7 twist 3.50" COL 270 winchester quickload request

[jjmp]

There's another member here that made he's wildcat 270/7 mm Remington magnum ,mybe he will chime in

 

[assasinator]

i ran some numbers and even at 106% case fill you barely make 45000 psi and your right will burn extremely dirty.

thank you. i shot it with 175 TGK and i had pressure signs.

powder speed on a chart is for reference only. as the bullet weight increases a overbore cartridge like the 270 with a extra 4 grains i have, can pop.

that is why i wanted a quickload run. its less conjecture and more empirical.

how about running what i am trying and posting it? please.

 

[assasinator]

Holy smokes you ain't kidding. I just consulted a handy burn rate chart…that's one above H50BMG!!!!!

I agree therefore. Way too slow. Not useless. But expect nowhere near top velocity realized with heavily compressed loads that burn FILTHY! I know this because I've done similar things, H50bmg in a .300 Winnie, h870 in a .270.

And I'm a big believer that the 270 data out there doesn't seem to want to include slower burning powder THAT DO GREAT! Imr 7828 and rl25 have proven to be some awesome powders in my 270, even with a 22 inch pipe. But that bmg burn rate is just waaaay to slow, even for me!

that powder is used for overbore loads in many calibers. i am not really running a 270 win. thanks for the feedback.

 

[assasinator]

i remind that i just shot150gr ablr 62 GRAINS OF MAGPRO WITH 2900 FPS AND LOW PRESSURE. I am adding .5 grains per 5 shots this weekend until i get the max.

that 62 grains was zero compressed load.

 

[assasinator]

Cartridge : .270 Win. (SAAMI)
Bullet : .277, 150, Nosler Accubond LR 58836
Useable Case Capaci: 60.976 grain H2O = 3.959 cm³
Cartridge O.A.L. L6: 3.500 inch = 88.90 mm
Barrel Length : 27.0 inch = 685.8 mm
Powder : Accurate MAGPRO

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 83 49.60 2272 1720 23222 8524 80.8 1.907
-18.0 85 50.84 2346 1834 25231 8885 82.9 1.834
-16.0 87 52.08 2421 1952 27404 9235 84.8 1.764
-14.0 89 53.32 2495 2073 29756 9574 86.7 1.697
-12.0 91 54.56 2570 2199 32303 9900 88.4 1.633
-10.0 93 55.80 2644 2328 35062 10210 90.0 1.573
-08.0 95 57.04 2718 2461 38057 10504 91.5 1.515
-06.0 98 58.28 2793 2598 41309 10781 92.9 1.460
-04.0 100 59.52 2867 2737 44843 11037 94.2 1.407
-02.0 102 60.76 2941 2881 48694 11273 95.4 1.356
+00.0 104 62.00 3015 3027 52893 11486 96.4 1.308
+02.0 106 63.24 3088 3176 57479 11676 97.3 1.261 ! Near Maximum !
+04.0 108 64.48 3161 3329 62466 11840 98.1 1.217 ! Near Maximum !
+06.0 110 65.72 3234 3484 67897 11978 98.7 1.174 !DANGEROUS LOAD-DO NOT USE!
+08.0 112 66.96 3307 3642 73824 12089 99.2 1.133 !DANGEROUS LOAD-DO NOT USE!
+10.0 114 68.20 3379 3803 80305 12170 99.6 1.094 !DANGEROUS LOAD-DO NOT USE!

these closely match what i saw at the range.


i also ran the numbers in a variety of ways. ordered retumbo. only wasted 45.00. i'll use it for other things.

 

[assasinator]

so this is the last post in this thread....there will be a new one next weekend....

i loaded the 270 long fast with 170gr nosler tipped. they just will never reach my goals. i mean if i could never do anything with my barrel, i would deal with it and take months to maximize accuracy for the velocity that i can get.

2800 fps is decent for a 170 in 270 win. i was hoping that with the lower pressures and higher capacity from my chamber, i could push it farther. i used magpro.

i havent tried magnum primers, but i doubt it would matter. so....

i am getting it rechambered to 270 weatherby mag tuesday. i dont waste powder, bullets, and time. at least i try not to.

the freebore will remain the same (shortened by .090") so it will perform like my other belted mags. at least i gave it the old college TRY lol.

i dont have any weatherby mags. i generally get specific chambers cut that meet my requirements. i am only getting the 270 weatherby cut because the gunsmith has it in his toolbox. I REALLY wanted 270-338 winmag with a .040 longer neck. my 338 based loadings dont split belts off like weatherbys do.

oh well. i will have to neck size the 270 bee and trim it. i just happen to have 75 270 weatherby brass because i always planned for this.

i also have 257 BEE cases i made 270-338 cases for fireforming. its hard to knock back the 270 BEE shoulder. anyway. later.

the retumbo and 24n41 may work for this. we'll see. 175 grain TGK.

