Benjamin Marauder .25 accuracy issues

[scruffy]

So yesterday I received a new PCP. It’s called the Benjamin marauder in 25 cal. I’m sure many of you have heard of it
After cleaning the barrel, I started shooting. Even after around 90 rounds, my gun was still shooting poorly with the 25.39 JSB pellets. I also tried some other pellets, but all were just as terrible. I have the .25 Nielsen test slugs, but I want to save for them for when I figure out the issue. I have already eliminated the following variables as the culprit of the inaccuracy: Shooters error, Parallax issue, shooting position, Winds, Scope mounts, velocity, weather and barrel cleanliness.


By the way, my backyard range is 43 yards, but recently I have only been able to shoot 35 yard due to reasons... so all my groups are at 35 yards.

Also, it seems that the accuracy is slowly improving over time, but there a few times I got two groups in my groups, where there are three shots in one hole and two in another hole. my groups are between 3/4” to 3.5”.

Here is one of the best 5 shot group at 35 yards. (Most of the other good groups were destroyed in the rain last night)

My question what could be causing my inaccuracy? Could my marauder require a break in period of a tin of pellets? Could the barrel still need more leading after my intense cleaning? 

 

[TNT19]

Well there's alot of things that could be affecting your poi. Do you know what barrel came with it? How did you ckean the barrel, did you clean the barrel like you would a powder burner? Did you use a metal brush in the barrel? Do you see any lead clippings with the magazine, this is not a normal marauder issue but still good to check as damaged pellet skirt causes poi issues. Look at the tip of the barrel do you see any damage at the crown? This is where I would start. Good luck.

 

[FuzzyGrub]

If you can take the noise, remove the shroud and test. Also test with single pellet loading, no mag. Push a pellet through and look it over. Burrs in TP/leade are common.

Unfortunately, the 25 barrels are not made by Green Mtn anymore. The crosman made barrels tend to have a very heavy choke and loose bores. I had some OK accuracy from the two I had. Sent one off to a machinist for a pistol barrel. Once he had the section cut, the pellet just fell through the barrel. Trashed it.

I don't think they will work well with slugs, but even the GM is not known to be that great at it.

 

[JimNM]

Borrow or buy a chronograph. Pellet gun s are capable of extreme accuracy, but the parameters for performance are crucial. Airguns are not easy to shoot, and require a different application than centerfire guns.

Do you have anyone local who can help you?

 

[scruffy]

I believe that the new marauders in .25 have Crosman barrels instead of green mountain. Is there a way I could check? I used two different types of cleaning pellets with some ballistol sprayed on them. I fired a few times without the moderator but nothing really changed. Could more leading tighten up the barrel? Thanks!

 

[FuzzyGrub]

From memory, the crosman has 6 lands/grooves and GM has 10.

 

[scruffy]

I have a chronograph, and I was getting consistent shot spread (1-3 fps) for each of the 15 shots before I pump it up again. Also, I had three other PCPs before, a hatsan flash which shot well for while until one day when I sold it, and a Kral Puncher Breakers using which I was able to easily shoot 1/3"-1/2" groups at 40 yards with them until both the first one and then the new replacement leaked all their air. I don't really consider myself a newcomer to shooting PCPs, but I feel that your advice was still very helpful. Thank you.

 

[Enkey]

Borrow or buy a chronograph. Pellet gun s are capable of extreme accuracy, but the parameters for performance are crucial. Airguns are not easy to shoot, and require a different application than centerfire guns.

Do you have anyone local who can help you?

Hi Scruffy

I agree with what Jim says Before looking for problems in your air pistol, you should know what fps it shoots at and, from that moment, it begins to look for errors

Regards

Enkey 

 

[scruffy]

Hi Enkey

Thank you for your reply, I have the Benjamin Marauder rifle in .25, and as I said before, I ran it over the chronograph and was getting very consistent velocities. Is it possible that the pellets are not good with this gun at the higher velocity it is shooting, of around 880 feet per second? Could it be more accurate at a lower velocity like 850 feet per second? 

thanks for the help,

Scruffy

 

[nervoustrig]

Try it without the shroud to eliminate the possibility of clipping the baffles. 

Also inspect the barrel. Is there a burr at the crown? Try the cotton swab test. And do pellets chamber cleanly or can you feel a hitch as you close the bolt?

 

[JimNM]

I may be able to help you with the Kral problem, too. Don't want to pollute thus thread. Send me a private message when you want to drill down on that problem.

