What is the best Marauder muzzle velocity for JSB10.3gr?

[Fred J]

I have a Marauder in .177 Cal. What is the best muzzle velocity for for JSB10.3gr pellets? This rifle is still out-shot by my AA TX200 and my Diana 34, and I would like to turn that around. The rifle is currently tuned to 850 fps, which gives me 45-50 good shots with an extreme spread of 17 fps.

I have replaced the barrel with a MAC1 reconditioned barrel (polished crown and leade) and removed the shroud baffles, which helped quite a bit. I polished the bore with JB Non-embedding pastes to smooth things out in the rifling and to extend the time between barrel cleaning. Other changes, such as removing the lawyer spring in the trigger and putting silicone grease on the shroud o-rings also helped. I also replaced the synthetic stock with a standard wood stock, which seems to fit my large hands better at the grip. I tried un-floating the barrel, but the best accuracy seems to come from a floated barrel configuration.

I have shot JSB 10.3gr, H&N 10.6gr, and JSB 13.4gr pellets through the rifle. The rifle seems to like the JSB 10.3gr the best. Some day I will try AA 10.3gr, but that is another day.

I know that I have posted several times regarding the accuracy of my Marauder, but I'm not ready to give up on this rifle. I am hoping that increasing the MV of the JSB 10.3gr pellets to 900 fps may help, but I am concern of pellet destabilization, and the barrel fouling even faster than it does now (about every 150 shots). I have tried MVs down to 825 fps, but that did not help.

Your advice is very much appreciated!

[DRAGON64]

I have read that the .177 exhibits best accuracy between 850 - 900 fps range using heavies.  Once my tank comes back from hydro, and my new LW barrel is fitted to my receiver, I hope to test this theory.

[Fred J]

In response to my own post: I was wondering if replacing the hammer with an aftermarket one would help the accuracy. I noticed that one offered by Hill Air claims that the extreme spread would be reduced. I'm sure there are other aftermarket hammers, as well. What has been your experience with these?

I am not interested in getting more power. Maximum power of 18-19 fpe is all I need. My quest is for good accuracy and shot string of 50 shots with an extreme spread of 2%.

 

[Frank in Fairfield]

Fred,

JSB makes pellets for AA.
As the dies wear out from making JSB pellets they make the AA.

RWS does the same thing with the new dies making R10, then Meisterkugeln, then Basics.

I use 10.34AA at 897fps.

I am 72 years old with all of the maladies of age including a few caused by Agent Orange during my Asian Vacation in 1968.

I can manage 3/8th of an inch at 50 yards all day long with the Marauder and 10.34s.

If my son shoots the rifle in a no wind condition it is 1/8th inch or less.

A light weight hammer will improve your shot cycle and I suppose that could improve your lock time which could improve accuracy.

Fred, I suspect with your vast experience with your springers, you have not yet adapted the techniques needed for PCP rifles.

I would shoot only your Marauder for one month, using 10.34 grain pellets off the bags.

BTW I have the Crosman Gen I barrel in my rifle.

[Fred J]

Tetatcdude,

I'm not real proficient at shooting off of bags: I'm a bucket and sticks guy who like to shoot hunter field target. I actually shoot my springers better off a bipod than a rest.

I do have a shooting table and a bean bag rest. I have been resting the Marauder at its balance point on the bag. This works well with my springers: in fact it is the only way I can get decent groups with them when I shoot off a rest.

So where do you rest your Marauder: at the balance point, which for my rifle is right in front of the trigger guard, or do you rest it further up the forestock? Do you use two bags (one under the forestock, and one under the butt of the stock), or do you  use just one bag?

Eventually, after my back heals (I had minor surgery a couple of weeks ago), I would like to use the Marauder in Hunter Field Target competition, which means bucket and sticks. Maybe I should rest the rifle on the bipod further up in the forestock area.

Your thoughts?

[Frank in Fairfield]

By shooting off of the bench you take all human error out of the equation.
Bench rest shooters do not even put their cheek on the stock.
If the gun shoots well off of the bench and not off the sticks, then the problem is yours.

I have a Boyd's Blaster stock on my Marauder.
I normally shoot with the stock sitting on the sticks just forward of the stock screw.

Like this:

[Fred J]

Frank,

Thanks for the advice. I think the Gen 1 stock screw is a little further forward than on the Gen 2. I have been resting the rifle near the pressure gauge, which is the balance point of the rifle.

