Powder max on .270 Winchester

[James Pearson]

my simple answer is "NO!"
If you are at 3/4" at that powder charge I think I would find a better powder.. I have always been partial to H-4831 and H-1000. but since I get more consistency and better groups with H-4831, I have dropped H-1000 to other cartridges that it performs better in. Come to think of it.. H-4831, H-4320, H-4350, IMR-4350 have all supplanted H-1000 in most every load I have unless it. nope, it has been taken out of my 338 win mag and 300 win mag as well. nope I do not use H-1000 anymore unless my red binder specifically calls for it.

What would you suggest I start with using H4831? Remember I'm pushing the 145gr pill.

 

[John Polk]

Follow the recommendation of the manufacture of your bullets for loads up to the Max and one.

 

[Capt RB]

What would you suggest I start with using H4831? Remember I'm pushing the 145gr pill.

start at 56.5 with H4831doesn't matter if it's short cut or regular. I would recommend you use a magnum primer with that powder or anything slower in burn rate. In smaller cases a standard primer will provide better standard deviations. With the 270 I found that the mag primers worked better for the slower powders like 4831 7828 and rl 26. H4831 is going to be accurate however both 7828 and rl26 will give you much more speed and get you to the next barrel node with safe pressures good luck

 

[DocDoc]

Max loads of H4831 and H4831SC will be different, because the SC version packs more densely. The lower case volume of the H4831 will cause it to reach max pressure a little sooner than the SC version.

 

[John Polk]

60 grains is 60 grains.

 

[DocDoc]

But 60 grains of SC does not have as large a volume as the standard, hence it is like a little larger case. Check the warning at Nosler on H4831 vs H4831SC and 7828 vs 7828SSC. Hodgen may have the same.

 

[Capt RB]

But 60 grains of SC does not have as large a volume as the standard, hence it is like a little larger case. Check the warning at Nosler on H4831 vs H4831SC and 7828 vs 7828SSC. Hodgen may have the same.

In magnum cases yes however in the 270 case with the 130,140 and 150's I have not seen this to be the case. You will have more issues with different lots of bullets with baring surface changes as well as different case volumes than ssc and regular H4831. 7828 with book loads will have the similar results as H4831 when it comes to short cut and regular. SSC will let you get above book max and that is when you need to know what your doing when it comes to component compatibility and pressure

 

[James Pearson]

Went out this afternoon and ran a series of H4831, 3 rd's each starting at 55.5gr up to 59.5gr in .5gr increments, .020 off the lands.

59.5gr shot a 3/4 MOA group at 200 yards. No over-pressure signs, other than a slightly flattened primer but it still had some rounded edge full circumference. FPS averaged 3013, which I think is fantastic! I think I'm gonna stop there and and run a series of the 59.5 and vary the jump a little either direction and see if it tightens up.

I also though about running 59.2 - 59.7 and just see what it produces.

Any other suggestions?

 

[James Pearson]

Just FYI, I'm running new Hornady cases which I sized and bumped .002, and CCI 250 primers.

I think things will tighten up better once I have a good stock of the once fired brass to work with.

 

[entoptics]

Went out this afternoon and ran a series of H4831, 3 rd's each starting at 55.5gr up to 59.5gr in .5gr increments, .020 off the lands.

59.5gr shot a 3/4 MOA group at 200 yards. No over-pressure signs, other than a slightly flattened primer but it still had some rounded edge full circumference. FPS averaged 3013, which I think is fantastic! I think I'm gonna stop there and and run a series of the 59.5 and vary the jump a little either direction and see if it tightens up.

I also though about running 59.2 - 59.7 and just see what it produces.

Any other suggestions?

Of course all rifles are different, but that seems like a pretty stout charge of H4831. Just checked online (Nosler/Hodgden), and the max charge for a 140 gr bullet is 58.0, and 150 gr is 55.7. The test barrels were 24", and they were getting around 2800-2900 fps with the 150s, and 2900-3000 with the 140s.

Guess what I'm getting at, is your substantially exceeding 140 grain 24" results and powder charges with a 145 gr in a 22" barrel.

As mentioned, all rifles are different, so you may be fine, but I'd proceed with caution. When you're running at the upper end, a change in temp, neck tension, etc might cause you to rapidly rise into the "harmful" territory.

 

[John Polk]

Went out this afternoon and ran a series of H4831, 3 rd's each starting at 55.5gr up to 59.5gr in .5gr increments, .020 off the lands.

59.5gr shot a 3/4 MOA group at 200 yards. No over-pressure signs, other than a slightly flattened primer but it still had some rounded edge full circumference. FPS averaged 3013, which I think is fantastic! I think I'm gonna stop there and and run a series of the 59.5 and vary the jump a little either direction and see if it tightens up.

I also though about running 59.2 - 59.7 and just see what it produces.

Any other suggestions?

Sixty grams of H4831 is usually a slightly compressed load with a 130 grain bullet. Every rifle is different and every chamber is different so if you are not getting signs of pressure, then you're not getting signs of pressure. I'm not sure why not, but if you're not that answers the question. Go ahead and develop your loads based upon what your rifle does with the each particular load. The .270 Win. is one of the all time greats, I wish you great success.

 

[Capt RB]

Case volume is greater in hornady brass than federal or winchester which is also more than most. I'd back off to 59.0 and test seating. Once you have that figured out work back up to where it shoots best.

 

[James Pearson]

Case volume is greater in hornady brass than federal or winchester which is also more than most. I'd back off to 59.0 and test seating. Once you have that figured out work back up to where it shoots best.

My 59gr load was near 2MOA at 200 yds., and as noted before the 59.5 was 3/4 MOA. I was jumping in .5 grain increments so I'm backing off like you suggested, to 59.2, 59.3 & 59.4 just to see. I had no heavy bolt, case head markings, etc., on a 94 degree day today. I purposefully let my loads get to ambient temperature before shooting.

Am I correct in thought process that as fall comes on and temps drop, this load will decrease slightly as well? I was guessing between the 140-150 and knew I was stepping on it, but as each load progressed with no indicators I kept loading until I knew it was time to stop. Self preservation factors start kicking in!

I was concerned about over-pressure so I was closely watching for any indicators. Only got the slightly flattened primer. FPS climbed with each load progression an average of 20+/- FPS.

Sound about right from your experience?

 

[John Polk]

Sounds good to me. Have your chronograph and your pressure signs be your guide as you experiment with new and different loads. Please let us know your results.