I want a .25 marauder for the extra energy, but they're unregulated and have crosman barrels.  The .22 marauder is available with lothar barrels and regulated.

The .25 energy might be used up to coyotes, but more likely squirrels and maybe coons.

What would I be gaining/losing by going .25 or .22?  The .22 would be the regulated version.

Is there another pcp in marauder price range that is better, and similar noise?

I am new to the air gun stuff too. I got a p-rod (Marauder pistol). It is an unregulated 22. So far, I like it. I thought firearms were a deep rabbit hole, but airguns seem at least as deep?!

Depending where you read, 177 is plenty for squirrels but 22 gives a bit more 'forgiveness' in shot placement. It always depends on stuff like range, surroundings, local rules, etc, but 25 sounded like it would be overkill. That is in the pistol version. In the rifle version, again from what I read, 22 should be good out to a couple dozen yards. If you use slugs instead of pellets for better BC, likely farther.

I got a hand pump for the p-rod. Since the tank on the pistol is pretty small it takes some work but nothing bad. I put previous beers to work pushing down the pump handle. ;) The rifle tank might get you looking for a tank to fill from or a compressor. Not that a hand pump is 'un-do-able', especially if you top up often, but filling from empty might leave you wishing for wind sprints.

There are a couple airgun forums that are more active than here. Gateway to Airguns has a LOT of info and members happy to opine. Airgun Nation is another good forum. Pyramyd Air and Airgun Depot, the same companies IIRC, have some decent videos. If there is not a good local airgun shop, if PA and AD are running sales, sure, but there are a number of others who are said to give better service  and better prices. Airguns of AZ was the best pricing last I checked, even without free shipping.

Regulators as I understand them, are used to level out the shot velocities. You can set them to get more shots from a fill or to get more consistency in fewer high power shots. In either case the hope is the POI doesn't move around much since the velocities are similar. I get the idea, but shooting the p-rod at the inside 20 yard ranges I expect to use it, I don't see much POI shift as the tank depressurizes over a couple dozen shots. Does it move? Yes. Enough to matter?? There are aftermarket sources and home brew solutions if you decide you gotta have a regulator later, if you decide to try unregulated first.

Either PA or AD had a 'chooser' where you put in your desires and they select the 'best' options. Among those desires was noise. I thought it wasn't definitive, but it sure narrowed things down a lot.

Also regarding noise, it may or may not be legal to get a 'moderator' to quiet your airgun. Do your own reading. If the PTB disagree with your legal opinion it can get pricey. Also subject to local rules...

Hope it helped.

The differences of going with .177, 22, 25 or even larger is how hard that pellet or slug hits the target for what is called when hunting "knock down power". A .177 while coming out the barrel muzzle faster, it does have knock down power, but the pellet being as small as it is will also zip right through the flesh many times without much effect due to the speed and not leaving as large of a wound. Yes, it will kill, especially if hitting head shots, but you hit that animal in the gut or rear quarter, using a .177, many times that animal will get away and die elsewhere.

Whereas, using a 22 or 25 caliber while the pellet will travel slower, it will have more knock down power the larger and heavier it is. It leaves a larger wound and disrupts the internal organs from the shock wave created by the pellet. You can tell much easier if shooting at metal targets. That small .177 will go "tink" a lot quicker due to the speed, but still with authority for its size, while a 25 will go "twack" but be slightly slower getting to the target, while hitting harder at the same distance. The 22 caliber pellet will split the difference in sound and speed. A 177 will generally go 975FPS, 22 going 890FPS and 25 going 850FPS. Same air chamber and pressure, but larger/heavier grain pellet needing to be pushed out the barrel.    

I don't know much about regulated v non-regulated air guns, so I'll leave that info to more educated users of these type of guns.

The biggest thought you need to decide, is do you want to go with a 25 caliber that is limited to on-line stores(that I've seen) with higher costs for less pellets in the tin, or go with a 22 caliber pellet that one can find even at some garage/yard sales and definitely at most any store with a sport/hunting dept.

IMHO, I'd go with the regulated 22 gun, even if it uses a Crosman barrel. Crosman barrels today are not the barrels of 50yrs ago. They use better barrel steel (4140) and the machining equipment is much better than long ago.

 

I have both regulated and unregulated. Both shoot well. An unregulated gun, if designed well, does not always benefit from regulation.

I stuck with .22 cal solely for price and availability of ammo. I can source .22 locally but .25 always has to be ordered.

I'm not hunting anything larger than small game, so that was my other critera.

Just purchased a .25 cal Marauder for my mothers property to deal the squirrels getting into the garage and chicken feed.
Had a left over Vortex Strike Eagle and a Harris bipod. Sighted in at 30 yrds. The hash marks for the bullet drop on the strike eagle seemed to coincide well at 10 yrd increments (30, 40, 50, 60 and the farthest 70). Took three at 70ish yrds using the lowest crosshair with a slight holdover. As stated above ammo will more than likely have to be ordered.

ETA: Purchased a compressor from amazon for around $370
Ammo used was JSB Diablo Heavy

Thanks, everybody.  It looks like a good compressor is difficult to get for anything like a reasonable price, which if you're unwilling to use a pump means you need to rely on scuba shops for tank fills.

Is there a reliable compressor that will last for less than 1000?

The air supply seems like the big obstacle to PCP.

In all the research I've done, all the cheap <$1000 compressors break eventually. If you going to be an occasional PCP shooter, a Hand pump is more reliable, but a bit more of a workout.

The Yung Heng compressors seem to be the best of the lot, but require some mods and tinkering. I like shooting way more than tinkering with compressors.
I'm in the PCP game for good as i think it's great and the guns are amazing. So, I'm saving up for a buy once cry one $3500 Alkin compressor. Warrantied and has parts and service available.  Then I can fill my 74CF tank to refill all my guns.

Guys drop way more coin on that for other hobbies, and since shooting in my #1 hobby, this is not a huge investment long term.

Just my $.02

3500 is the price of a nice reloading setup...if you like shooting air rifles, and you plan to get into the bigger sized rounds like .457 and .50, then an air compressor and various sized tanks are necessary; it is how you load / reload...You do not want to depend on a scuba shop...

I am debating that right now, as I want to get into the PCP hobby, but not sure I will enjoy it as much as the pewpew side of my hobby which i love and am quite invested in...to get a FX M3 at 2500.00 plus 1000.00 for a scope and mount, 3500.00 scuba compressor, 800.00 for a great white or omega Carbon Fiber 100 Cubic Foot tank, 300.00 for bipod, plus hundreds in pellets, slugs, air hoses, tethers, fittings, seals, modifications, parts, etc...it is just one more sink hole for money to pass through with the force of 10,000 black holes...Just like my other hobbies...

I started out with a $500 Benjamin Cayden and a $150 scope along with a $50 pump. Pumping was not as bad as everyone made it out to be. But once I fell in love with the ammo price, the accuracy and the quietness and not having to wear Ear pro, I was hooked.

It was later that i bought a 74CF Omega tank and then I sold my Garand to fund the Brocock.

For me I was not above selling off guns I just don't shoot anymore.