Marauder accuracy problems

Forums PCP Airguns Marauder accuracy problems

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    russinbaja
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    My 177 loved the eunjin heavy weights. Kinda like shooting a 22.

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    30cal
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    Here is a before and after I changed my barrel These are JSB 18.13 pushed all the way through. Can you tell which is which?

    Even going through the choke the factory barrel does not touch the head significantly.

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    ajshoots
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    Spash, I worked on a .22 for a gentleman that wanted the gun setup for high power. We managed 50+fpe with the 28gr eunjins and he also had an oversized bore. The eunjins fit the bore great. The only problem you may have if they do fit the bore well, is getting them going fast enough. A stock gun might not push them fast enough to be accurate? Keep us updated and hope you can find a pellet solution so you don’t need to purchase a barrel!!

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    hillairgun
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    Crosman barrels for the .22 Marauder rife:

    Pushing the pellet through the first couple of inches is used to test for pellet damage from a burr or sharp edge on the barrel port, or the leed going into the barrel may need to be “cleaned” up.

    The choke is ( and especially the crown ) are important as that is the last part of the barrel, before the pellets exits. 

     

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    ajshoots
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    Damn 30cal!! You take the best pellet pictures I have ever seen!! That TJ Gaska barrel is tight!!

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    Spash
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    I really hope I find a good pellet because who is not to say that if I buy a new barrel I won’t have the exact same problem and then I’ll be standing there with 2 oversized barrels and a couple $$ less…

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    hillairgun
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    “30cal”Here is a before and after I changed my barrel These are JSB 18.13 pushed all the way through. Can you tell which is which?

    Even going through the choke the factory barrel does not touch the head significantly.

    Did you try the 5.53 or 5.54 diameter pellets? If yes, how did they do ?

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    ajshoots
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    Tim, I have done alot of barrel work and custom size pellets. Pushing a pellet in a few inches and back out is for ALOT more than checking for a burr!! I have 3 marauders that have shot sub moa 100 yard groups. If the bore is loose, the crown and choke don’t mean anything. Ask 30cal, NMshooter, and many others that have or have had oversized bores. If the pellet doesn’t show decent engagement in the first 1-3 inches, that pellet isn’t going to shoot worth a damn!!

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    30cal
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    Spash I would not buy another factory barrel for that reason. This is the one I got. http://www.marmotmilitia.com/hammer-forged-barrels.html It is a very high quality barrel made to very high tolerances. It is hammer forged the way many high quality firearms(and air gun) barrels are made. The stock barrels are very inexpensively made from drawn tubing is my understanding. However it is an expensive upgrade.

    Thanks AJ! Its fun showing small things up close.

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    30cal
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    Tim I did try the Baracuda’s up to 5.53 but did not notice any improvement in accuracy. They do touch the choke better. I just tested the stock barrel just now and the JSB 18s literally slide back and forth the full length just by tilting the barrel and will fall out the end with just a little shake. The 5.53 Baracud’s will not. The loose barrel does allow for more power though! LOL! I lost 20 fps with the new barrel.

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    30cal
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    In fact that would be a good test Spash. Take the shroud off load a pellet and see if it will slide just from gravity or not. You may have to pull the bolt out so you can push it with a rod to get it started. You can at least get a sense of how tight (or not) it is.

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    hillairgun
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    “ajshoots”Tim, I have done alot of barrel work and custom size pellets. Pushing a pellet in a few inches and back out is for ALOT more than checking for a burr!! I have 3 marauders that have shot sub moa 100 yard groups. If the bore is loose, the crown and choke don’t mean anything. Ask 30cal, NMshooter, and many others that have or have had oversized bores. If the pellet doesn’t show decent engagement in the first 1-3 inches, that pellet isn’t going to shoot worth a damn!!

    My .22 Marauder rifle shows very little pellet engagement the first 1-3 inches, but shows a lot of pellet engagement the last 1-1/2 or so inches near the muzzle. I’m content with the accuracy. 

    Cheers

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    ajshoots
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    A little engagement is one thing, but none is a different story. For anyone that takes long range accuracy as serious as I do will know how hard it is to shoot sub moa at 100 yards. I have shot very few sub moa groups, but can make moa a regular occurance and not 3 shots. I work very hard and don’t have to prove anything. Simply stating that your statement was incorrect. 

