Author Topic: Grinding on the sear of a 397 (Read 9910 times))

dwk54rak · « **on:** October 16, 2012, 01:53:19 PM »

Got the 397 I purchased from a member. Nice wood grain. Fired two shots and took it apart to work on the trigger. Found this informative procedure for grinding the sear. I'll probably grind to much, make the gun unsafe, order new sear, start again.
www.airgunsmith.com/392/triggertune.htm
Darrell

Powder burner · « **Reply #1 on:** October 16, 2012, 03:48:27 PM »

i can't get the link to work.

D14Jeff · « **Reply #2 on:** October 16, 2012, 04:41:08 PM »

http://www.airgunsmith.com/392/triggertune.htm

this is another option for changing the trigger .

aack73 · « **Reply #3 on:** October 16, 2012, 05:44:48 PM »

i ground down one for a newer .20 with great results. no creep breaks like a fire arm. very crisp. maybe i just got lucky. but for the cost of the parts i would be willing to try it several times as opposed to having a bad trigger.

if you get it too light or unsafe throw it away and start over

. just test it diligently.

EBSW0820-e · « **Reply #4 on:** October 16, 2012, 07:21:34 PM »

Short of that, you can polish the contact points and forcibly lighten the mainspring. I did. The difference is huge.

dwk54rak · « **Reply #5 on:** October 17, 2012, 01:54:00 PM »

I got it down to about 4lbs. using the airgunsmith method. Adding the wire to the trigger and sear looks interesting also. I just tested the link I posted yesterday and it popped right over there.
Darrell

aack73 · « **Reply #6 on:** October 17, 2012, 04:40:50 PM »

the link didnt work for me either. got this message: Forbidden

You don't have permission to access /392/triggertune.htm on this server.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
Apache Server at www.airgunsmith.com Port 80

dwk54rak · « **Reply #7 on:** October 18, 2012, 12:35:39 PM »

For those of you having trouble with link I posted. I am using google chrome browser and an apple computer (can't imagine the brand of computer being an issue. I started on my query buy typing into the browser " Benjamin 397 trigger"
Darrell

aack73 · « **Reply #8 on:** October 18, 2012, 09:29:56 PM »

maybe its my firefox or my pc. i have seen that before, but it might benefit others.

TimmyMac1 · « **Reply #9 on:** October 19, 2012, 10:24:47 AM »

Changing the angle of the sear is easy to get it to stop moving the hammer aft during trigger pull. The parts most pepole miss is the dressing of the hammer edge with a stone and the Kasenite rehardening of the sear surface following the grinding and stoning of the sear engagement area.
If you do not reharden the sear the glass hard Hammer digs a trench in the sear and the trigger gets worse and worse as the trench deepens. This is what we see ion the work people do to the Ben-jamin and SheriDan sears most of the time.
That wire assist looks like the governor overide on my minibike motor. Very west virgini (VWV)

BE SAFE GUYS!

BALLISTIC1 · « **Reply #10 on:** October 19, 2012, 11:27:10 AM »

Personally I believe I prefer a single stage trigger... Although I haven't done it yet I really like the idea of the link... I thought it was a good idea and wondered about making it adjustable or use several holes so you could tune the ratio... There is a lot more involved in the modern trigger than the simple stamped sheet metal triggers of yesteryear.. I think the new box trigger units are a lot safer and can be reduced to satisfactory pull weight and trigger action with a little work... I hate the safety interlock that is intended to keep the rifle from firing with the bolt open because it keeps me from being able to de-cock if I choose.... Greg

dwk54rak · « **Reply #11 on:** October 19, 2012, 01:48:05 PM »

I have now done both mods to my trigger. Adding the wire actually hurt what I had accomplished by just grinding. I'm retired, I have plenty of time to play. We'll keep working on it.
Darrell

ebarnes419 · « **Reply #12 on:** October 19, 2012, 11:46:26 PM »

Does CharlieDa Tuna offer a trigger for the 392/397?

TimmyMac1 · « **Reply #13 on:** October 20, 2012, 10:49:23 AM »

Quote from: ebarnes419 on October 19, 2012, 11:46:26 PM

Does CharlieDa Tuna offer a trigger for the 392/397?

I don't think so. I reprofile the sear all the time as it is part of the porocesses I do in the Steroid Tune. TimmyMac1 DaTuna
CDT stuff is springer related
The key issue with the Benjamin Sheridan triggers is the sear contact surface angle. You can observe the hammer moving aft as you pull the trigger and that is what makes the trigger so heavy. Once the proper angle is achieved the trigger is quite good without doing anything to the springs. It is a drop in mod with no grinding required.

