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What is a "Ladder Test"?

 
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  #15  
Old 09-03-2005, 08:41 PM
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Re: What is a \"Ladder Test\"?

Recommend that you keep the jump in powder increments to no more than .3 gr. If you use .5 you can skip over a node completely.

You are looking for 3-4 bullets to group together AND have similar MV. Both will group together normally to indicate the node.

I use either .2 or .3 grain increments over that 4 grain range and normally find about 3-4 nodes.

You will find that the groups normally match similar grouping of MV. That is your node normally. A chrono is an absolute must.

You can fine tune from there and I normally try to pick a powder weight in the middle of the node with the target MV that I am looking for. That way I am not subject to groups deteriorating on a hot day etc.

BH
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  #16  
Old 09-03-2005, 09:31 PM
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Re: What is a \"Ladder Test\"?

[ QUOTE ]
<font color="purple"> Recommend that you keep the jump in powder increments to no more than .3 gr. If you use .5 you can skip over a node completely....I use either .2 or .3 grain increments over that 4 grain range and normally find about 3-4 nodes. </font>

[/ QUOTE ]
You really need to normalize your powder increments (pi). Suggesting .2g for a 50 BMG with a starting load of 213gr - you'd wear out your barrel before you found your nodes.

The guy that dominates 50 BMG hunter class in this area told me he uses 3gr pi on his new guns (as do many of the best competitors). That's 15x higher pi than you suggest. I go with 2gr for my 50's, slightly less that 1%

PI is only meaningful if you give it as a % of starting/max load. Maybe you were talking about your your 17 Hummer [img]/ubbthreads/images/graemlins/smile.gif[/img]

Go too low and you'll be at the range all day waiting on your barrel to cool (or cleaning it).

"Toby" Bradshaw A local shooter and Biology Professor at the UW recommends 1gr pi - 2gr for bigger cases (he's talking about my 300 RUM)
The Toby link is an archive of his pontifications on load build up.
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  #17  
Old 09-04-2005, 11:35 PM
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Re: What is a \"Ladder Test\"?

Tacshot, id be happy to email you a copy, however, there is not one provided in your profile, or post. Let me know where to send it and ill get it headed your way.

Steve, Ricka, emails sent.
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  #18  
Old 09-05-2005, 12:04 AM
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Re: What is a \"Ladder Test\"?

I used the ladder test in my .270 Win to test for a load with 140 gr AB. I had 4 consecutive rounds go throught the same hole, the next one was a 1/4" high and right, next one cut the same hole then they went up 6 inches and I got pressure signs. In theory, I should pick a range from the 4 that shot in the same hole and ladder them again at a longer range? or shoot say 3 of each for groups?
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  #19  
Old 09-05-2005, 12:22 AM
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Re: What is a \"Ladder Test\"?

If you shot this ladder at longer range... say 300, then I would load 3 (or 5) rounds of the #2, #3 and #4 loads, and shoot them again at 300-400yds (longer if you like, or are planning on shooting this laod at longer ranges) Then take the best performaing of that test, load 9 of them, then shoot them at 3 different target at the same range. Then you will have 4, 3shot groups with this load to make your determiniation as to its accuracy. You also have teh option of marking through the bullet holes of the targets onto another blank target to see what the results would have been if you had fired:
4, 3shot groups,
3, 6 shot groups (1 and 2) (2 and 3) (3 and 4)
2, 9 shot groups (1, 2, and 3) (2, 3, and 4)
Or a 1, 12 ahot group.
Here you have effectively have 48 rounds to analyze to see how accurate your load is, at the cost of 12.

If you shot the rounds at a closer distance, this may or may not be the best advise, But it would probably still be what I would do.
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  #20  
Old 09-06-2005, 10:17 AM
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Re: What is a \"Ladder Test\"?

B1gBore

Was not aware anyone had mentioned 50 cal? .5 is correct for that but not any 30 cal IF you care about finding the nodes. In a 30, the node is normally .5 gr spread anyway max. Your interval needs to stay less than .5% or you will miss the node many times.

Assumed that we were talking normal calibers such as up to big 30s. Which means that .2-.3 should be the interval over a 4-6 gr difference which is the amount mentioned previously. Still done with less than 40-60 rds normally to zero, shoot ladder and fine tune load and seating depth. That includes at least 2-3 five shot groups for confirmation of group and MV also

By the way I use .3gr PI for 338 Lapua Ack Imp LR mile comp gun and LR hunting and .2 for 300WSM comp guns. Works great and I have won more than my share of matches with this method so I know it works, plus that is the way Creighton Audette set it up originally.

BH
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  #21  
Old 09-06-2005, 12:52 PM
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Re: What is a \"Ladder Test\"?

[ QUOTE ]
B1gBore

By the way I use .3gr PI for 338 Lapua Ack Imp LR mile comp gun and LR hunting and .2 for 300WSM comp guns.


[/ QUOTE ]

Ok, fella's what's PI? 3.14? Powder Increase? Post Icon? Don't laugh, I'm just a dumb shooter in Idaho, but I'm learnin'

Thanks [img]/ubbthreads/images/graemlins/blush.gif[/img]
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