270 twist rate

[jmason]

I've looked at some charts on the net with no good answers to this. IS a 90 gr bullit a bad weight to shoot from a 1:10 twist in a 270. I loaded up some 90 gr bullits but something bad seems to happen after 300yds. I ahve good consitant sub MOA goups to 300 then they open up. I could just need more gun time, but I was wandering if it could be this combo.

I chose a 90 rg varmint bullit to shoot this summer as I only have 1 place to hunt where I can safly shoot over 400yds ( evan at that I think I only have about 200 yds worth of useful energy). I wanted a bullit the comes apart on impact for these quarters.

 

[royinidaho]

What's the MV of your load?

Also what about Extreme spread?

And of course with their squat of a BC any wind at all starts messing with your mind.

I've shot the Sierra 90s for years out of a Douglas barrel @ 3400 FPS and they were great on chucks out to 420 or so. Little parachutes open at about that distance with that MV and they became useless at that point. But that was before I know what I know now which ain't a whole heck of a lot.

With that MV shooting a chuck head on would spit the hide between the shoulders nearly every time at distances well beyond 300 yds.

 

[jmason]

Roy,

MV 3500

ES 28fps

I'm using IMR 4350. Sierra's book says RL15 was most accurate. I was simply using what I had a surplus of. What are/were you using?

 

[royinidaho]

back in the day it was IMR 4895. 53.5 gr gave 3480 I most probably used CCI-250s.

You may wish to use non mag primers as the greatest improvement with the new Lilja barrel was when, with the 130 BT or 140 Hornady, I went to the CCI-200 primer. Groups went from largest of 0.75" to well under 0.5" with smallest (luck I suppose) of 0.11".

In the new barrel (Lilja) 56.5gr IMR-4350 gave 3380 FPS MV.

Again, at distance wind has a pretty fair effect on that stubby little bullet.

 

[jmason]

Roy,

Would it be your opinion that the bullit/load is fine to say 600yds, or that 420 would be about the useful limit of this load? It just seemed like after 300 yds it all fell apart. I did have gusting wind in two directions down range, but I thought the wind would only screw me up horizontally and not vertically. I had (guessing here on speed) a 1-O'clock gusting from 0-10 @ my location and about 300yds downrange had a 9-O'clock doing the same thing.

When I mentioned the 200 yds of useful energy I meant after the 400 yds mark. I didn't make that statment too clear. I think I need to answer my own question here by telling myself I need to go shoot more (in less wind) and see what happens.

 

[royinidaho]

Yup, I'd shoot some more.

With good hot loads, shooting as many as 300 rounds a day, during the jackrabbit bunny bash days, the barrel otta last at least 3000 rounds.

 

[petenz]

I've used the 90 grain sierras,

From memory with 61gr of AR2209 I was getting 3580 out of a 24" barrel but I don't have it written down anywhere so take that figure with a grain of salt.

I got good 100 yard accuracy, consistently sub-minute, but what I found was that with the poor BC, past 250 yards they dropped like a rock, and blew around a lot in even slight wind. I never shot them at paper past 100 yards, only at rabbits/wallabies. My barrel is a 1:10"

I found that the .223 was a better bet, and now I use 130gr ballistic tips in my .270 when I want to shoot rabbits with it.

The 90grainers were very effective on rabbits and wallabies though. I shot a couple of goats at close range with them and was less than impressed.