No good can come of reading the contents of this blog.

Viewing or use of this blog or any contents or links contained herein by any person or entity within the confines of the states of Arizona and/or Tennessee is prohibited .

Violators of this policy agree to hold the owner of this blog, its contents and all links contained herein, harmless to any harm or offense taken or perceived.

Permission to use any content on this site is explicitly denied to Robert Farago, his family, his friends, his associates, his pets, and his employees and/or employer and/or their employees either in part or whole.

16 February 2013


I have had house rules for changing between 1:12 ammo and 1:7 ammo for a long time for GURPS.

Previously it had been:

5.56x45mm and .223 Remington weapons are listed with the rifling pitch listed with their ammunition, for example 5.56x45mm 1:12 has a 1:12 barrel. 1:8 is treated as 1:7 and 1:10 is treated as 1:9.
1:7 barrel, M193 Ammo. -1 Acc.

1:7 barrel, NATO, Mk262 or 69gr SMK Ammo. No effect.

1:9 barrel, M193 or 69gr SMK Ammo. No effect.

1:9 barrel, Mk262 Ammo. -2 Acc. If the temperature is 15°F or lower, then halve ranges, -5 Acc.

1:9 barrel, NATO Ammo. No effect unless using tracer ammunition or the temperature is 10°F or lower, then halve ranges, -4 Acc.

1:12 barrel, M193 Ammo. No effect.

1:12 barrel, Mk262 or 69gr SMK Ammo. Quarter ranges, -4 Acc.

1:12 barrel, NATO Ammo. Quarter ranges, -4 Acc, change to pi-.

An additional penalty of -1 to Acc if changing between loads without zeroing the weapon.

Based on this report I think I shall change my rule to:

Ammunition 62gr or heavier will give a -5 penalty in 1:12 barrels. Ammunition 75gr or heavier will give a -3 penalty in 1:9 barrels. There is a -2 penalty to changing ammunition weight without zeroing the weapon.  If the temperature is below 10˚ F add 5gr to the effective weight of the bullet.  -2 if you change loads without rezeroing with the exception of matched ball/tracer combinations; M193 and M196 are identical in 1:12 weapons and M855 and M856 are identical in 1:7 weapons.

M193 ball and M196 tracer are 55gr.  M855 ball and M856 tracer are long for their weight so are treated as 69 and 72 grain respectively.  Mk 262 is 77gr.

No comments:

Post a Comment

Try to remember you are a guest here when you comment. Inappropriate comments will be deleted without mention.