Sig 553LB

[Bret]

I bought a Swiss Sig 553LB earlier this year from JDI. The engraving's done and I have the stamp, but the buttstock I bought for the rock and lock lower has not come in. So, I decided to put a Swiss NATO lower on it that I have.

[SteyrAUG]

Doesn't the LB sorta defeat the purpose of a 553? Why not go to a 551?

[Bret]

The 553LB has a 13.7" barrel length versus the 551SB's 14.3" barrel length. 0.6" isn't much. However, the 551 has the longer gas system. You get longer hand guards with it plus the associated weight out front. If you think that the longer hand guards are worth the additional weight, the 551SB is probably a better choice for you. I like them both, but would go with the 553LB if I could only have one. I prefer the 553LB over my 552SB simply because the 5.56x45 performs significantly better out of the longer barrel. Of course the overall compactness of the 552SB it great.

[SteyrAUG]

The 553LB has a 13.7" barrel length versus the 551SB's 14.3" barrel length. 0.6" isn't much. However, the 551 has the longer gas system. You get longer hand guards with it plus the associated weight out front. If you think that the longer hand guards are worth the additional weight, the 551SB is probably a better choice for you. I like them both, but would go with the 553LB if I could only have one. I prefer the 553LB over my 552SB simply because the 5.56x45 performs significantly better out of the longer barrel. Of course the overall compactness of the 552SB it great.

That is sorta where I was going. I also believe the longer gas system is more reliable and durable. The point of the 552/553 is a compact package and acceptance of related ballistic performance.

I had a 552 and a 551 Swat (14.3) and the 551 was pretty handy, to the point that I was able to let my 552 go. He'll even a 551-LB isn't very bad at all.

I still want a 553 one day, just to keep my Sig collection rounded out and if you have a 553-LB just for the reference collection I can understand that. Honestly if it was up to me, I'd have two of everything, one in black and one in green.

[TheAlsatian]

I had a 551LB and a 551SB, as well as my current 553SB. I can tell you the 553s are way handier than any 551, at least to me. As far as reliability, I suppose theoretically the longer gas system might be more "reliable." I've owned my 553 for almost 8 years and have never had any sort of reliablity issue, nor have I heard of others. The 552s did have some issues...hence the transition to the 553 system.

[Mongo]

I agree, the 553 LB seems to be an anachronism. The shorter gas system means you have a shorter dwell time and are yanking the cartridge out of the chamber at higher pressures. I wonder what the weight difference between a 553LB and a 551? I have enjoyed my 551 and have not had an issues with it as far as reliability.

[Bret]

The shorter gas system means you have a shorter dwell time and are yanking the cartridge out of the chamber at higher pressures.

All else being equal I agree, but every 55X gun that I own came extremely over gassed from the factory. Use a gas plug with smaller holes and you'll go a long way towards reducing excessive wear. I run my 552SB with my 553LB gas plug and it's still sort of over gassed.

[SteyrAUG]

I had a 551LB and a 551SB, as well as my current 553SB. I can tell you the 553s are way handier than any 551, at least to me. As far as reliability, I suppose theoretically the longer gas system might be more "reliable." I've owned my 553 for almost 8 years and have never had any sort of reliablity issue, nor have I heard of others. The 552s did have some issues...hence the transition to the 553 system.

That's sort of what I was wondering. But as well made as the rifles are, we might never notice.

[SteyrAUG]

All else being equal I agree, but every 55X gun that I own came extremely over gassed from the factory. Use a gas plug with smaller holes and you'll go a long way towards reducing excessive wear. I run my 552SB with my 553LB gas plug and it's still sort of over gassed.

I wonder if there is a difference between the gas ports on the Pre 86 dealer sample SBRs I have and the ones that were imported as handguns.

[Bret]

Here's the current chart. You could measure if you have a pin gauge set. The JDI imported pistol valves that I've measured have been spot on to what's in the chart.



BTW, the original batch of 551LB that JDI imported came with 551SB gas valves. I informed Dave of this and to his and Swiss Arms credit, they sent out the correct ones.