Crosman Steel Breech vs. ???

WaltWhite · July 06, 2014, 09:56:07 AM

Looking to potentially upgrade the breech on my Crosman 1377. Primary reason is to part with the lackluster OEM rear sight. I like the idea of the MIM rear sight but have heard sometimes they're a loose fit in the Crosman breech.

So basically I'm looking for the best rear sight/breech combo for the 1377 undeR $100. I prefer click adjustable sights over the strange "hang off the back" sights that industry and similar offer. Does someone have a precision fit breech for the MIM sight, does the Crosman breech work just fine, etc etc?

redpcx · July 06, 2014, 04:49:00 PM

I have 2 Crosman steel breeches with the Mim sight. Both fit well, and are very solid when the two set screws that mount the sight are tightened. I wonder if reports of poor fit are a result of not tightening the set screws?
Some dovetail sights are a pressfit, these are a loose fight with setscrews to lock them in position.
Paul

BillK · July 06, 2014, 08:06:58 PM

I dremmeled down the front section of a Discovery sight and mounted it on the OEM plastic breech. As you can see it doesn't have the click adjustment but is very adjustable.
I stayed with the plastic breech because, for me, it is much easier to load a .177 pellet than it is with a front screw steel breech. The rear breech screw location is good loading w/.177 but it's a pia to drill & tap a 1377 air tube for a rear screw loc. breech. I don't plan on any optics for this gun so the plastic breech works best for me.

WaltWhite · July 08, 2014, 05:02:34 AM

Hmm, very interesting BillK. I've had some minor issues with pellets nose-diving into the screw recess in my stock plastic breech...I'd hate for that to become worse with a steel breech. Does one have to drill and tap the stock tube in order to get a steel breech to fit? Don't really feel like doing that if so.

Seems like I might be better off sticking with the OEM plastic breech and learning to live with stock rear sight, which at the end of the day really isn't horrible.

Tater · July 08, 2014, 05:15:55 AM

Quote from: WaltWhite on July 08, 2014, 05:02:34 AM
Hmm, very interesting BillK. I've had some minor issues with pellets nose-diving into the screw recess in my stock plastic breech...I'd hate for that to become worse with a steel breech. Does one have to drill and tap the stock tube in order to get a steel breech to fit? Don't really feel like doing that if so.

Seems like I might be better off sticking with the OEM plastic breech and learning to live with stock rear sight, which at the end of the day really isn't horrible.

If it's a fairly new 1377, I don't believe you have to drill the tube. I think that's mostly for older models but if I'm wrong, I'm sure someone will correct that.

BillK · July 08, 2014, 05:44:02 AM

Quote from: WaltWhite on July 08, 2014, 05:02:34 AM
Does one have to drill and tap the stock tube in order to get a steel breech to fit? Don't really feel like doing that if so.

Crosman makes their steel breeches with the breech screw located in either the "front" position or the "rear" position.

The front loc. breech is just the same as the plastic breech and it's a direct replacement. No drilling needed.
The rear loc. breech has the screw under the bolt. On the CO2 tubes of the 22xx guns there is a front & rear screw hole taped in the tube for either type breech. On all the 13xx tubes I have seen there is only a front loc. screw hole.
Some guys have filled over the front screw w/crayon or wax to make a smooth transition over the screw. I haven't tried that so not sure how well it works.
Decisions, decisions.........

WaltWhite · July 08, 2014, 06:21:37 AM

My particular 1377 is about as new as it gets, something like 4-5 weeks old. Looking at the breech you posted Bill, it appears there's some sort of set screw on the front portion of your breech in front of the bolt and above the chamber. I know mine doesn't have this, but rather a small allen screw that's right behind the chamber and below the bolt when the bolt is in battery. This small screw is in the pellet channel and exposed when the bolt is retracted. The pellet sometimes nose-dives into this screw recess right before entering the chamber.

I would ideally like to replace the stock breech and upgrade to the MIM, as the stock sight is pretty poor. From what I'm extrapolating there should be a drop-in fit 1377 steel breech, no? Specifically I'm looking at the following part: http://www.pyramydair.com/s/a/Crosman_177_Cal_Steel_Breech_Kit_Fits_1377_1740_1760_PC77_Air_Guns/4386. It doesn't mention the need to drill or otherwise alter the gun?

crossliner · July 08, 2014, 02:01:37 PM

Quote from: WaltWhite on July 08, 2014, 06:21:37 AM
My particular 1377 is about as new as it gets, something like 4-5 weeks old. Looking at the breech you posted Bill, it appears there's some sort of set screw on the front portion of your breech in front of the bolt and above the chamber. I know mine doesn't have this, but rather a small allen screw that's right behind the chamber and below the bolt when the bolt is in battery. This small screw is in the pellet channel and exposed when the bolt is retracted. The pellet sometimes nose-dives into this screw recess right before entering the chamber.

I would ideally like to replace the stock breech and upgrade to the MIM, as the stock sight is pretty poor. From what I'm extrapolating there should be a drop-in fit 1377 steel breech, no? Specifically I'm looking at the following part: http://www.pyramydair.com/s/a/Crosman_177_Cal_Steel_Breech_Kit_Fits_1377_1740_1760_PC77_Air_Guns/4386. It doesn't mention the need to drill or otherwise alter the gun?

Yours is the old screw location..Check this out..

http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,185.msg57888.html#msg57888

BillK · July 08, 2014, 04:27:13 PM

Quote from: WaltWhite on July 08, 2014, 06:21:37 AM
1. Looking at the breech you posted Bill, it appears there's some sort of set screw on the front portion of your breech in front of the bolt and above the chamber.
2. I know mine doesn't have this, but rather a small allen screw that's right behind the chamber and below the bolt when the bolt is in battery. .

3. I would ideally like to replace the stock breech and upgrade to the MIM, as the stock sight is pretty poor. From what I'm extrapolating there should be a drop-in fit 1377 steel breech, no? Specifically I'm looking at the following part: http://www.pyramydair.com/s/a/Crosman_177_Cal_Steel_Breech_Kit_Fits_1377_1740_1760_PC77_Air_Guns/4386. It doesn't mention the need to drill or otherwise alter the gun?

1. That is a set screw to hold the barrel in position. Not the screw we are talking about.
2. That is the breech screw in the front location.
3. That would be a direct swap. No drilling necessary.

Crossliners pic shows what I have been talking about. Nice pic.

WaltWhite · July 08, 2014, 07:02:22 PM

Thanks guys! I apologize for the who's on first routine.

BillK · July 09, 2014, 04:02:39 AM

Been there, done that Walt. No apologizes necessary.

agninja · July 10, 2014, 09:41:09 PM

I made that mistake of not tightening the set screw as well. You can also use a small amount sticky putty and smear it inside the grove of the breech. It will gum it up enough to make the sight stay put, but still allow you enough side to side movement so you can still adjust it with your fingers if needed.

tomykay12 · July 14, 2014, 07:12:05 PM

Mim sight was a good fit in my steel breech on a 1377. It is a decent quality all metal piece. My Mim came on a used bugout I bought recently, which also has a steel breech installed. Good fit on both, though the Mim was too close to my eyes on the bugout, so it was replaced with a dot I had on hand, and the Mim went on the pistol where it belongs, tk