Testing the same load in two different rifles (New chronograph - data inside)

[DaveMachine]

So I recently picked up a chronograph so that I can start to make use of the ballistic calculator on my phone. I tested the same load in my Tikka T3 Lite and Tikka T3 Stainless Varmint, both in 6.5x55 and got some results that I thought were interesting. The load is 49.0gr of H4831 behind a 143gr Hornady ELD-X in F/L sized Winchester brass trimmed to 2.155" @ 3.170" COAL, which has produced decent accuracy at 200yd. Looking at the numbers though, I think there is room for improvement.

Shot	Tikka T3 Lite (ft/s)	Tikka T3 Varmint (ft/s)
1	2759.8	2791.0
2	2729.3	2789.0
3	2766.7	2765.4
4	2737.2	2780.5
5	2744.1	2789.0
6	2743.4	2763.5
7	2737.2	2773.0
8	2764.1	2764.8
9	2780.5	2783.1
Average	2751.4	2777.7
ES	51.2	27.6
SD	17.0	11.3
High	2780.5	2791.0
Low	2729.3	2763.5

Thoughts?

 

[dan belisle]

I'm surprised they're that close, actually. - dan

 

[cdn1canhunt]

How in depth are you going with you loads? Have you gone "down the rabbit hole" and weighed cases and bullets have you checked neck tension etc... the variables are endless. It looks to me that the varmit rig must have tighter tolerance to its chamber or differing head spacing. All in all your results are very good. IMO

More experienced guys will chime in

 

[Ganderite]

Those velocities are almost identical. I was expecting you to report average velocity over 100 fps apart.

 

[DaveMachine]

In the past, I have separated cases by weight. I figured there is no point because I didn't think I was likely to see any distinct improvement in a factory rifle. As for neck tension I don't really know how to measure and/or make it more consistent. As for tightness of the chamber, I have neck sized loads fired out of both guns and found that brass fired in the Lite would fit in the Varmint but not vice-versa. That says to me the Lite has a tighter chamber, but correct me if I'm wrong.

I'm wondering if I should worry about tweaking the load further by changing the powder charge +/- 0.1gr or trying variations of seating depth or just be happy and shoot the load I have.

 

[stubblejumper]

To me that indicates that the barrels and chambers are quite similar dimension wise, which could be due to fairly tight manufacturing tolerances.

 

[WhelanLad]

I hear u SJ, be cool to test a Ruger, winnie or Browning say in same Cal with the same loads


but hey cool as test thanks for posting your results!
cheers from Aus
WL

 

[Sherlock Gnomes]

I see the varmint rig has a Lower spread between high and low velocity. This load looks quite good and the velocity spread is not that bad. Are the barrels identical lengths? From the results I would guess the varmint is a touch longer or like others have said it has a tighter tolerance for chambering.