Sportco 303 4t barrel info No4mk1*

[KMA]

I have a no4 mk1 303 sporter with a sportco 4t barrel on it.The barrel is in very good condition ,was probably a fullbore rifle in the past.Like my other 303 i shoot 180 grain ppu soft points& its the most accurate 303 i have owned.Bought some 150 grain sp on special & they shoot like rubbish all over the place.So back to the 180s & 40mm group,150s200mm group? I know these barrels were made by lithgow ,back in the day.Anybody have any knowledge on these. All ammo was ppu & the 150s shoot fine in my other 303.

[sungazer]

It is most likely just seating depth causing the issue. 150s should shoot fine in the 303.

[No1Mk3]

G'day KMA,
What base are the projectiles? One thing we have learned over the years is that some barrels will shoot flat base better than boat-tails and vice-versa, whether Enfield or Lithgow made, Cheers.

[KMA]

Thanks for the ideas guys.I am not a reloader .Both rounds are the same length & all the ppu 303 are boatail.Found out from a old fullbore shooter today that the sportco 4t barrell was a target barrel made for them by lithgow to replace worn 303 ones.Designed to very tight tolerances to shoot 174 gr fmj long range.And yes all the projectiles were probably flat base.Will try some just have to find out which brand are flat base.Its just a interest thing i have been happily shooting pigs with the 180s for years.Cheers