Crosman 1377 transfer port query

[Damo666]

I keep seeing various aftermarket transfer ports & seals available for the 1377, many claiming to increase power by around 20%.

Are these transfer ports plug & play, or do they require redrilling of the barrel(s) to fit them?

Is there an optimum size transfer port hole size, as I've heard going bigger than a certain size will reduce the power?

[Back_Roads]

Many of us use Ice maker water supply tubing cut to fit.

[Damo666]

Many of us use Ice maker water supply tubing cut to fit.

I've read about people doing this, but when people say the restricted transfer ports are smaller (Canada/UK models) - is it the actual physical dimensions of the transfer port that are smaller than the American TP, or are people just referring to the exhaust hole size being smaller?

What I mean is, will an upgraded transfer port fit into say a Canadian 1377, or will the gun barrels need redrilling because the physical dimensions of the TP are larger?

[Walther]

Many of us use Ice maker water supply tubing cut to fit.

I've read about people doing this, but when people say the restricted transfer ports are smaller (Canada/UK models) - is it the actual physical dimensions of the transfer port that are smaller than the American TP, or are people just referring to the exhaust hole size being smaller?

What I mean is, will an upgraded transfer port fit into say a Canadian 1377, or will the gun barrels need redrilling because the physical dimensions of the TP are larger?

Only the transfers ports are a different size if you are using crosman transfers ports. They all fit the same.

IF however you do the Icemaker mod (poly tube transfer port mod) I recall opening up my barrel TP hole just a touch to get optimum flow and  seal with RJMachine LongRiser steel breech (a rare highest quality breech ever made)

[rsterne]

Some Canadian models use a hole drilled through the back of the valve parallel to the stem, through from the throat to the outside, to reduce the power.... others just have a smaller ID transfer port installed.... The TPs are all interchangeable, just the hole size varies.... There is no advantage to replacing the stock 0.134" ID TP in a .177 cal.... In a .22 cal, you can go up to 5/32" or a whisker larger, PROVIDING you also drill out the barrel port and valve exhaust port to take advantage of it.... Just changing the TP itself does little....

Bob

[UCChris]

Some Canadian models use a hole drilled through the back of the valve parallel to the stem, through from the throat to the outside, to reduce the power.... others just have a smaller ID transfer port installed.... The TPs are all interchangeable, just the hole size varies.... There is no advantage to replacing the stock 0.134" ID TP in a .177 cal.... In a .22 cal, you can go up to 5/32" or a whisker larger, PROVIDING you also drill out the barrel port and valve exhaust port to take advantage of it.... Just changing the TP itself does little....

Bob

Sort of off topic, but do you happen to know what length of ice tubing should be used for the stock steel breech? I know you want it a hair proud so it will compress and seal...

[Damo666]

Many thanks for the input, guys.

The transfer port in my 1377 is restricted.

On the exploded diagrams for the 1322, 1377, and 2250 the transfer port part number is 1322A026.

I bought several "1322A026" transfer ports from various vendors, but unfortunately, they're all 3.9mm (0.15") ID.

It seems these will be far too large for the 1377, but ideal for the 1322 or 2240.

Anyone know anywhere that stocks transfer ports with an ID of 2.9 > 3.00mm, as it seems these would be perfect for .177?

[rsterne]

I believe the only optional transfer ports from Crosman are the stock one (which is 0.140") used on virtually everything.... a tiny one used on the Challenger PCP (about 0.050")…. and the one used in the Canadian 1377, which IIRC is 0.078".... Either of the smaller ones can, of course, be drilled out to whatever size you need.... I always just use the stock 0.140" port on .177s, as the stock Crosman barrel porting is 0.134", close enough it makes no difference.... In fact, unless you drill out the barrel port on a .22 cal, the gains from going to a larger than stock transfer port are negligible....

Bob

[Damo666]

I believe the only optional transfer ports from Crosman are the stock one (which is 0.140") used on virtually everything.... a tiny one used on the Challenger PCP (about 0.050")…. and the one used in the Canadian 1377, which IIRC is 0.078".... Either of the smaller ones can, of course, be drilled out to whatever size you need.... I always just use the stock 0.140" port on .177s, as the stock Crosman barrel porting is 0.134", close enough it makes no difference.... In fact, unless you drill out the barrel port on a .22 cal, the gains from going to a larger than stock transfer port are negligible....

Bob

Hi Bob,

When you say stock transfer port, are you referring to part # 1322A026?

I've purchased several 1322A026 over here in the UK from 4 different sellers, and all these are 3.9mm ID, 0.154".

I've still not had chance to crack open my 1377 to do any performance mods, but won't pellets hang on my "stock" 1322A026 TP?

It seems this 1322A026 is universal & used in the 1377, 1322, 2240, 2250 & others according to exploded diagrams - but isn't it oversized for .177 and going to be a pest loading pellets in the case of mine at 3.9mm ID?

What on earth are Crosman thinking!

I'm waiting on some 2.5 (0.098"), 2.8 (0.110"), 3.00 (0.118"), and 3.3mm (0.130") custom made transfer ports arriving in addition to a chrony. I believe the 2.8 (0.110") & 3.00mm (0.118") will be optimum size.

If the stock 1322A026 transfer port on your side of the pond is 0.140" and the one we have here is 0.154", I'm now seriously confused.

[IntegratorDx]

Damo asked a question about pellets possibly hanging up on the stock Transfer Port in the 1377. Does anybody know if this happens because of it being a generic size even used for the bigger .22 barrels? 

I only ask this because I tried to load up a 4.52 mm HN Barricuda Match pellet into my 1377 and it seemed to get stuck… I had to push it back out with a rod.

The original question I wanted to ask you all about but did not feel worthy of starting another Topic is this… On the 1377 blue prints from Crosman, it shows one transfer port gasket between the air cylinder and the transfer port… around the short side of the transfer port.  It shows No second gadget between the transfer port long end and the barrel.  Is there supposed to be one there?

 I just watched a YouTube and this guy from the UK put a smaller gadget there and a “bigger” gasket around the little/air cylinder side of the transfer port.

Two (Top/Bot) of TP or one gasket (Bot) only? 

[IntegratorDx]

After looking at more old posts here at the Gateway to BB gun Heaven, I see that others have seen a video of a mod adding this upper gasket to the transfer port and also extending the bolt probe.  I also think the past concern for some was the pellet somehow getting stuck inside the bigger opening transfer ports… these are not worries of mine and I believe I found the answer to my earlier questions.

I did have a HN 4.52 mm pellet get lodged in the chamber… the bolt wouldn’t go all the way forward…. I wonder if these 1377 barrels are tighter than Daisy 880s….

This website is so Vast, I will look for this exact same question asked in 2012 and probably find the answer to some else’s exact same query!  I can’t believe I almost abandoned this 1377 of mine… Backroads is right, Modding to these guns is infinite… fun to tweak and improve for sure

[ALWIII]

  For the OP. While gains can be had by porting, barrel length quickly becomes a factor. As an example, the stock valve/port pass too much CO2 for the stock barrel on a 2240. Having said that, I've modded my valves, springs, and transfer ports on both my 22xx pistols. The .177 has a 10" LW barrel and the .22 has a 18" Crosman barrel. Fortunately, valves and transfer ports are relatively cheap, so experimentation doesn't hurt too much.