Closing in on 140 gr. AB in 270 Win.

[NYDAN]

I have been working on a load for the 140 gr AB in my .270 Win for a while now.

First I couldn't get the velocity I wanted with H4831sc. I haven't yet found the correct seating depth with RL22. Then I couldn't get IMR 4831 until just recently.

I previously worked up to 55.0 gr. of IMR4831 to get near 2900 fps. So, I finally loaded up four cartridges with an OAL of 3.350" and shot the top group. Bullets 2 & 3 went through the same hole or I missed the entire target and backboard. The first shot, the fouling shot, I believe I pulled low and right by a 1/2". If I did, in fact, pull it, then the first shot would have been just left of shots 2 & 3. Shot 4 looked good in the scope but still hit a little high. I think that variation is real.

Since I had been pleasantly surprised with IMR 7828 ssc with both the 150 gr. ABLR and the 150 gr. CTBST I decided, as a whim, to try it with the 140 gr. AB. The results speak for themselves.

In my previous reloading projects, I just picked one bullet, one powder and then adjusted the powder charges and the seating depth to obtain good accuracy. I did not have a chronograph back then.

I have never worked with multiple powders before in one cartridge so these results generate two questions in my mind.

1. I was under the impression that a particular rifle would probably "like" a different powder for each bullet. But, so far in my experience with this rifle, it seems to "like" the IMR 7828ssc for three bullets. Is this unusual or is this common?

2. Referring to the first shot on the second target - when testing two loads with different powders, is it usual to need a fouling shot between the two loads? Does the powder residue from the different powders give different results for the following shot? Should I count the first shot on the second target as part of the group or just the 2nd, 3rd, and 4th shots.

I think my next tests are to try to some varying OAL with the IMR 7828ssc. I think I will try to seat the bullets deeper in .005" or .010" increments. Also, I need to switch to my supply of Norma brass since that is what I have the most of.

 

[JD338]

Dan,

Nice work buddy.
Try seating deeper in .005" increments and it should pull in the "flyer".
You are pretty much there.

JD338

 

[Sas874runner]

Yup good shooting. I have found that one rifle can shoot well with one powder. And that seems very common yet it is very uncommon to have a rifle that will shoot multiple powders well. Tune that seating depth and you should be looking good to stretch the legs of that 270 a little.

 

[DrMike]

I1. I was under the impression that a particular rifle would probably "like" a different powder for each bullet. But, so far in my experience with this rifle, it seems to "like" the IMR 7828ssc for three bullets. Is this unusual or is this common?

Not at all unusual. Many rifles show a preference for a single powder.

2. Referring to the first shot on the second target - when testing two loads with different powders, is it usual to need a fouling shot between the two loads? Does the powder residue from the different powders give different results for the following shot? Should I count the first shot on the second target as part of the group or just the 2nd, 3rd, and 4th shots.

Since each rifle is a law unto itself, it is difficult to make a universal pronouncement on this. Some rifles will prefer a fouling shot; others will not.

You are very thorough in your efforts, and you are asking all the right questions. JD338 is correct, you are about "there."

 

[hubcap]

I think you have nice problem to deal with. Both powders are showing the potential to shine.

 

[NWBlacktail]

This is from my Remington 700, 270 win. I'm using 140 grn Accubonds with 58.0 grn H4831sc, WLR primers. Im only getting 2806 fps with a standard deviation of 6. I'd like another 100 fps but my rifle has a lot freebore. I could probably go over book max without pressure issues, but it's shooting so well I just don't want to change anything. :mrgreen:

 

[Darkhorse]

Let's address the fouling shot. I have had rifles that shot into the group from a squeaky clean bore. And I have had rifles that wouldn't.
For example I test fired around 200 rounds working on a load and BOSS setting in my .300 Win. I saved all my targets for reference (have since lost them) and I noticed that at almost 100 shots to the round accuracy suddenly improved dramatically.
I also discovered this rifle must have a minimum of 3 fouling shots to settle into the group. If shot from a clean bore a 3 shot group was about a 1", from a fouled bore my whitetail load was in the .180's, so this rifle always hunts with a minimum of 3 shots down the barrel.
All my testing is now done with 3 fouling shots first. Then the barrel is allowed to cool before shooting my test groups. This removes any question of the affect a clean bore might have on your tests.
After I decide on my final load I will clean the barrel then go shoot that load from a cold, clean barrel. Now I know how the combo performs from both a fouled and clean bore.
Yeah it's a lot bullets down range and a lot of time but when it's done I know everything I need to know about that load, rifle combo.
You might want to incorporate this into your load testing.

