.257 POI Shifts while shooting
Hi all, Asked on the GTA forum too. Have 2 .257 rifles. Randy built first in Feb with Ultima stock. I built with my gunsmith doing machining on one pictured here…..This one has TJ bbl 34″, carbon sleeved, HATSAN airstripper, 105 gram brass hammer, dyotat valve and one piece stem, also have his spring but used a tad heavier one on there now. Maddog BENCHREST STOCK, 4′ aluminum machined one piece barrel bushing. Can shoot 1/2 moa and then throw shots high, low and right left, Have to use another mil dot for awhile and then it goes back to same mil dot for same POI??? I didn’t chrono these but records shot with PW 0 and 3200 psi, shooting 72 gr fp at 1000-1010 fps..All screws blue locktite and are not loose. have tried 3 scopes and same thing….Try hard hold and free recoil and in between…………i have 4 molds. these were the 257420 . Have tried Porters bullets, and now mikes from Randy and all will shoot a good group or 2 then spread out 2-4 inches at 100 yds? Have hit rock size of mop bucket at lasered 460 yds…….If it shifts like that indicates to me something moving or loose but all seems tight to me? Bottom 2 groups were yesterday at 220 yds.. Help any IDEAS?
Thanks…………Carl
Click on pics for larger view
All Replies
Hey carl, probably getting a bit off topic here, but it is the TAG forums here where everyone seems pretty cool with it and it is your original post anyways…… But the tiny .20 pill ruger action you built sounds pretty cool and was kinda along the lines of the way i would kinda “handicap” myself many years back shooting high power service class with a back then very unpopular black rifle and puny 55gr .224 BEFORE THE 69gr and faster twist barrels were 100% “service class” however , being so uncompetitive such was often overlooked or uncontested. I was shooting 1:7 twist with 70gr speers and imr powders compressed and federal 209 magnums…. This caused me to go into a major 223 fetish for all kinds of unconventional experiments. Especially lightweight loads for varmint like 48gr hornady sx rounds with volume filled case of extruded compressed….. Really got into these loads with Contender pistol….of course the next extreme I took was necking down the cases and fumbling around loading .17 rem……. That was interesting load before I got a Sako action in .22ppc which of course .22ppc on the Contender too……… Yup always a fondness for things a bit different and unconventual.
Funny thing is that Black Stoner Rifle is all I ever see in high power service class nowadays, and they certainly arent service rifles either! I would take the Garand over the others these days…. Of course my vision sure aint what it used to be! :rofl:
Thanks………I have NO AIR sensation when shooting and i am all over the rifle :suprisedn: ………..Will try tissue trick…….I suspect all is good though at this time, as all is pretty new…..Carl
Try placing a piece of tissue paper over the breech when you fire and observe if it gets excessive blow- by. Obviously if you can feel air blow upon your face, that would be excessive too. Really shouldnt blow the tissue around at all, if ya git good seal. :tag:
dougroundup………..Thanks for your tip on possible Breech O rings leaking……….Now my ignorance on AIRGUNS….How does one KNOW if air is leaking or NOT during the very brief firing cycle????
Also Thanks for your WELCOME…………………Carl
i have this “SICK” sort of a goal  I want to show up at a High Power match with and airgun… We have every other month a 300, 600 800 yd match with 20 shots for record at each distance………I WANT TO BE ABLE TO COMPETE at the 300 yd distance with AIR….They use .308 and 6mm mostly and also .223……They use iron sights to and differ from us in F-Class who use rests and high power optics……….Our x rings are 1/2 MOA and High Power is 1 moa x ring………Just MOA consistency will make it easy for me………Have to get match director to let me shoot a HIGH POWER CENTER?? Not send that relay to NRA as just for giggles, and i will compete at F-Class rest of match with a 6mm Dasher or 6.5 CREEDMOOR……….I can get access to the range during week to see if feasible ??? I like doing what others won’t or can’t,,,,,,,,,I built a special .204 ruger last summer. Standard are good to around 400 yds…….Built for the Bullet weight, twist and barrel length and weight, and experimented with POWDER they don’t even think about in this case……….I showed up with it at an F-CLASS match for 3 relays at 600 yds……..20 caliber wth 55 grain bullet at 3500 FPS. F-CLASS is highly competitive……….First 2 relays i shot HIGH MASTER level………3rd relay wind came up and i dropped 8 points from 200…..That TINY Bullet is supersonic to 1100 yds in this SPECIAL BUILD, and wasn’t sure how much wind pushed bullet……Was also first time shooting it past 100 yd load testing  ……I am going to shoot it at the 800 yd line and probably never shoot it again..Achieved my goals……….. I am so old i don’t care and just excites me doing something VERY DIFFERENT……………Will keep you posted on the adventure………………..Carl
Carl,
You are a man of my own spirit!
