Help decide how to upgrade this old FSB Sabre Defence upper

[markm]

I think I remember you posting about that before. Did you ever check what the actual twist rate is?

I've never been able to do that Jag thing to check twist rate. That would actually be a good way to see if the barrel had any tight spots too.

[georgeib]

I have a 24" heavy fluted SS Sabre Defense 1:8" that also would spin apart bullets of 50gr and less. Fiocchi Extrema 40gr V-Max you would see the lead powder.

Makes me wonder what the actual twist rate is. Have you ever checked it to verify? I'd be surprised if it wasn't faster than 1:8.

I've never been able to do that Jag thing to check twist rate. That would actually be a good way to see if the barrel had any tight spots too.

Do it. I'm curious.

[SuperOmega]

I used a rotating cleaning rod a piece of tape (like depth flag for drill bit) and measured approx 7.7" per rotation.

[maximus83]

Good ideas in the thread for shedding some weight.

After seeing some of the comments and running some numbers after changing to certain rails, swapping rear sight, etc, it's probably going to be difficult to significantly lighten up this upper; it's an uphill battle with that beefy barrel. Changing rail and maybe rear sight would shed a few ounces but not a lot. Now I'm toying with the idea of keeping it as-is, shoot it until accuracy degrades. And instead of investing approx $300 to upgrade a rail on an old upper that's probably 2/3 thru its useful barrel life, I'll put the $$$ into a new Centurion upper with a lighter barrel and the rail that I want.

[Disciple]

Is the barrel a "government profile" or something else?

Do you use a hammer grip on the VFG? If you grip with part of your hand on the rail and part on the VFG don't you need some rail in front of it?

[georgeib]

I used a rotating cleaning rod a piece of tape (like depth flag for drill bit) and measured approx 7.7" per rotation.

I'm not surprised about the 40 grain stuff coming apart, but I am about the 50 grain.

Good ideas in the thread for shedding some weight.

After seeing some of the comments and running some numbers after changing to certain rails, swapping rear sight, etc, it's probably going to be difficult to significantly lighten up this upper; it's an uphill battle with that beefy barrel. Changing rail and maybe rear sight would shed a few ounces but not a lot. Now I'm toying with the idea of keeping it as-is, shoot it until accuracy degrades. And instead of investing approx $300 to upgrade a rail on an old upper that's probably 2/3 thru its useful barrel life, I'll put the $$$ into a new Centurion upper with a lighter barrel and the rail that I want.

Probably the way to go. I will tell you though that those Sabre barrels have a lot of life in them, if reputation and my sample of one is any indication. You might consider getting the upper you want before things get weirder coming up to the election and just save your Sabre upper as a spare. 2 is 1 and 1 is none, and all that.

[SuperOmega]

They do! My 16" carbine gas has around 12k rounds and chuggin.

[Hammer_Man]

That setup looks like a battle tank as is. Looks like it could take a beating and keep chugging along without issue.

[maximus83]

^Yeah it *is* kind of a tank, super tough, super reliable. But it kind of weighs like a tank too.

One related question about rail strength, since I considered moving away from the shorter quad to a longer Mlok (and also looking at the same type of rail change on an older SS410 BCM upper I have):

* Assuming a quality brand/model rail is used, does there tend to be a noticeable difference in precision/accuracy when you change out from a quad rail to an Mlok? I've read about issues like "deflection", and some argue that a quality-made quad rail is inherently stronger than an Mlok thus better for accuracy. I've not seen this firsthand on any rifles I've shot, but have heard it discussed often enough that you wonder if it's a real issue.

[Hammer_Man]

^Yeah it *is* kind of a tank, super tough, super reliable. But it kind of weighs like a tank too.

One related question about rail strength, since I considered moving away from the shorter quad to a longer Mlok (and also looking at the same type of rail change on an older SS410 BCM upper I have):

* Assuming a quality brand/model rail is used, does there tend to be a noticeable difference in precision/accuracy when you change out from a quad rail to an Mlok? I've read about issues like "deflection", and some argue that a quality-made quad rail is inherently stronger than an Mlok thus better for accuracy. I've not seen this firsthand on any rifles I've shot, but have heard it discussed often enough that you wonder if it's a real issue.

Are you referring to the urban legend that says slim hand guards flex, therefore allowing the zero of your designator (PEQ-15, Dbal) to shift? Or are you referring to your weapon’s zero/POI shift?