It is easy to have your hammer dressed and the sear recut and rehardened to Steroid specs. Both parts need to be sent in so I can make sure the ragged edge of the factory hammer is stoned so it is compatible with the recut sear and works best.
For the Hobbiest the most important thing to realize is the glass hard Hammer will dig into any sear that has not been properly hardened and the trigger job you do today will get worse and worse till the hammer has ruined the sear. Kasenite is required to get a hard surface coat that is durable and will not degrade.
Be Safe

yoshi800 · « **Reply #14 on:** October 20, 2012, 12:48:24 PM »

Do they still sell Kasenite? The sites I've checked say its a discontinued product.

TimmyMac1 · « **Reply #15 on:** October 21, 2012, 10:55:13 AM »

No Can get Kasenit Brand anymore but there are other products that will give good surface hardening results with a little practice.

http://www.midwayusa.com/product/119479/cherry-red-surface-hardening-compound-1-lb

3204K5 is the McMaster Number for a 1 lb can of Quench type surface hardening compound. They no longer list Kasenit and I guess it has gone the way of Sperm Whale Oil and half the stuff I used 30 years ago. Suitable repalcements exist is the point.

Whenever you grind file or polish more than a few thou you have compromised the surface hardness and the smart thing to do is reharden it. A normalized material isn't adequate for a sear engaement surface against a glass hard hammers sharp edge. I always recomend dressing the sharp edge with a stone and surface hardening the sear so it lasts. Otherwise the great trigger job you do will degrade rather quickly and you will need to do it again correctly anyway. May as well get it right in the first place.

chuck_steak · « **Reply #16 on:** October 21, 2012, 10:01:02 PM »

Quote from: aack73 on October 17, 2012, 04:40:50 PM

the link didnt work for me either. got this message: Forbidden
You don't have permission to access /392/triggertune.htm on this server.

Try going to the website, and then clicking on the link on the right of the page..
I'm not allowed to post the link, but just do the airgunsmith(dot)com
and look to the top right..........

Dan

Mr.Bojangles · « **Reply #17 on:** February 03, 2014, 12:11:46 AM »

Quote from: TimmyMac1 on October 21, 2012, 10:55:13 AM

No Can get Kasenit Brand anymore but there are other products that will give good surface hardening results with a little practice.

http://www.midwayusa.com/product/119479/cherry-red-surface-hardening-compound-1-lb

3204K5 is the McMaster Number for a 1 lb can of Quench type surface hardening compound. They no longer list Kasenit and I guess it has gone the way of Sperm Whale Oil and half the stuff I used 30 years ago. Suitable repalcements exist is the point.

Whenever you grind file or polish more than a few thou you have compromised the surface hardness and the smart thing to do is reharden it. A normalized material isn't adequate for a sear engaement surface against a glass hard hammers sharp edge. I always recomend dressing the sharp edge with a stone and surface hardening the sear so it lasts. Otherwise the great trigger job you do will degrade rather quickly and you will need to do it again correctly anyway. May as well get it right in the first place.

Had to dig this up. Has anyone tried a standard carbon steel hardening and tempering process? Does anyone know if they have any carbon in em? You can usually tell by the sparks they produce. Gonna be doing mine, and would rather do a simple method I'm familiar with.

Mr.Bojangles · « **Reply #18 on:** February 05, 2014, 01:31:48 AM »

Well did mine yesterday. Nothing to crazy, just some sandpaper on a file to smooth it up and change the angle a bit. I didn't harden the sear at all. I guess ill see if it starts galling. If so, ill pull it out, build it up with some weld, and grind it back. Pry use hard facing. I also put a pre travel adjustment screw behind the upper part of the trigger, below where it protrudes into the receiver. Took a lil tinkering, and a lot of disassembly/ reassembly of the trigger unit, but for as little as i really did, its got a nice, crisp 4lb or so break, and no creepy take-up.

On a separate note, WTH do they build these things out of?!? Pot metal and some kind of brass apparently. Its not regular brass either. A few years ago, i carelessly leaned my rifle against a counter, and it got nocked over, breaking off the front sight blade. A couple months ago, i attempted to build it back up. Long story short, i couldn't get it molten, and even though i was using a heat absorbing gel, i was afraid i was gonna melt the silver solder out from between the barrel and tube. I was able to get some brass globbed on there good enough to file back to an original looking blade, i don't think it would take much to snap it off again.

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Grinding on the sear of a 397

Author Topic: Grinding on the sear of a 397 (Read 9910 times))

EBSW0820-e

ebarnes419