I have the exact mindset as of you, but just dont always have the resources to follow it through!
You are in my hero book , along with a few others from around here. Definetly high status!
Do please keep us posted.
Wouldnt it be something to start a high power air postal for med bore air gunners? 😀

rifle50
Posts: 18
Joined: Fri Jan 30, 2015 8:52 pm
No offense taken and you don’t know my credentials and it COULD BE ME but i posted good groups to show it can shoot but can scatter them to be 3 inches at 100 yds and not wind. With 2 guns acting similarly, i doubt it having altered my pressure on the gun while firing..Gun is SOLID as if it was in a vise. ….Why i put in initial post, i have tried hard hold, free recoil and in between…….Tried bullets from 4 of my molds and purchased others, same thing….Below pic is my setup…….I shoot 1000 yard F-CLass and have rifles that at 100 yds groups are measured in the .1″ of even zero’s…..OR pretty much same hole………..The front rest is a joystick SEB NEO . The Rolls Royce of rests $1000 and 13 months wait to get one now. I waited a year……..Custom sized bag with heavy sand at rear……I also shot all through the 90’s at the World Championships for 50 bmg at Raton NM, 1000 yds…….1995 i won the World Championships……I compete in Rimfire Benchrest ARA at 50 yds….If your gun can’t at least group in the .150″ consistently you might as well be throwing rocks 😯 Thanks for the input and I DO HAVE A PROBLEM somewhere………I also don’t consider 220 yds a long way, even for a .257 airgun.My F-Class rifles i can hit 4″ clays at 1100 yds in back berm sighting in for 1000 yd play days …..Carl CLICK PIC TO ENLARGE
:8:
Impressive credentials, welcome aboard. That is the type of shooting I aspire for when shooting these rifles. To me its like a benchrest wildcat, unique and elite type of shooting that I am into…..
I know that it can be many different things. One observation that I intially noted on my .257, while it was quite accurate and able…. It didnt exactly shoot itself and required alot on my part. I also almost exclusively have shot tethered to the bottle, not regulated but tethered and not on a sled but always off the sandbags. I noticed at times I would get on target right away and at other times it would take an extra amount of time and effort. But every outing did require a bit of setup before we were grouping spot on….. I expressed this to doug and he had my gun for awhile experimenting, just checking it out. Turned out that there was a bit of an issue with the clearance of the breech to the valve causing inconsistiency because of the spinlock bushing being just a hair too proud. After milling down the spinlock, it was able to get a more consitient lockup. In other words the breech or air bridge wasnt getting 100% consistent sealing with the valve every time the hammer struck. I would also check your breach o rings and also test for any amount of air leakage around the the breech.
I dont shoot mine as often as I would like and probably have a few small bugs to iron out. But it seems that whenever I experience blow-by at the breech end, is usually when I have less consistiency at my p.o.i. Interestingly, the last time I experienced blow-by at the breech o-rings was when I was experimenting with devices on the end of my barrel that created a bit of back pressure.
I dont know if this helps ya but its some things to consider. Also as spring gunners are often reminded of the artillery hold,,, as we drive up the air pressure and utilize heavier hammers and springs,, we might consider similiar physics at work against our accuracy goals.
Anyways, welcome aboard, i look very forward to following some of your postings, looks like ya got some nice rigs and great experience. 
If this is the case, then an end cap would certainly add more stability to the barrel. But you have an end cap, don’t you? At least you do in your pictures…
The end cap in pics is the stock one, plastic and for finished look is all…..Hole larger than barrel and does and touches NOTHING…the full float [DIDN”T WORK]…I will now have a FRONT bushing made and probably extend 3-4″ forward of frame end…. Carl
Yes- a new end cap should work quite well!! The barrels are quite thin when compared to powder burner barrels- the TJ’s are barrel liners after all! My .257 build will be very similar to yours: 1 piece barrel bushing, Uni CF on the rest of the barrel. Though my end cap will have threads on it to fit a shroud. Please keep us updated!! My goal is also long range accuracy, but for varmints… Though I’d like to achieve as much accuracy as possible! My stock will be made similar to a KRG Whiskey-3 chassis, in a urethane plastic. I’m hoping it’ll be nice and stiff!
