocity up a bit.

However. I may end up sticking with a 130 grain. And H 1000. Trying to tweak that load. Velocity was stellar. I was surprised to see 3300 FPS with a starting charge in a 22 inch barrel.

If I find a higher BC 130 grain bullet that's shoots good at that velocity. I will have a great mid to long range deer cartridge.

Although the slower 140 grain load will be great as well.
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