Tuning Umarex hammer tunes or mods

Mine is on the way back from Umarex now, only mod on power I might want to make is reduce hammer spring to get a 4th shot on the regulator. And this will depend on the power I get with the ammo I want to use.

IMG_20220226_205710.1646276616.jpg
 

Looking for about 600fpe from a 320 to 375 grain bullet, no desire to fling the massive 550 grain stuff. Even the 450 grain stuff I cast is a little big, it just empties the lead pot fast. I have 4 different styles of mold to try, and two of those were only ordered last night so like 6 weeks out. Shown above is 320gr Lee REAL, 450gr Lee 50-70, and Umarex SLA 550gr. All sized to 0.510 inch. I'll probably tumble lube the Umarex rounds, only got those because I had nothing else to cast yet.

Otherwise the only other thing I'm going to do is add a muzzle brake, I'm machining the muzzle brake now using a DonnyFL m18x1 adapter made for the Hammer.
 
I should update the above post. I got the second one in and promptly sent it back. They called last week and said nothing was wrong, and that their gunsmiths had over 20 years each and travelled the world, so the problem I have on video with my borescope couldn't exist so I must be stupid to have seen it. The conversation finally got back to sending it back to the shop to have another look. Yes I am very insulted, this is not a good way to keep a customer.



In general I have a feeling that all these barrels are really rough inside and if I get one that is actually reamed on center, I should just be happy and try to polish it so that I don't shave off lead on the rough parts.
 
I guess I did get lucky mine shoots good. I would also like to detune it to get a 4th shot
thats great !! i hunted with mine all last deer season and it done very well for me.
still holding the 200bar fill as i left it with a couple months ago.
about to get it out and give her the once over before november opener.
i have noticed the pressure gauge looks like it needs to be replaced soon from
exterior conditions, thats my next project. i really like my Hammer 👨‍🌾
 
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Hammerspring has no adjustment. It just fires the pilot valve. It will not do anything to the tune. It's not a standard knock open valve. To adjust power you have to actually modify the barrel seal and/or adjust the regulator. The gun uses a QEV valve design with a port in the barrel seal to reseat the seal after the shot.
 
Mine is on the way back from Umarex now, only mod on power I might want to make is reduce hammer spring to get a 4th shot on the regulator. And this will depend on the power I get with the ammo I want to use.

View attachment 192353

Looking for about 600fpe from a 320 to 375 grain bullet, no desire to fling the massive 550 grain stuff. Even the 450 grain stuff I cast is a little big, it just empties the lead pot fast. I have 4 different styles of mold to try, and two of those were only ordered last night so like 6 weeks out. Shown above is 320gr Lee REAL, 450gr Lee 50-70, and Umarex SLA 550gr. All sized to 0.510 inch. I'll probably tumble lube the Umarex rounds, only got those because I had nothing else to cast yet.

Otherwise the only other thing I'm going to do is add a muzzle brake, I'm machining the muzzle brake now using a DonnyFL m18x1 adapter made for the Hammer.
What is the green stuff on the slugs?
 
In the back of the stock is a place that looks like it could be a hammer spring adjustment, might be able to back that off a little. Haven't tried it yet, haven't been able to get out and shot in weeks.
How do you like your hammer overall? I really am thinking of getting one. A hammer or a Texan but I am leaning towards the hammer right now. I held both at a local shop recently and liked the feel of the hammer a little more but I like the overall quality and tunability/customizability of the texan more. hard choices.
 
thats great !! i hunted with mine all last deer season and it done very well for me.
still holding the 200bar fill as i left it with a couple months ago.
about to get it out and give her the once over before november opener.
i have noticed the pressure gauge looks like it needs to be replaced soon from
exterior conditions, thats my next project. i really like my Hammer 👨‍🌾