.257 bullet issues

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  • Last Post 11 November 2023
JeffinNZ posted this 31 October 2023

I have been shooting a NOE pattern bullet in my .257 Roberts AI.  The mold belongs to a friend who bought it as part of one of the early group buys that Al at NOE did.  The mold throws a plain base 90gr bullet and a 120gr GC version.

The GC version is rather inconsistent.  I have been casting in ACWW and burning numerous powders under it.  Some groups will be very good and others will 1) throw a couple of rounds out of the group and/or 2) produce oval holes indicating tipping.  This is happening with PC and lubed bullets.

I wonder if the bullet is collapsing due to the wider lube groove created by lengthening the bullet from 90 to 120gr.  

Thoughts?

Cheers from New Zealand

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.22-10-45 posted this 31 October 2023

I am shooting a NOE 100gr. G.C. in a .25 Ackley Improved Krag.  Full length krag case version.  Rifle groups jacketed in 3/4" at 100yd.  The NOE will also...sometimes!  Anyway,getting back to your question...I have been using smokeless in an original Sharps Borchardt .40-70 Mid-Range.  Bullets are cast 20-1.  Bullets with "smokeless" type lube grooves (narrow/shallow) shoot very accuratly.  I wanted to try a couple of Brooks bullets that have proved very accurate with straight Black these have "black  powder" grooves..wide and deep. No matter how much I tweaked the smokeless charge, I couldn't equal the accuracy of the "smokeless" grooved bullets. I figured those high unsupported driving bands were the culprit.

 

 

 

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Ken Campbell Iowa posted this 31 October 2023

my first thought is just that the bullet isn't spinning fast enough for that length ...

ken, simple questions for complicated answers ...

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delmarskid posted this 31 October 2023

Water drop them and try to make 2200 fps?

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JeffinNZ posted this 31 October 2023

my first thought is just that the bullet isn't spinning fast enough for that length ...

ken, simple questions for complicated answers ...

Doing 1800-2000fps. Plenty fast for the 1-10 twist.

Cheers from New Zealand

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OU812 posted this 31 October 2023

Will this long bullet chamber without being pushed back into case? Try a soft alloy 10 bhn. LOTS of things you can try. The majority of NOE designs are undesirable IMO.

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JeffinNZ posted this 31 October 2023

Will this long bullet chamber without being pushed back into case? Try a soft alloy 10 bhn. LOTS of things you can try. The majority of NOE designs are undesirable IMO.

Alloy is 9.8BHN. Front band touches rifling and bullet does not push into the case.

Cheers from New Zealand

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Aaron posted this 31 October 2023

Run the 120gr bullet length through the Greenhill Formula. Sometimes the obvious answer is the answer despite us.

 

 

With rifle in hand, I confidently go forth into the darkness.

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Larry Gibson posted this 31 October 2023

my first thought is just that the bullet isn't spinning fast enough for that length ...

ken, simple questions for complicated answers ...

 

^^^^^^^^this........

LMG

 

Concealment is not cover.........

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OU812 posted this 31 October 2023

Target does not show unstable keyholing, but it does show vertical stringing (screw greenhill). Vertical stringing is caused by wide spread velocity caused by powder or powder positioning in case.

BTW bullet fit is king. Bumping and fitting better always works.

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delmarskid posted this 31 October 2023

4064 powder seems a little slow

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Shuz posted this 31 October 2023

4064 powder seems a little slow
Try some Reloder 7 if you can get that powder " down under".

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OU812 posted this 31 October 2023 

Cartridge          : .30-06 Spring.  (SAAMI)
Bullet             : .309, 170, LEE C309-170-F
Useable Case Capaci: 65.616 grain H2O = 4.260 cm³
Cartridge O.A.L. L6: 3.340 inch = 84.84 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : Hodgdon TiteGroup

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms
-38.5   16     8.00   1187     532   12776   1431    100.0    2.484
-34.6   17     8.50   1225     566   13845   1516    100.0    2.388
-30.8   18     9.00   1262     601   14932   1600    100.0    2.302
-26.9   19     9.50   1298     636   16037   1684    100.0    2.223
-23.1   20    10.00   1333     671   17161   1768    100.0    2.151
-19.2   21    10.50   1367     705   18302   1851    100.0    2.086
-15.4   22    11.00   1400     740   19460   1934    100.0    2.026
-11.5   23    11.50   1433     775   20636   2017    100.0    1.970
-07.7   24    12.00   1465     810   21829   2099    100.0    1.919
-03.8   25    12.50   1496     845   23039   2181    100.0    1.871
+00.0   26    13.00   1526     879   24266   2263    100.0    1.826
+03.8   27    13.50   1556     914   25510   2344    100.0    1.784
+07.7   28    14.00   1586     949   26772   2425    100.0    1.745
+11.5   29    14.50   1615     984   28050   2506    100.0    1.708
+15.4   30    15.00   1643    1019   29346   2586    100.0    1.673
+19.2   31    15.50   1671    1054   30658   2666    100.0    1.640

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     26    13.00   1529     883   25068   2258    100.0    1.803
Data for burning rate decreased by 10% relative to nominal value:
-Ba     26    13.00   1522     875   23260   2270    100.0    1.855

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OU812 posted this 31 October 2023

Have you tried Titegroup? The chart above is for 30-06 , but similar for 257 i would think.

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Larry Gibson posted this 31 October 2023

"Doing 1800-2000fps. Plenty fast for the 1-10 twist.

 

Cheers from New Zealand"

Probably not a stability problem.  However, the 9.5 BHN may be a bit too soft for that speed level depending on the groove depth.  Suggest adding 2% tin to the COWWs. WQing out of the mould immediately when the sprue hardens should bring the BHN up to 14 - 16.  

LMG

 

Concealment is not cover.........

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JeffinNZ posted this 06 November 2023

Issued sorted.  Powder coated results much better.

26gr IMR4985, .260 diameter air cool clip on wheel weight (approx 10 BHN), Hornady GC.  1940fps.

50m/55y target.  First shot low ex a clean barrel.  4 shots in 5/8 inch.

Cheers from New Zealand

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JeffinNZ posted this 11 November 2023

Confirming the load at 50m/55y again. Seems consistent.  Three in one hole.

HP version not bad with one wide shot I can't explain.  HP is the full depth of the ogive and in air cooled wheel weight at just shy of 2000fps it will be dynamite on goats and wallabies.

Cheers from New Zealand

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