So, How I got this mod to work, was simple for creating the weapon, but a lot harder to find out how to remove the Iron Sights, in order to have it just zoom in the FOV like in Fallout 3. It is a custom weapon, with the stock object model, and animations, that are being modified to remove the iron sights.

This is a full detailed and comprehensive guide to how I made this mod.

WARNING: Iron sights cannot be removed from items like the laser rifle, that already do not have Iron Sights, nor Scoped weapons. It also may not work on certain items. You're mileage may vary.

To re-open a saved .esp file, simple go into GECK, under "Open", deselect every file except for the .esp file you are trying to re-open, and the "FalloutNV.esm" file. Make sure to press the "Set as Active File" button on the bottom right while the .esp file you want to open is selected, in order to make it active, so that it will save to the actual file. If not, it will try to make you save it as a new file.

Legend:
.nif: Object Mesh file used in Gamebryo
.kf: Animation File used in Gamebryo

Prerequisites: You must know how to mod Fallout New Vegas, and have the following mods installed: Latest version of xNVSE, Latest kNVSE plugin, NifSkope, and A mod manager like Vortex (I Find it to be the easiest mod manager, but use the one you like.). kNVSE allows for the custom animation to override the original animation for ADS (Aim Down Sights, or the iron sights animation) for the Plasma rifle. xNVSE is required to run kNVSE other mods. Vortex is required to run other mods without manually installing them. And NifSkope for removing the Billboard and Sighting Nodes on the object.

One last thing, you will need FOMM, or BAE (Bethesda Archive Extractor) in order to get the files from the games directory, and Stewie Tweaks and Stewie Tweaks.INI in order to grab the animation name from inside the game using the tilde key in order to see it.

Ignore Step 1 if you don't want to remove the Iron Sights.

Step 1 uses FOMM. BAE is the Same. Just press on the "File" tab, and open up the "Fallout - Meshes.bsa" in the same location as below, and follow the same steps. FOMM just has 1 extra step to extract the .nif files.

Step 1: Open up FOMM and Under the Tools tab on the top left bar, open up the BSA Browser. After the new window Pops up, click on "Open". It should pull up the Fallout NV installation directory. Find "Fallout - Meshes.bsa" without the quotations, and select it and press open. Next, find what ever weapon you want to create a custom model for, for removing the iron sights, by searching for it in the newly opened archive window that generates after having opened up the Fallout - Meshes.bsa archive file. Next, select the weapons .nif file, and click extract, to extract it to a folder on your computer. Usually it is one that starts with "meshes\weapons\". Just make a new folder, and name it whatever you want it to be named, and save it in there. Now we have the .nif file of the object. Lets move onto making the custom weapon in GECK. Don't forget to save your progress.

Step 2: Open Geck. In Geck, Load only the FalloutNV.esm file and deselect any other additional files in the list displayed from pressing the little open button, below the file button. This is not found in the Files button tab, but rather is a small, square box below, that when hovered over, says "Open". GECK is a really slow and un-optimized program, so give it some time to load. It may crash a lot during this, so just make sure to say. It may complain about needing to close all dialog boxes before it will allow you to save, so just go ahead and close out of any window you will open up in the next step, to save as frequently as possible. The save button is another small square box with a floppy disk icon on it, next to the open button. Don't forget to save your progress.

Step 3: On the "Object Window", find the sub file under "Items" on the left column of the window, and select "Weapons". Search for the item you are going to use as a basis, and right click on it's name in the main part of the window. After right clicking, press "Edit". Now, this is very important in order to not mess up the stock weapon you are going to modify. Make sure to change the "Name" and especially the "ID", in order to not mess up the original item. Next, before we edit the values, press "Ok" at the bottom right of the popup dialog window, and it should say something about creating a new Form in order to not replace the original item. Press "Yes". DO NOT PRESS NO. That will apply the edit to the original item. Don't forget to save your progress.

Step 4: Right click on the new weapon ID you just created, that should pop up in the left side column, and press "Edit". The rest of this step for changing the weapon values, and implementing it into the game are best show here in this Youtube Video. All credit for the video goes to CxrruptDream on Youtube. If the link is removed, the title of the video is: Fallout New Vegas Geck Tutorial Episode 1: Making Your First Custom Weapon

