Professional Big Bore Airguns .457

Jump to latest Follow Reply
Prouzy

Prouzy

Member
May 7, 2015
194
3
NH, United States
I dont see this here much, but thought there might be some interest. I went with the pepper stock to mix it up a bit, and really like it (I have a .308 in nutmeg). So this gal has a 28in TJ barrel, and is a 3000psi fill. Today was very windy, steady 15-20mph winds and 25-30mph gusts, a bit rainy to start and approximately 45deg. All the ammo I tried measured the same, .4570 I shot all initial chrony and then some groups tethered at 2700-2800. I wasnt going to shoot at all given the weather but couldnt resist to at least try something. NSA 372gr @ 678.7 fpsLee 340gr @ 655 fpsNSA 308gr @ 752 fpsNSA swaged 265gr @ 800 fps I was a little surprised at the Lee, but it does have many bands to it. I may size down a bit, but I do not have high hopes. Im hoping at a slightly higher fill, I can get closer to 800fps with those 308gr for reasons you will see in the next post. I have others of similar design, but really like what NSA has done in the bullet with the hybrid-like ogive and long bullet head to help with these fast twist rates (as seen in the 372gr and my Texan). That is just my observation and maybe has nothing to do with anything ;D I will post some groups and shapes in a bit.    
 
As per earlier post, steady 15-20mph winds and 25-30mph gusts, a bit rainy to start and approximately 45deg, and shooting tethered 2700-2800psi. Target distance was just over 50yd (53+/-), shooting off a bipod and a rigid rear rest that hardened after getting wet :mad:

These are the swaged NSA 265gr
.html]
photo204.jpg
[/url][/img][/URL]

I shot these in different session, same POA.

3 shots:
.html]
photo202.jpg
[/url][/img][/URL]

5 shots:
.html]
photo203.jpg
[/url][/img][/URL]

9 shots:
.html]
df12f248-e9a1-41e5-9067-ad6325fbe830.jpg
[/url][/img][/URL]

That last shot was the orange dot, decided to try and holdover. I guess it worked. I put a new Vortex on this one, and really like it. was on 7x, nice and clear image, great eye relief.

This is a 3 shot group, same parameters, with the 308gr (mushroomed from hitting the backstop)
.html]
photo%201.jpg
[/url][/img][/URL]

.html]
1f4c61c0-eba3-49fd-ae7a-2463616b6399.jpg
[/url][/img][/URL]

I finished by shooting off hand at my AR squirrel target. Nice balanced rig and good shooting bullets. We will stretch it out soon, and the test will be to see if they stay true at further distance, but this is promising.
 
Upvote 0
Nice looking rifle!

It's true that you don't see much about the extreme big bores here as they are too powerful and loud for what many of us use air guns for but I always like to read about what they can do. 

What twist rate is used in that TJ 28" barrel? I assumed they would use a slow 1:16 rate like rimfire but I would be the first to admit that I have no idea what it would take to stabilize such monster non-drag stabilized projectiles at 700fps from a 28" barrel. 

Do you know who made the stock? I kinda like the pattern. I wouldn't mind checking out the stock maker's work. 
 
Upvote 0
Thanks guys! More and more state regs are accepting of big bore for medium to large game, so maybe we will see things grow more rapidly. 

This is a .457 with a 1:20, you would need some monstrous for a 1:16 in this. Although, the NSA 372gr shot around 800fps and MOA to boot. I did get away with shooting the swaged 276gr rebated boat tail pretty well in the Texan as well. These are meant to shoot relatively heavy slugs for their purpose. The 308gr .457 will shoot 800fps at full fill with the existing spring.

I will post my .308 as well, 26in 1:20 TJ barrel. Thus far has done quite well with everything 110-156gr. I like that its not too picky. 

These are Boyds Stocks. Id read about them and thought about 1 for the Mrod and another on a Ruger American but never went put of my way as I thought, "how good they be for that price." I'll tell you, pics do not do these stocks justice. Im very impressed with these and will be picking up another very soon. 
 
Upvote 0
"Prouzy"Thanks guys! More and more state regs are accepting of big bore for medium to large game, so maybe we will see things grow more rapidly. 

This is a .457 with a 1:20, you would need some monstrous for a 1:16 in this. Although, the NSA 372gr shot around 800fps and MOA to boot. I did get away with shooting the swaged 276gr rebated boat tail pretty well in the Texan as well. These are meant to shoot relatively heavy slugs for their purpose. The 308gr .457 will shoot 800fps at full fill with the existing spring.

