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 Author  Topic: 40mm Bofors Guns on PTs
Daniele Klay

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Daniele Klay  Posted on: Jan 20, 2018 - 5:54am
This may seem a silly question but since I firmly belive there are no silly questions just silly answers; here you are:
Later PT boats and retrofitted early ones had a 40mm Bofors as stern gun.
Many of those visible on pictures show the railing with reay ammo and obviousely are 40mm M1 guns on M3 carriages.
Some guns show no railing-for example PT195- were tthose M3 carriages without railing or M2s?
The "army" stile sights on PT195's gun would support this hypothesis( M1 guns on M2 carriages), but I'd like to know the other member's opinion.

Daniele Kly

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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Jan 20, 2018 - 9:51am
Daniele;
Allied Coastal Forces VOL ll, page 224-225.

The 40MM MK3 is the Navy version of the Army 40MM M1, on an M3 carriage. RON 12 was the first to take these to the South West Pacific. Their 40MM's were installed, stateside, in either in Bayonne or Brooklyn. That aft railing you mention was removable, some crews removed it to speed up loading from the main 40mm ammo box, and ease of getting onto the loader platform.
RON 21 did some kind of cumshaw deal and got their 40MM's from the Royal Australian Navy.
Take care,
TED


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Daniele Klay

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Daniele Klay  Posted on: Jan 21, 2018 - 5:24am
Thanks a lot Ted, I don't want to question Allied Costal Forces Vol II as a source,but some details just don't add up:
The Mk3 40mm was a M1 gun on a M3 carriage with rear rail,no power traverse/elevation,no trigger for the loader, Mk 6 direct "iron" sights.

Some early boats had this gun mounted:

So the question is. was this arrangement a Mk3 gun with rear rail removed and M3 sight fitted or a straight M1 gun on M2 carriage?

Greetings

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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Jan 21, 2018 - 10:26am
Daniele;
I think I have reached the limit of my 40MM carriage knowledge. I have used the MK3 and the MK 3 MOD 7.
The MK 3, the carriage weights 1035 LBS and the Gun with barrel weights 1015 lbs, total fitted out with ammo 2275 lbs.@@

I think a few things were involved here.

1.If this is not a RON 12 photo, It maybe the way, they were received from the Army, after removal from the trailer,

2.I do know everything was removable. It is possible since this looks like an early boat, in the naked guy photo, and the frame is just tubing, that the platform was removed,

3.Early boats were more concerned with weight and speed, The removal of tubes allowed for the 40MM. An ELCO having been in the water for several weeks with 40MM on the stern could make a sustained 38.5 knots.*** However, in this case I think it was just more convenient for the crew.

4. But with RON 12 boats, I think they removed the platform. As I detailed in an earlier post, RON 12, other than their development of the roll off torpedo rack, was into removing stuff, they removed most of the aft depression rails and removed or modified the forward ones, Since they used the 20MM and MK 12 scarf ring mount in the turrets, the railings were more of an obstruction, than an aid.
Take care,
TED


*** REF: pg 161 U.S. Small Combatants, Norman Friedmann.
@@ REF: pg 445 U.S. Small Combatants, Norman Friedmann.


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Jeff D

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jeff D   Send Email To Jeff D Posted on: Jan 21, 2018 - 11:42am
The M1 gun / M3 mount for reference:

jpcHi.jpg

Looks like the one on the 195 except for the sight and railing:

jpLh8.jpg



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  Jerry Gilmartin

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jerry Gilmartin   Send Email To Jerry Gilmartin Posted on: Jan 22, 2018 - 1:20pm
I have noticed the sights are different as well. On one of the illustrations it calls out an "azimuth" sight, which looks like 3 vertical bars and not the spider web. (It is used for turning the gun side to side, where the spider web is for elevating the barrel vertically) I wonder which gun mod used which sights.

Jerry Gilmartin
PT658 Crewman
Portland OR

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Stearman

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Stearman  Posted on: Jan 22, 2018 - 7:39pm
Didn't RON 10 boats use Australian Army 40mm mounts? I have wanted to convert the Italeri 1/35 PT-109 into PT-174 after she arrived in the Solomon Islands. As a side question, does any one know if the 174 kept her zebra scheme, or was she repainted after her damage from the sinking Stanvac Manila?


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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Jan 23, 2018 - 8:38am
Stearman;
The Adapter scheme on RON 10 boats only lasted a short while out in the warzone. It was modified to Green decks and superstructure light green and black stripes on hull which was not very successful either 20 July PT 164, PT 166, PT 168 were returning in the morning and were bombed by US B-25's losing PT 166, and damaging the other two. 164 was destroyed later in 1 Aug Japanese bombing raid, On 1 Nov PT 167 performing escort duty was attacked by 12 Japanese torpedo planes and torpedo went through bow, damaged but survived. RON 10 crews thought the paint scheme attracted attention. By late Nov-Dec 1943, all RON 10 boats were repainted. Here are some photos of PT 174 for you: http://www.navsource.org/archives/12/05174.htm
Take care,
TED


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Stearman

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Stearman  Posted on: Jan 23, 2018 - 9:53pm
Any idea as to the date when the 40mm was added to the bow, in the combat zone, as apposed to the Elco mount state side?


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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Jan 24, 2018 - 4:27pm
At ELCO:
PT-174.jpg


PT-174-3-3ea53d.jpg

They did remove the shielding around the gun prior to shipment. In photos of USS Atascosa (AO-66)the 40 MM was removed for shipment. Then reinstalled when they reached Noumea after repair. LINK: https://www.history.navy.mil/our-collections/photography/numerical-list-of-images/nara-series/19-n/19-N-40000/19-n-43374.html

Later, in 1945 the 40MM was removed and a Thunderbolt mount was fitted on the stern.

Here is a link to a outstanding 1/35th scale build of PT 174: http://www.modelwarships.com/reviews/ships/misc/pc/35-pt-174-ss/feature.html
Take care,
TED


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