Benchmark?

[Paddyd]

I've been playing with Gordon's reloading tool and have a question. I put in all my parameters, ie h2o capacity in case, jump bullet length, etc., and it gives me a charge weight of 28.3 gns of Benchmark with Hornady 105s that gives me a bullet lead time of 1.2465 mps and an optimum barrel time of 1.2466 mps which is nearly perfect.
However,Sierra's data for the 107s ( yes 2gn heavier, but not really enough to matter)max charge weight is is way way lower @25.6.
Gordon's tells me max psi is just 55,750 which is well below the limit.
I guess Im asking for an opinion on whether to trust the Gordon's data or not and has anyone ever tried Benchmark in the Norma?

 

[Cloudrepair]

Are you talking about the 6br?

 

[AccelR8]

Since no one has answered yet, at the stage you are at I would not use Gordon's data. I would load a few rounds with Sierra's data maybe midway between starting and maximum, shoot them over a chronograph to get velocity data. Then enter that data (charge weight and velocity) in Gordon's "Measurements" table, then use the Optimum Barrel Time function, Compute OBT& Charge Adjustment, create grtload file with the calibrated values. Then use that file with your data such as case volume, bullet length, temperature, etc. and see what Gordon's tells you for velocity and pressure at various charge weights. Gordon's predictions will be a lot closer to reality after you generate a file with the calibrated values. Hope that makes sense.

Hopefully someone with more knowledge will chime in.

 

[Paddyd]

Are you talking about the 6br?

Yes BR Norma

 

[LCazador]

That sounds a bit ambitious but give it a try starting out a bit lower and working your way up. Make a note of your head diameter at start and measure each batch of loads as you move up the latter. Remember more than .0008" is too much head expansion. I like Benchmark and have had very good success in 6BR.

 

[C.E.Smith043]

I've been playing with Gordon's reloading tool and have a question. I put in all my parameters, ie h2o capacity in case, jump bullet length, etc., and it gives me a charge weight of 28.3 gns of Benchmark with Hornady 105s that gives me a bullet lead time of 1.2465 mps and an optimum barrel time of 1.2466 mps which is nearly perfect.
However,Sierra's data for the 107s ( yes 2gn heavier, but not really enough to matter)max charge weight is is way way lower @25.6.
Gordon's tells me max psi is just 55,750 which is well below the limit.
I guess Im asking for an opinion on whether to trust the Gordon's data or not and has anyone ever tried Benchmark in the Norma?

I'm just assuming the difference between Sierra 107s and the Hornady 105s is a combination of the additional 2gr. And more than likely added bearing surface of the 107s. Requiring it to have a lower max charge.

 

[Fire Dog]

I'm just assuming the difference between Sierra 107s and the Hornady 105s is a combination of the additional 2gr. And more than likely added bearing surface of the 107s. Requiring it to have a lower max charge.

I am running Sierra 107’s in a 6BR at 2’850 with 30.1gr of Varget, CCI450’s and getting great accuracy in my barrel with a 7 thou jump.
Of course, you must approach the loads of others with caution but 2’850 is an accurate node in the 6BR.

 

[DLT]

That sounds a bit ambitious but give it a try starting out a bit lower and working your way up. Make a note of your head diameter at start and measure each batch of loads as you move up the latter. Remember more than .0008" is too much head expansion. I like Benchmark and have had very good success in 6BR.

Good luck with the 105gr class bullets ?