Now Brandon,If you do replace the barrel on your 1377 and install a steel breech, save the parts.Someday soon get yourself a 2240 and put the 177 barrel and bolt in that and you got a 1740.You will not be sorry.Then you can get a steel breech for that one later... anddowntherabbitholeyougo.
It's been discussed in the past in detail. Especially a "pistol gate".Can you imagine the work involved to weed through all the previous posts to get them sorted into their respected gates?!Try having a '90 Co2 Sheridan "F"! Where the heck would that go?Too new for Vintage, not made by Crosman/Benjiman, and not a "HPA" but it is considered a PCP...
Admittedly, I haven't read all three pages of replies so it's possible that this post is inappropriate due to the OP's decision being made by now . However, if it's not too late, I'd like to share my take on a 1377 carbine. It's been so long since I built her that I can't tell you what supplier's parts were employed. The stock and forend were made by me from hard maple and finished with a bedliner coating. Steel breech, aluminum bolt and handle, High pressure , flat faced valve. High pressure piston assy. 1377 barrel. Delivers well over 800 fps with Crosman Premeres. I call her "The Stinger".
You can get a considerably good setup for 1377 for around $150 (not including scope).In this setup the crosman customs shop is actually cheaper than DIY. On the menu pick 18" crosman barrel in .177, the long steel breech, and the shoulder stocked grips (If you only pick those 3 options it's cheaper than DIY)An aftermarket metal piston makes a big difference too. Those are the mods that give you (in my opinion) the most performance increase, and only the last one needs to be done yourself.
It's a wider forearm that was on a discontinued Crosman 2289 Backpacker. I've seen people also put them on the stock for a cheek rest. I'd post a pic, but don't have enough posts yet. You can google Backpacker and see the wider forearm.
My Bad....fatty on my built 1322, before I found out about the deals at CCS...