 

[NYDAN]

I'm using 140 grn Accubonds with 58.0 grn H4831sc, WLR primers. Im only getting 2806 fps with a standard deviation of 6. I'd like another 100 fps but my rifle has a lot freebore. I could probably go over book max without pressure issues, but it's shooting so well I just don't want to change anything. :mrgreen:

NW Blacktail,

At 58.0 gr. H4831sc I had an average of 2773 fps. I worked up to 59.0 gr. H4831sc and only got an average of 2791 fps. An increase of only 18 fps I just wasn't gaining velocity with the increase in powder. At the suggestion of others in this forum I tried other powders and gained the velocity I was looking for. That is a good group you posted and I can see why you wouldn't want to change your load. Good shooting on your part.

Dan

 

[sask boy]

Dan, thank you for that info I was able to pick up a couple of pounds of IMR 7828ssc yesterday.
I am going to try it with all three bullets 130gr. ABs, 140gr. ABs & the 150gr. ABLRs.

Blessings,
Dan

 

[6mm Remington]

Another good one to try in addition to the IMR7828ssc would also be good old IMR4350 if you have some of that. Does look like the 7828 is working out nicely though.

 

[NYDAN]

Another good one to try in addition to the IMR7828ssc would also be good old IMR4350 if you have some of that. Does look like the 7828 is working out nicely though.

6mm Rem, I did not try IMR4350 but I did try some H4350. I started at 52.0 grains and worked up to 54.5 grains. Just as I reached 2900 fps at 54.5 grains I also had a flattened primer. At that point the RL22 looked more encouraging so I left the H4350.

 

[CatskillCrawler]

I've shot the 140gr AB over 58.0gr of H-4831 for some time now and have been extremely satisfied with the accuracy of this load. Velocity has been mid-2800's thru several 1lb jugs if powder from different lots. Accuracy was always consistent though.

I've been tossing the idea around to look into RL-22 and IMR-7828 in this rifle with the ABs as they both performed well with 140gr PTs. You're post is quite timely and will be followed
with interest.

 

[sask boy]

I have been using IMR4350 in my 270win for over 40years :wink:.
Load info for 130gr. ABs is 54.5grs. of IMR4350 right around 3000fps. & .5 MOA if I am on that day :mrgreen:. It close to max so remember start lower & work up.

Blessings,
Dan

 

[NWBlacktail]

At 58.0 gr. H4831sc I had an average of 2773 fps. I worked up to 59.0 gr. H4831sc and only got an average of 2791 fps. An increase of only 18 fps I just wasn't gaining velocity with the increase in powder. At the suggestion of others in this forum I tried other powders and gained the velocity I was looking for. That is a good group you posted and I can see why you wouldn't want to change your load. Good shooting on your part.

Dan

I've heard that before. I kind of don't get how Nosler's reloading data shows it relatively decent (3000 fps), but a lot of guys are getting much worse. I get the whole custom barrel/chamber tolerances (used in Nosler data) compared to factory barrels, but still, relatively speaking, it seems it should be doing better. :?:

 

[sendero]

Always get god velocety with
Norma MRP and w N-560 in 270w regardless of barrel length.
Lapua brasses has allways given a litle more speed (compared with norma, federal and winchester) and pressure.

 

[SJB358]

I know I would try RL22 or 7828 should I ever have a 270 Win in the safe. It works really well in my WSM as well.

Great shooting Dan. I wished I had your "troubles" of picking a powder... HA!

 

[hubcap]

I just happen to have a jug of new 7828 and some 150 LRAB,s. got to try it. Like others I do not get any velocity with H4831 either. NYDAN done got my attention.

