QL help needed

[HuntClub]

Finally bought a Chronograph w/bluetooth and finally got to use it today. Checked on two different loads with one good and one really off. Shooting Tikka T3 in 7mm08

1st load 120 TTSX using RL-15 - these loads were in line (about 30-40 fps less) with published data on Barnes website.

2nd load Sierra 150 Game King SPBT were no where close. Loading with 38.7 gr my FPS AVG = 2351 Published fps is closer to 2650 fps. Any suggestions on what happened with the fps on this? I am certain on the load measure I used. BR2 primer on this load

Thanks for your help.

 

[Keith Glasscock]

You might want to look at the background information in the loading manuals. Sierra tends to use Federal brass, that has smaller internal capacities, at least in 308, they do. If Barnes uses Winchester brass, for example (didn't bother checking), and that is closer in internal capacity to your brass, that would explain the discrepancy.

I'd suggest checking other reloading manuals and getting a feel for the differences between them.

 

[std7mag]

RL15, with a 22" barrel, shooting the Gameking, yeah i could see your results.

Most people use a slower burning powder with the heavier bullets in 7mm-08 for a reason.

 

[vonb]

Couple things. Tikka/Sako barrels are known to be slower compared to published book loads. On average, I find that my loads run around 200 fps slower in my Sako .260 and Tikka .22-250.

With that said, you can run your own load pressure data using Gordon's Reloading Tool. It's free and offers great information provided you input good information. You will need to provide some specifcs such as water volume of your case, case length, powder, COAL, twist, etc. Many folks ask for generic QL data and it's not going to be accurate for your chamber.

Here's a good post on how to use it:

Gordons Reloading Tool (GRT), How to Start Using - The Reloaders Network

EWA Thoughts - If you watch this Weiderlader video, just click your browser Back button to return to this article.

www.thereloadersnetwork.com

 

[HuntClub]

Couple things. Tikka/Sako barrels are known to be slower compared to published book loads. On average, I find that my loads run around 200 fps slower in my Sako .260 and Tikka .22-250.

With that said, you can run your own load pressure data using Gordon's Reloading Tool. It's free and offers great information provided you input good information. You will need to provide some specifcs such as water volume of your case, case length, powder, COAL, twist, etc. Many folks ask for generic QL data and it's not going to be accurate for your chamber.

Here's a good post on how to use it:

Gordons Reloading Tool (GRT), How to Start Using - The Reloaders Network

EWA Thoughts - If you watch this Weiderlader video, just click your browser Back button to return to this article.

www.thereloadersnetwork.com

Thanks for sharing this!

 

[jelenko]

+1 on GRT [Gordon's Reloading Tool].
Several people over on the usrifle team site have been doing some work with GRT.
Based on that work and inputting average MV from 10 shots, it predicts the loads I've found to be accurate - within a .1 gr of powder. Once calibrated to your rifle and to the muzzle velocity with a load in your rifle [load = case volume and length, bullet, COAL], GRT via the OBT function tells you the powder charge needed for the various accuracy nodes.
It has a library of powders, chambers and bullets. Be careful with the data for the bullets. I found the lengths of H75, S77's and TMK 60's to be off a few hundredths. Also, be careful to choose the bullet that has the right base [flat vs boattail].

With all the snow on the ground and the recent temps, I haven't had a chance to try predicted accuracy nodes. At least one other person has and confirmed GRT's prediction.

GRT's info include the Fill ratio and the % burn of the powder. There's a warning that loads with less than 90% burn add uncertainty to the results.