I was shooting one of my 270 Win. M-70s this past weekend and found quite a surprising difference in velocities between two different bullets.
The first chronographed shots were with 130 gr. Rem. C-L bullets over 57 gr. of H-4350, Partial resized Win. brass and the new style WLR primers. I got 3145 to 3158 fps. with 3 rounds.
Then I fired 3 rounds of 130 Win. Silver Tips, (these are the real-deal Silver Tips with the aluminum cupped tip from 15 years ago) over the same 57 gr. of H-4350 in new Win. brass with the former silver cupped WLRM primers,
Amazingly the velocity jumped from 3285 to 3324 fps. with a three round salvo. No sticky bolt lift, no sticky case extraction.
All loads came out of the cool at appox. 73 degrees F. The barrel was as cool as it can get in 95 degree heat with 80 percent humidity.
The latter was loaded up some 12 years ago and after going through my notes, I couldn't find where I ever chronoed the Silver Tips. I have always gotten 3100 fps. mininum with any 130 gr. bullet and 57 gr. of 4350 in that rifle.

With those bullets/loads I am getting the same velocities as my 270 WSM is with handloads.

Actually 180fps between different loads isn't a great deal unless you're red-lining things. I would contribute the difference to the different bullets you're using. Have you miked a couple of the C-Ls and Silvertips?

quote:

Originally posted by wasbeeman:
Actually 180fps between different loads isn't a great deal unless you're red-lining things. I would contribute the difference to the different bullets you're using. Have you miked a couple of the C-Ls and Silvertips?

No, I have not miked any yet. Short on time.
It's not the 180 fps. dif that I am impressed with it is the 3300 plus velocities I am getting with a 24" factory barreled rifle. This is well into WSM and Roy Weatherby territory.

Hey Rae, If you have any of the Silver Tip ammo left, you could try barely Seating the bullet into the case on 3 just enough more to "break the bond" and see if your velocity retuns to where you expect it to be.

I've noticed Loaded Cartridges that have set on the shelf for awhile tend to have a very tenacious bond between the Case Neck and the Bullet. Perhaps it is some form of corrosion, or just that the two metals tend to cling together better after some time passes - beats me. Then again, it may not be that at all, but it sure sounds like it.

Best of luck to you.

The one i really notice it in is 7x57. I can only use W-W cases for my 175 grain bullet red-line load. Remington cases show bad pressure signs once I get over 51 grains of RL-22.

I've chronographed many a load in the .270 Winchester. 100 -200 fps change between bullets is very common, especially if the bullets have a different ogive and engage the land at a different point, and have a different bearing surface.

In addition brass can very alot between manufacturers. In the .270 Win, Winchester brass is thinner and tougher then Remington brass. consequently I drop back a full grain of powder when switching from winchester to rem brass in the .270 Win.

quote:

Originally posted by Antelope Sniper:
I've chronographed many a load in the .270 Winchester. 100 -200 fps change between bullets is very common, especially if the bullets have a different ogive and engage the land at a different point, and have a different bearing surface.

In addition brass can very alot between manufacturers. In the .270 Win, Winchester brass is thinner and tougher then Remington brass. consequently I drop back a full grain of powder when switching from winchester to rem brass in the .270 Win.

I too chronograph alot and have found the very same things you have in particular with the Winchester/Remington brass comparison. For some reason when I went back over my notes, I could not find where I had ever chronographed the old Winchester SilverTips. I was quite amazed at those velocities.