 

[sendero]

Is it possible to get enough 7828 in a 270w to give 150lrab speed? Tryed some MRP2, just do not have enough case volume.
I use 58 grains MRP with 150grains LRAB, next load i trye 58.5

 

[DrMike]

Is it possible to get enough 7828 in a 270w to give 150lrab speed? Tryed some MRP2, just do not have enough case volume.
I use 58 grains MRP with 150grains LRAB, next load i trye 58.5

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 150, Nosler AccuBond LR 58836 G7
Useable Case Capaci: 58.520 grain H2O = 3.800 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : IMR 7828 SSC

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 84 46.56 2311 1778 31600 10379 85.6 1.478
-18.0 86 47.72 2374 1878 33852 10767 87.2 1.438
-16.0 88 48.89 2439 1981 36273 11146 88.8 1.398
-14.0 90 50.05 2503 2088 38880 11513 90.3 1.352
-12.0 92 51.22 2569 2198 41688 11866 91.6 1.308
-10.0 95 52.38 2635 2312 44718 12203 92.9 1.264
-08.0 97 53.54 2701 2429 47990 12522 94.1 1.222
-06.0 99 54.71 2767 2550 51528 12822 95.2 1.182
-04.0 101 55.87 2834 2675 55362 13099 96.2 1.143 ! Near Maximum !
-02.0 103 57.04 2901 2803 59518 13353 97.1 1.105 ! Near Maximum !
+00.0 105 58.20 2968 2934 64033 13580 97.9 1.068 ! Near Maximum !
+02.0 107 59.36 3035 3068 68948 13780 98.6 1.033 !DANGEROUS LOAD-DO NOT USE!
+04.0 109 60.53 3102 3205 74310 13949 99.1 0.999 !DANGEROUS LOAD-DO NOT USE!
+06.0 111 61.69 3169 3346 80170 14088 99.5 0.966 !DANGEROUS LOAD-DO NOT USE!
+08.0 113 62.86 3237 3489 86593 14192 99.8 0.934 !DANGEROUS LOAD-DO NOT USE!
+10.0 116 64.02 3304 3635 93647 14261 100.0 0.903 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 105 58.20 3124 3251 78159 13281 100.0 0.984 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 105 58.20 2756 2530 51812 13020 90.7 1.177

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 150, Nosler AccuBond LR 58836 G7
Useable Case Capaci: 58.520 grain H2O = 3.800 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : IMR 7828

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 89 46.56 2311 1778 31600 10379 85.6 1.478
-18.0 91 47.72 2374 1878 33852 10767 87.2 1.438
-16.0 93 48.89 2439 1981 36273 11146 88.8 1.398
-14.0 95 50.05 2503 2088 38880 11513 90.3 1.352
-12.0 98 51.22 2569 2198 41688 11866 91.6 1.308
-10.0 100 52.38 2635 2312 44718 12203 92.9 1.264
-08.0 102 53.54 2701 2429 47990 12522 94.1 1.222
-06.0 104 54.71 2767 2550 51528 12822 95.2 1.182
-04.0 107 55.87 2834 2675 55362 13099 96.2 1.143 ! Near Maximum !
-02.0 109 57.04 2901 2803 59518 13353 97.1 1.105 ! Near Maximum !
+00.0 111 58.20 2968 2934 64033 13580 97.9 1.068 ! Near Maximum !
+02.0 113 59.36 3035 3068 68948 13780 98.6 1.033 !DANGEROUS LOAD-DO NOT USE!
+04.0 115 60.53 3102 3205 74310 13949 99.1 0.999 !DANGEROUS LOAD-DO NOT USE!
+06.0 118 61.69 3169 3346 80170 14088 99.5 0.966 !DANGEROUS LOAD-DO NOT USE!
+08.0 120 62.86 3237 3489 86593 14192 99.8 0.934 !DANGEROUS LOAD-DO NOT USE!
+10.0 122 64.02 3304 3635 93647 14261 100.0 0.903 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 111 58.20 3124 3251 78159 13281 100.0 0.984 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 111 58.20 2756 2530 51812 13020 90.7 1.177

They will be compact loads, but you should be able to get them in the case.

 

[Sas874runner]

Sendero try mag pro or magnum. I'm using 64.0 gr of magnum with the 150 ablr in my 24" 270 win. Velocity average is 3054. Accuracy is .5" I did work up to 66.5 gr where I met pressure. Magpro gave me 2950 where accuracy was best. But it was right at moa on a good day. I was unable to shrink the group any more than that. Magpro is my powder of choice for the 140 ab. 62.5gr is giving me an average of 2988 fps