 

[assasinator]

didnt want to start a new thread.

hornady has h1000 in stock.

just ordered 4 lbs. i mean the 60 pounds of different powders i have now isnt enough lol. i believe it will work great with the 270 weatherby with 3.50" COAL.

 

[assasinator]

so FINALLY.....i just got my 270 weatherby mag 7 twist back from the gunsmith.

of course its the 270 winchester rechambered.

same throating at .600" for the winchester chamber now makes it .591 for the Bee.

i mentioned using 24n41 powder for the 270 fast, long Win, but now the real reason for that powder.....

3.50" COAL 175 grain sierras.

i cant really shoot 130grain bullets, IMO but the range will decide it they will shoot accurate enough.
its only taken since october to get the barrel back.

i had to buy a custom reamer with a 1" longer pilot than any other reamer PTG sells. my gunsmith has a 270 weatherby reamer, but it didnt touch the rifling. the PTG reamer POPPED. it was about 1.5" into the chamber then it broke. that forced the gunsmith to hand ream it the rest of the way. the chatter mark cleaned up and the chamber looks like a million bucks. he is just as crazy about details as me, and he loves it. he is retired from a major gun manufacturer at 35 years. he started this stuff in 1979. i started in 1987.

NOW the real fun starts. developing loads for the best caliber i have owned. the previous 270 shot 1/2" at 100 sitting on my led sled. it maxxed at 2950 with 150 ABLR.

since the day i saw 6.8 western reviews, i wanted to exceed them. so MGM sells .277 barrels in 7 twist. here we are today.

this is about speed yes, but accuracy first. one of the great side effects of long freebore, is using faster, cheaper powders and still getting the speed i love. faster powders by a bit lol.

lets see what a 27", 7 twist 270 BEE can do at 3.50" COAL. 140,150,165,170,175gr.

 

[backwoodsshooter]

fwiw, this was what my 270win did at 200yards with 60.5 grains of magpro, and the 170EOL. though i have a 1:8 barrel at 29" long

was clocking in at 2932

BTO is 2.830

i worked up a load with the 165 ABLR around the same speed and haven't fine tuned it but it was grouping right at .800" at 100.

 

[assasinator]

Cartridge : .270 Weath. Mag.
Bullet : 170 nosler ballistic tip
Useable Case Capaci: 74.038 grain H2O = 4.807 cm³
Cartridge O.A.L. L6: 3.500 inch = 88.90 mm
Barrel Length : 27.0 inch = 685.8 mm
Powder : Vihtavuori 24N41 *C

Predicted data by increasing and decreasing the given charge,
incremented in steps of 3.0% 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

-30.0 75 54.25 1961 1451 18996 7647 69.1 2.292
-27.0 78 56.58 2059 1600 21315 8270 72.2 2.165
-24.0 81 58.90 2159 1760 23913 8896 75.3 2.045
-21.0 84 61.23 2262 1931 26830 9520 78.3 1.933
-18.0 87 63.55 2366 2114 30109 10137 81.1 1.827
-15.0 91 65.88 2473 2308 33803 10739 83.9 1.729
-12.0 94 68.20 2581 2514 37976 11320 86.5 1.635
-09.0 97 70.53 2690 2731 42700 11874 88.9 1.547
-06.0 100 72.85 2800 2960 48076 12393 91.1 1.464
-03.0 103 75.18 2912 3201 54206 12871 93.1 1.385
+00.0 107 77.50 3025 3454 61235 13300 94.9 1.311 ! Near Maximum !
+03.0 110 79.83 3139 3718 69333 13672 96.4 1.240 !DANGEROUS LOAD-DO NOT USE!
+06.0 113 82.15 3253 3995 78717 13981 97.7 1.173 !DANGEROUS LOAD-DO NOT USE!
+09.0 116 84.48 3369 4283 89649 14217 98.7 1.110 !DANGEROUS LOAD-DO NOT USE!
+12.0 119 86.80 3485 4583 102438 14373 99.4 1.049 !DANGEROUS LOAD-DO NOT USE!
+15.0 123 89.13 3601 4896 117550 14440 99.9 0.991 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba 107 77.50 3123 3681 68332 13457 97.6 1.252 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba 107 77.50 2914 3205 54686 12956 91.0 1.378 ! Near Maximum !



i am pretty sure this is low for my actual barrel. low in pressure and speed from what the barrel did as a 270 win.

i cant be sure until i get range time. all i have to do is mess with seating depth. i have space to mess with, making it longer to maybe 3.55".




now 175 TGK with 24n41.....

