So I have an item where when you use it, it extracts one itemstack from an IItemHandler. The problem is that it extracts more than once for some reason, the same issue if I were to insert an itemstack.

Item Class https://github.com/NindyBun/UsefulGuns/blob/5a8ebc68f4f68081f08afd4102182abaffcf52b0/src/main/java/com/nindybun/usefulguns/items/guns/AbstractGun.java#L64

package com.nindybun.usefulguns.items.guns;

import com.nindybun.usefulguns.UsefulGuns;
import com.nindybun.usefulguns.inventory.PouchData;
import com.nindybun.usefulguns.inventory.PouchHandler;
import com.nindybun.usefulguns.inventory.PouchManager;
import com.nindybun.usefulguns.items.AbstractPouch;
import com.nindybun.usefulguns.modRegistries.ModItems;
import com.nindybun.usefulguns.util.Util;
import net.minecraft.client.gui.screen.Screen;
import net.minecraft.client.util.ITooltipFlag;
import net.minecraft.entity.Entity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.item.*;
import net.minecraft.util.*;
import net.minecraft.util.text.ITextComponent;
import net.minecraft.util.text.StringTextComponent;
import net.minecraft.util.text.TextFormatting;
import net.minecraft.util.text.TranslationTextComponent;
import net.minecraft.world.World;
import net.minecraftforge.common.util.LazyOptional;
import net.minecraftforge.items.CapabilityItemHandler;
import net.minecraftforge.items.IItemHandler;
import net.minecraftforge.items.SlotItemHandler;

import javax.annotation.Nullable;
import java.util.List;

public class AbstractGun extends Item {
    private final int bonusDamage;
    private final double damageMultiplier;
    private final int fireDelay;
    private final double projectileSpeed = 3;
    private final int enchantability;
    private final boolean ignoreInvulnerability = false;
    private final SoundEvent fireSound = SoundEvents.BLAZE_SHOOT;

    public AbstractGun(int bonusDamage, double damageMultiplier, int fireDelay, int enchantability) {
        super(ModItems.ITEM_GROUP.stacksTo(1));
        this.bonusDamage = bonusDamage;
        this.damageMultiplier = damageMultiplier;
        this.fireDelay = fireDelay;
        this.enchantability = enchantability;
    }

    @Override
    public ActionResultType onItemUseFirst(ItemStack stack, ItemUseContext context) {
        return super.onItemUseFirst(stack, context);
    }

    @Override
    public ActionResult<ItemStack> use(World world, PlayerEntity playerEntity, Hand hand) {
        ItemStack gun = playerEntity.getItemInHand(hand);
        ItemStack pouch = Util.locateAndGetPouch(playerEntity);
        if (pouch == null)
            return ActionResult.fail(gun);
        ItemStack bulletInfo = ItemStack.of(gun.getOrCreateTag().getCompound("Bullet_Info")).split(1);
        LazyOptional<IItemHandler> optional = pouch.getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY);
        if (optional.isPresent()) {
            IItemHandler handler = optional.resolve().get();
            for (int i = 0; i < handler.getSlots(); i++){
                ItemStack stack = handler.getStackInSlot(i).copy().split(1);
                if (bulletInfo.equals(stack, false)) {
                    handler.getStackInSlot(i).shrink(1); //Extracting twice?
                    break;
                }
            }
        }
        playerEntity.getCooldowns().addCooldown(this, getFireDelay(gun));
        return ActionResult.consume(gun);
    }

    @Override
    public void inventoryTick(ItemStack stack, World world, Entity entity, int slot, boolean held) {
        super.inventoryTick(stack, world, entity, slot, held);
        PlayerEntity player = null;
        if (entity instanceof PlayerEntity) player = (PlayerEntity) entity;
        if (!held || player == null)
            return;
        ItemStack pouch = Util.locateAndGetPouch(player);
        if (pouch == null)
            return;
        AbstractPouch.getData(pouch);
    }

    @Override
    public void appendHoverText(ItemStack stack, @Nullable World world, List<ITextComponent> tooltip, ITooltipFlag flag) {
        if (Screen.hasShiftDown()){
            ItemStack bulletInfo = ItemStack.of(stack.getOrCreateTag().getCompound("Bullet_Info"));
            if (bulletInfo != ItemStack.EMPTY) tooltip.add(new StringTextComponent("Selected Bullet: ").append(bulletInfo.getHoverName()).withStyle(TextFormatting.AQUA));

            double damageMultiplier = getDamageMultipier(stack);
            double damageBonus = getBonusDamage(stack);

            if (damageMultiplier != 1) {
                if (damageBonus != 0) tooltip.add(new TranslationTextComponent("tooltip."+ UsefulGuns.MOD_ID +".gun.damage.both" + (isDamageModified(stack) ? ".modified" : ""), ItemStack.ATTRIBUTE_MODIFIER_FORMAT.format(damageMultiplier), ItemStack.ATTRIBUTE_MODIFIER_FORMAT.format(damageBonus)));
                else tooltip.add(new TranslationTextComponent("tooltip."+ UsefulGuns.MOD_ID +".gun.damage.mult" + (isDamageModified(stack) ? ".modified" : ""), ItemStack.ATTRIBUTE_MODIFIER_FORMAT.format(damageMultiplier)));
            }
            else if (damageBonus != 0) tooltip.add(new TranslationTextComponent("tooltip."+ UsefulGuns.MOD_ID +".gun.damage.flat" + (isDamageModified(stack) ? ".modified" : ""), ItemStack.ATTRIBUTE_MODIFIER_FORMAT.format(damageBonus)));


            int fireDelay = getFireDelay(stack);
            tooltip.add(new TranslationTextComponent("tooltip."+ UsefulGuns.MOD_ID + ".gun.firerate" + (isFireDelayModified(stack) ? ".modified" : ""), (60*20)/fireDelay));

            if (ignoresInvulnerability(stack))
                tooltip.add(new TranslationTextComponent("tooltip."+ UsefulGuns.MOD_ID + ".gun.ignores_invulnerability").withStyle(TextFormatting.GRAY));

        }else{
            tooltip.add(new TranslationTextComponent("tooltip."+ UsefulGuns.MOD_ID + ".shift"));
        }
    }

    @Override
    public UseAction getUseAnimation(ItemStack stack) {
        return UseAction.BOW;
    }

    public static int getBonusDamage(ItemStack stack){
        return ((AbstractGun)stack.getItem()).bonusDamage;
    }
    public static double getDamageMultipier(ItemStack stack){
        return ((AbstractGun)stack.getItem()).damageMultiplier;
    }
    public static int getFireDelay(ItemStack stack){
        return ((AbstractGun)stack.getItem()).fireDelay;
    }
    public static double getProjectileSpeed(ItemStack stack){
        return ((AbstractGun)stack.getItem()).projectileSpeed;
    }
    public static boolean isDamageModified(ItemStack stack){
        return false;
    }
    public static boolean isFireDelayModified(ItemStack stack){
        return false;
    }
    public static boolean ignoresInvulnerability(ItemStack stack){
        return ((AbstractGun)stack.getItem()).ignoreInvulnerability;
    }



}

 

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Please update to a modern version of Minecraft to receive support.

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