Let me tell you a story. Awhile ago, I traveled to my FFL to recertify for my CCL. In my state, we do this every 4 years with a check every 2 years. I arranged with them to rent a revolver to certify with as well as my normal carry pistol, a Taurus G2S. They gave me a Ruger Blackhawk with a 6" barrel that I was using to shoot .38 ball ammunition. During my range qualification, my instructor asked me to shoot the revolver first. I picked it up, and noticed that it had to weigh at least 4 pounds. I asked the instructor sonmme questions about proper grip (I had not shot a revolver in about 50 years) then I shot the course. I was very surprised. In spite of its weight, the revolver was rock solid in my hands. I completed the course, and scored 100% then it was time for my EDC. I think it weighs about 19 ounces fully loaded. I held it on target, and could not get it to quit wandering for the life of me. The gun would not settle down. The instructor said I was gripping it to tightly. I shot the course, and at 7 yards, i scored 0. I could not seem to hit anything at that range. I shot the rest of the course and barely qualified (70%). I am not understanding what was going on. I would have thought the revolver would have been harder to control than my Taurus, but that was not the case. I could not seem to control the sight picture on my Taurus no matter how hard I tried. Iām looking for advice and suggestions, and, unfortunately, I do not have a lot of money for training. Any suggestions or advice would be appreciated!
it had to weigh at least 4 pounds.
It reminds me of the time I used medicine ball before shooting with a regular basketball.
It has that exact same effect holding a gun that heavy then switching to one that weighs only half as much.
Iām a retired LE. When I first started in LE I started with a S&W
6 inch, 357. Carried it for years. When I bought my first semi auto pistol it was S&W 9mm. I am not an expert but Scored high 90s with my 357. I was all over the target when I tried the 9mm. The 9 was liter than the 357. Same problem your having. Took me a while but got my scores back up. Later I moved up to a heavier S&W 40. Scores went back up. Heavier works for me. I carry a MP 40 Shield for back up and off duty. Liter but not as accurate as my duty weapon. It is what it is my friend.
Brother Henry_A,
I Believe that brotherās Bean and VernonTwo-three Nailed it!
Heavier firearms work BETTER for me also. My 6" Smith S/S revolver was a beast!
but she was MY BEAST! and she hit what I aimed at. That is why (for me) My S&W 2.0 M&P
works for me also. I love all my guns but the smaller lighter oneās I have are TOO LITE!
My Taurus G3c stuffed w/ Hollow points is more easily concealable but I do far better with HEAVY METAL!
I recently bought a Rock Island M-206 revolver ($250-) .38/hollow Points, On a payment plan if you canāt purchase out right something like that may solve a problem or two. (Just a suggestion).
Sheās got weight to her, Concealable, and relatively inexpensive (she came with (2) Grips also: Rubber and wood). I didnāt want a $600+ Revolver, I wanted one that wouldnāt break the bank and still pack a punch (it was a gift for my Sister (70) years old and as I said A LOT here she out shoots me (on a rare day! 
of course!)ā¦ Rent one next time and see if she works for you. God speed.
Vernon too tree, WELCOME to the fold Brother, Enjoy your stay @ the Retired LE Continental (Excellent post)
Who is the financier? There is a Staccato I need. 
You may be joking Brother but on Guns.com (thereās Credova financing)
and on Grabagun there is Monterey Financial? although they both might be Credova.
Ijust bought a Tokarev Shottie (12G)
Tokarev TX3-12HD Afghan National Police 12GA 18.5" Barrel 6rd Pump Action Shotgun Dropped only ONCE!
for $299! I wanted to see how easy the process/Interest rates were, and they were surprising good! If you donāt have the bread to buy outright, this is an excellent (my opinion only) way to go. this was on Classic firearms by the way.
Iām waiting for a polymer Staccato or a left hand bullpup that can run mini shells
Brother
I keep hearing Staccato, Staccato, Staccato from you and I looked them up on Guns.com
$2400-$4400+ !!! Woah Dude way outta this Gunnerās Hemisph$r$!
thatās like āFirst Bornā prices to a cheap-skate like me!
As those above mentioned larger heavier pistols can be helpful as long as they arenāt too heavy. A lighter pistol can also be noticeably snappier on the recoil making follow up shots slower and even leading to flinching issues for some people. Longer barrels also mean a longer sight picture with iron sights which can make aiming a little easier.
The cheapest way to learn how to overcome those issues is to do a fair amount of dry fire practice. 10 or so minutes per day 3 or 4 days a week can make a big difference.
For an inexpensive dry fire training video program I would recommend something along the lines of the 21 Day Alpha Shooter by Mike Ox:
https://dryfiretrainingcards.com/
It is only $37 at the moment and helped me to noticeably improve my shooting skills. He has other training options as well from cheaper introductory courses to more expensive intensive courses. The alpha shooter video quality is nothing fancy but the information and drills are top notch.
The USCCA also offers a bunch of online training options depending on your membership level.
āIām waiting for a polymer Staccato or a left hand bullpup that can run mini shellsā¦ā
That reminds me (OFF TOPIC TOTALLYāand to add a little levity to the current insanity)
As a Boy Scout (tender feets) . I and another green horn footer was sent to the Camp Director (ten Mile River in Upstate NY) to ask him for a ā¦wait for itā¦ āLeft handed Smoke Shifterā The fires kept blowing the smoke into the 'Committee Menās Lean-tooās they saidā¦ Man were we greenā¦ He almost had a stroke the Consular! but good naturedly went into his kitchen and came out with a 'Splatter Cover" Mesh screen to keep hot oils from nailing your stove top, hands and armsā¦ We were so over joyed! we went back and showed the MEN (who I suspected had been drinking a bit too much!) This was New york after allā¦ They were a little too over joyed at the kitchen implement!!! (50 years+ later I think itās phunnie, but I NEVER screwed with anybody younger/ greener ever). My Fellow Warriors did a bit of ribbing with the Newbieās but I remember that story and kept it real for them until they got seasoned up a bit.
Anyway Lesson learned
Yup, up there with the better Masterpiece Arms 2011. 
These days Iāll need to finance a tank of diesel. Last month price was $4.20 a/gal, last night was $5.16, today, $5.39 a/gal.
Yessir, they are really stickinā it to US now,
Reg.Gas is now Avg.: $4.00/galāCHEVRON the biggest offender is $4.60+/gal
Diesel is avg.ā $4.50- 5.00 !
Anytime you get Jacked @ the pumps, just remember Puddinās 10% for the Big Jerk and āI did that!ā
(It gets me through the fill up process without stranglinā anybody!)
Iām sure I just got taxed for reading your post!
Hey, you can get a John Wick 3 Combat Master for 6k and it comes with a number two pencil, if your interested. 
Good One āKā
I have a silver lining post (finally)
My ānew to meā British car (sometimes still look in my garage and marvel itās really there)
She is a 25T (turbo)
I now work just (3) days a week, w/ daily running about town in my old xterra I would
fill once a week. (4x4 bruiser).
In this car , Iāve now gone (8) days and the needle barely budged! Color me shocked!
That is how my Audi TT roadster was, until the stock 4ā turbo spooled up!
Welcome
Oh my God Karacal sheās Gorgeous!!
Wanna Race?
I canāt say for sure about the intent of the instructor. However shooting a heavy gun then switching to a lighter one throws the muscles/body off. Whereas switching from a lighter to heavier one doesnāt.
Your body remembered the weight of the heavier gun making it harder to shoot the lighter gun. Personally I would, if possible, find another to recert with or not agree to fire the heavy gun first. What was his reasoning for you to shoot something you donāt carry?