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View Full Version : HK rear sight base TIG weld or braze?



webbed feet
04-30-2009, 05:55 PM
Hello folks. I just joined this forum in anticipation of receiving a CAI CETME newly purchased from JGSales.

I have read that swapping out the rear paddle sight for the HK drum sight requires TIG welding, but wanted to know if it is possible just to silver solder (lower temp) or silver braze (higher temp) the sight base onto the receiver. It seems that the CAI receivers are heat treated and I've read that brazing heat treated metal is a bad idea, but I have had more than one gunsmith tell me that brazing should be fine. So, should I have the sight base welded, brazed, or soldered?

Also, does anyone know where I can purchase a CETME front sight adjustment tool? I've been looking online, but the TAPCO tool seems to have been discontinued. I have run across this - http://www.sandygunworks.com/articles/a002.htm - but do not know how well it is made.

I would appreciate hearing your thoughts.

drine
04-30-2009, 06:16 PM
Welcome to the site first off.

The front sight tool may be found at SARCO. Check gunbroker too if all else fails. They can be made too, just remember to loosen the screw on front of the tripple frame first.

You may want to keep the CETME sight after you look at it. I don't bother with the V-notch but have zeroed using the 200m peep. I don't know if anyone here has removed a CETME rear in favor of a HK sight. It's easy to do with a new receiver but getting the sight off with harming the thin receiver will need to be done with extra care.

My machinist use silver solder to make tooling to mill metal with so it may be OK. Good looking welds would leave no question though.

bladeworks123
04-30-2009, 06:24 PM
First and foremost, Welcome Aboard:thumbup:
I thought about soldering mine on, but didn't feel like I had a good or tight enough fit between the sight base and the top of the receiver to accomodate a good joint. I wouldn't braze as the brazing would not parkerize correctly. I suppose you could simply paint the receiver to overcome that issue. I opted to tig weld the ones I have done, and smooth the welds. to blend them into the lines of the receiver. (I am a clean lines freak.) I think it is simpler and a better joint. As far as the heat issue is concerned, If tig welded, a heat sink or thermal gel used in conjunction with the welding process would pretty much isolate the heat to the immediate area being welded. The fornt sight tool looks OK to me, but you probably won't know for sure until you see one in the flesh,,,I never have seen this one.

webbed feet
05-01-2009, 10:12 AM
Thanks to you both for the welcome. I appreciate your taking the time to answer my post.

Drine – I will call Sarco. I have read differing accounts of how effectively the front sight post can be adjusted. Many folks say that the adjustments made with the front post can be nearly as precise as the HK91, but others say that having the ability to adjust windage with the rear sight is invaluable. I have not seen my rifle and you might be right; I just might decide to keep the rear paddle sight as is. However, with a new in white HK sight base, drum sight, and other necessary parts being about $35, I thought I should buy one, and if not needed, just put it away for future use (I have read accounts of at least a couple of CETME owners who have had the paddle sight fall off their rifles).

Bladeworks123 – you are an artist. I saw the work you’ve done here: http://militaryfirearm.com/Forum/showthread.php?t=12005. Based on the photos in that thread, I can see why you decided to TIG instead of solder.

One of the gunsmiths I’ve talked to says that he can TIG weld the sight base onto the receiver for $100. This seems a little high. Many gunsmiths do not weld. I have also gotten estimates from journeyman welders who say they can weld the base for $20, but I am concerned that they will (1) do a sloppy job or (2) destroy the sight base, receiver, or both. I will ask to see samples of any welder’s work before letting them work on my rifle, but based on my conversations with some so far, I am not confident that the results will be good. Most of these guys seem to have a background in auto body work.

Do you think I am on the right track in talking to these welders? Should I stick to finding a gunsmith who will weld for a reasonable fee? Or should I look outside of the gun world and try to find a welder who does other types of fine metal work – e.g. custom bicycle fabrication?

rustypirate
05-01-2009, 10:44 AM
You can go to an outside fabricator, so long as you do not turn over the parts to their possession without you being present. i.e. overnight.

A lot of fabricators such as folks who make custom exhaust systems are used to welding on thin material like the sheet metal used in the receiver and should be able to perform the welds with ease.

drine
05-01-2009, 10:44 AM
If you are are going to do it, use a good welder. Unless the gunsmith is a closet builder who is a whiz with a welder, I'd feel better with a someone who does welding for living doing the work. Just let the person doing it know how critical it is to have it perfectly straight and aligned with the front. Make sure your CETME front sight isn't canted as soon as you get it. Look down the full length of rifle to check it.
I had an HK91 years ago. Loved the diopter sight but the cetme peep sight picture is about the same. Sighting the CETME requires the elevation to be set first then little tweaks left or right to center the group. I can see where the G3 sight would be easier and maybe a little more exact but as long as your front sight is straight to start, it shouldn't be an issue. It will be a blast either way.
Of course we are all getting the cart in front of the horse. You need to check the gap, cocking tube stop clearance, etc..before shooting it to see that Century didn't do something wrong. These latest CETMEs they are sending out seem to better built all the way around so we'll keep our fingers crossed.

bladeworks123
05-01-2009, 10:29 PM
Most experienced body shop guys understand welding thin pieces and keeping the heat controlled so as to not cause warping. And, you are on the right track... just tell the guy that you want a clean, straight cosmetic weld that looks like it belongs there. Yeah $100.00 is a little steep...... IMO. Get the rifle and shoot it a little before you make up your mind. There is absolutely nothing wrong with the Cetme sights as far as function, if they were put on correctly...And to be honest, I think I personally get a better sight picture looking against the flat blade on a Cetme sight as opposed to the HK drum....It's just a matter of personal preference.

webbed feet
05-04-2009, 11:02 AM
Thanks again for the advice.

I ordered the CETME front sight tool from APEX gunparts. I called Sarco, but they had a $20 minimum on orders. I also just bought a feeler gauge set to see what the bolt gap is when I receive the rifle. Last I heard, the rifle should be shipping in a couple days so I should get it late this week or early next week.

When it comes in I will be sure to break it down and clean it before I take it out to the range for the first time. Of course, I will be sure to post pics.