Upgrading an older Marauder to work like the Field and Target gun

still working on the tune. Tried 1800 PSI and 2000 PSI on the regulator. Goal is 830fps with JSB 18 grain pellets. However, the 2000 PSI wastes much more air, with shot count dropping from 50 to 35. will return to 1800 psi and recheck. Looks like the sweet spot will be a touch over 1800 psi, 

I think I'll bite the bullet and pick up the Hill 20 gram hammer. It looks like the precision of hit requires a lighter hammer, and matched spring.

It's been interesting. My Impact is ready to shoot, but lately, I've been tinkering with the Marauder so much that the Impact just sits. I'll get back to it, but for now, tinkering and learning about the relationship between air pressure behind the valve, regulators, transfer port sizes, and more. It's all a balancing act that takes time to get working. I don't think there's a single right way, just a million ways to balance it all to get something close to what you want.

I think I've finally hit the sweet spot. Here's the setup.

Regulator set at about 2000 PSI, Hill HF Transfer Port, Hill Valve Spring, Hill 262 hammer spring, Hill 20 Gram Hammer with Hill striker. Transfer Port set at 5 or 6 for full flow.

With this setup, and the Hammer Spring adjustment at Zero, the Crosman 14.3 Dome's hit 840 to 850. With about 1/8 turn, the JSB 15.89's run right at 830 fps. With hammer spring at 1 rotation, the JSB 18.13 grain hit about 830.

Went to the range today on my lunch hour. Windy, gusting up to 30 mph, but the range is fairly well protected with berms. Still, I could tell when the wind gusted. Airport was under high wind aviation warning, and it's only a couple miles away. Not best for shooting groups. Here are a few 50 yard groups with the JSB 18.13's:

First group, 9 shots through one hole with one outlier. I think the wind died, so far pretty good. With the flier, about 9/10 of an inch. Without the flier, a touch under 1/2 inch.



This group wasn't quite as good but the next best for the day:



I think it 6 in the left hole and 4 in the right hole. Wind was very bad and inconsistent. And to be honest, I may have pulled a couple of them.

All in all, very happy with this setup!

Oh, best part, gun is quieter than ever before and a touch over 60 shots per fill.

Mr. Holland, I thank you for the help and support through this. Your advice was spot on!

I may be posting more groups later, but that's after the wind and rain dies down a bit.

Oh, and I have a correction. The last two groups of the day were 5 shot groups, not 10 shot groups. The first group with 1/2 inch is only 4 shots. Still, I'll take it!

Good luck in the next tourney, shoot straight!

Oh, and another question. What did you drill your transfer port out to?

maybe after shooting for a while, I'll drill out a port, but for now, I'll just shoot!

many thanks