Borrowed a chrony....

[curan]

Stoke er up more then. Imagine this emoticon as stuffing powder down the tube instead of stiring shit

[Branxhunter]

Home by myself today so hit the bench with a variety of rifles and loads.

First off was the Anschutz .222. With its light barrel, slim stock (with Euro style stock with a lot of drop in the comb) and rear locking action it doesn't look much like a varmint slayer but it has shot a few 1/4" groups using its favoured load of 19.5gn AR2207 and 40gn v-maxes in Rem cases. I have been told before that I would see a lot of case stretch due to the rear locking action, however that has never been a problem. Now I know why

19.4gn AR2207, 40gn v-max - 2873, 2847, 2948, 2896, 2827 fps

That's not much quicker than a K-hornet! Oh well, it is my fox whistling rifle so ranges are usually less than 150m so I guess it doesn't matter too much.

The Parker Hale .243 got a run next. A few months ago I had loaded up some 85gn Sierra FBSPs but never got round to testing them for groups. Loads used AR2208 from 36.0gn to 38.0gn in 0.5gn increments. Top load was 3358, 3388, 3363fps.

I had a couple of leftover 155gn Dyer HBC loads for the Omark that then got a run. 45.8gns of AR2208 in Lapua brass gave 2839 and 2883fps. I also has some 130gn Speer TNTs over the same charge of AR2208 in Win cases I had put together for shits n' giggles. They gave 3055, 3066 and 3041 fps.

Next was the Rem 700 .22-250 again. Last weekend I tested its standard load using AR2208 with the he 50gn v-max which I suspect is getting pretty warm. Back when this load was tested I had also developed a load that uses 35.0gn of BM2 and the same 50gn v-max and Win cases, which shot groups very slightly larger than the AR2208. I had never found the max load with BM2 so loaded one each between 35.0 and 37.0gns at 0.5gn increments and sent them down range, watching for pressure signs with each shot (sticky bolt lift, flattened primers, ejector marks) - the results were:

35.0gn - 3786 fps
35.5gn- 3840 fps
36.0gn - 3941 fps
36.5gn - 3964 fps
37.0gn - 4015 fps

No pressure signs and good velocity. Hmmm, might have to look into some of these a bit further.

The Sako .20-222 got wrung out next. I loaded AR2207 with the 32gn z-max to check for pressure signs and got:

22.0gn- 3948fps
22.3gn - 4063fps
22.6gn - 4104fps
22.9gn - 4158fps
23.2gn - 4263fps.

The five shot group was 0.40".

I also loaded up 25.0gns of BM1 with the 32gn z-max and got 4305, 4359, 4290, 4341, 4304, 4250 and 4290 fps Bolt lift was starting to get slightly sticky at this charge, but primers were fine and no ejector slot marks.

Given the previous results for the Sako .222 I stoked it up a bit, loading 4 cases each of 22.0 (current load), 22.3, 22.6, 22.9 and 23.2gn of BM1 with the 40gn v-max. Velocities for the top load were 3434, 3495, 3443, 3408 fps. Groups were nothing special but I did see two split groups - two groups of two shots cutting.

I also loaded 4 cases each of 21.4, 21.7, 22.0 and 22.3gn AR2207, again with the 40gn v-max. The 22.0gn loads showed 3567, 3533 and 3527. I got no reading for the last of the four at that charge weight, nor for the four shots at 22.3gns. I suspect that the angle of the sun was causing the shadow from the chrony rods to cast across the sensors. Again I had a two split groups.

So some interesting results. I have a bit more work with the Sako .222 and the .22-250 but I think I am done with the others.

Marcus

[MISSED]

Your load at 36.5 gr of BM2 is 14 fps faster than that load in my Sako 22/250.

How close was I

[Branxhunter]

Your load at 36.5 gr of BM2 is 14 fps faster than that load in my Sako 22/250.

How close was I

Yes, both your suggestions (BM1 in the 20 cal, BM2 in the .22-250) have been spot on.

Marcus

[Branxhunter]

More loads over the chrony on the weekend - I decided to chrony 10 shots each from the .22 and the .17hmr to provide some sort of reference:

Brno Mod 2:
- Win555 ave 1290 fps
- Fed bulk ave 1286 fps

Ruger M77/17 CCI 17gn v-max:
- ave 2646fps

The averages below were then for five shots:

Sako .20-222 32gn v-max: with BM1:
- 23.2gn ave 3855fps
- 24.4gn ave 4298fps
- 24.7gn ave 4355fps

I have decided on 24.1gn as my load based on these and previous results (both velocity and group sizes).

Rem700 50gn v-max with BM2:
- 35.5gn ave 3935fps
- 36.0gn ave 3936fps

No difference in velocity but the higher charge was more accurate at 200m - go figure.

Marcus

[Branxhunter]

I recently picked up a Beta Chrony (the blue one) from abusedgnus, and as I haven't yet returned the borrowed Chrony (a red one) I thought it would be interesting to undertake a back-to-back comparison to see if there might be something to explain some of the unexpected results I had got earlier this year.

I used the Sako .223 with the 21" barrel I bought from Chappo, shooting 55gn loads. The blue Chrony was set up closest to the rifle:

image.jpeg (117.22 KiB) Viewed 1378 times

The results were revealing:

Shot 1:

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image.jpeg (120.42 KiB) Viewed 1378 times

More to follow,

Marcus

[Branxhunter]

Shot 2:

image.jpeg (105.67 KiB) Viewed 1377 times

image.jpeg (112.08 KiB) Viewed 1377 times

Shot 3:

image.jpeg (111.8 KiB) Viewed 1377 times

image.jpeg (119.32 KiB) Viewed 1377 times

Two more to come,

Marcus

[Branxhunter]

Shot 4:

image.jpeg (109.44 KiB) Viewed 1375 times

image.jpeg (111.44 KiB) Viewed 1375 times

Shot 5:

image.jpeg (117.72 KiB) Viewed 1375 times

image.jpeg (117.5 KiB) Viewed 1375 times

So the results using the red Chrony are consistently 100-120fps faster than the blue one.

Marcus

[mick_762]

Oh come on Marcus thats easily explained . . . . The bullets are still accelerating!!!!!!

[Camel]

I was sorta hoping that this might have been the first time recorded that two cronies had been shot with the one shot. alas it was not to be.


Might be time to check the 20/222 and see how the results go.

[Rabbitz]

The Test Engineer in me says that the positions of the Chrony's should be reversed to see if there was and outside influence, such as muzzle gases etc.

[Branxhunter]

Yep, reversing the chronies is the next plan, as is testing with the .22 and the .22-250 to see if the 100-120 fps difference is consistent at differing velocities.

Marcus

[albow]

I expect the speed variance will be consistent for no other reason than like cars, the red one is obviously faster

[Branxhunter]

The Test Engineer in me says that the positions of the Chrony's should be reversed to see if there was and outside influence, such as muzzle gases etc.

I did get around to reversing the positions of the chronys with the same result - red one was always faster, with the discrepancy between the readings increasing with increased velocity. So Albow's conclusion in correct!

Marcus

[Tony Z]

So which chrony is lying?