I will post my .308 as well, 26in 1:20 TJ barrel. Thus far has done quite well with everything 110-156gr. I like that its not too picky. 

These are Boyds Stocks. Id read about them and thought about 1 for the Mrod and another on a Ruger American but never went put of my way as I thought, "how good they be for that price." I'll tell you, pics do not do these stocks justice. Im very impressed with these and will be picking up another very soon.
Click to expand...
Every time I think I understand twist rates some new information presents itself to show me that I don't know anything. Most of what I read said non-stabilized ammo needs a faster twist rate to stabalize it while skirted ammo needs a slower rate. In these guns, non-skirted ammo is used with an ever slower twist rate and at slower pellets speeds but it's still accurate. My head hurts.

I would be looking for a source of helium to get the most from a gun like that (along with some very good hearing protection). 
 
Upvote 0
I think you are on the right track and conceptually it is similar to powder burners. I am far from a twist rate expert, amd Ive found when the planets align, some things do not abide by all of our projections :) So twist rates in airgun bullet shooters tend to be slower as to accomodate with the amount of pressure available to push its relative caliber in weight/sectional density. So the problem with agreesive twist rates is they will require a highsr SD (weight/length) to stabilize, as I know you gather. But our limitation is avaible air pressure and it will move slower. To some degree, not a bad thing, as drag will be less, but with lower velocity it also effectts terminal outcomes.

Haha! Well, Im not sure Im ready to graduate to helium just yet :) In fact, I still prefer airguns that are 3000psi fills, which is what still amazes from what we can accomplish. Certainly these big heavies are very impressive but in a different context, my .257 and .308 being able to push 70gr and 120gr to 900fps at 3000psi respectively, makes me grin too :) Ive had one of Extreme's rifles, and they are impressive for sure and cant imagine with helium!
 
Upvote 0
Thanks AK! I had an Extreme and they are superb rifles! With that Titanium tube, must be even nicer to carry! Im going to have to find out more about the triggers on these, they appear Timney or like and I find it superb. Have not tested yet, but Terry tuned both of my guns and they spot on for me. If anything, I may lighten the .308 for some bench shooting as well.

Cneck with Nick at Nielsen Specialty Ammo, supper nice guy. The thing with those swaged is it is possible to vary the size to specs. That Extreme can push some large bullets for sure. The 372gr cast that he makes shot MOA 100yd for me, Nick and Tofazfou. 
 
Upvote 0
"Prouzy"I think you are on the right track and conceptually it is similar to powder burners. I am far from a twist rate expert, amd Ive found when the planets align, some things do not abide by all of our projections :) So twist rates in airgun bullet shooters tend to be slower as to accomodate with the amount of pressure available to push its relative caliber in weight/sectional density. So the problem with agreesive twist rates is they will require a highsr SD (weight/length) to stabilize, as I know you gather. But our limitation is avaible air pressure and it will move slower. To some degree, not a bad thing, as drag will be less, but with lower velocity it also effectts terminal outcomes.

Haha! Well, Im not sure Im ready to graduate to helium just yet :) In fact, I still prefer airguns that are 3000psi fills, which is what still amazes from what we can accomplish. Certainly these big heavies are very impressive but in a different context, my .257 and .308 being able to push 70gr and 120gr to 900fps at 3000psi respectively, makes me grin too :) Ive had one of Extreme's rifles, and they are impressive for sure and cant imagine with helium!
Click to expand...
I (very) occasionally use cast bullets in my 25 Career 707 and get 90-100fpe but I have zero chance of hitting anything past 40-50 yards and those bullets are traveling at over 800fps and over 900 in some cases. I assumed the lack of accuracy past 50 yards was due to the slow twist rate. Maybe the rules change once you get projectiles past a certain size or weight.

The results posted with Helium on the Extreme Big Bore site are very impressive. Some of those guys were getting 1500fpe. I think it is necessary in some states as they have really high lower power limits to hunt certain game and it's not possible to get there with air. 

What at size air tube does your gun have? I wondered why they don't make a bottle version for one of the extreme big bores (or even a double bottle version). If anything needed the extra air capacity it would be one of those. 


 
Upvote 0
Maryland is one of those states, but most are caliber related and not fpe. However, there is an assumption of caliber and fpe to some extent.

I dont know the twist rate in the Career, but it could also be the opposite, where it is too fast for the projectiles and you actually need longer. Certain a relation to speed to capitalize on SD but need the twist as well, so theorized.

