Help with front sight dovetail mount

[Kaitum]

Looking for some tech support. I ordered a Lyman hooded front sight and a front mount to replace the factory post sight. The mount and sight have a 3/8" dovetail. The dovetail on the sight slides all the way through the mount. It does not wedge tight and there is no set screw. Tech support at Brownells said it should fit tight. He suggested I 'peen' over the dovetail edge on the mount for a tighter fit, then set with red Loctite.

Any other suggested options for mounting this sight? Follow Brownells tech advice or just return part?

 

[Indianajoe]

If the old sight was tight do not peen it. Send it back. Dovetails can be tricky to machine and very easy to get out of spec making them to loose or to tight.

 

[p_ham]

You can get a cheap set of feeler gauges and make a shim to put in the bottom of the dovetail. If you're not comfortable doing that, send it back for a replacement. As Indiana Joe said, they're easy to cut wrong.

Were both parts made by Lyman?

 

[OntarioHunter]

I agree with previous two posters. Don't try to make do with something that is made wrong. Send both parts back to Brownells and tell them to check the replacements before sending them off.

Most shims or feeler gauges are made of aluminum. Wedge that between two pieces of steel and there will be corrosion from electrolysis. Eventually the sight would probably come loose.

I'm thinking peening part of the base might also be a dicey solution. The sight and base will be subjected to heat and cold extremes when hunting. Expansion and contraction could result in the small section peened loosening. Unequal expansion/contraction would also be an issue with aluminum shims (plastic shim might be better). I wouldn't trust it. Frankly, I can't imagine Brownells advising a customer to beat on a gunsight. Wow! If you whack on it and can't get it right, they're not going to take it back. Are you getting the picture?

 

[p_ham]

Most shims or feeler gauges are made of aluminum. Wedge that between two pieces of steel and there will be corrosion from electrolysis.

Almost all feeler gauges are high carbon steel or stainless, the ones that aren't are brass.
You can get shim stock in carbon steel, stainless, copper, PVC, aluminum, titanium etc...

 

[OntarioHunter]

Another issue to consider with shim suggestion is how to remove excess shim without marking the sight or its base. Yes, it can be done but might be tricky.

 

[Elevationwerks]

Looks like the mount is off the barrel. It also looks like the mount sets to the barrel with a screw at the base of the dovetail. Have you done this with the mount attached to the barrel? May flex enough to tighten the dovetail if not.

 

[44hunter45]

I can't tell from your picture. Does the base have a screw inside the dovetail, or is it designed to be silver soldered?
If there is a screw inside the dovetail, you need to fit the base to the barrel and try the sight fit again. It is possible that pulling the base tight against the barrel with tighten up the dovetail.
You could c-clamp the base to the barrel (with the appropriate padding to prevent scratching any finish) to see if that pulls the base flatter as well.

 

[OntarioHunter]

I can't tell from your picture. Does the base have a screw inside the dovetail, or is it designed to be silver soldered?
If there is a screw inside the dovetail, you need to fit the base to the barrel and try the sight fit again. It is possible that pulling the base tight against the barrel with tighten up the dovetail.
You could c-clamp the base to the barrel (with the appropriate padding to prevent scratching any finish) to see if that pulls the base flatter as well.

Good suggestion!

 

[Kaitum]

I can't tell from your picture. Does the base have a screw inside the dovetail, or is it designed to be silver soldered?
If there is a screw inside the dovetail, you need to fit the base to the barrel and try the sight fit again. It is possible that pulling the base tight against the barrel with tighten up the dovetail.
You could c-clamp the base to the barrel (with the appropriate padding to prevent scratching any finish) to see if that pulls the base flatter as well.

The screw is inside the dovetail. I put the mount in the barrel. Maybe it tightened up the dovetail very slightly but not enough to hold the sight snug. The mount is made by Marble Arms, the sight is made by Lyman.

 

[Kaitum]

You can get a cheap set of feeler gauges and make a shim to put in the bottom of the dovetail. If you're not comfortable doing that, send it back for a replacement. As Indiana Joe said, they're easy to cut wrong.

Were both parts made by Lyman?

Hadn't considered tbe feeler gauge route, I do have a set. Sight is made by Lyman, mount is made by Marble Arms.

 

[Seamaster]

Peening the base is the common solution and it is what most gunsmiths would do. I would not use Loctite

 

[OntarioHunter]

Peening the base is the common solution and it is what most gunsmiths would do. I would not use Loctite

Good to know. Sometimes the barrel is dovetailed so there must be a common remedy for sights that don't fit tight. Can't send the barrel back. Obviously not every shaping tool will be set up exactly the same to cut precisely the same notch every time.

 

[HandgunHunter]

Well it appears your base is also removable. I’d buy a new base of the same height. Brownells sells those too.