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    Dan25
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    Im with some of the others here. ajshoots appears to really know what he is doing with the Marauder.  Be advised if you start tweeking you may void the warranty and be on your own.  The accuracy issues with the 22 are well know here.  That’s why, on Teds advice, I went with a 25 and am very happy I did.  The 25s are know to be very accurate but you only get 16 to 18 shots per fill unless you are willing to tune or have the gun tuned.

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    jps2486
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    Sounds like a Marauder.
     

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    WAR
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    First of all AJshoots is dead on and ill explain why. The pellet must engage the rifling from right after seating all the way to the choke. Why?  if the head of the pellet is not stabilized in the bore it will chatter down the bore till it either hits the choke and is again resized by the choke and stabilized but not effectively because it never rides correctly in the rifling. Or it goes threw the lose bore till it hits the rifling and is then stabilized by the twist of the rifling. Both instances end up with poor shooting guns at all distances  The Crosman barrels in the .22 are very thin and made in china, some shoot well others dont its a crap game. I personally will not shoot groups with a stock .22 Marauder that comes into the shop due to the fact the barrels are all over the place. Now lots of people say shoot the over sized H&N pellets but to me this is a band aid and limits you to only one pellet and still only makes it better not great. What would I suggest and have hundreds of times Get a Marmot militia HF barrel or buy the .25 Marauder with the USA made Green mountain barrel. Lets not let others with their own agenda screw with known results that have been tested by professionals repeatedly and proven correct. Thanks all for taking the time to read threw my LONG post. Travis

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    Yrrah
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    An experiment with a very good barrel showing how groups go very wild as soon as the head-to-bore relationship crosses a criterion where the head is of a size that allows in-barrel yaw; whether during loading or during travel down the barrel (as Travis suggests and Aj implies);
    25 yards groups and discussion. All groups are of 5 shots.
    Here the skirts are all sized to 4.52 mm or pretty close to groove size.
    The middle group has the head at 4.47 mm and  the lands are compatible with the fit.
    The top group, same skirt but heads of 4.44/4.45 mm – the group is starting to spread.
    Bottom group – same skirts but heads of 4.43 mm and things are wild. Expect that when your bore is over-sized to some criterion degree, regardless of choke.

    Now to find the barrel’s tolerance for head size and to show that it is not so much skirt size, providing the skirts are at least groove size:
    These groups had skirts from 4.53 to 4.66 mm (recall groove size was 4.52 mm).
    Heads were 4.50 mm top and bottom groups; 4.51 mm left group. There is little to pick in group size between these and the middle group above with heads of 4.47 mm.

    However we see that at 4.44 / 4.45 mm the group was beginning to spread a little and then at 4.43 mm top target bottom group and then 4.41 mm, bottom target middle group, group size has suddenly exploded.

    Further testing has confirmed that, for this barrel, head sizes from groove size at 4.52 down to 4.46 mm groups are excellent, with my preference going to the median size of 4.49 / 4.50 mm but anything from 4.46 to 4.52 is digested. Above groove size of 4.52 heads are too big and again it is very difficult to introduce them to my own barrels without the loading pressure inducing some yaw.
    Barrels which have had chambers and leades specifically machined to allow progressive centering of heads and skirts can, I think, be tailored to shoot over-sized (fractionally) heads acceptably.

    I hope my experiment has been of some interest and is found to be relevant in the context of this thread.  …    Regards to all, Harry. (Some spelling corrected)

     

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    NMshooter
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    Harry, you are amazing!
    thanks, 
    doc

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    WAR
    Spectator
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    Harry very well written up and nothing proves a point better than pictures. The head size is so very important for 1 main reason it doesnt change at all unlike the skirt that expands to meet the rifling. If the head is loose in the bore before firing then it will be loose after firing but the skirt will expand out as the air behind it forces it to expand into the grooves. Thank you Harry for taking the time to explain in pictures and well written text what I try to do with only words. Bravo sir

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    30cal
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    WOW that explains almost exactly what my experience shows. Thanks guys for confirming that I made the right decision getting the TJ/Gaska barrel.

    Boy did this thread take on a life of its own! Spash I hope all this answered your question and was of some use to you.

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