Loads vs. barrel twist ????

[foxtail207]

How do you find information regarding what bullet weights (and possibly powder loads) are best for certain rifle barrel twist ratios?

Example: .270 Win, 1 in 10 twist. (Browning Bar)
I know factory loads are mainly found with 130 grain bullets. I assume they think that's the best combo. But, I load 140 grain Nosler BT with very good accuracy and consistency.
I just loaded 4 sets of 5 round varying powder loads with 150 grain spitzer soft points to test and did not get very good groups with 3 out of the four, and the better one was not great. (The wind was factor also, but when doing the same type testing with some new 30-30 loads (170 gr. FN, Marlin 336, also 1 in 10 twist) at the same 100 yard range, I didn't have such erratic groups.)

 

[NeuseRvrRat]

http://www.varminthunters.com/tech/barreltwist.html

if i went to a different bullet that weighs 10 gr. more and shot 4 groups with one powder and one COAL and didn't get groups like i did with another bullet, i would not automatically suspect that i didn't have the right twist for that bullet.

 

[NCsmitty]

Most factory barrel twists are designed to handle the range of factory ammunition that's available. As with other things in life, it is a compromise and extreme ends of the range can be marginal for accuracy at times.
Your example of the 270 Win 1in10" twist, will usually handle from 90gr to 170gr flat base round nose bullets in handloads.
Twist stability is usually not a factor with 150gr .277 bullets if you are getting decent velocities, and your issue may just be load choice, which you didn't mention.

I have a 270 myself, and I happen to think that 140gr loads are about the best choice for all around use. I use Remington and Sierra 130gr only because I bought a bunch on sale.


NCsmitty

 

[kingmt]

A longer bullet needs to go just a little faster then the shorter one. You may switch to a slower powder to get a better group with the beaver/ longer bullet.

 

[rcmodel]

150 grain spitzer soft points

More likely an issue with the quality of the bullets then the weight of the bullet.
Or even less likely, the 1/10 barrel twist.

That has been the standard twist for the .270 since it was invented in 1925.

Lyman #49 lists "potentially most accurate" loads for the .270 ranging from 90 grain HP to 170 grain SP.

In almost every case, it is a Max load of a specific powder best suited for the bullet weight.

rc

 

[foxtail207]

Good replies everyone, thanks.

BTW - My favorite load, which also gives me the best grouping results, are loaded with 140 grain Nosler BTs and 52 grains of IMR4831.

The new loads with 150 grain Spitzer - SPs are Sierra bullets, and the "best" results were loaded with 48 grains of H380. The 50 grain (max load with H380) loads I tried did not produce as good results as the 48 grain loads.

I did also try H335 but I got better results with the H380, just not what I was looking for to compare with the 140 gr. loads I'm used to... for either of the H380 or H335 loads.

I would have liked to have used the IMR4831 with the 150 grain bullets but found no load data.

Does anyone load .270s with 150 grain bullets and IMR4831 that could give me their favorite recipe?