Actually I do own a Lead Sled DFT I picked up at a garage sale 8-10 years ago for less than the cost of a pizza dinner, but I use it (and it makes a HUGE difference) only for patterning my 12ga 3.5" magnum turkey loads, and brother let me tell you have to move on up to dedicated dangerous game calibers to begin to equal the recoil of a 3.5" magnum 2oz turkey load at 1200fps/mv when fired from a 6.75lb shotgun off the bench who's stock design suxs. No my rest of choice is a Older Bald Eagle front rest. The only recoil absorbing mechanism I have available for use is me. Save for my dreaded turkey loads recoil is a non-factor fro me. I can easily shoot 30-40 300wsm loads from the bench with no issues. Granted I use a PAST Super Mag Plus recoil shield and all my rifles wear Limb saver AM recoil pads both combined work wonders reducing felt recoil. I have over time combined personal experimentation with reading much about bench shooting form and feel I have my bench form down reasonably well especially my grip on the stock and trigger but must admit I still experience form induced fliers more frequently then I'd like, which is hard to avoid with light heavy recoiling rifles.Hopefully you aren't using a lead sled...
Factory rifles would explain one part of your problem. Most stock hunting rifles aren't capable of shooting less than moa consistently, especially after the barrel heats up.
Time to go to a premium barrel, etc. We were in the same place you were before we went "custom".
When ever I shoot any rifle I never allow the barrel or receiver to become more than moderately warm and use a laser thermometer to check the temp of both to insure they never get to hot to grasp and hold. I have a battery powered minnow bucket aerator air pump I use to pump air through my barrel to cool it quickly to allow me to shoot more in less time. One end of the tubing for the air pump goes into a cooler full of ice to allow cold air to be sent down my barrel when the temps get above 40*/F outside. Works fantastically and has cut my cooling off time between shot strings by 80% or more. I have also used a 12v mattress air pump to do the same thing but the aerator and ice seem to work better.
My crowns all look to be in perfect condition, and I'd consider a custom barrel but at $500-$600 I will only after I become reasonably certain I have ruled out any issues with my reloads and would likely try bedding an AM stock like an HS Precision as all my rifles (save for my M77 in 300wm) presently wear factory synthetic stocks. My gun smith will bed any stock for me quite reasonably.
As anyone reading this can see and begin to understand my predicament of what to do and where to begin. Do I try a custom barrel, or bedding a high quality AM stock, or invest in more reloading equipment that allows me to more precisely control the consistency of my reloads.
I am an emergency maintenance electrician who's job is when a piece of equipment (90% of the time it's multi-million dollar piece of equipment) is not working correctly or has failed I am tasked with first diagnosing the cause then fixing it. When ever I am confronted with a problem the immediate cause for which is unknown to me I am a HUGE believer in trying the simplest and most cost effective thing first.
In my case I think I will begin with trying as high of quality brass I can find and that means Norma in the case of my T3 in 300wsm and going to extreme lengths to insure each piece of brass is as close to exactly the same as every other then do the same with my bullets of choice. I will then inspect and measure every loaded round to ensure they are all as close to exactly the same as I can make. Previously I was measuring one in five. I will then record the results of every fired round. I will also anneal after each firing.
Lastly I have several very accurate reloads that have been giving me on average .75" MOA at 300 yards in my T3 Lite that I have used different die combinations to make my reloads with. I will now stick strictly with FL/RS using Redding body only RS dies and bump my shoulder back 0.002-0.003" then size the case neck using my Lee Collet die. This should reduce (if indeed it is a factor) any run out in either my brass or loaded rounds to having no effect on my accuracy. I am also going to give coating my bullets and barrel with HBN a try on my very next reloads.
Unless someone convinces me to try an alternate course of action I will begin with brand new Norma brass and take great care to prep and load as close to the same exact for every reload as I can and keep exact notes on all steps and results for over all as well as individual reloads.
If after all this I have not seen a measurable reduction in the numbers and frequency of fliers i will then have to consider other actions.
If anyone has anything to add or a addtional step i should consider please by all means let me know. And yes I will build me some good solid performing wind flags. I'm sure YouTube is littered with affordable DIY wind flag designs.
Again thanks for the replies and for your time in doing so.
Arthur.