Typicaly there is as much metal in either. It's just distributed differently. 2 lug usually requires 90� bolt lift while 3 lug only requires a 60� bolt lift. Both systems leave about 1/2 of the steel for engagement while removing 1/2 for clearance (a little more removed on the bolt, a little less removed in the receiver). It's not the number of lugs that really makes the strength difference so much as the cross sectional thickness of those lugs.
But this is just a laymans opinion (Engineer, not a gunsmith). I'm sure someone more familiar with these specific actions will give a better answer.
Posts: 211 | Location: Little Rock, AR. USA | Registered: 23 May 2002
Since about 99% of the bolt action rifles ever produced, and 99.99% of the target rifles ever built are on two lug bolts, I don't think I'd loose any sleep over using the Sako 591 vs. the M75.
Posts: 13266 | Location: Henly, TX, USA | Registered: 04 April 2001
Many of the super high end target rifles are built on 4 lug actions like the RPA Quadlock. That said, it is a matter of action rigidity,not strength that makes that so. I would not worry about it unless you are trying out for the US Palma Team and have a chance at making it.
Posts: 1541 | Location: NC | Registered: 10 June 2002
The question you have to ask yourself is, "How strong is strong enough?"
For example, I've fired thousands and thousands of rounds through various Model 70 Winchesters over the last twenty-five years. Most of these have been pre-64 and current Classic Model 70s, complete with two-lug bolt system and coned-breech. In theory and in demonstration, these Model 70 actions are not as strong as some others, undoubtedly including the Sako 75. Yet, even the old pre-64 '70 was tested with 70,000 lb. proof loads at the factory (far more than any SAAMI-spec cartridge produces), and it takes a real catastrophic goof on the part of the shooter (or hack gunsmith messing with it) to blow one of these actions up. I haven't had so much as a leaky primer out of one of them in all these years.
Of course, other excellent two-lug actions such as the Remington 700, Ruger 77, and push-feed, post-64 Model 70 are enormously strong - more than strong enough for any task a level-headed shooter will put them to, and you can bank on that to be the truth.
The pre-Model 75 Sako is another excellent two-lug action (a third, Mauser-style lug on the pre-'72 actions) that's plenty strong for any task, and given the difference in quality and bolt sleeve configuration between the old Sako action and the current one, I'd take the older action and run with it in a heartbeat.
The one possible advantage to the three lug action is in the stability of the bolt from the tripod effect. Just how unimportant this is though, is easily seen by the fact that most of today's BR actions are two lug actions! The only other advantage to the 75 over the 579 is a little closer tolerance between the bolt body and receiver and a better trigger on the 75. From a pure accuracy standpoint, only a direct comparison would really show the difference. If you want to use a detachable mag then the 75 is the way to go. Regards, Bill.
I understand another feature of multi-lug actions (more than 2) is their stability when firing military ball ammo or factory ammo. If you are going to use factory ammo then maybe a multi-lug will be more accurate. If you are going to tailor your loads then a 2 lug should be more than adequate. I followed this logic when purchasing 2 lug and 3 lug Sako rifles.
quote:Originally posted by rupert: I understand another feature of multi-lug actions (more than 2) is their stability when firing military ball ammo or factory ammo. If you are going to use factory ammo then maybe a multi-lug will be more accurate. If you are going to tailor your loads then a 2 lug should be more than adequate. I followed this logic when purchasing 2 lug and 3 lug Sako rifles.
Where do these notions come from?
Allen Day: Express is talking about the medium length Sako actions, which were never made with the third (safety) lug at the rear (a la '98 Mauser). Only the L 61R had the third lug, and then only those made prior to 1972 were so equipped. That said, the "strength" of the action is so much greater than the failing point of the brass case that the issue is irrelevant. Much more important is the way in which an action handles escaping gases from a failed case (whether failing from fatigue or defect at normal pressures or from an overload). Some actions are much less prone to let gas back into the shooter's eyes than others, and that's where the concern should be.
Posts: 13266 | Location: Henly, TX, USA | Registered: 04 April 2001
Multi-lug target actions have less to do with strength than they do of stopping cant of the bolt during firing. A 2 lug action can move back and forth during firing, a 3 or 4 lug action trys to eliminate this.
Posts: 593 | Location: My computer. | Registered: 28 November 2001
I built a custom rifle based on the Sako 591M action. It is a very nice action, and very strong. I've blown a primer and had no problems, but haven't seen a Sako come apart. The only thing I don't like about the new Sakos is the removeable recoil lug as opposed to the integral lug on the older models. It's not sandwiched between the barrel and action like a Remington, but rather, it's an L-shaped aluminum lug fitted around the front action screw post (and a little too sloppy a fit for my taste). I had a new lug cut from good steel that fit very snugly, and bedded it right over the front pillar in the bedding system on my McMillan stock. It works fine.
You won't notice the difference in the bolt cycling speed between the 2 lug and 3 lug actions that the 20-some degrees difference in rotation affords you..
Posts: 529 | Location: Missouri | Registered: 31 January 2002
And, if you notice a difference in cycling speed between a two-lug action and a multi-lug action, it may well be in favor of the two lug action. In action design as in any other mechanical assembly design, there ain't no free (without cost) lunch.
Yes, in a multi-lug action, there is less distance of bolt lift. That also means that cocking the action has to take place over a shorter distance. In turn, that means the cocking cam angle has to be steeper, which requires more effort to accomplish the same amount of work.
Try cocking an RPA, a Weatherby, a Champlin, or even a Steyr-Mannlicher sometime. Then compare it with cocking a pre-64 Model 70 Winchester.
There is a reason that high-power shooters who do not shoot an M1-A or a mouse gun do not usually select a multi-lug action for their rapid fire rifle. They almost always select a M-70 or similar two-lugged action. The reason is, it is easier (and faster and smoother) to operate in rapid fire.
The Sako two lug action is a very good action. You won't be sorry if you build a rifle on it.
AC
[ 06-27-2003, 05:27: Message edited by: Alberta Canuck ]
Posts: 9685 | Location: Cave Creek 85331, USA | Registered: 17 August 2001
Albert is certainly right, in theory, about the greater torsional force needed to cock-on-opening with a 60 vs. 90 degree bolt lift. That said, all three of my Sako TRG-s (three lug bolts) seem to require no more lift than my numerous L-series Sakos. I have fired, but do not own, a Sako 75, but I would expect its required cocking effort to be similar to the TRG-s. In short, I doubt the three lug bolt will make any appreciable difference in actual function.
One thing I do like about the three lug bolt is that the shorter bolt lift keeps the bolt handle further from the scope and helps prevent "skinning" your knuckles on a very low-mounted scope.
Posts: 13266 | Location: Henly, TX, USA | Registered: 04 April 2001