My idea- but only from the grip forward, all one piece:
Caboose212………..That is quite a sturdy stock……..Reminds me at first glance of when i started competing in 50 BMG early 90’s of the then IVER JOHNSON AMAC rifle…That rear section anyway http://www.50bmgstore.com/amac50bmgstore.htm If it was my rifle i would ADAPT that rear section by cutting of the top what was necessary to have bottle fit………But that is just me! Good luck with your project and do keep us posted…….Yes if you are HUNTING a smaller rifle to carry is necessary…I am for absolute best accuracy and from the bench…. To old and barely walk, so bench is fine for me 😀
I have also modified thoughts of what i am doing to end of barrel……..Small bushing at frame end and then like you folks with shrouds, i just ordered drawn aluminum 1″ tube….thick walled and inside hole, .624″ is .008″ smaller than OD of carbon fiber tube on bbl………SHave the CF, Mount that on end bushing and epoxy the entire length of skinny bbl to Stripper……That will certainly stiffen it up, and enough i hope…………
You see i have this “SICK” sort of a goal 😎 I want to show up at a High Power match with and airgun… We have every other month a 300, 600 800 yd match with 20 shots for record at each distance………I WANT TO BE ABLE TO COMPETE at the 300 yd distance with AIR….They use .308 and 6mm mostly and also .223……They use iron sights to and differ from us in F-Class who use rests and high power optics……….Our x rings are 1/2 MOA and High Power is 1 moa x ring………Just MOA consistency will make it easy for me………Have to get match director to let me shoot a HIGH POWER CENTER?? Not send that relay to NRA as just for giggles, and i will compete at F-Class rest of match with a 6mm Dasher or 6.5 CREEDMOOR……….I can get access to the range during week to see if feasible ??? I like doing what others won’t or can’t,,,,,,,,,I built a special .204 ruger last summer. Standard are good to around 400 yds…….Built for the Bullet weight, twist and barrel length and weight, and experimented with POWDER they don’t even think about in this case……….I showed up with it at an F-CLASS match for 3 relays at 600 yds……..20 caliber wth 55 grain bullet at 3500 FPS. F-CLASS is highly competitive……….First 2 relays i shot HIGH MASTER level………3rd relay wind came up and i dropped 8 points from 200…..That TINY Bullet is supersonic to 1100 yds in this SPECIAL BUILD, and wasn’t sure how much wind pushed bullet……Was also first time shooting it past 100 yd load testing 😆 ……I am going to shoot it at the 800 yd line and probably never shoot it again..Achieved my goals……….. I am so old i don’t care and just excites me doing something VERY DIFFERENT……………Will keep you posted on the adventure………………..Carl
If this is the case, then an end cap would certainly add more stability to the barrel. But you have an end cap, don’t you? At least you do in your pictures…
The end cap in pics is the stock one, plastic and for finished look is all…..Hole larger than barrel and does and touches NOTHING…the full float [DIDN”T WORK]…I will now have a FRONT bushing made and probably extend 3-4″ forward of frame end…. Carl
Yes- a new end cap should work quite well!! The barrels are quite thin when compared to powder burner barrels- the TJ’s are barrel liners after all! My .257 build will be very similar to yours: 1 piece barrel bushing, Uni CF on the rest of the barrel. Though my end cap will have threads on it to fit a shroud. Please keep us updated!! My goal is also long range accuracy, but for varmints… Though I’d like to achieve as much accuracy as possible! My stock will be made similar to a KRG Whiskey-3 chassis, in a urethane plastic. I’m hoping it’ll be nice and stiff!