An extra step for sounds: In order to add in custom sounds, in GECK, open up the "Sounds" tab on the left column, and follow the same steps as the following step (Step 3) in order to make a new custom entry. Once done, you can go to your Fallout Directory, and in the Data Folder, find the "Sound" Folder, in that Folder, Find the "FX" Folder, in that Folder, Find the "WPN" Folder, and in the Folder named after the weapon you are making (If there is no Folder, Make one.) add in any custom short sound effect you would like to add to the weapon. Back in GECK, in the new custom sound entry you made, press the "..." box button, in order to pull up the File Explorer, and just find the Folder containing the sound you just placed in your game directory, and Press "Open". Now press, "Ok", in order to make the changes. Make as many entries as needed, for only one can contain one custom sound. Now, under the "Art and Sound" tab, in the weapon editor, click on the "3D", "2D", and "DIST" sound effects, and replace them with the ones you added by clicking on the custom sound entry you made earlier. And now, when you press "Ok", it should play the sound effect, and now you have custom sounds. Don't forget to save your progress.

Step 5: Now that you have a custom weapon, and it is in the game, you can either be done, or, continue on reading this article if you want to remove the Iron Sights. Open up NifSkope, and press the "Open" button, under the top left "File" tab. Next, select the .nif file which contains the weapons object mesh, that you exported earlier, and open it up. On the Left, there will be a "NiNode" downward opening tab on the left column of NifSkope that should populate data once the .nif file has been opened. Click it until it opens up all of it's data. Next, find on the right side of the column, 2 nodes that are named ##BillboardNode and ##SightingNode. On both of those, right click their tab, and on the little box that pops up, hover over "Block", and when other box opens to the right, click on "Remove Block". Do this to both in order to delete them. Now, save it by pressing the "Save As" button in the top file tab, with the name you gave your custom weapon in GECK, in the same folder you exported the .nif file you just edited. What we just did, allows us to not have to turn off "True Iron Sights" for the new animations to work. Don't forget to save your progress.

Step 6: Watch this Youtube Video first, in order to grab the right animations, and folder layout for the weapon. Just remember, to replace the IS (Iron Sights) animations, you have to replace them with the HipFire animations, but then name them the same as the Iron Sight ones, so that they will be used to override the original Iron Sights animations. To do this, just find the animations using Stewie Tweaks in-game debugger, and find ones that end in "is.kf". Next, you find those in your game directory using FOMM or BAE like earlier, and instead of extracting the ones ending in "is.kf", you take their non "is" varian, and extract them in the same Folder you made for the .nif file. Remember, Animation files end in .kf, not .nif. Once you have them Extracted them, add "is" at the very end of the name, before the ".kf" part, in order to not change the file type. By adding "is" to the name, it now will detect those as the new Iron Sights animations, and thus making it use the Hipfire animation instead. Remember to place it in the correct file path, and to make the right folders, as shown in the video. For me, instead of "FalloutNV.esm", it was "Experiment 18 A Alpha.esp", as the file name, so that it will ONLY REPLACE THIS WEAPONS ANIMATIONS. Anyways, Credit goes to Xolerys on Youtube for making this tutorial. If the Link is broken, the videos name is: Fallout New Vegas-How to make a kNVSE set for Vanilla/DLC/Custom Guns with animation replacers

Step 7: In GECK, after making the weapon, go back into the Weapon editor, and under the "Art and Sound" tab, in the Model box, replace the "1st Person Model Object" that is selected currently, by clicking the drop down arrow, and scrolling up to the top of the list, and Selecting the "NONE" option. Next, in the "Model" section, press the "Edit" button, and in the "Model Data" window that just popped up, press the "Edit Button", under the "Model File Name" section, and find the File you just placed in the game directory: Data\meshes\Weapons\. Select it, and press "Open". Then, it should have selected the new mesh you edited in Step 5 in NifSkope, that has the ##BillBoard and ##SightingNode removed. Press "Ok", and then "Ok" again. Don't forget to save your progress.

Step 8: Make sure you have the other steps completed prior to this, and are ready to implement you're item into the game. You must place the folders in the correct sub folders, leading back in a chain of Folders, to the "Data" Folder, which will be contained in the Main Folder of the modded weapon, named whatever you want it to be. Here is an Example of the file structure of this mod: (The "V"s are to represent down arrows.) You will grab the .esp file for the weapon out of your "Data" Folder, and place it in the "Data" sub folder in your mod folder.
DataV
meshesV-SoundVExperiment 18 A Alpha.espV
WeaponsV-AnimGroupOverrideV-FXV
plasmarifleadjustedironsights.nifExperiment 18 A Alpha.esp (Folder) VWPNV
0f000adeVRiflePlasmaV
_1stpersonVWPN_RiflePlasma_Fire_Semi_01FO4.wav
2haaimis.kf2haattackloopis.kf

That's it. Thanks for reading.