.270 and H4831SC velocities

S

SEHunter

New member
I went on a rampage today with H4831SC and the 130gr SGK in my .270. There were loads that will make good hunting rounds but after a lot of research combined with data in several of my loading manuals, I'm not seeing the velocity that's advertised. I went from 58.0 grains to 62.5 in .5 increments. I have a 24" barrel.

This gun has a long throat and I played with several COALs. At 62.5 grains, my chrono read 3014-3045. This group was 2.5". My best group was right at 1" with 62 grains at 2990-3030 fps. These are considered hot loads in most cases even though I had no high pressure signs. No sticky bolt, no flattened primers. You read about the .270 becoming famous at 3100-3150 fps. So I'm wondering if my scale is off or if my chrono is off. The scale is a manual Hornady and I individually weigh. The chrono is a Chrony brand.

I'm considering going up in charge to see if I can find the next accuracy node at higher velocity or maybe trying H4350 to see if it pushes a 130 grainer faster. This is for a hunting gun but is also a hobby/past time so I like the challenge of finding max performance. I know the deer won't know. What's everyone's experience with velocity in a .270 with these components?
 
I don't load for 270 so no personal experience. According to Noslers data 59 gr should give you over 3100 fps.

http://www.nosler.com/nosler-load-data/270-winchester/

I have seen some individual rifles shoot slower than expected though. I own and load for several 30-06 rifles between myself and family. None shoot the exact same ammo to the same speed. There is only about 25-50 fps difference between most of them. But a friends rifle, with an equal length barrel shot 130 fps slower than my fastest barrel. This is with ammo from the same box. That much difference is unusual, but not unheard of. You may just have a "slow" barrel.
 
IMHO, there is nothing wrong with the velocity you are getting with your 1" load. What exactly are you looking to do with that extra 100 - 150 fps? I am not sure the additional stresses on the gun is worth it. Do you like to drive your car with your foot on the floor? Years ago, I used to like to get the utmost velocity I could from every rifle I had just to prove to myself that I could. Then I realized I was spending more money on powder and components than I needed to and I was wearing my guns out faster to boot. For what? Just to prove that I could? (I never really did figure out the 'why'... :o)

The faster you push a bullet, the faster it loses its momentum to air resistance because the faster the bullet travels, the more air molecules it comes into contact with and the harder it is for the bullet to push them aside. Kinda like rain drops on your windshield.
I suggest, rather than increasing the powder charge you are using, try a 130 grain VLD (Very Low Drag) bullet design by Berger, Barnes or Nosler. The .270 with a 130 or 140 grain bullet in a VLD design has a higher ballistic coefficient than most standard bullet designs. The neat thing about the VLD bullet is that by the time the projectiles get beyond about 350 - 400 yards, the slower starting bullet usually has more retained velocity than the one launched 150 fps faster. If you can find a copy, I highly recommend reading Van Zwoll's Shooter's Bible Guide to Rifle Ballistics. He explains it far better than I can.

Let me add this: Just because you are punching 1" groups at 100 yards it does not necessarily mean there will be a straight line expansion of the group size of that load down range. Some will open up, some will actually be smaller (proportionally) because the bullet has a chance to travel far enough to "go to sleep". That's usually somewhere between 250 to 300 yards.

My .270 will consistently shoot right at 0.85" at 100 meters for a five round group. Move the target frame out to 500 meters and it "should" be 5 times as big, or 4.25", yet it will consistently print 2.75" groups at 500 meters from a sand bags front and rear rest. (That load is 52.0 grains IMR4831, CCI 200 primer, Berger 140 grain Hunting VLD in Remington brass and .045" jump to the lands and, as I recall, has a MV of 2855.) The rifle is a bone stock, out-of-the-box Tikka T3 Lite with a Vortex 6.5-20x50. I use it for Hunter Class Metallic Silhouette competition. Unfortunately, it shoots a lot better than I do.

Oops! I see I got out of control again. Sorry about that! :o
 
H4831SC is a pretty slow burning powder that I think is better suited to 150 grain bullets in the 270. I burned up a pound of it in my 270 and I never got the accuracy I hoped for. Not saying it was the fault of the powder. My 270 wears a 24" barrel and it generally shoots best with 150 grain bullets driven fast. I've used a number of powders and pushed 150 grain bullets right up to 3,000 fps. If you are set on using 130 grain bullets, you should probably try IMR-4350. With 150 grain bullets, I have been using slow burning powders like H-4831, Reloder-22, IMR7828, MagPro, etc. But the powder that has been outstanding for best accuracy at 300 yards and beyond, plus the highest velocity, is Norma N-205. N-205 has been long out of production. If you find any at a gun show, be aware that it is probably at least 30 to 40 years old. Supposedly, Norma Magnum Rifle Powder, (MRP), is the replacement and should definitely be worth a try. I have some but haven't had time to test it. But that N-205 is the Cat's Meow in a 270.
 
