Author Topic: poor velocity out of 270...aint this something!!! (Read 539 times)

myronman3 · « **on:** August 01, 2003, 08:38:56 AM »

in working up loads for my 270, i am runnig into problems. i was using 7828 and was getting lots of unburned powderin the action of the gun after firing. folks here said to use 4831, so i got a pound of 4831sc and loaded em up, ran it through the chrono and am getting clean burn, but way poor velocity. book says i should be in the 2850 ball park, but i am running way under that, at 2642 fps. the book uses the same gun with the same barrel length i have, so that isnt a consideration.
the ONLY thing i can figure is that the brass i have was primed when i got it and i am not sure whether they are magnum primers or not. could it be possible that is the problem? i wouldnt be too concerned; 210 fps is quite a difference in potential. any experience with this guys?

Ol` Joe · « **Reply #1 on:** August 01, 2003, 01:45:25 PM »

You don`t mention bullet weight but if it`s a 150 gr your not too far off my findings.
I have a 270 with a 26" bbl and the best I feel comfortable getting from it with 150s is around 2750 fps with H4831. I get a couple more FPS useing R22 but not enought to make a differance.
This is out of a rifle that drives factory Win 140 Silvertips (BTs) at almost 3100fps, (the only factory stuff I`ve tried in it) and hits 3000 with 130gr with out any problem, acually at -3 grs from Speers max.............55gr of R22, Hornady 130 sp).
I`m sure others have got the vel listed in the books from theirs But I haven`t been that lucky. The 130s work fine, 140s come close to the books vel, but the 150s just don`t seem to get it for me.

BruceP · « **Reply #2 on:** August 01, 2003, 04:34:40 PM »

I am also guessing you are using a 150gr. bullet and beleive it or not I have never in about 8 years of owning it shot 150's in my 270. I did have about the same experance as you with H4831SC and the 130gr. bullets though. Velocity was way low. I know that some barrels will be slower than others even if it is the same make gun and the same barrel length. BTW unless you are shooting the exact gun used for the load manuel (as in you bought it from the company that wrote the manuel) then dont expect the same velocities. Yours could be lower ar higher. In my case though the 4831SC was slow, but the same bullet and a load of AA3100 gave just about what the book called for so I cant say it was just a slow barrel. Oh and IMR4831, at least the can I have wont reach the book velocities either but I also have to stop below book max charges due to high presure signs. The only thing I have found for sure about this reloading thing is that even though there are rules that mostly hold true It will keep you on your toes.
BruceP

myronman3 · « **Reply #3 on:** August 01, 2003, 05:24:48 PM »

well you guys are right, i am talking about 150 nosler ballistic tips. i know that different guns will post different velocities but i thought that this was way more of a loss than what should be. i guess i will have to unprime the brass and re prime with magnum primers and see what i get. i will check back (might be a week or so, i live a ways from my reloading store). interesting that you guys had similar results. thanks for your input.

myronman3 · « **Reply #4 on:** August 05, 2003, 05:42:06 PM »

well i primed up some brass with mag primers today and charged with 55 grains h4831sc. pushed those 150s at 2718 fps. which was an improvement, though it is a small one. hell if i know. i guess the next thing is to screw with bullet seating depth. maybe that makes a difference. i also ordered some 130's today from midway(among other things) in hopes that maybe they would be a bit closer to book velocities. i will update again in a few days...

Graycg · « **Reply #5 on:** August 05, 2003, 06:30:15 PM »

Greetings,
I have an old Parker Hale Mauser that absolutely refused to shoot 130s worth a hoot and doesn't like the 140 Hornady much better, but loves both speer and nosler 150s. Like you, I was disappointed by velocities at first, but using IMR 4831 I got to 2830 FPS from my 24 inch barrel. If you look at the BCs of those 150s and the trajectory charts, you'll find that it is still a very flat shooting round and delivers plenty of energy and with the correct bullet, penetration.
Sometimes the less lackluster loads deliver just fine. I'd dig out your BC charts and trajectory tables and see if what your getting will meet your needs. If not, get a 270 Weatherby....or one of the many 7mm mags.

regards,
Graycg

Questor · « **Reply #6 on:** August 06, 2003, 02:25:36 AM »

During load development for 130 grain 270s I noted a significant jump in velocity when I increased powder charge from 58 grains to the 59 grain maximum charge for that bullet.

myronman3 · « **Reply #7 on:** August 06, 2003, 11:06:24 AM »

well here is some peculair news. today, i figure i will tackle the problem again. so i went up to 55.5 grains h4831sc. velocities posted were 2733, 2745, and one cartridge loaded to factory oal of 3.340 (the others were made custom length for my rifle) which posted 2721. :x RATS!
so before i left, just for kicks and giggles, i loaded some with my old powder (imr7828) with 57.5 grains. the only thing different was the primer, a cci 250. the same nosler 150 grain bt burned clean this time AND posted velocities of 2888, 2889, and one cartridge loaded to factory oal posted 2881! :grin: holy cow! all i had to do this entire time was stick with the original load i had chosen, just to use primers i knew were magnums. these velocities were higher than published and were shot out of a shorter barrel. why one would be so different and off, and the other load right on and even a tad faster than published is beyond me. live and learn i guess.
anyhow, i dont mean to ramble on, just thought some might find this information useful, or at least interesting.