how short 75gr from a 1-9" can you go?
weird day today--
and this ain't no april fools joke either.
today i want out and tried some 75gr ammo on my 11.5" barreled 1-9 twist DPMS XM-177a2 replica.
conventional wisdom is that 1-9" twist rate is ok with a 20" or 24" barrel with the 75gr ammo.
it might work with a 18" or possibly 16" 1-9 barrel but is getting iffy.
75gr slugs in a 1-9" twist rate barrel- 14.5" 11.5" or shorter is a no-no as the bullet is going to tumble as close as 25m. this is where a 1-7" twist barrel is a MUST HAVE.
having some extra 75gr ammo , hand-loads and wolf, i thought i would just see how far out the 11.5 DPMS 1 in 9" could shoot before it started tumbling the overly long bullets.
@ 25m i fired a string of 5 hand-loaded rounds through a cardboard box that was about a foot deep.
no tumbles at all. so i loaded up some 75gr wolf ammo and tried again. and a got another string of perfectly round holes in and out of the cardboard.
so i moved the target to 50m and fired 12 rounds of wolf 75gr--same result--perfectly round holes with no signs of a tumble in or out.
the target then moved to 100m and another 12 rounds fired same results!
12 clean round holes in and out of the box!
ok i am getting all weirded out because all the mall-ninjas say you GOT to have a 1-7" twist barrel this short to stabilize a 75gr!
i move the box one more time to 175M from my shooting position just KNOWING it HAS TO KEYHOLE @ 175m
with iron sights i pop of another 12 rounds of wolf at the bottom of the box which is much smaller than the sides of the box i was shooting at.
about 8 of the rounds hit the bottom of the box and go through the top --again perfectly round holes in from the bottom and out through the top!
now i am thinking this wolf must be 55gr and miss-marked 75gr on the package i'll try ONE MORE TIME with my 75gr hand-loads.
i fire off another 12 rounds 7 hit the box square and one glancing hit.
all the hits are perfectly round with no sign of a keyhole wtf??? --LOL
the 75gr ammo didn't make that "worring" sound the 63gr makes when it hit the ground and bounced up either--
it shot almost exactly like 55gr except the poi was slightly left and slightly low @ 25m very nearly one the money @ 50m
i didn't try further as a 11.5" is not likely to be used much beyond 175m --200 max and that box was getting awful small @ 175m about the limit for my 47 year old eyes off handed with iron sights--
i would have never thought the 1-9" could do that well that short with the 75gr slugs--
ya never know till ya try though!