I shoot the Nosler 130 gr BT in the 270, over 59 gr of H4831sc. That was the best load for my rifle. If you are after velocity, try Ramshot Hunter.
 
Good info, I appreciate it. I've heard in other places what pathfinder45 mentioned about 4350 possibly working better with 130 grain bullets. I have some on hand so that will be my next test.

Beepy, thanks for the point of view and the recommendation on the VLD. I'll keep that in mind. You're correct on my motivation. To just see if I can achieve accuracy with velocity is exactly what I want. It's a challenge. If I would be happy with a 1" group at 2950 fps with a 130 grainer, I'd sell the press and just buy premium production ammo. Jmo.
 
Jmr40, what's your understanding of the cause of the slow barrel syndrome you mentioned? Is it burred up rifling that fouls bad and causes drag or maybe a tighter bore? I would assume either of these conditions would also show pressure signs earlier. I don't seem to have high pressure signs with what I consider hot charges of powder. It may be because of poor accuracy but I shot a group of H4831 at 62.5 grains with no high pressure signs and yet I haven't heard anyone using that much powder in load development.

I've came across more that one example of people that fill a .270 case with H4831 to the brim of the mouth and pack the bullet in there. That would have to be at least 65 grains. I don't plan on doing that but it's another reason I want to go to a faster powder just to see how it responds in my gun.
 
With 1 inch out of a 270 I would stick with the 62 grs.

You can go faster but it only gets you more barrel wear.,
 
That's going to be my load if I don't find a different load that works better. The first group I shot with 62 grains was not good. It was around 2.5". I had the bullet seated at Hornadys recommended COAL for 130 gr bullets (even though I'm using Sierra bullets). Later I went back through all the previous tested charges with the bullet seated out closer to what the Sierra manual says. That's when the 62 gr charge groups shrunk to around 1". Velocity didn't change significantly.

The Sierra #3 manual shows 3100 fps with their max of 59.5 gr of H4831 but that's from a 26" barrel. I'm going to go through the same motions with H4350 and see what happens. In a way it will be convenient if 4350 works better because that's what my 39-06 loves. Then I'll be able to buy larger cans of powder and have the same lot for a longer period. I still wonder how some guys get 3100+ fps from 22" barrels. I'm prone to think there is a difference in accurate readings from different chronographs.
 
Think it was 1973 or so that the last of the old H-4831 was sold and we started with the Newly Manufactured H-4831. When Bob Hagel did his review on that powder he got 100fps less than Hodgdon data and there was lot to lot difference.

When Ken Waters did his update on the 270 in Pet Loads, his best accuracy was with 130gr Sierra,58gr/H-4831 @ 2941fps.

I haven't shot H-4831/H-4831sc in my 270 in years. There too many other powders.
 
SEHunter,

Several things will cause a barrel to be slower than another. SAAMI standard test barrels have minimum chamber dimensions, a standard throat, and a specific bore cross-sectional area so their pressures tend to be worst case higher than average. If your chamber is more average in size, if you have a longer throat than SAAMI, or if your rifling profile takes up less of the area of the bore, you will tend to have lower peak pressure and velocity than the SAAMI test barrel does. It's not at all uncommon for production rifles to shoot 50 to 150 fps slower than the test barrels do. Occasionally you get one that shoots faster.

But before we go too far into the gun differences, I note that Hodgdon has 60 grains as the maximum load of H4831 with a 130 grain Hornady Spire Point, and reports 3019 fps from that maximum load. That's close enough to the velocity you get with 62.5 grains that I suspect 62.5 grains is your maximum with that powder using your case, primer and bullet combination in your chamber. The powder maker will know his current lot process output best, and the other data may not be current in that regard. It depends when they purchased their lot of the powder.

Hodgdon's maximum loads for the two 4350's both exceed 3100 fps in their gun with that bullet weight.

As to exceeding 3150 in the original guns, back in the day, load manual authors seldom worked loads up with pressure test double-checking. It was all eyeballing pressure signs, which isn't really a very consistent way of working, as case brass hardness varies from brand-to-brand, and they aren't calibrated in any event. So you might have had someone with nice, hard brass who had to work the load up pretty far to see pressure signs. They could well have been running close to 70,000 psi and never known that was what they really had.
 
I did more load development yesterday with H4350 and H4831SC and carefully increased powder charge in .5 grain increments while inspecting primers and paying attention to extraction of each spent case. Apparently my gun has a chamber on the large side.

Before I forget..

"CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information."

With H4350, I went from 54.0 to 57.5 grains. Velocity reached 3100 fps with groups averaging from .8" to 1.5"

With H4831SC, I went from 60.0 to 63.5 grains. Velocity reached 3150-3200 fps with groups ranging from .6" to 1.2"

These are 100 yard, 4 round groups. Temp was 43 degrees. COAL to the ogive was 3.800" with a Hornady comparator tool on my dial indicator with a 130 grain Sierra Game King bullet.