I gave a .25 Mrod that shoots superbly with the AA diabolos. I can send you a sample of those if you want to try some different ammo the Hades shoot almost as good.. I am not a huge fan of all of the JSB ammo. 

 

[FuzzyGrub]

Try it without the shroud to eliminate the possibility of clipping the baffles. 

The shroud can be putting uneven tension on the barrel, too. The 35 yd group is essentially two groups. One showing vertical stringing tendencies and the other horizontal. Happens when shroud end not square or not threaded well.

 

[Enkey]

Do a series of groups at different speeds to determine which speed your keg likes best, do it by manually inserting the granules without a loader and if the best group is still bad then start checking what the other mates are saying.

 

[JRR]

Have to Mrods get good groups around 850fps back off hammer shoot 5 shots each time. If no crony go 1/4 turn an shoot 5. Hope this helps.

 

[scruffy]

Hi Jim,

After my replacement Kral leaked out air I sent it back for credit to buy this marauder.

Sean

 

[pnwairgunner]

A leaking transfer port seal will cause erratic groups like you are seeing as well as a bad breech seal. Do you notice any noise in the breech area when shooting? If you place tissue paper over the breech area and fire the gun you can detect small leaks by watching for movement of the paper.

Next thing to check is the striker and tube. If the tube is dirty then the hammer/striker will give inconsistent strikes on the valve pin. I clean and lube both with a very thin coat of silicone grease.



The marauder is easy to work on and trouble shoot, and there is a massive amount of information on marauderairrifle . Com for you to peruse. Just always remember to completely degas the reservoir and never use petroleum based lubricants. 100% silicone oil and silicone grease are great for use.

 

[nervoustrig]

FYI all those issues will cause erratic velocities that would have been revealed with the chronograph readings. 

 

[GLPalinkas]

Sean, I have an older Marauder .25 with the green mountain barrel. It shoots superbly with the JSB 25.39 Kings. I know that what has been said already, that Crosman is making the new barrels for the .25. I have heard good things about the new Crosman barrels. 

My thoughts on your problem are what Jim FuzzyGrub and Jason Nerouvrtrig have already stated. I would rely on their advise as they are at the top of our airgun game. 

With that said, no one yet has suggested it could be your scope. I would try a different scope, if you have one. It doesn't have to be a high end scope. A loose reticle has had me chasing my point of impact poi at times. 

That would at least narrow your accuracy issues to the rifle. 

Hope this helps.

Gary
Venice, FL

 

[TNT19]

I have a chronograph, and I was getting consistent shot spread (1-3 fps) for each of the 15 shots before I pump it up again. Also, I had three other PCPs before, a hatsan flash which shot well for while until one day when I sold it, and a Kral Puncher Breakers using which I was able to easily shoot 1/3"-1/2" groups at 40 yards with them until both the first one and then the new replacement leaked all their air. I don't really consider myself a newcomer to shooting PCPs, but I feel that your advice was still very helpful. Thank you.

That sucks man. I have a 1st gen puncher breaker in 22 and that thing is a tack driver. I did some personal modifications to get the desired fps etc but it shoots lights out. I also had a gauntlet in 25 which shot lights out after some tuning just tooooo heavy for good field work. Then I had an Rti priest 2 in 25 which i should never had sold, as they put a side lever cocking kit for that. That gun was beyond lights at past 100 yards. Sounds like you got a bum barrel.

 

[FuzzyGrub]

With that said, no one yet has suggested it could be your scope. I would try a different scope, if you have one. It doesn't have to be a high end scope. A loose reticle has had me chasing my point of impact poi at times. 



Good catch on the scope. I had read his initial statement "I have already eliminated the following variables as the culprit of the inaccuracy: Shooters error, Parallax issue, shooting position, Winds, Scope mounts, velocity, weather and barrel cleanliness. "  and thought he tried another scope. Rereading verified a number of scope items, but not that specifically. What is also common with scopes, is too much vertical recital adjustment is made, such that it as its limits, and will see those type of groups. Re-center the reticle and shoot for groups. If that is it, simple scope shimming to resolve.

I also looked for a picture of the JSBs I pushed through the crosman 25 barrels, but didn't find it. The whole perimeter of the head had been re-sized going through the choke. It took significant effort to push the pellet through the choke. I had done that prior to mounting in a Mrod, and was surprised the accuracy was within 1" @ 50yds. My only thoughts were that the softer lead of JSB/AA must be very forgiving.