Rear locking lugs vs. front locking lugs?

[Mosinguy]

Ideas are flying through my head for my build. I'm having no luck finding local parts, so I'm thinking about doing some slight machining work since I know a friend who would do some machining cheap. It seems like rear locking lugs would be much easier to make and I hear no real cons against them. However, I have read that rear locking lug actions are less rigid. But Steyr made incredibly accurate rifles with rear locking lugs so I'm not sure how true that statement is.

Basically, I want to know the real differences between a front locking lug vs. a rear locking lug. Price, ease of manufacture, accuracy, that sort of thing. This design may be used on anything from .22lr up to .223/5.56. This may be a future project since it would require an AR-15 lower and a custom upper receiver design.

 

[hrearden]

Im not sure there is a reason for rear locking lugs. They are present on some designs, yes. Every rear lug rifle I have ever dealt with was either something old or a 22. I think the real difference is simply in what the design entailed. In other words, there is no real advantage to rear lugs. In fact, they are less desirable as they are not as sturdy at holding back all that pressure and more difficult to keep square with the bolt face, etc.

All that being said, depending on what caliber you plan on using, they wont necessarily be a bad idea, If they are part of your home build, will work, and will work safely, then go for it. I just wouldnt build a 300 mag going for 1000.

 

[Mosinguy]

Yeah, it won't be a large powerful caliber shooting long distance. Just a plinker to get my feet wet.

 

[VinceU1]

Remington sold a rifle with rear lugs, the Model 788 I think. Anyway, it was supposed to be a bit more accurate, and less expensive than the 700. I don't know if this is true or not, but supposedly the 788 was harder on cases than a bolt with forward lugs because either the bolt would deflect or compress on firings. Like I said, I don't know cuz I never had one, but that's what I was told by a couple of guys I met that had one.

 

[chipdog4]

Remington 788's had 9 locking lugs on the rear of the bolt body. I read where someone had done some analysis and found that the bolt was compressing a couple thousandth's of an inch every time it was fired. Of course, this was in the higher pressure rounds, 308, 6mm and so on.

 

[Leo]

If the lugs are at the rear, the receiver has to be as robust at the rear as it is at the front. An open bridge style action will have a lot more problem with this than an closed bridge.

If you examine a model 96 mauser and a K98, you will see that for the bigger caliber, only the front ring of the receiver was made larger to accomodate the rearward bolt thrust caused by the bigger caliber round. The rest of the reciever was plenty strong to do everything that it was required to do. The farther the recoil lugs are from the chamber, the more the the action has to do.

On the other end, the common AR design has chamber NO pressre control duty because the bolt is meshed in the barrel extension. All the upper has to do is keep the parts inline, that is why pretty marginial strength aluminum alloy holds up just fine.