Benjamin Benjamin Marauder POI Shift

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UDABEGGER

UDABEGGER

Member
Nov 28, 2023
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MOSES LAKE WA US
I am new to pcp rifles.Old to shooting.I have two 22 cal Marauders[only needed one].One is 2019 syn with crosman barrel the other a 2022 wood with LW barrel both unregulated.The marauder has many reasons for poi shift.I will discuss one that I have made better and one that I am working on.If my info is old news remember I am old too_OK taking off shroud and shooting both rifles at at spot [one at a time] at around 30 yds-no wind-on bench.Pretty much one hole group.Put shroud on snug and shoot again at same target.Yea diff poi.Now adjust shroud by shimming.Both of mine shot lower[2 inch to 3 inch] with shroud on.For test purposes I simply put layers of tape on the bottom of the barrel band until it shot into same hole as when the shroud was off and the group was first made.If conditions stay about the same[TEMP] POI is way more consistent day to day then before.Now I am working on temp change effects on POI. Rifles are inside[72] shooting from inside garage[40] Both rifles seem to change poi since it has got colder outside.When I figure something out I will post again.Mabe some of you more seasoned pcp men can enlighten me before I go through several thousand rds more.Oh yea that is the fun of it!
 
UDABEGGER said:
Are they adjustable or a little like an o-ring that just stabilizes.
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If you mean the TH barrel band it is a snug slip fit so it needs no O-ring to stabilize and prevent shroud movement and droop.

If you do a search on eBay for Marauder clamps you will find several sellers who make or print clamps. Some of them will custom print as was done for my Super Light.
 
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UDABEGGER said:
OK not adjustable THANKS
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The TH band does not need to be adjustable because it holds center. As do the printed bands on eBay. The stock barrel clamp allows the shroud to droop and which impinges upon the barrel causing a POI change. Also, without a snug fit of the air stripper in the ID of the shroud, the barrel will move around inside the shroud dependent upon which way those baffles and spring push the barrel preloading it.
 
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The Green Mountain barrels were the best....then LW....I have the green mountain barrel in .25 caliber.
Hunting Descanso July 3 2014 002.JPG
 
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3Crows said:
Green Mountain or Crosman barrel, the same forces act upon the barrel and shroud. I also have a GM barrel in a .25 caliber Gen 1 and the Crosman barrels in my other three .25 Marauders and they are as accurate as the GM or more so. It is not the barrel the OP is dealing with, it is all of the things pushing and pulling on the barrel and the inadequate rigidity of the system failing to keep the barrel centered, day to day, heck, minute to minute, resulting in a changing POI.

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I know that some people have taken the OE band clamp and drilled it for three screws to use as adjustment, each at 120 degrees. So as to allow centering and fixing of the shroud. I have considered this approach but do not really like the idea. The center of the band clamp should be the center of the barrel which should be center of breech bore. It should be a straight line. Assuming the barrel is straight (?) and bore on center and the breech is bored on center then why should I need to push the shroud around other to hold it at exact center? I think Crosman considered that the barrel was free floated inside the shroud and the O-ring on the stripper is a loose fit as supplied. But the O-ring is compressible and the shroud is not supported by the OE clamp so it impinges on the barrel. And then there is that spring inside there that compresses between the stripper and the first baffle cone and preloads the system. The barrel is therefore not free floated. Anyways, the short of the long, I do not see the point of an adjustable band clamp, the system should be rigid and on center to start with and my efforts have been to make it so, not to make it adjustable.
 
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fishbone said:
hey 3Crows, I see you have a side cocking lever on your marauder. How did you do that ? Never seen that before.
Also great info about the barrel issues.
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It is from JSAR (Jefferson State Air Rifles). It is a very nice and very expensive piece. And worth it. He has them in stock once in a blue moon. The breech takes several mods to the rifle, transfer port and the breech has a higher barrel axis so the barrel band is no longer useable. Must do without or print one (or buy on eBay).
 
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Thanks for your input Airgun.I have tried the o-ring trick.It is a 1/16x7/8 o-ring that fits like a sock over a chickens head.I used two actually one on each side of the band for integrity and had the two band screws lose so it would self center.It all gets back to shooting in the same spot with the shroud on as it does with the shroud off.IE the same place that a total unrestricted free floating barrel hits.The temp poi change is on going.Need colder weather.Thanks! PS THE ORING STABLIZED BUT ACCURACY SUFFORD
 
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