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All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Big Bore AirGun Gate => Topic started by: dreuf on January 07, 2020, 05:07:56 PM
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does anyone ever tried this type of barrel from lothar walther? what are you results?
It could be an option for my future barrel on the 457 tex.
black powder 45N7 barrel from lothar walther:
Twist: 28"
Material: chrome-moly steel
Outer diameter [OD]: 1.26"
Length [L]: 33.46"
Bore diameter: .447"
Groove diameter: .459"
Grooves: 6
the twist seems pretty interresting but grooves are deeper than a regular 45-70 barrel (2 times deeper in fact). can it lead to accuracy issue with an airgun?
the bore dimaeter is also a bit on the high side for my molds (bullets before sizing to 257).
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I have a 1 in 26 twist on my extreme.I think brent tryed 2 guns with that and mine was one of them.Accurate with everything I have tryed from 250 gr - 400 gr!The only problem I think you will see is the bore and groove dia.!.447 bore with a .459 groove,thats .012 which will cause a lot of drag during the initial engraving of the bullet to get moving.You will make up speed with the slower twist but lose with that dia.
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It is exactly my fear with this barrel. Slow speed and massive leading.
I would like to clear those risks before spending my money.
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I have a 1 in 26 twist on my extreme.I think brent tryed 2 guns with that and mine was one of them.Accurate with everything I have tryed from 250 gr - 400 gr!The only problem I think you will see is the bore and groove dia.!.447 bore with a .459 groove,thats .012 which will cause a lot of drag during the initial engraving of the bullet to get moving.You will make up speed with the slower twist but lose with that dia.
No other feedback on the pros and cons for these barrels?
Which one would be the best on the paper 1 or 2 ?
1) black powder 45N7 barrel from lothar walther:
Twist: 28"
Material: chrome-moly steel
Outer diameter [OD]: 1.26"
Length [L]: 33.46"
Bore diameter: .447"
Groove diameter: .459"
Grooves: 6
2) .45-70Govt barrel from lothar walther
Twist: 20"
Material: chrome-moly steel
Outer diameter [OD]: 1.26"
Length [L]: 35.43"
Bore diameter: .450"
Groove diameter: .456"
Grooves: 6
Weight: 10.908 lbs
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From my experience with shooting White Rifles (50cal.), I would opt for the faster twist, rotation is what stabilizes the slug. I was shooting 450 plus grain slugs. I also used a milk carton wad under my slug, i felt that it helped with sealing the slug to the barrel and waxed cardboard had some cleaning / lubing qualities.
BobH.
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i would suggest a TJ's barrel, i just ordered one, it shipped out the same day, a .457 28" for airguns, cost @$170 w/shipping, 1 in 24 twist
this will be going in my winchester/evanix 70-45
TJ's was quick to answer my questions and fill my order
tjsliners1992@gmail.com
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I have a 1 in 26 twist on my extreme.I think brent tryed 2 guns with that and mine was one of them.Accurate with everything I have tryed from 250 gr - 400 gr!The only problem I think you will see is the bore and groove dia.!.447 bore with a .459 groove,thats .012 which will cause a lot of drag during the initial engraving of the bullet to get moving.You will make up speed with the slower twist but lose with that dia.
No other feedback on the pros and cons for these barrels?
Which one would be the best on the paper 1 or 2 ?
1) black powder 45N7 barrel from lothar walther:
Twist: 28"
Material: chrome-moly steel
Outer diameter [OD]: 1.26"
Length [L]: 33.46"
Bore diameter: .447"
Groove diameter: .459"
Grooves: 6
Ok... this barrel does not make a lot of sense to me... it has patched round ball rifling height but the twist rate for stuff like Lee R.E.A.L. and conical and sabots... might work well for subsonic round ball, and maybe some of the up to 350g stuff... just do not hear about people running subsonic with black powder much...
2) .45-70Govt barrel from lothar walther
Twist: 20"
Material: chrome-moly steel
Outer diameter [OD]: 1.26"
Length [L]: 35.43"
Bore diameter: .450"
Groove diameter: .456"
Grooves: 6
Weight: 10.908 lbs
This is a barrel that is meant to send very long heavy rounds... 400g-500g
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From my experience with shooting White Rifles (50cal.), I would opt for the faster twist, rotation is what stabilizes the slug. I was shooting 450 plus grain slugs. I also used a milk carton wad under my slug, i felt that it helped with sealing the slug to the barrel and waxed cardboard had some cleaning / lubing qualities.
BobH.
