243 AI hulp

[geelslang]

Goeie naand.

Ek is besig om te fireform vir my 243 AI. Ek wil graag die fireform lading akkuraat kry sodat ek nie 200 skote hoef te mors nie.

Dop: Lapua
H2O na hy in 243 AI kamer geskiet is: 56gr H2O
Punt: 70gr Nosler Varmageddon
Tpl: 67.77mm tot teen die lands(tpl so gelaai vir spoed skiet)
Kruit: S355# 012-18
Primer: CCI 200
Loop: 24"
Spoed:
41.0gr =3445fps
41.5gr =3481fps
41.8gr =3508fps

Sal iemand my asb. help om by 'n akkurate node uit te kom.

Dan, ek het net 2 blikke S355 oor en het toe solank 3 blikke Norma URP gekoop, wat kan ek as begin lading gebruik hier om op node te kom.?

Groete
Ernst

[Dale SH]

IF you going to use this batch of S355 and keep your existing TPL (bullet in the lands), then your accurate node is at 40.4 grains for 3405 fps at the muzzle.
+-55000 psi
I assumed you measured with a magnetospeed or Labradar.

Your 41.8 grain load is right on max pressure.

In terms of Norma URP and once again if you continue to use the same TPL (bullet in the rifling) then I would suggest the following.
Load 42.0, 43.0 and 44.0 grains
Shoot them from lowest to highest and stop with the load which gives you closest to 3400 fps.
If your lowest load gives you close to 3400 fps then don't shoot the others.

Give us the data of the load which gives you closest to 3400 fps and we can fine tune it from there.

[geelslang]

Dankie Dale, ek post die resultate sodra ek skiet kans kry

[geelslang]

I measured the speed with a prochorno at 5m from the muzzle. If I were to back the bullet up to 0.5mm from the lands how much will the load have to change to be on node. I see that on other threads some guys use 44.3gr of S355. Isn't that a pipe bomb if max pressure is at 41.8gr?

[tripodmvr]

Geelslang, die feit dat jy in die lande laai is waar die ekstra druk vandaan kom. Vir my sal die belangrikste wees of die koeëls 'n mooi groep vorm.

Jy noem nie wat die spoed was nie?

[Dale SH]

If you remove the bullet from the lands your pressure will drop substantially and your load would of course change as well.
We would need to re analyse your data once you have given us new data to work with.

[geelslang]

Hi Dale. Thanks for the help. This is the results. I tried the 40.4gr load more than once but 41.3 seems to be as good as I will ever get in this setup.

[tripodmvr]

Nou mooi die data deurgegaan. Maak net seker ek het reg bereken en dat al die inligting reg is. Daarvolgens is jy op die node. Een bekommernis is die verskil in spoed wat jy eerstens met 41,3gr gekry het. Die TPL is nou baie fyngevoelig en maak groot spoedverskille 'n moontlikheid.

Geelslang 243AI S355_12 70 Varm Node 3.png

[Dale SH]

Ya.
I was also wondering why your muzzle velocities changed.
As a matter of interest how did the 40.4 grain load group ?

[geelslang]

Die koeel is nie in die lande gejam nie, hy is presies die gemete tpl. Dit kan seker die ekstra druk veroorsaak?

The 40.4 group were no good, I shot 3x 5shot groups and one 3 shot group but none gave a result better than 15mm

[geelslang]

Hallo Dale, Oom Tripod

Ek het die tpl verander na 1mm van die lands af. Dus is die nuwe tpl 66.77mm

Spoed met 41gr 355 was 3436 fps.

Help my asb om by node te kom. Die vorige goeie groep moes 'n gelukskoot gewees het want nou wil hy glad nie groepeer nie en die es/sd is belaglik.

Groete

[Dale SH]

Please confirm your case trim length.

[Capt. Yoda]

Jou spoed is dan nou amper 60fps stadiger as die spoed wat jy gehad het met die mooi groep daar bo. Vir wat sal jy aan die TPL verander as hy so goed geskiet het?

[Dale SH]

If your case trim length is around 51.80mm then you need 42.0 to 42.1 grains for 3521 - 10 fps on the chrony = 3511 fps true muzzle velocity.
This will take you back to round about your previous accurate velocity when the bullet was in the lands.

[geelslang]

So fireforms is klaar geskiet. Ek het asb. hulp nodig met die berekening van 'n lading met die gevormde doppe.
Punt: 70gr NBT
Alle data soos bo.
44.0gr - 3652
44.3gr - 3703
44.5gr - 3724
Spoed geskiet met silencer.
Tpl: 67mm wat beteken ek jump 0.5mm

Die spoed klink effens warm, waar moet ek wees?

[Dale SH]

Geelslang.
We normally ask that you measure your MV with silencer off as we need true muzzle velocity and end of silencer velocity.
I will take a chance here and calculate with your recorded speeds as is.
Your entry level load is already at 64 000 psi.
With the data supplied and provided you don't change any of your parameters your highest achievable node is now 42.7 grains for 3566 fps muzzle velocity.
Pressure is predicted top be right on max at 60 000 psi
I recall you shooting with a magnetospeed.

[geelslang]

Hi Dale
Thanks again for helping.

I am using a Prochrono 5m from the muzzle. I will shoot the 42.7gr load without a silencer tomorrow morning and give the results. The loads shot is definitely in the red as there is clear ejector marks on the cases.

Cheers

[Dale SH]

Your 44.5 grain load is running at 71000 psi