I believe the air tubes are somewhere 300-400, closer to the 300cc likely. Many of these tend to be on the heavy side, so a CF bottle if anything would be of choice. However, Extreme now has a titanium option, so maybe two tubes could be possible. They certain are not designed for large volume shooting off a fill, but then again for larger game and limit, no much is needed. I think American Air Arms has some of the most efficient shooting Ive seen in big bores: Hi-Power Pup[/QUOTE]https://americanairarms.com/air-guns/hi-power-pup/embed/ You can also see the twist rates for their rifles.
 
Upvote 0
"Prouzy"This is a .457 with a 1:20, you would need some monstrous for a 1:16 in this.
Click to expand...
Somehow above statement makes no sense to me. Subsonic pb .308 bullets are in 150g range - about same weight and speed as yours. Yet subsonic .308 requires < 1:10 twist rate to hit anything at 100 yards.

1:20 twist - thats barrel for 3800+ fps velocity. 
 
Upvote 0
As I mentioned, Im no expert in twist rates, not to mention sometimes its good to actually put theory to test. Yes, Ive the contrary and varying opinions, but never seen that a 1:20 is for 3800fps. It is also related to SD. You quote a comment regarding a .457 and then get into .308. You may want to actually try shooting them and see what happens. But in any event, using a marginal .308 BC .175, a 120gr, .6OAL, 800-1000fps the SG is over 2.0 for all, and using G1 or G7. This is true for 156gr I shoot as well. The faster twist may increase SG, however it needs to be accurate, not just stable. Many of us with Texans have also found this out and it requires very large bullets to be accurate, or on the flip side, short and stubby like RB or EPP UG. Yes, there are also some other models, and bullets such as boat tails are different stories. 

So if you need such a fast twist in subsonic rounds .308 to hit 100yd, its not the end all if you dont have that twist and want to shoot. Based on what many of us have seen with airguns, there may be some things you need to change. 
 
Upvote 0
"Prouzy"As I mentioned, Im no expert in twist rates, not to mention sometimes its good to actually put theory to test. ...

So if you need such a fast twist in subsonic rounds .308 to hit 100yd, its not the end all if you dont have that twist and want to shoot. Based on what many of us have seen with airguns, there may be some things you need to change.
Click to expand...
No, not me. Simple visit to your local range or google or youtube search for .308 subsonic twist will lead you to very hands on results, no formulas. If you look at 300 AAC Blackout - it requires even more radical 1:7 twist.

i understand when airgun people are talking about drag stabelized pellets etc, but gun above is using pretty much standard projectiles - no skirts there.
 
Upvote 0
I do not use a calculator for skirted pellets when evaluating flat base projectiles. I read and watch my fair share of youtube vids, including subsonics in powder burners. You can always find to the contrary, let alone the fact youtube and google may not be the best place to locate quality information without further indentification. 

My hands on results are my hands on my guns and also have had the wonderful experience of communicating with developers of airguns and projectiles. So both the formulas and hands on results suggests my bullets are both stable and accurate. Not sure what else to tell you. 
 
Upvote 0
"airkrazy"Very nice looking rifle. That's the first big off the customs that I see with a real safety. What trigger does it have and where does it break? I have a Extreme .457 with a titanium tube and 22 inch barrel, I think I may look into some of the swedged rounds.
Click to expand...
These have Bold 3Y triggers. Im actually impressed with this trigger and apparently shipped with factory settings. Will have to play with adjusting a bit, but thus far is pretty good. 
 
Upvote 0
"Prouzy"Maryland is one of those states, but most are caliber related and not fpe. However, there is an assumption of caliber and fpe to some extent.

I dont know the twist rate in the Career, but it could also be the opposite, where it is too fast for the projectiles and you actually need longer. Certain a relation to speed to capitalize on SD but need the twist as well, so theorized.

I believe the air tubes are somewhere 300-400, closer to the 300cc likely. Many of these tend to be on the heavy side, so a CF bottle if anything would be of choice. However, Extreme now has a titanium option, so maybe two tubes could be possible. They certain are not designed for large volume shooting off a fill, but then again for larger game and limit, no much is needed. I think American Air Arms has some of the most efficient shooting Ive seen in big bores: Hi-Power Pup
Click to expand...
https://americanairarms.com/air-guns/hi-power-pup/embed/ You can also see the twist rates for their rifles. [/QUOTE]
Titanium is not particularly light. It's dense and heavy. It just happens to have a better strength to weight ration than steel (which is particularly heavy). IMO the amount of cost it adds is not worth it for the benefit it delivers. There are certain new alloys of aluminum which would be better metals if weight savings without losing strength was the goal (and it had to be metal). 