The 63.5 charge of 4831 grouped a .8" horizontal string with perfect vertical. Im going to retest this load in hopes that the horizontal string was me and not the gun. If so, this will be my load. I was pleased. I never had a sticky bolt or primer cratering. There was maybe slight flattening of the primer but it still looked almost identical to the primers of cases with 2 grains less powder. Could have been my paranoia because it definitely was not flattened in a way that was obvious.
 
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63.5 gr of H4831sc is well above what I'd consider shooting in my 270. And how is that load going to work for you in hot weather? Be careful. You might have passed up another accuracy node at a lower powder charge, so if you aren't just in pursuit of MV you might want to retest some lighter charges.

Also, you might want to try some IMR 4831. It's a bit faster and should give you higher velocities. Note that loads of the two powders are not interchangeable. Do NOT put 63.5 gr of IMR 4831 behind the 130 gr bullet in your 270.
 
Good advise. You're right and I've considered temp change. I can't say I'll never use this gun in the hotter months but it's my dedicated deer gun from Nov-Jan.

That's why I've switched all my powder to the Hogdgen extreme line (except for RL22 in a .300 Wby). I know it's more tolerable than other powders but that it will still be affected to a degree so I will always keep this in mind with my hotter handloads. I'm just pumped I have good velocity that's MOA or smaller. This is what keeps me in hand loading.
 
If you are just at 3,200 fps with 130 grain bullets using H-4831, SC or regular, you are probably OK with those loads in your rifle only. But if you find that after 3 loads of that recipe causes loose primer pockets, you should likely reduce the charge a little. This happened to me with my model 70 in 270 Winchester. I had 140 grain Hornady bullets clocking out at 3,285. There were no other pressure signs visible but loose pockets after 2 and 3 load cycles. While a chronograph is an unnecessary device for reloading, when you are trying to reach a safe maximum load, it becomes an indispensable tool. I now consider velocity itself a pressure warning sign. I have reloaded for the 270 Since 1973 as a main caliber and I have come to look at it this way: The maximum safe pressures WHEN USING OPTIMUM POWDERS, will yield 3,200 fps with 130 grain bullets; 3,100 fps with 140 grain bullets; 3,000 with 150 grain bullets and all in 24" barrels. With a 22" barrel you should reduce that expectation by at least 50 fps. This is with slow burning,
propellants. With faster burning propellants more suited to a 308, you will hit dangerous pressures before you get to these velocities. On the ragged edge of maximum, stick with extruded powders like H-4831, IMR-4350 and the like. Weigh every charge. My experience with H-450, the spherical, "equivalent", of H-4831, is to avoid it if you find any, as it can vary widely from lot to lot. One lot of it gave over maximum expected velocity from a listed starting charge. What do I like about sperical/ball propellants? Well, you can use a powder measure and only weigh every tenth round or so, speeding up the whole process. But I use that stuff for bulk, "milk-jug/plinking ammo", and keep it well away from maximum. If you simply must dance on that red-line, use the best, most forgiving powders for the job. In the end, your quest may end with nothing practical being gained. Or, like what happened in my case, I found my most accurate load by far to be a rather hot one, pushing 150 grain Nosler Partitions to 3,000 fps.

May you find that polished arrow, and safely.
 
Pathfinder, thanks for your post. I always appreciate advise that's backed with experience. From my own experience, what you've shared is dead on. I'm not afraid of hot loads relatively speaking. I believe all chambers can easily handle any load within a few grains from any past or present maximum published load but I also know safety comes first so sometimes I hold my opinions even if it's supported by real world testing. Anyway, as for the chrono, my philosophy with that tool is if I have multiple loads that group the same, I simply choose the fastest one. I figure why not.

At the same time, the chrono aggravates me too. I retested those same 4831 loads today and my groups were still around MOA but the velocity reading was 75 fps slower on average. ???!! Who knows. It's got to be the Chrony but I'm not going to sweat it. It'll drive me crazy. Besides, at 63.5 grains of H4831, I just can't keep going up. It's just not worth it. Even though I don't see any obvious pressure signs, surely I'm at the line that shouldn't be crossed.
 
Funny you mention that. I filled a case today flush with the brim of the mouth. 67 grains of H4831SC. I've read where some guys load that load. Lol. Seriously.
 
What brand of cases are you using? I do know that the SC version will allow you to get a heavier charge to fit in the case than the standard version. I currently have some WWII surplus H-4831 and some recent manufactured H-4831 powders, and you simply cannot get that much of it to fit in the case. Currently, I am out of the SC version and don't plan to get any more since I am well stocked on other propellants that I prefer. But I've burned a pound of it through my current 270 and taken some load notes.
 
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