JARACAL • View topic - Stabiliteit in 243 met 100 gr Sierra GK's
Stabiliteit in 243 met 100 gr Sierra GK's
Post subject: Stabiliteit in 243 met 100 gr Sierra GK's
Joined: Tue Jul 18, 2017 5:35 pm
Goeie dag al die 243 kenners. Is dit moontlik om 100 grein Sierra Game Kings te skiet met een in tien twist loop? My Sako werk mooi met 87 gr Berger VLD's maar ek wil bietjie swaardwr gaan vir die bosveld.
Sako A111 30-06; Sako A11 243; Star Mod28 9mm P.
Post subject: Re: Stabiliteit in 243 met 100 gr Sierra GK's
Ek gaan myself nou nie uitmaak as 'n 243 kenner nie, maar ek weet my oom skiet al die jare met Sierra 100gr in sy Brno, glo jy sal regkom.
In myne het hulle baie mooi geloop.
Kyk hoe lank die koeëls is. Lyk asof 27mm lengte nog werk.
Ek sal bietjie meet, dankie!
Hulle het ook bitter mooi in my 1in10 howa gewerk
Meeste van die basic 100 g jag koele werk in die 1 in 10 twist. GK, PMP, Interlock etc. Dis die hoë BC lang koele wat lol.
Ek het bietjie met my ladings gespeel en wel n verbetering gekry maar ek is nog nie tevrede nie.
Is daar dalk iemand wat asb kan help met QL vir korrekte lading vir 100 grein SGK in my Sako 243.
Spoed gemeet met Magnetospeed by tromp.
Loop is 588mm (23.15”);
Dop: Lapua, Dopvolume: 53.88 grein;
Dop lengte:51.59 mm lank
Punt: 100 gr Sierra GK;
Bump TPL: 69.11 mm
a) Kruit: S365(80);
Lading: 41 gr
TPL: 68.35 mm
Temp. 20 grade
b) Kruit S365(88)
Spoed: 3064 ‘/s
TPL: 68.84 mm
Do you still have both tins of S365 or are you only going to be using Lot88 ?
From now onwards only lot 88
Ek het toe gemeet: die 100 grein Sierra Game Kings is omtrent 26.82mm lank
Volgens n stabiliteitsformule wat ek van n vriend ontvang het, is hierdie koeel nie heeltemal stabiel met een in 10 twist en teen 3065’/s nie?
Im only working on your data from Lot88
At 3064 fps from your barrel length you are 6500 psi over pressure @ 66500 psi
SAAMI max is 60191 psi
Your COL is long, are you sure you are not in the rifling ?
What is your jump to the rifling ?
You need to drop your charge to approx 40.8 grains and look for 2950 fps on the magneto
Thanks for the feedback Dale!
Jump is 0.27mm or just over 0.010”
You are taking me back close to my original load of 41 grains though with different lot?
I did not get good results with that at all? Maybe jump adjustment?
Posted: Thu Jul 05, 2018 8:49 pm
Different lot has different burn characteristics so it does not mean that your bartrel time will be the same.
0.27 mm is as close to 0 as can be especially with a lead tipped bullet which may be deformed or different to the others.
Shoot the 40.8 grain load with a jump of at least 0.50mm and see where your muzzle velocity and grouping is at.
Shoot with the magneto on first ( to verify MV) and then remove it to shoot a grouping.
Dont try and shoot a grouping with the magneto on.
Dale, Just to put your mind at ease, I’m measuring the jump with an ogive tool and I do not try to get groups with the magnetospeed mounted, already discovered that it affects the point of impact, (normally 100 mm higher)
Will try what you proposed and see what gives. Thanks for your feedback!
Ek het twee ladings probeer met die punt 1mm van die lands af maar glad nie n goeie groepering gekry nie. 100 grein Sierra SBT GK’s met 40.8 grein S365. Daarna weer 87 grein Berger VLD Huntings geskiet en puik resultate gekry. Lyk my asof my geweer net nie die 100 greiners kan stabiliseer nie...
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