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Proof PXT testing with Alex Wheeler
- Thread starter Rhovee
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RH300UM
Well-Known Member
I'm just a dumb peckerwood.
So I have to add more powder to increase velocity
Doesn't this add more energy to erode the throat?
I'll sit back and wait for the egg heads to prove this out.
I'm still trying to wrap my very small brain around this
So I have to add more powder to increase velocity
Doesn't this add more energy to erode the throat?
I'll sit back and wait for the egg heads to prove this out.
I'm still trying to wrap my very small brain around this
You aren't alone. Less friction and exposure time counts for something but that amount of flame and gas still exists.
At 80,000psi
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I don't feel like it's really that slow vs a 26"? Maybe a little bit but I would expect to lose about 40 fps per inch in a 28 nos with N570. No way you're only gonna lose 20 fps per inch in a case that size. That's optimistic for a creedmoor sized case.
Rifleman97
Well-Known Member
I don't know if I missed it but did you do a saami throat or a long freebore?
Alex Wheeler
Well-Known Member
Its throated for the 195
I was surprised to see my wholesaler with these in stock, limited selections but some are in stock. I'm a FFL in case someone wondered.
Rhovee
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Alright guys. Went out last night to try and gather some more info. What we have seen in the past with Ackley Improved cases and 40 degree shoulders is they allow you to run higher speeds but it doesn't shoot up at really high pressures. One thing is certain, this groove geometry does reduce pressure. Therefore it reduces the speed of the bullet. The standard load for the 28 Nosler and 195's with N570 is around 80 grains over (3) 26" barrels that I have shot. In this 22" barrel, it's 2850 ish. This is close to 100 fps less than where it should shoot based on a shorter barrel.
Last night I loaded up 83 grains of N570 for 2950 and did a seating depth test at 600 yards with @Jakeweb09. We went from .015 off to .065 and best we came across was 4.1" @ .040 off. Conditions were great. I then did 1 shot ladder with 83.5-84-84.5-85. It was a shotgun and couldn't be covered with a paper plate. Clearly this won't shoot the 195's in the 2950 area. We did get clickers in the 84-85 area on once fired brass.
One claim that is true, the throat has only moved .002 in 90 rounds. Extended barrel life is looking to be true. BUT I believe you are going to give up velocity. Testing isn't over yet, but I bet the standard load of 80 grains will shoot, but in the sub 2900 fps range. I am going to switch over to using a muzzle brake, try 184's and Retumbo, etc. As of right now, I'm not excited about what I am seeing with speed or accuracy of the barrel. I'm curious what other people's experience is with shooting ammo from one barrel to another. I have seen some videos of increased accuracy, but curious how the velocity compares.
Last night I loaded up 83 grains of N570 for 2950 and did a seating depth test at 600 yards with @Jakeweb09. We went from .015 off to .065 and best we came across was 4.1" @ .040 off. Conditions were great. I then did 1 shot ladder with 83.5-84-84.5-85. It was a shotgun and couldn't be covered with a paper plate. Clearly this won't shoot the 195's in the 2950 area. We did get clickers in the 84-85 area on once fired brass.
One claim that is true, the throat has only moved .002 in 90 rounds. Extended barrel life is looking to be true. BUT I believe you are going to give up velocity. Testing isn't over yet, but I bet the standard load of 80 grains will shoot, but in the sub 2900 fps range. I am going to switch over to using a muzzle brake, try 184's and Retumbo, etc. As of right now, I'm not excited about what I am seeing with speed or accuracy of the barrel. I'm curious what other people's experience is with shooting ammo from one barrel to another. I have seen some videos of increased accuracy, but curious how the velocity compares.
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Jakeweb09
Well-Known Member
.002 throat erosion in 90 shots with a 28 nos and N570 seems pretty good, and I could probably get over the velocity loss for that alone. But accuracy needs to be there first and foremost and what I've seen it isn't yet..potentially just doesn't like this bullet here and might have better luck with a 184. I'll be curious to see on that one. One thing I'd sure like to test is how it performs on a less overbore cartridge like a 7 Saum and a 168 or something similar to keep speeds up, if you could run that combo and get 2000+ rounds out of it I may still be interested
Rhovee, great test man!
Thanks for posting!
Thanks for posting!
Rifleman97
Well-Known Member
Wow that does seem slow then. Granted mine was a 26" tube but I was getting about 3200 with my long throat 28 nosler done by Ryan Pierce. I don't remember my charge weights off the top of my head though I'll have to look when I get back to my bench today or tomorrow, but I used N570 mostly.
.002 in 90 rounds on a 28 nosler is nutty. I'm definitely not interested in it for magnums if there's that much velocity loss, but for smaller cartridges with high volume shooting that may be a winner for us budget guys, sacrifice a bit of speed for a lot of barrel life
Rhovee
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I will add that I will be testing another carbon barrel from a different manufacture in a few weeks. This will be in a 300 prc which I have a 22" carbon that's shooting amazing. The geometry of the grooves with this other brand are different which should help with retreating some of the velocity loss, but still having extended barrel life. I am going to run 184's and Retumbo next.
