Proof PXT testing with Alex Wheeler

Alex Wheeler said:
Chambered this last night. Initial thoughts... Dialed in like any other barrel and cut like a 5r. Bore scoping it, it looks to me like an extreme 5r land. My guess is they did that to make the jacket survive such an extreme gain twist. I would assume a 4 grove like this would destroy jackets. Its not a straight gain twist though. You can see it speed up mid barrel. The first 6 inches doesnt speed up much. Seems to be a consistent barrel. I saw nothing that I would critique. It does have a lapped looking finish, not sure how they did that. I cant see how you could lap a barrel like this with a traditional lead slug. I assume they used something else, maybe a felt plug to put the finish in there. So far so good. Initial thought from a hunting point of view... I would want to do some gel or other media testing before shooting game. I do wonder how such an extreme gain twist will effect the jacket and how that will effect expansion. In time we will get plenty of reports to know. I just wouldnt want an animal to be the first thing I shot, especially with a Berger or other thin cup and core bullet.
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Is the PXT twist ever actually exceeding the stated twist rate, in order to achieve stability? I'm not sure I understand why gaining twist throughout the barrel, only for it to just end up at 1-8 would make any negative difference for jacket durability, vs. just slamming a bullet straight into a 1-8 twist for the entire length of the barrel.
 
Phil Rizzo said:
Well, he got some weird readings land to land and on the long rod. So he stopped…
The discrepancies were 90&180* I think he said
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He went ahead with it in normal fashion and will be firing this week.
After pre-boring he reset the long rod and went off it, said it fell right in.
 
Consider this. The bullet only gets the stress it would get in a barrel with a consistent twist. In fact, when you consider how quickly a bullet must come up to speed in a normalbarrel, stress may be less.

Shooting 5000 rounds of factory 7 Backcountry at 80k psi through one tells me I wish I wasn't retired and had more disposable income.
 
The stress comes from the land twisting on the jacket as the rate speeds up. I would bet you could not do this type of barrel with a standard 4 groove without blowing bullets up. My assumption is they went to this extreme 5r to fix that. But I don't know for sure.
 
Alex Wheeler said:
The stress comes from the land twisting on the jacket as the rate speeds up. I would bet you could not do this type of barrel with a standard 4 groove without blowing bullets up. My assumption is they went to this extreme 5r to fix that. But I don't know for sure.
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Like the initial groove into the bullet is essentially straight. Then as the bullet travels down the bore, the lands want to add curvature to the land grove in the bullet? So the land groove is actually getting manipulated throughout the length of the barrel?
 
Well as I suspected the pxt is not hard on jackets . The lands appear to be shallow compared to other barrels . There almost hard to see with bore scope . I shot these bullets into wet newspaper at 100 yards . Have not ever seen a X bullet not separate at that velocity at 100 yards with other barrels . The vld and x had the exact penetration. The Nosler had the most .
IMG_0458.jpeg
 
Can you see any engraving on the bullet from the rifling? those are good velocities, any room to go up in powder charge?
 
Yes, ELD X. All I can see is the boattail , so I cannot see engraving. I played with the eld x some more to see how far up I could go with powder to hit pressure. With Ramshot Grand they come together good at 69,5 gr, 2955 fps. 70 gr went 3010, still shot good but had light bolt lift. Brass looked good, but stopped there. Was on the second firing of brass today.
 
lager said:
Well as I suspected the pxt is not hard on jackets . The lands appear to be shallow compared to other barrels . There almost hard to see with bore scope . I shot these bullets into wet newspaper at 100 yards . Have not ever seen a X bullet not separate at that velocity at 100 yards with other barrels . The vld and x had the exact penetration. The Nosler had the most . View attachment 761287
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Good job Lonnie
 
FEENIX said:
Unless @Hugger-4641 is referring to a different Stalker, it is one of Kirby Allen's (@Fiftydriver) wildcat line chamberings.

View attachment 759927
Click to expand...
Its one of my wildcats in my Stalker family based on the 300 norma mag parent case, necked down to 270 cal and fireformed to my case body and shoulder design. It replaces my old 270 Allen Magnum and will match its 30" barreled performance in a 26" barrel.
 

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