Home Forums Hunting & Shooting Deer Hunting Round Nose Interlock Min Impact Velocity?

With a round nose Interlock bullet, what is the minimum impact velocity that you want to ensure adequate effectiveness on a quartering lung shot on a deer?

Do you expect/see expansion at this lower velocity limit?

Do you expect/see full penetration (exit wound & blood trail) at this lower velocity limit?

I've heard some folks claim that round nose bullets expand at lower velocities but Hornoday insists (I've asked them twice) that the minimum impact velocity of all Interlocks, including the round nose bullets, is 1800 FPS.

And to this, I've heard some folks claim that expansion, while helpful, isn't needed for effective killing performance.


I hunt with a 32 WSP and never see deer beyond 50 yds, much less at 100 or beyond.

Still... one wonders...

Would love to hear first hand experiences

I have used the 250 grain Hornady RN innerlock out of my Whelen a lot started at 2300 fps. It always gave some expansion and exited. Not sure if I ever had one impact slower than 1600 fps.

I've taken several deer with Hornady flat point and round nose bullets just past 100 yards. I would try to drill shoulders to aid in expansion.

Here's an old thread with a few pics.

https://www.24hourcampfire.com/ubbt...82/25-caliber-bullet-test-2#Post11497482

Only experience I can give you. 30 cal 180 gr Hornady RN, jug tested at 20 yds with a reduced load with an estimated MV of 1975. Estimated impact velocity of roughly 1925. Went into the 6th milk jug, expanded to between .575-.600 depending where I measured, and weighed 143 grains, so yeah that particular bullet does expand at lower velocities.










Comparison of the same bullet launched at roughly 2725 with a estimated impact velocity of around 2675. That went into the 4th jug, expanded to .645 and weighed 108 grains. MV of 2725 is on the right obviously.

@rickt300, Thanks, this is helpful.

@Chrome & @Shadetree, I'm particularly interested in the bullets performance UNDER 1800 fps.

How slow can they hit and still get lethal results on deer?

I have used a number of bullets in a .30-40 and a .300 Savage in timber quite a bit, never had a cripple, but I eventually just stayed with Sierra 180 RN.(match grade accuracy) I was always fond of neck shots (a campfire no-no) and it seemed the Sierra gave more dramatic expansion at Krag impact velocities at 100 yds more or less. The impact velocity at an estimated 1,450 fps worked well, even though Sierra's own quote was that they worked best above 2500. I fiddled with 170 Flat Nose one season...too much of a good thing...they expanded when dropped on the floor. This is all opinion, no scientific fact.

It's a good bet that they meant something along the lines of "These bullets work best at impact velocities experienced at typical hunting distances with the bullets having been launched above 2500 fps."