With airguns we are not shooting fast enough. I had a 50 cal barrel made and it is 1:32. Shoots 400 gr good
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i would suggest a TJ's barrel, i just ordered one, it shipped out the same day, a .457 28" for airguns, cost @$170 w/shipping, 1 in 24 twist
this will be going in my winchester/evanix 70-45
TJ's was quick to answer my questions and fill my order
tjsliners1992@gmail.com
That was my first choice but unfortunately it can not be shipped outside US.... I have to mention that he is a really nice man and replied quickly to all my request.
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From my experience with shooting White Rifles (50cal.), I would opt for the faster twist, rotation is what stabilizes the slug. I was shooting 450 plus grain slugs. I also used a milk carton wad under my slug, i felt that it helped with sealing the slug to the barrel and waxed cardboard had some cleaning / lubing qualities.
BobH.
With airguns we are not shooting fast enough. I had a 50 cal barrel made and it is 1:32. Shoots 400 gr good
Hi Dyotat100, I would be more than happy to have your opinion on the black powder barrel style. I follow your build since a long time and you might have a better idea than me of the best choice.
thx
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Twist is not a issue with that barrel. Not sure how the grooves will effect performance.
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For the caliber, .006" deep grooves are not outrageous. To prevent high friction, you might want a custom mold for a bullet that:
has a frontal "bearing band" that rides snugly on the top of the lands, with a narrow drive band at or just under groove diameter at the rear. In between the bearing band (.002 over land diameter) and the drive band, you would have a cylindrical section .005" under land diameter.
Or you can size the a conventional bullet down to .004" over land diameter, backed up by a felt wad for good sealing, as someone else suggested.
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So I will go with the standard 45/70 barrel. I fear that the deeper groove lead to accuracy issue.
Regarding the chamber what do you guys think about the joined drawing?
is 0.5° slope a good value to engage bullet in the rifling?
(https://nsa40.casimages.com/img/2020/01/20/200120072842310650.jpg) (https://www.casimages.com/i/200120072842310650.jpg.html)
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A one degree included angle is plenty gentle for loading slugs. It suggests the need to load the slug in fairly deep, preferably until the front bearing "band" has full land engagement. So, you need to look at the position of the transfer port relative to the projectile base, and the loading probe length / stroke in context of your proposed chamber.
I would think that a leade angle twice as steep would load easily enough, and could make juggling the rest of the dimensions easier.
If the slug runs a significant distance before substantially engaging the lands, the projectile will tend to skid in the rifling to some degree. This may be less than ideal for accuracy. Of course, the exact projectile design you plan to use is part of this dimensional equation. So, your question cannot be answered in a vacuum. That said, a 14.6 mm deep chamber hardly seems "too deep" for this caliber.
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This barrel will be for my 457 tex so no transfert port issue.
My bullet are 15mm long (length of the body section only) -> saeco 458 mold around 380 grains.
So the chamber design seems ok and your reply help me to be more confident with that.
thx
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So dreuf,
If I understand correctly, your tex does not have probe to load, so you push the bullet into the chamber with your fingers? The bullet will be positioned so that the front runs into firm contact with the tapering section of the rifling? That is better alignment than if the bullet were in a cartridge waiting to be fired.
What is the bullet's rear drive band diameter? If it is larger than 11.58 mm, you may need something to push it into the chamber. Or, you could get some sizing dies and reduce the bullet diameter until it is snug, but not too hard to load by hand. If one sizing die makes the bullet loose, and the next larger size, tight; then the tight die can be lapped a little at a time to open it up a "half size". Some die makers will make custom size dies on special order.
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Bullets are handloaded in the rifling. I size my bullets down to achieve a tight fit since it gets out from my mold a bit oversized.
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The twist rate will not make a measurable difference to the velocity.... IMO the rifling on the blackpowder barrel is too deep for airgun use, unless you use a slug designed for it, particularly with the Texan where you load by pushing the slug into the chamber with your finger.... There are some slugs where the front drive band of the slug is a smaller diameter to ease loading, about 0.002" over the land diameter.... while the rear drive band is the groove diameter within 0.001"....
For most slug shapes, you will need a deeper parallel chamber section before the lead starts.... You want to be able to push the base of the slug flush with the breech of the barrel, or nearly so.... There is nothing wrong with a 1 deg. included angle for the leade, but I think most guys cutting their own chambers use 1 deg. per side (2 deg. included angle)….
Bob
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Bob, the OP has chosen to go with a LW .45-70 barrel; rather than the BP barrel....