Cartridge : .270 Weath. Mag.
Bullet : .277, 175, Sierra TGK 4475
Useable Case Capaci: 56.383 grain H2O = 3.661 cm³
Cartridge O.A.L. L6: 3.500 inch = 88.90 mm
Barrel Length : 27.0 inch = 685.8 mm
Powder : Vihtavuori 24N41 *C

Predicted data by increasing and decreasing the given charge,
incremented in steps of 3.0% 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

-30.0 98 54.25 2330 2109 35594 8552 80.7 1.697
-27.0 102 56.58 2453 2338 40976 9122 83.8 1.592
-24.0 106 58.90 2579 2585 47356 9664 86.7 1.487
-21.0 111 61.23 2709 2852 54990 10167 89.4 1.389 ! Near Maximum !
-18.0 115 63.55 2843 3140 64224 10620 91.9 1.296 !DANGEROUS LOAD-DO NOT USE!
-15.0 119 65.88 2980 3450 75542 11008 94.2 1.207 !DANGEROUS LOAD-DO NOT USE!
-12.0 123 68.20 3121 3785 89642 11316 96.1 1.123 !DANGEROUS LOAD-DO NOT USE!
-09.0 127 70.53 3266 4146 107570 11526 97.7 1.043 !DANGEROUS LOAD-DO NOT USE!
-06.0 132 72.85 3416 4535 130958 11618 98.9 0.967 !DANGEROUS LOAD-DO NOT USE!
-03.0 136 75.18 3572 4958 162520 11567 99.7 0.893 !DANGEROUS LOAD-DO NOT USE!
+00.0 140 77.50 3734 5419 207107 11338 100.0 0.822 !DANGEROUS LOAD-DO NOT USE!
+03.0 144 79.83 3906 5928 274402 10951 100.0 0.752 !DANGEROUS LOAD-DO NOT USE!
+06.0 148 82.15 4093 6510 386588 10420 100.0 0.683 !DANGEROUS LOAD-DO NOT USE!
+09.0 153 84.48 4308 7212 608819 9651 100.0 0.613 !DANGEROUS LOAD-DO NOT USE!
+12.0 157 86.80 4586 8171 1252167 8382 100.0 0.537 !DANGEROUS LOAD-DO NOT USE!
+15.0 161 89.13 cannot find match, try to lower shot start pressure

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba 140 77.50 3803 5619 231579 10964 100.0 0.794 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba 140 77.50 3647 5170 184488 11669 99.4 0.855 !DANGEROUS LOAD-DO NOT USE!


this is a case where i am 100 percent sure the pressures are accurate.

i shot this powder in the 270 WIN with these sierra 175TGK and the pressures were out of bounds. the case stuck in the barrel even at 3.50" coal. the load was a starter at 47 grains of 24n41.


i HAVE already shot it with 150 ABLR at 3.50" and a starting load of 63 grains of retumbo.

the shots were for checking headspace and extraction, and to assure that moderate loads were not over pressure.

i say that it is likely low because i have .591" freebore and 3.5" COAL is going to cause very low pressures initially.

-bill

 

[assasinator]

fwiw, this was what my 270win did at 200yards with 60.5 grains of magpro, and the 170EOL. though i have a 1:8 barrel at 29" long

was clocking in at 2932

BTO is 2.830

i worked up a load with the 165 ABLR around the same speed and haven't fine tuned it but it was grouping right at .800" at 100.

yes, great!!!!

so i was a bit low on speed because i have a .600" throat and my pressures are low. even at 62 grains of magpro i have NO pressure signs.

i just gave up and dropped off the barrel for rechambering.

i could have added a few more grains maybe. at 62 grains the speed was a little low because the jump drops pressure by a estimated 10k psi for the first milliseconds. 1" travel lol.

i am not sure about your rifle or chamber, but if you stick with 270win and fast twist, but a single loaded bullet and a long throat can at least exceed most 270 win.

so, IMO doing what i did and rechamber to 270weatherby is best. i have a few grains more capacity than 3.25" with .25" longer COAL for both 270win and 270 weatherby.

sierra has load data for a 150TGK using 24n41. 24n41, magpro, h1000, and retumbo were my choices for my long COAL 270win and now long 270 weatherby.

even though quickload has limiations for 270win 150gr in 'theory' it does achieve pressures in practice. i did overpressure a 175TGK in my .400" chamber at 3.50". so, you need to be careful when you finally use a 175TGK in that 270 WIn, if you do.

the 175TGK has the same ogive as any other sierra 140/150 gameking. it has a crazy long bearing length, and drag. it also hits the lands early compared to high BC with a tangental ogive bullets.

i measure my contact points. i have tools, but i was unaware that the 175tgk drags so bad. the overpressure happened with a starting load. in 37 years that was the first.

anyway, it will help you to add freebore to your rifle, even if you are limited to a box magazine COAL.

later, and good luck. be careful. if you want raw stock 270 win quickload data, just ask and i will post it. i have 450 x165gr and 170gr .277 bullets in the mail. i will be loading the HOT! i lost .009" freebore by rechambering to 270 weatherby mag. i have the tool , and i can add .009" any time i like.



