338 Ultra Mag Issues

SLCBill · December 4, 2009, 10:50 AM

So after borrowing my uncles chronograph and getting use to it with an airsoft gun inthe house, shooting a 22LR over it to verify its working when I went out shooting. I shot my big gun across it and got this data with only 1 error per string (my fault, missed back sensor) by the way its a Shooting Chrony Beta Master.

Data below is use at own risk although it was obtained from Sierra Edition 5

H1000 97.4g GM215M SMK 250.1 OAL 3.780 11/28/2009 44 Deg 3:00 PM 1 st Shot 3008 FPS

String 1 String 2
Low 3038 3016
High 3095 3086
Average 3073 3054
Ext Sprd 57.5 70.02

Std Dev 19.1 23.23
Full Avg 3063.85
FL die only 2/3 on neck
Brass not weight sorted

String 1 String 2
3053 3016
3057 3026
3066 3086
3038 3068
3088 3038
3086 3068
3095 3040
3088 3075
3089 3072
3073 3055

Sorry the chart/graph looks rough it won't turn out as good as it looks in Excel

So my problem is I can't figure out why my ES is so High. I am very meticulous when loading. Does anyone else have a 338 RUM that they have loaded for and recorded data on.

This load shot tighter groups in the summer heat than the winter cold, unfortunately I didn't have access to a Chrono in the summer.

How are anyone elses loads, do you get as tight of spread as you hear others brag about or is this just what I get.

GeauxTide · December 4, 2009, 01:32 PM

Welcome to the head scratching world of "chronography". Your rifle apparently doesn't like H-1000. I'd change powders until I get under 10 on SD, which usually means around 30fps ES. I'd try 7828 and even H4831 and use a minimum of 250gr bullets.

December 4, 2009, 10:50 AM	#1
SLCBill Member Join Date: October 31, 2009 Location: Salt Lake Utah Posts: 18	338 Ultra Mag Issues So after borrowing my uncles chronograph and getting use to it with an airsoft gun inthe house, shooting a 22LR over it to verify its working when I went out shooting. I shot my big gun across it and got this data with only 1 error per string (my fault, missed back sensor) by the way its a Shooting Chrony Beta Master. Data below is use at own risk although it was obtained from Sierra Edition 5 H1000 97.4g GM215M SMK 250.1 OAL 3.780 11/28/2009 44 Deg 3:00 PM 1 st Shot 3008 FPS String 1 String 2 Low 3038 3016 High 3095 3086 Average 3073 3054 Ext Sprd 57.5 70.02 Std Dev 19.1 23.23 Full Avg 3063.85 FL die only 2/3 on neck Brass not weight sorted String 1 String 2 3053 3016 3057 3026 3066 3086 3038 3068 3088 3038 3086 3068 3095 3040 3088 3075 3089 3072 3073 3055 Sorry the chart/graph looks rough it won't turn out as good as it looks in Excel So my problem is I can't figure out why my ES is so High. I am very meticulous when loading. Does anyone else have a 338 RUM that they have loaded for and recorded data on. This load shot tighter groups in the summer heat than the winter cold, unfortunately I didn't have access to a Chrono in the summer. How are anyone elses loads, do you get as tight of spread as you hear others brag about or is this just what I get. __________________ Insert extremist comment here.

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December 4, 2009, 01:32 PM	#2
GeauxTide Senior Member Join Date: April 20, 2009 Location: Helena, AL Posts: 4,423	Welcome to the head scratching world of "chronography". Your rifle apparently doesn't like H-1000. I'd change powders until I get under 10 on SD, which usually means around 30fps ES. I'd try 7828 and even H4831 and use a minimum of 250gr bullets.