Conflicting Data between Quickload and GRT - any help?

[Matabele]

Hi all,

I'm trying to develop a load for my 9.3x74R and am getting quite different suggestions from the two programs. I don't own Quickload but a friend ran some numbers for me:

Namely:
Nosler 250gr Accubond, with 61.5gr of Viht N550, 20" barrel (default inputs for the rest)....it gave 40720psi chamber pressure and a velocity of 2314fps

I've only just downloaded GRT, and may be doing something wrong, however using the same information as above (and also using the same defaults as were input into Quickload)...it gives a chamber pressure of 51151psi (well over the maximum allowed pressure of 49313psi) and a velocity of 2487fps.

Could anyone offer some advice on what I might be doing wrong, and I would really appreciate it if someone could run the same numbers in the two programs to cross check myself.

Many thanks!

 

[jellmers]

I’ve had exactly that same scenario. Friend sorted a round out for me that shot well and then I sorted same calibre and same gun using GRT which suggested the QL numbers would be way over pressure…I ended up using the GRT numbers. Shot 5 with Chrono and then rerun GRT using the OBT tool with the speed…. That then dropped the powder even more.. difficult to get a decent location her shooting benches type groups. But the resulting round was bang on the money with dope and got me onto a mile with 300WM…

 

[Will the chippy]

It's just a computer simulation. Sometimes there good sometimes nowhere close. Just start in the middle of the data and work up from there.

 

[royalewithcheese]

Hi all,

I'm trying to develop a load for my 9.3x74R and am getting quite different suggestions from the two programs. I don't own Quickload but a friend ran some numbers for me:

Namely:
Nosler 250gr Accubond, with 61.5gr of Viht N550, 20" barrel (default inputs for the rest)....it gave 40720psi chamber pressure and a velocity of 2314fps

I've only just downloaded GRT, and may be doing something wrong, however using the same information as above (and also using the same defaults as were input into Quickload)...it gives a chamber pressure of 51151psi (well over the maximum allowed pressure of 49313psi) and a velocity of 2487fps.

Could anyone offer some advice on what I might be doing wrong, and I would really appreciate it if someone could run the same numbers in the two programs to cross check myself.

Many thanks!

There's lots of variables in GRT that it populates with stored values but you should change to reflect your own, namely:

Case capacity
Bullet length (measure a bullet with calipers)
Cartridge OAL or Seating Depth (changing one changes the other)

For every bullet ive used it for, ive found the stored bullet length value differs from the bullets i had in front of me, which goes on to affect its pressure calculations

 

[Matabele]

Thanks very much for the replies everyone, much appreciated! I'll remeasure all my components, and probably start with a safe load off of GRT and use some real velocities to dial it in.