BTW my 27" 7 twist using 150gr ABLR (2950) and 62 grains of magpro shot one hole 1/2" at 100 in the encore with isolated foregrip and lead sled, meopta 3x18.

cant wait to shoot the 270 weatherby 7 twist. 140, 150ablr, 165ablr, 170AB, 170oel, 175TGK.

 

[backwoodsshooter]

yes, great!!!!

so i was a bit low on speed because i have a .600" throat and my pressures are low. even at 62 grains of magpro i have NO pressure signs.

i just gave up and dropped off the barrel for rechambering.

i could have added a few more grains maybe. at 62 grains the speed was a little low because the jump drops pressure by a estimated 10k psi for the first milliseconds. 1" travel lol.

i am not sure about your rifle or chamber, but if you stick with 270win and fast twist, but a single loaded bullet and a long throat can at least exceed most 270 win.

so, IMO doing what i did and rechamber to 270weatherby is best. i have a few grains more capacity than 3.25" with .25" longer COAL for both 270win and 270 weatherby.

sierra has load data for a 150TGK using 24n41. 24n41, magpro, h1000, and retumbo were my choices for my long COAL 270win and now long 270 weatherby.

even though quickload has limiations for 270win 150gr in 'theory' it does achieve pressures in practice. i did overpressure a 175TGK in my .400" chamber at 3.50". so, you need to be careful when you finally use a 175TGK in that 270 WIn, if you do.

the 175TGK has the same ogive as any other sierra 140/150 gameking. it has a crazy long bearing length, and drag. it also hits the lands early compared to high BC with a tangental ogive bullets.

i measure my contact points. i have tools, but i was unaware that the 175tgk drags so bad. the overpressure happened with a starting load. in 37 years that was the first.

anyway, it will help you to add freebore to your rifle, even if you are limited to a box magazine COAL.

later, and good luck. be careful. if you want raw stock 270 win quickload data, just ask and i will post it. i have 450 x165gr and 170gr .277 bullets in the mail. i will be loading the HOT! i lost .009" freebore by rechambering to 270 weatherby mag. i have the tool , and i can add .009" any time i like.



BTW my 27" 7 twist using 150gr ABLR (2950) and 62 grains of magpro shot one hole 1/2" at 100 in the encore with isolated foregrip and lead sled, meopta 3x18.

cant wait to shoot the 270 weatherby 7 twist. 140, 150ablr, 165ablr, 170AB, 170oel, 175TGK.

oh i agree with more free bore and lower pressures.

i stopped around 63.5grs due to grouping looking like a shotgun pattern. but never hit pressure with the 170 EOL.

Speaking of freebore, i'll have to measure mine but i do know that with the 170, the base of the bullet is a few thousandths in to the shoulder area.

now the 165ablr is a different story, but i've ran it up over 3k and no pressure signs even being more in to the case.

I've thought about the 175tgk but the 165ablr and the 170EOL do everything i need it for now.

i did thought mine specifically for the 170s since they are long. but i run them about 35 thousandths off the lands. so BTO is 2.830, and the COAL is like 3.650.

Either way sounds like you got yours taken care of lol.

 

[Calvin45]

The 270 and 7mm weatherby magnums are both sleeper cartridges in my opinion. And with better twist rates they're almost, dare I say, efficient haha.

 

[assasinator]

oh i agree with more free bore and lower pressures.

i stopped around 63.5grs due to grouping looking like a shotgun pattern. but never hit pressure with the 170 EOL.

Speaking of freebore, i'll have to measure mine but i do know that with the 170, the base of the bullet is a few thousandths in to the shoulder area.

now the 165ablr is a different story, but i've ran it up over 3k and no pressure signs even being more in to the case.

I've thought about the 175tgk but the 165ablr and the 170EOL do everything i need it for now.

i did thought mine specifically for the 170s since they are long. but i run them about 35 thousandths off the lands. so BTO is 2.830, and the COAL is like 3.650.

Either way sounds like you got yours taken care of lol.

i called sierra and talked to a engineer concerning the 175TGK....
it is simply a long 150. it has a overly long bearing. it has a low BC for the weight. i have maybe 45 left of 50. even with long freebore, the 175 TGK will overpressure. its almost like a older barnes copper. no relief for pressure.

i can see a usage for it. my standard length, 3.50" and very slow powder at starting levels. just accept low speed, bc, in exchange for terminal weight.

the good news is, i have 450 x 165/170 bullets in the mail. i wont ever be buying another 175TGK unless they completely change the ogive design.

to address the 170 EOL, with its ogive, it adds freebore without a modded chamber. they sent me load data for it.