[moorepower]

What if YOUR gun does not like JSB pellets? Your comparing two high end barrels to a mass produced Crosman barrel. The .177 Marauder barrel "can" be very good,  but possibly you did not get a hummer of a barrel. I would agree, shoot it off a bench and see what the gun can do first. What groups are you getting at say 50yds with the Marauder? Have you tried many other pellets?

[Fred J]

I have tried Baracuda Match (10.6gr) and Crosman Premiere Heavies (10.5 gr). The Crosman pellets shoot all over the place. The BM shoot OK, but the JSB 10.3gr shoot pretty well.

I have two barrels for the rifle: One is a stock replacement barrel, which really shoots bad. The other barrel is a MAC1 reconditioned barrel (polished lead and crown), which shoots much better.

Yesterday, I remembered that the rifle was extremely hard to cock when I first got it. To fix it, I took the action apart and put a light coat of moly grease on the hammer, which took care of the hard cocking problem. Maybe I need to polish the hammer cylinder and replace the moly with graphite.

Yesterday, I decided to take the action apart again and polish the hammer cylinder with JB paste, then I wiped off the moly and JB paste off the hammer and cylinder until there was no visible paste or moly left. Then I lightly sprinkled graphite power on the hammer edges and put things back together.

While I was at it, I polished the bore of the rifle with JB paste with 6 passes through the choke and 6 additional passes through the full length of the barrel. I did this because the barrel tend to foul badly after only 100 shots or less.

Unfortunately, my SCUBA tank is running low, so I will need to get the tank refilled before I can test the rifle again. The cocking is nice and smooth with the graphite lube, but sounds a little different than when I had moly grease in it.

[Frank in Fairfield]

Cocking effort?

I do not know what all motorhead did to my .177 Marauder.

This I do know..I can cock and fire 10 shots almost as fast as you can say 10 shots.

I use one finger.

Yesterday, at the Sacramento FT match I finished with 5 pellets still in the magazine.

Seeing as how I missed the last target and there was no one behind me I figured I would down-load the magazine there...

Five shots in a blink of the eye.

I missed it all five times which made a total of 7 misses on that target...

Almost sounded like a semi-automatic.

You may want to PM motorhead (he is on vacation for a week) and see what all he suggests.

[Fred J]

Since I polished the hammer cylinder, the cock became much easier. Yesterday I replaced the moly lube in the bolt action with a touch of graphite. Now I can cock the maruader with my little finger.

I reached out to Scott (Motorhead) about a week ago. He sent me a PM on his services, but we both agreed that I need to get the accuracy a little better on my end before he works his magic on the rifle.

Di he put a regulator in you Marauder?
 

[Frank in Fairfield]

Yep
80 shots at 900fps with 10.34
I think he put in one of his hammers too.

[Fred J]

It stopped raining yesterday, so I took the Marauder out to test it after polishing the barrel bore and the hammer cylinder with JB paste and relubing the hammer with a touch of graphite.

The conditions were not perfect with a 7 mph cross wind, so I did most of my shooting at 40 yards. The gun is tuned to shoot JSB 10.3gr pellets at 870 fps.

First I had to re-zero my scope at 20 yards, which took about 10 shots. The groupings during sighting in did not look promising, but after I had the scope zeroed at 20, I moved the targets out to 40 yards to see what would happen.

The first 40 yard target was totally uninspiring, which a c-t-c group of 1.25". I was so disgusted, that I did not take a picture of this target.

But then, on the next three 40 yard targets (I took a picture of these), a minor miracle occurred: The groups shrunk to 7/16" to 7/8". Still not stellar, but on par with my TX200 and D34. I am speculating that my first 15 shots were clearing out residual JB polishing past out of the bore, or maybe the graphite was still working its way around the hammer, and hence the larger groups)

At this point, the pressure in the rifle was down to 1750 psi, which is a bit on the low side for my tune (PSI range 2375-1650), so I brought the target in to 20 yards just for fun.

The first 20 I shot in this set was a uninspiring 1/2". So per Frank's recommendation, I loosened the shroud 1/2 turn from finger tight. The next 20 yard group produced a aesthetically pleasing 1/4" group (took a picture of this). I quit after this, since I was down to 1400 psi at this point.

Thank you for all your great recommendations. I think that the groups will even be better in the future with the loosened shroud and as I get more shots down the barrel.

[Fred J]

For some reason, the 40 yard targets did not post. Here they are:

[DRAGON64]

Excellent work, and good on you for not giving up on the Marauder.