QuickLoad figures for RS50?

[VarmLR]

Would anyone have some QL figures available for some loads using RS50 please?

 

I'm testing some loads next week, but in advance just needed to be sure that I'll not be pushing things. I've based my start loads just under max that I'd used for N140 based on the fact that it'll take a little more mass of RS50 to equate to the N140 loads:

 

.223 cal, 1/8 twist, 26 inch barrel, 77gr STMK, seating at 10 thou off lands for one batch and at a COAL of 2.260 (mag length) for a second batch

 

Start load 23gr RS50; Max Load: 24.4gr

 

 

.308 Cal, 1/11 twist, 24 inch barrel, 175gr STMK, seating at 2.795 COAL

 

Start load 42gr RS50; Max load: 45gr

 

Steps are 0.5gr for the first few steps, then 0.2gr thereafter.

 

Any help much appreciated!

[VarmLR]

Thanks to GT3_Richy for kindly running some QL numbers.

 

I'm always a little surprised at how conservative the QL predictions seem, but will stay safe and not load above their recommended values.

[Laurie]

The QL default setting for 223 case capacity is low, presumably to account for the many thick-walled cases around. At only 28.8gn water capacity it has a major effect on the results - increasing pressures. I can't remember off the top what my actual fireformed case capacities with Lapua Match and Winchester brass have been, but something around 30.5-31gn seems to suggest itself. If so, in such a small case this makes a vast difference to the results reducing pressures by several thousands psi.

 

Another major factor is COAL v chamber with a bullet like the 77gn SMK and similar designed to be seated deep to magazine length and make large jumps. When I had an AR-15 with a modified Wylde type chamber, actual allowable COAL with a 15 thou' jump to the lands was way above the 2.26" COAL they were loaded to, and this applied to all makes of 77s. As the bullet moves out of the case before peak pressures are attained, the latter are determined more by the actual combustion chamber volume at this point when the bullet is in the process of being engraved in the rifling than when loaded at a much shorter COAL and is still sitting unfired in the chamber with a long jump ahead of it. Factor this in, and another few thousand psi come off the QL calculated pressures.

 

The good news is that using QL with default settings produces 'right side' errors - ie pressures are lower than predicted. What one doesn't want is the risk of 'wrong-side' failures that see the program underestimate pressures for one reason or another. There are two powders that I either won't use the program for, or if I do set the maximum predicted charge / pressure at 5,000 psi below where I want to be for an initial top charge weight trial batch, which in turn will be somewhat below the SAAMI or CIP MAP values.

[VarmLR]

Thanks for the explanation Laurie, it makes perfect sense.

 

I had intended to load two batches for the .223 at different COLs. Whilst the SMK77 is very jump tolerant with its more forgiving and shorter Ogive shape, the TMK version seems to have a shorter bearing surface with a more aggressive transition between shank and Ogive, and certainly in 69gr versions, they have been very fussy to tune. Therefore, I was going to load one batch at 2.26COL and the other about 10 thou off the lands to decrease pressures and allow slightly higher loads, and just see which one shot best.

 

I'll play safe I think and limit the 2.26 loads to the safe side of QL predictions but may load a few more in 0.1 intervals just to see where actual pressure signs start. A rule of thumb for me, irrespective of calibre, is to find this point and drop back about a grain to allow a good safety margin.

 

I would normally not load so hot with SMKs because they seem to have several decent accuracy nodes, some of which are at about the mid way between start and max recommended loads, but almost exclusively (at least in my .223) the TMKs seem to shoot better the harder they have been driven.

[exmarksman9870]

hi..i just got a tub of rs50 for my .308 and 175grain tmk also so looking for load data...

[VarmLR]

From QL, based on a 24 inch 1/11 .308/COL 2.795

 

Start: 42gr/2489fps/96%FR/Pmax46288

 

Max: 45gr/2664fps/103%FR/Pmax57818

 

The max wasn't actually right at the top, but I rarely load to more than 103 or 104% FR. Perhaps loading a bit closer to the lands and using a higher charge for a little more pressure might prove best for velocities as .308 I've found does tend to perform pretty close to Pmax, especially where TMKs are concerned.

 

 

I'll be trying some loaded to mag length initially, and pressure tresting to 45gr. If ok at that, I may try a second batch loaded close to the lands with a slightly higher charge (testing in small increments naturally).

 

I just want to find an accuracy node that isn't too hot a load but achieves at least 2600 fps.

[exmarksman9870]

good luck -...i will be loading .308 soon as i get the .243 load done..

[VarmLR]

I'll post my results here when done. There's so little data as you say that evry little helps, at least hopefully giving folk an idea of start points. As with all reloading, it has to be taken with caution as everyone should work their own loads up carefully etc etc.

[VarmLR]

I'll post my results here when done. there;'s so little data as you say that every little helps, at least hopefully giving folk an idea of start points. As with all reloading, it has to be taken with caution as everyone should work their own loads up carefully etc etc.