Carbon fiber has a much better strength to weight ratio than titanium, steel and aluminum. It would be good to see some enterprising company trying carbon fiber tubes as well as bottles. 

American Air Arms seems to be getting some excellent air efficiency from their guns. They are certainly doing their part to make high power air slug guns more user friendly and attractive to a broader market. A lot of people are put off by single shot designs and only getting 2 shots per fill. I know that no more are needed usually when big game hunting but people like to practice at the range too. 

I guess tethering works well enough for range time. I also like the Inovairtech solution for their Macr 357 and 257. Their implementation is apparently not so great (leaky cartridges) but the idea makes a lot of sense for high power big bores. I like the look of their guns too.
 
Upvote 0
Im assuming they are able to use a thinner wall to reduce the weight?? Its reposrted to be 1-2lb lighter than the standard. I like the idea of a CF tube over a bottle; just not a fam of the bottle look personally but understands its purpose. Im working on getting beyond that. Never thought Id get an Airforce either, but have had three. 

AAA has done a great job with their designs and efficiency. Im in love with the new .30 Evol Tactical. They are getting darn good power for the number of shots and being a repeater. I too like the looks of the Inovairtech. Comparatively, they are a low in power for slugs in most calibers and not much can be done about improving plenum. And most of the power achieved is on full pressure fill and may still fall short to lower pressure fill guns. I still may consider it, as it is unique amd enjoy the shooting experience. Yes, I shoot big bores tethered often, especially for purpose and/or distance. If I want to shoot round ball for trigger time I get plenty (for a big bore) of shots and even in .457 inside 60yd can get 4 shots before topping off. I like the side filling port on the Texan (as a big bore) and can recharge relatively quick amd easy without moving too much. Even in semi auto pb, Im made fun of for having smaller mags as I dont mind taking my time and reloading, at least from a bench. 
 
Upvote 0
"Prouzy"Im assuming they are able to use a thinner wall to reduce the weight?? Its reposrted to be 1-2lb lighter than the standard. I like the idea of a CF tube over a bottle; just not a fam of the bottle look personally but understands its purpose. Im working on getting beyond that. Never thought Id get an Airforce either, but have had three. 

AAA has done a great job with their designs and efficiency. Im in love with the new .30 Evol Tactical. They are getting darn good power for the number of shots and being a repeater. I too like the looks of the Inovairtech. Comparatively, they are a low in power for slugs in most calibers and not much can be done about improving plenum. And most of the power achieved is on full pressure fill and may still fall short to lower pressure fill guns. I still may consider it, as it is unique amd enjoy the shooting experience. Yes, I shoot big bores tethered often, especially for purpose and/or distance. If I want to shoot round ball for trigger time I get plenty (for a big bore) of shots and even in .457 inside 60yd can get 4 shots before topping off. I like the side filling port on the Texan (as a big bore) and can recharge relatively quick amd easy without moving too much. Even in semi auto pb, Im made fun of for having smaller mags as I dont mind taking my time and reloading, at least from a bench.
Click to expand...

I think the issue with most bottle guns is the lack of imagination around where they are positioned and how they are covered (or not). 

The Evanix GTK bottle gun may look like a toy but one thing they did a good job of is making the bottle part of the design so it isn't just sticking out the front like an afterthought. 

Unless it's a bullpup, the bottle looks best when it's at the back and hidden inside the stock. I can't think of any gun where it looks good protruding past the front of the stock. 

The issue on the Innovairtech power is obviously the size of the cartridges. They could maybe make it so you could use the 357 size cartridges on the 257 or, using helium on the regular cartridges would also give them a boost. 

The Innovairtech marketing message does make me chuckle a little when they talk about how nobody thought it was a good idea to store the power plant in a central reservoir for powder burners (so why should we do it with air). If you put all your gunpowder in one large cylinder, you would have a bomb while doing it with air gives you an air tank. It's hardly the same thing....
 
Upvote 0
Actually, I stand corrected. I do in fact like some of those bottle Evanix hidden and even the Sniper is growing on me. 

LOL! Yes, that is a good marketing bit from IT! Who knows, they may yet make changes. I think using the larger MAC would be a good idea for the smaller calibers as well. Helium could certainly be a ticket. Ive not even looked into accessibility for that. 

Maybe even PBBA wpuld at some point make a repeater. Using mags similar to spring or magnetic advancement seems to make it much more feasible. 
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu