Aluminum vs. Steel Picatinny Rails

[Goss]

Greetings,
I'll be adding a Picatinny Rail Mount on a rifle but I do have a question. Most Picatinny Rail Mounts come in one version or another of aluminum. It just seems like the difference between thermal expansion between aluminum and steel makes an aluminum Picatinny Rail less accurate than a steel one. It's no big deal to machine one up, but the aluminum rails are quick and cheep.

Your thoughts please,
Goss

 

[brentc]

Greetings,
I'll be adding a Picatinny Rail Mount on a rifle but I do have a question. Most Picatinny Rail Mounts come in one version or another of aluminum. It just seems like the difference between thermal expansion between aluminum and steel makes an aluminum Picatinny Rail less accurate than a steel one. It's no big deal to machine one up, but the aluminum rails are quick and cheep.

Your thoughts please,
Goss

Aluminum rails work fine. I prefer 7000 series material over 6000. Seekins rails are aluminum and they are of reputable quality. Another one I've used that works well is the Talley rails. When talking about expansion rates, there is always a steel to aluminum transition it's your choice where it's at. Even if you're using a steel rail and rings you'll most likely attach it to an aluminum scope tube. I've used aluminum rails and rings with no problems if they are manufactured properly.

 

[bruce_ventura]

If weight is not an issue I recommend steel. As brentc said you have an aluminum/steel interface somewhere. The stress on the aluminum rings due to differential thermal expansion at the steel base is much less than the stress on an aluminum base on a steel receiver. The real benefit is that the steel rail holds up to recoil much better than an aluminum rail. If weight is an issue, just go with aluminum base. More than likely bigger compromises have already been made on the rifle to keep weight to a minimum.

 

[Outlaw6.0]

In preference, it's steel or steel for me. I just don't feel aluminum is the best option for a picatinny rail. If weight truly is a concern as in an ultra-light build, perhaps titanium would be a better option?


t

 

[Deleted member 46119]

Aluminum rails work fine. I prefer 7000 series material over 6000. Seekins rails are aluminum and they are of reputable quality. Another one I've used that works well is the Talley rails. When talking about expansion rates, there is always a steel to aluminum transition it's your choice where it's at. Even if you're using a steel rail and rings you'll most likely attach it to an aluminum scope tube. I've used aluminum rails and rings with no problems if they are manufactured properly.

What "brentc" said.

Steel is not available for all actions.
Bench rest rifles often have aluminum.
Heat is in the barrel, not the action.
Ambient temperature thermal expansion differences are

 

[Sully2]

Greetings,
I'll be adding a Picatinny Rail Mount on a rifle but I do have a question. Most Picatinny Rail Mounts come in one version or another of aluminum. It just seems like the difference between thermal expansion between aluminum and steel makes an aluminum Picatinny Rail less accurate than a steel one. It's no big deal to machine one up, but the aluminum rails are quick and cheep.

Your thoughts please,
Goss

The expansion rate between the two materials can be calculated by taking "point squat" and dividing by infinity! Its not going to amount to jack squat. Now...if you are in Africa...preferable the Sahara and leave your scoped rifle lieinf in the sunlight all day...then you got a problem. Otherwise even normal common sense wont allow you to do that.

Unless you intend on shooting 3-4 shots into exactly the same hole at 100 yards dont sweat the hypothetical....you arent going to break one and its not going to let you down.

 

[Brewer]

In preference, it's steel or steel for me. I just don't feel aluminum is the best option for a picatinny rail. If weight truly is a concern as in an ultra-light build, perhaps titanium would be a better option?


t

Aluminum moves about 3 times as much as Titanium per degree and about 2 time as much for steels. so Titanium is always a better choice than Al for weight. of course, if you can afford it, its best to get the same metal rings and rail for consistent expansion. just my $0.02

 

[Outlaw6.0]

Aluminum moves about 3 times as much as Titanium per degree and about 2 time as much for steels. so Titanium is always a better choice than Al for weight. of course, if you can afford it, its best to get the same metal rings and rail for consistent expansion. just my $0.02

Very interesting, thank you for that. I learned something today!



t

 

[Buttermilk]

The rule of thumb I use for myself:

Aluminum base = Aluminum rings

Steel base = Steel rings or Aluminum rings

Using steel rings on an aluminum base increases the risks of the rings damaging the base over time due to the recoil impulses.

I don't personally worry about thermal expansion rates of the two materials.

Regards,
Rog

 

[Timber338]

I have always used aluminum rails and aluminum rings. I understand thermal expansion and all that, but in the field I've never noticed my rifles to lose zero or shoot poorly in adverse temperatures. And I've shot my long range rifles in temps over 100 degrees, and was just out shooting a couple weeks ago and it was 1 degree. That is just my experience. I have never had any reason to consider steel.

 

[Brewer]

I am not sure the Coefficient of expansion is such a big deal that you needto be concerned with it. It's just one of those things that if you are reallyinto your sport, and you are shooting competitively and want every edge, youmight do it. Of course you may just be a nerd like me and do it because you area nerd and know what that is .

 

[sp6x6]

Ditto 338. And I have friends in bench 1000 shoot alium action soo.... in tiny holes.I like the NF ULTRA alum with tit. cross bar

 

[Sully2]

I am not sure the Coefficient of expansion is such a big deal that you needto be concerned with it. It's just one of those things that if you are reallyinto your sport, and you are shooting competitively and want every edge, youmight do it. Of course you may just be a nerd like me and do it because you area nerd and know what that is .

Its not any sort of deal at all. I had the wife sit here last night and do my calculations (I had a LG glass of chocolate milk to drink.... ) and a 5" AL rail from the temp of 32F to 150F ( figured that was about the limits upper and lower) of growth was .00015 and that the difference between steel of a receiver in the same temp extremes and the Al rail was .000046...soooo the growth difference dont amount to jack squat
(Wife is a metallurgical engineer)

 

[Brewer]

I am not sure the Coefficient of expansion is such a big deal that you needto be concerned with it. It's just one of those things that if you are reallyinto your sport, and you are shooting competitively and want every edge, youmight do it. Of course you may just be a nerd like me and do it because you area nerd and know what that is .

Its not any sort of deal at all. I had the wife sit here last night and do my calculations (I had a LG glass of chocolate milk to drink.... ) and a 5" AL rail from the temp of 32F to 150F ( figured that was about the limits upper and lower) of growth was .00015 and that the difference between steel of a receiver in the same temp extremes and the Al rail was .000046...soooo the growth difference dont amount to jack squat
(Wife is a metallurgical engineer)

yep, you are correct, though I think you have an extra zero in the Aluminum figure. so I guess it just comes down to being a nerd.