Remington 742 question

[kingj]

Will a 742 barrel of the same caliber swap with another without major modification??

[gunnut69]

In therory yes but in practice the headspace should be checked. If needed the depth can be adjusted but that gonna require a reamer. The real problem with the 742's is their propensity to wear themselves out.. If the bolt head actuating cams aren't lubed with a high pressure grease type lubricant they will self destruct is just a couple of hundred rounds.. wearing out the cam action slots in the bolt head. It's likely the reason the 742's self as cheap as they do. Parts (the bolt head) are not available.. and continued use of a badly worn 742 can lead to a situation wear the gun can fire with the bolt  head not fully engaged. The result is spetacular but USUALLY no one gets badly hurt as the receivers solid construction sends the fragments down away from most body parts.. I would advise against rebarreling the 742 as addressing a problem that only allows a worse problem to flourish. The 760 (pump) rifle on the other hand seldom causes problems and is usually quite accurate..

I forgot to mention this and hesitate to mention it but it is possible to convert the 742 to a close approximation of the 760.  The gas port is plugged  and the gas system eliminated. The forearm is replaced or altered to operate as a pump handle. The disconnector must be replaced and the trigger housing modified to allow the new disconnector button to protrude to allow the slide to operate. I've a lovely 742 in 30-06 that I'm going to operate on and confirm some of the problems I forsee.. I'll report back when I get some where with the project..

[BBF]

Gunnut:
First off I have no gunsmith knowledge so my idea is Kindergarten level.
 
For a minimum conversion wouldn't plugging the gasport and installing a larger operating handle(finger grip) for convenience be sufficient? The magazine could be replaced with the 760 type to eliminate the bolt hold open feature. Everything else stays as is.

[parkergunshop]

Scatterbrain,
As Gunnut69 notes, most old 742's should be related to the scrap heap.    The modification to be a pump should only be done if the bolt and receiver and receiver rails are otherwise sound and not worn out.  Even then only a professional gunsmith who knows what he is doing should attempt this modification.  When you mess with the diconnector you can allow the gun to fire with the bolt not fully closed as noted.   Many gunsmiths refuse to work on these guns feeling that they are a liability which is the stance the Remington Factory takes but will not admit.
Less than good design, some parts cheaply made,  better to spend money and time on a better investment, this is kind of like buying a car at the local metal salvage yard and refurbishing it to operate like new.   A pig in a poke to be avoided.
 

[gunnut69]

Scatterbrain- Yes it would be possible and the result would be a 'straight pull' bolt action and while it would work would not be nearly as handy as the pump conversion.  I've a couple to work with now but there was a shop advertising in SGN that made the conversion. The problem was the price since they swapped 742 parts with 760 parts purchased from a supplier. The gas tap on the 740-742 is fairly easy to block as it is drilled thru the gas block and the resulting hole is capped with a ball bearing and 2 set screws. Bore the ball down further and lengthen the set screw column and the gas tap is off. This conversion still allows the port into the barrel to be cleaned occasionally to aviod pitts.. The check for a damaged 740-742 is to open the gun and examine the rails that the carrier rides on that are machined from the receiver wall oposite the ejection port. If there are notches in those rails the bolt head has worn to the point it is over rotating and the locking lugs are notching the carrier guide rails.. Some simptomes include the bolt sticking to the rear after firing when there are still rounds in the magazine. If this occurs stop firing that rifle and take it to a smith immediately as continuing use can lead the the rifle firing with the bolt not totally locked into battery. Parkergunshop is right though, while the rifles usfullnes can be extended it is still what it always was. Still if converted to a pump or straight pull they can provide some use and if theres sentimental value it mey be worthwhile.. A smith may well avoid this as there is a liability.. If you truly want an autoloading rifle I reccomend the excellant Browning BAR..

[BBF]

gunnut
 
 I read you well on the Browning. In my neck of the country a new one will set you back close to 2K's. That is not something I would expect my "Little Woman"  to digest without some justified hollering.
 
The 742 I have was recently checked by a g-smith with years of experience, found sound and I'm satisfied with that old piece of ordnance.

[gunnut69]

If you are using a 740-742 that is still in good shape to keep it that way clean the gun and when reassembling be sure to use lubrication. The part that causes the problems in the Remington is the cam slot in the bolt head. It is subject to huge forces as the bolt is thrown back and then slammed to the locked position. The force is concentrated on the relatively small area of the cam slot. This area should be lubed with a high pressure grease type lube. You don't need enought to grease a wheel bearing on a Kenworth but the high pressure grease will stay put and will not lose it's lubricant properties under extreme loads.. I use a light coat of water proof disk brake wheel bearing lube. If this is done and kept lubed this way the problem is at the very least greatly reduced and perhaps even eliminated.  Parkgunshop is right in that the gun was poorly engineered and produced shoddily. I've found the Browning BAR's on som of the internet auctions have a poor resale and the last I bought (several years ago) was a 243 Win and it was in the $400-450 neighborhood.. They don't have the problems the Remington's do and so a used one with a good bore should be fine..

[BBF]

This is the small diagonal slot that turns the bold head? I lube mine but didn't think it needed grease. So noted.

[gunnut69]

Yes the little zig-zag rotates the bolt head to lock the action. It wears on the impact points at the start of the cam surfaces. The most damaging one is the forward cam. It wears into the groove for the bolt lock lever. This will allow the bolt head to over rotate causing those notches in the carrier rails..and possibly allowing the gun to think the bolt is fully forward (and thus locked) while it is still unlocked.. That gets truly scarey... A local shooter had one blow. While the guns construction kept him from too much hurt he was rather disturbed. After contacting Remington they told him to send it to them and they would look it over. They did NOT return the damaged rifle,. instead giving him a voucher for a new rifle.. The grease is certainly important.. and high pressure grease is a very good idea..