My idea- but only from the grip forward, all one piece:
Thanks………….I WILL GET IT……..I have NEVER OWNED a gun i couldn’t make better………In this case it has been trying as NEW to AIR…..But really same as a Powder rifle………If it isn’t tight, stable or is flexing, problems in accuracy WILL occur…………Carl
I am out of my comfort zone here – your kit and experience way outstrips mine. Love your gun and benchrests. Awesome. As you say intermittent problems are the hardest to find. Good luck, hope you solve it. :fishinghole:
If this is the case, then an end cap would certainly add more stability to the barrel. But you have an end cap, don’t you? At least you do in your pictures…
The end cap in pics is the stock one, plastic and for finished look is all…..Hole larger than barrel and does and touches NOTHING…Yes i have a 4″ single piece bbl bushing where the stock ones mount…I thought i would FLOAT the bbl as in my 1000 yd rifles……But they are STIFF and 1.250″ dia and this .257 vermicelli dia barrel is a noodle….DIDN”T WORK the full float….I will now have a FRONT bushing made and probably extend 3-4″ forward of frame end also, and support even more of the bbl………..My next go round should have close to 1/2 moa pretty consistently??? Talked to gunsmith and is BUSY……AT BEST may get some time at end of NEXT WEEK and if not, he is on vacation till JUNE 1st?????? If i LIVE LONG enough, I will get it working primo……Carl
Ah-ha- so you have a 1 piece barrel bushing, instead of using two short bushings- like factory, but forward of the bushing you have nothing? Did I read your explanation correctly?
If this is the case, then an end cap would certainly add more stability to the barrel. But you have an end cap, don’t you? At least you do in your pictures…
When building the gun i FREE FLOATED the barrel forward from the one piece bushing and 4″ long…………At the time wasn’t sure if a end of frame BARREL BUSHING would be necessary with carbon sleeve on bbl………..Today i locked onto the frame and other fist grabbed the barrel and pushed pulled……..Not a LOT of movement but the barrel can be moved 1/8″ – 3/16″ back and forth, up and down………..Just grabbing the gun leaning against the wall by the barrel will not FEEL the movement……………Hard hold on frame and barrel and MOVEMENT is there………..I knew something had to be moving. When gunsmith able will get a LONG bushing made……..Should be stable then???
Should clarify my explanation………BARREL or screws NOT LOOSE, but there is FLEX from rear barrel bushing forward with the barrel, not having a frame end bushing…….
So what was the issue??
- You must be logged in to reply to this topic.
Funny thing is that Black Stoner Rifle is all I ever see in high power service class nowadays, and they certainly arent service rifles either! I would take the Garand over the others these days…. Of course my vision sure aint what it used to be! :rofl:
Yes you are like me in it is MORE FUN to be competitive with something that isn’t what EVERYONE is shooting….I am 73 yrs old……Retired for 14 yrs….From injuries i gave up golf 12 yrs ago, all my motorcycles at age 70, most of my landscape photography as can’t walk real far anymore……….Had given up shooting year 2000……not much left i could do interested me..Dug a couple of guns out of safe and started again……..Learned about F-Class and started about 3+ yrs ago……..6mm Dasher and 6.5 Creedmoor are purpose built 1000 yd rifles…….BUT, for F-class have built an AR-15 with 6mm barrel…Necked down 6.5 Grendel brass and have shot it at the 800 yd line….Built a tactical .223 as had a Rem 700 and shot that at the 800 yd matches…My stock .204 RUGER i always shoot at the 300 yd relay on the 300, 600, 800 yd matches………..Then i got rid of the 1-12″ bbl and 39 gr BK bullets, put a 1-8″ bbl, 28″ long, 1.25″ dia and it is heavy for .204 round…………Berger 55 gr bullets………and as mentioned powders no one would even consider and i did a LOT OF TESTING and it is a compressed load and is an impressive varmint rifle if i killed animals anymore, which i don’t…..And as mentioned the B.C. of the Berger at 3500 fps and depending on altitude and temperatures is supersonic to about 1125 yds…….SHot that 600 yd match……….I will take it to the 800 yd range but not a match and that will be all…….I will still use it at the 300 yd line but can’t barely get down on the belly and get back up……NOT FAT, but arthritic joint pain and hip replacement etc……….Done building powder rifles and as mentioned want to get the .257 AIR consistently shooting the good groups and if and when that happens, don’t know what OTHER AIR accuracy thing to build??? Then will probably just go for DISTANCE then……4500 psi bottle and just see but that has already been done. I think the .257 bullets are best as opposed to a larger caliber IMO……Roachcreek with his very long bbl and i read like 4000 psi, so any increase in distance won’t be much??? I read on here or GTA someone shooting like 700 yds? But target is 45″x45″ and that isn’t accuracy as far as i am concerned….Lob them in like a morter too i believe 😯
Cheers and keep in touch…………..Carl