xtra hammer travel mod (marauder)- "CHEAP"

[shorty]

There's some of us that may want some extra travel on the hammer for higher FPS/FPE. Here's one mod you may want to do. Head to your favorite hardware store and pick up a 3/8" concrete drill bit. AND drill that hardened hammer like it was swiss cheese. Don't go too much, you may not end up with enough threads. I only went far enough "slightly" and counter sink the HT.

Nice little trick with the concrete bit. Your regular bits won't touch the hardened hammer ( don't even try it ).

I did it on the lathe but I am positive a hand drill will do it.

[JPowell490]

A lathe is one thing, a hand drill is another.  I wouldn't use a hand drill.  You need that to be straight, perfectly straight.  I doubt it would be with a hand drill. 

[shorty]

It's a little taper on the hole and not like a bottom out flat end mill. It would work. Have fun with 5 to 8 turns negative. Well worth the 4 dollars to drill through hardened steel.

Expect a minimum of 8 to 15 fpe increase. Maybe more. I won't be able to tell you because I made lead inserts for the hammer and JB welded them in. Takes 24 hrs to cure before cleaning it up and testing.

Love the comments. It's like that little kid telling you to try something. Try it. You'll like it. It works.....

[Motorhead]

Indeed greater stroke can pay dividends if needing more dwell.
Had been doing this as well in the LW reg conversion hammers i was making for a couple years.
@ .080" counter bore flushes up the striker.

[shorty]

Right on motorhead.

The Mod/trick, is to use a concrete bit to drill the hardened hammer as you probably know already ( sorry- this ain't your normal handbook of drilling holes in hardened steel.). The seasoned guys really do know their stuff, even if it's not airgun stuff.

I tell ya, Those 70's and 80's engineers really did a great job with what they had. Us new guys (younger generation) have alot to learn.

[PakProtector]

You can also use a set screw and sink its head 'till you run out of threads. Grind the set screw flat so you're not attacking the valve stem with a cup-point set screw feature.

The end ov the valve can also be shortened by 0.1" and the stem by a good .125 for even more travel. At this, it may be best to go and get a 2.75" spring.
cheers,
Douglas

[shorty]

Pak I am so glad you chimed in. I was running the set screw mod (got me almost 40fps-50fps with the .357/9mm conversion). Just thought it could be better using the original parts. But is was your idea and a great one at that.

As for the stem and valve, Your right, there's more there. I just hate to de-gass.

If I do de-gass, I am going the full monty and extending the poppet seat to allow for a larger TP. I ain't there yet.

No turning back from well over 100fpe. Rstrene is asking for double of what I have before I can join the big bore club.

[Buschmaster]

sorry but i dont understand how you get more travel becaus the sides of the hammer are just the same  height as the Original height ? (still black) al least in youre picture.

Or did you grind the outer sides later ?

[Rocker1]

sorry but i dont understand how you get more travel becaus the sides of the hammer are just the same  height as the Original height ? (still black) al least in youre picture.

Or did you grind the outer sides later ?

   The sides of the hammer do not hit the valve, only the pintle in the center of the hammer hits the valve stem, recessing it gives it a small bit more hammer speed therefore a few more fps.  that pintle in the center of the hammer is adjustable.  David

[Buschmaster]

Ah i think i understand !

Because you can turn in the pintle more if you drill out the center ? and because of that the hammer has a little more trow ?

[PakProtector]

I am going to take a breech, tube and trigger to the mill soon( and probably the stock ). I plan to slide the trigger group backwards by ~1/8". All the stuff back of the hammer needs to move a bit; slot for the sear to clear, clearance for the cocking screw on the hammer and bolt. Fortunately the stock mounts to the trigger so I doubt I will have to remove any wood...LOL
cheers,
Douglas

[Buschmaster]

wonderfull ! im curieus to see how you idea works out !! i want to get my 51 grain boat tails flying at 935-950 fps.

What about drilling into the center of the pintle of 2 or 3mm deep also ?

[PakProtector]

wonderfull ! im curieus to see how you idea works out !! i want to get my 51 grain boat tails flying at 935-950 fps.

What about drilling into the center of the pintle of 2 or 3mm deep also ?

Use a flat-ground set screw... set the depth where you want it. Lock it up with a set screw.

The additional hammer energy is needed when a big enough valve is used. If throat diameter is less than .280 it should not be needed. This trouble getting more travel where the spring force is weakest is of limited use I have to say. Up the spring, then worry about travel. Don't forget to consider the stress on the sear...
cheers,
Douglas

[Buschmaster]

i have a war high energy valve ,i dont know if that has a .280 throat ? (dont know what a throat is eather in this sentence but ok)

but the 2 set screws have to be flat ground but how do you get the last one out when adjusting ?


I have a 17 lb war hammerspring on max preload when i get the 51 grain boat tails only to 820 fps or do you mean the valve spring ?

Edit; just opened my marauder took the hammer out the war nbh already is adjustable beyond the point of touching the valvestem so i have to search for other ways to get the 51 grains up to speed.

If someone makes thinner TP,s then the WAR tube and i can drill the war valve hole a bit more open to blow some more please let me know !

Btw the 17lb spring is not hard to cock now so maybe a heavyer spring is an option ?

[Buschmaster]

In this link reply number 38 Travis gets the eunjin 43.2s to decent speeds if someone know how he did that then please let me know !; http://www.gatewaytoairguns.org/GTA/index.php?topic=76875.20