Using Monte's Quick Out (Love Em & Leave Em) / EPR Method 
or My Trans Bay Off Set & AST (Agressive Sweep Technique) method (Love Em, Identify Em, Plug Em & see what's underneath Em), have previously been discussed on the various forums like Treasurenet, Findmall and Treasure Depot.
This method was first developed by professionals/detectorists after motion detectors came onto the scene in the late 1970s with such models as the Bounty Hunter Red Baron 7 and White's 6000 D Series I.
While TRs, when properly tuned had no problem rejecting the steel bottle caps with lower discrimination levels, the motion detectors required higher levels.
Currently there are so many different make and models
(different frequencies, filter systems) of motion discriminators on the market today with increasingly refinements being made both Audio and Visually.
In my opinion, the Safe Strategy method employed to DEAL with the Steel Bottle Caps and other low conductive trash is to readily Identify Caps rather than reject them. Clean REJECTION or NULLING over trash can MASK deeper & desireable target signals.
Certain Motion Based Frequencies above 15 kHz tend to be more reactive to Iron and this includes the steel bottle cap. The bottle cap, because it is round, disrupts the magnetic field of a motion based metal detector in such a way as requiring much high levels of discrimination to cleanly reject it.
Unfortunately, HIGH levels of discrimination mean, ignoring most of the gold jewelry and nickels. So, my suggestion is to IDENTIFY rather than REJECT using lowered Discrimination Levels in combination with a sophisticated Visual Target ID system like the White's DFX Signagraph. By IDENTIFYING, you can choose to Avoid or Investigate.
The White's Spectrum/XLT/DFX Signagraphs in my opinion does the BEST job in Visually IDENTIFYING the bottle cap while using lowered discrimination levels to locate elusive gold jewelry and nickels. This Wide Resolution Display is like a Target-Finger Print ID System.
Typically with these lowered disc levels, the signal on fine gold jewelry, nickels and other lowered conductors is improved. This Signal improvement can also apply to higher deeper conductors (silver coinage), that are in close proximity to shallower trash, thus avoiding the DEEP NULLING or TARGET MASKING of desireable targets.
In this tuning scenario, your best BET is to IDENTIFY the Bottle cap (using lowered discrimination level), not REJECT IT CLEANLY (requiring significantly higher discrimination levels causing loss of depth/signal).
A Bottle cap on a White's Signagraph tends to Smear Bars across the -95 to 0 Ferrous to +1 to +95 NON-FERROUS Scale. Using the Monte or Trans Bay Method, enhances this identification characteristics. The choice to remove the bottle cap is up to you. Frequently a shallow bottle cap can be masking deeper desired targets.
When it comes to hunting in the sand, I generally just scoop up the bottle cap since removal is so easy, and it occasionally pays off with discovering other targets in close proximity including rings, watches, coins etc. The aforementioned analysis method is best used as a time saver in TURF Conditions.
As an example, although not a White's made detector, but also helps to explain my strategy method in this post, last summer, using my Minelab Excalibur 800 @ Lake Tahoe, I dug all the bottle caps in the water and frequently found coins in the same scoop using the minimum discrimination level, which still rejected the ferrous bobby pins, nails etc (maybe too much)by a prolonged dip in the threshold or null BEFORE recovery... so frequently, I'd stop, wait for the threshold to return before sweeping forward. Occasionally, I might re-trace around the area of the rejected target and finding other targets hidden in the shadow of the bottlecap which started to react before the nulling.
Conclusions: Your better off to tune your detector to Identify Trash rather than a Clean Rejection. Too many good desireable targets like jewelry hides in that -20 to +60 area, and with a DFX Signagraph, you can not only Identify the bottle cap, but spot close proximity target scenarios based on the Signagraphic Display of the Targets encountered.
This 'Shaping' Technology is a White's Exclusive: One SOLO Bar up is an indicator of a round target. The height of the bar in relationship to the depth indicator is also one of the many clues.
or My Trans Bay Off Set & AST (Agressive Sweep Technique) method (Love Em, Identify Em, Plug Em & see what's underneath Em), have previously been discussed on the various forums like Treasurenet, Findmall and Treasure Depot.This method was first developed by professionals/detectorists after motion detectors came onto the scene in the late 1970s with such models as the Bounty Hunter Red Baron 7 and White's 6000 D Series I.
While TRs, when properly tuned had no problem rejecting the steel bottle caps with lower discrimination levels, the motion detectors required higher levels.
Currently there are so many different make and models
(different frequencies, filter systems) of motion discriminators on the market today with increasingly refinements being made both Audio and Visually.In my opinion, the Safe Strategy method employed to DEAL with the Steel Bottle Caps and other low conductive trash is to readily Identify Caps rather than reject them. Clean REJECTION or NULLING over trash can MASK deeper & desireable target signals.
Certain Motion Based Frequencies above 15 kHz tend to be more reactive to Iron and this includes the steel bottle cap. The bottle cap, because it is round, disrupts the magnetic field of a motion based metal detector in such a way as requiring much high levels of discrimination to cleanly reject it.
Unfortunately, HIGH levels of discrimination mean, ignoring most of the gold jewelry and nickels. So, my suggestion is to IDENTIFY rather than REJECT using lowered Discrimination Levels in combination with a sophisticated Visual Target ID system like the White's DFX Signagraph. By IDENTIFYING, you can choose to Avoid or Investigate.
The White's Spectrum/XLT/DFX Signagraphs in my opinion does the BEST job in Visually IDENTIFYING the bottle cap while using lowered discrimination levels to locate elusive gold jewelry and nickels. This Wide Resolution Display is like a Target-Finger Print ID System.
Typically with these lowered disc levels, the signal on fine gold jewelry, nickels and other lowered conductors is improved. This Signal improvement can also apply to higher deeper conductors (silver coinage), that are in close proximity to shallower trash, thus avoiding the DEEP NULLING or TARGET MASKING of desireable targets.
In this tuning scenario, your best BET is to IDENTIFY the Bottle cap (using lowered discrimination level), not REJECT IT CLEANLY (requiring significantly higher discrimination levels causing loss of depth/signal).
A Bottle cap on a White's Signagraph tends to Smear Bars across the -95 to 0 Ferrous to +1 to +95 NON-FERROUS Scale. Using the Monte or Trans Bay Method, enhances this identification characteristics. The choice to remove the bottle cap is up to you. Frequently a shallow bottle cap can be masking deeper desired targets.
When it comes to hunting in the sand, I generally just scoop up the bottle cap since removal is so easy, and it occasionally pays off with discovering other targets in close proximity including rings, watches, coins etc. The aforementioned analysis method is best used as a time saver in TURF Conditions.
As an example, although not a White's made detector, but also helps to explain my strategy method in this post, last summer, using my Minelab Excalibur 800 @ Lake Tahoe, I dug all the bottle caps in the water and frequently found coins in the same scoop using the minimum discrimination level, which still rejected the ferrous bobby pins, nails etc (maybe too much)by a prolonged dip in the threshold or null BEFORE recovery... so frequently, I'd stop, wait for the threshold to return before sweeping forward. Occasionally, I might re-trace around the area of the rejected target and finding other targets hidden in the shadow of the bottlecap which started to react before the nulling.
Conclusions: Your better off to tune your detector to Identify Trash rather than a Clean Rejection. Too many good desireable targets like jewelry hides in that -20 to +60 area, and with a DFX Signagraph, you can not only Identify the bottle cap, but spot close proximity target scenarios based on the Signagraphic Display of the Targets encountered.
This 'Shaping' Technology is a White's Exclusive: One SOLO Bar up is an indicator of a round target. The height of the bar in relationship to the depth indicator is also one of the many clues.