Bullets, bigbore, medbore, smallbore anyone?

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  • #195193
    dougroundup
    Participant

    So whichever platform one decides upon for a .257 , the barrel should be a minimum 1in 10 twist for up to 100 -110 gr bullet? How do you or where does one find the formula to find what twist rate is required for which bore and weight? Or is this trusted hard earned experience? Forgive me if this addressed elswhere! I have read the importance slugging your bore and mic’ing the bullet and to get rid of any choked down section of barrel as the choke just robs performance with additional unneeded friction for a proper diameter bullet. What about the breech end? What is exactly cut or done to it. Is it simply just reamed a bit to allow the bullet some “chamber” space or freebore before contacting the lands of the rifling. I know that bullet seating depth is on of the greater variables to affect accuracy when handloading . Is this similiar in what has to be done to the breech end of the barrall when firing bullets in an airgun? Are the RL .257 drop in condor barrels any decent and what would they entail to properly fire a bullet? What does it entail to mod any air rifle barrel to fire slugs ? Remove choked section recrown and chamber breach?
    Should I start a new thread elswhere such as the machine and mod section?
    To stay on topic what if I simply cut off the end of my LW .177 barrel, recrowned and opened up the breech end to facilitate loading 40 gr sliced up sections of 4.5 mm lead rod or drawn wire? Probably its doubtful that the stock pelletgun twist rate would optimally stabilize a heavier solid leaded projectile?
    Sorry guys I am not trying to reinvent the wheel…. just very inquizzative. Is there any good books on practical ballistic theory that arent too overly crazy with the advanced physics or extreme quantum physics …. ya know kinda like maybe an intermediate ballistics for dummies crash course… Maybe someone wants to come over and get my lathe up and running for me too….. oh and the ol lady needs someone to pick up her groceries on the way over too! :rofl:

    #195203
    tofazfou
    Participant

    Doug,

    A standard LW or BSA or whomever 177 pellet barrel probably has a twist rate of 1-16 at is fastest and maybe 1-18 or so. Regardless, I can for sure tell you that those twist rates are much too slow for what you want in a 177 cast bullet gun. MUCH TOO SLOW. Not that it CAN’T be done but seriously, I would give up on thinking 177 cal heavy slug air guns for right now. No one seems the slightest interested in spending a grip of money on a PROJECT that might not work out anyways especially if they are loosing and will see NO GAINS.

    So yeah, in this case, its sorta is re-inventing the wheel. You stand MORE of a chance on finding a 40-55 gr 22 sleek cast bullet than you do a 172 or 177 caliber 40 gr sleek cast bullet. They just ARE NOT made and would require a lot of money and research to even begin to get results.

    Now, I really have no idea on what would happen with your theory on cutting the crown and choke off a 177 barrel and stuffing lead wire into the breech and shooting it. Im sure the results WILL NOT be favorable.

    A machinist could actually make a bullet CHERRY on a lathe. And then start making his own molds using that cherry. There are videos of it on youtube. But half the problem with airguns/airgunist is that a lot of airgun/gun NOOB machinist get into this and they don’t understand guns, ballistics, triggers, barrels, twist rates, valving, inertial, HPA/VALVE Balance, airtube fill pressures and so on. They just see that one can make 2000 dollars for a custom gun. So its tough for the guy with a lot of ideas and NO machining skills to get ahead but its easy for the novice machinist to copy something that’s already been done and make money on it.

    CHOKE VS NON-CHOKED barrels: Here it is in short. For a pellet barrel to shoot cast slugs with any type of accuracy, the choke needs to be removed. This is usually about the last 2 inches of the barrels MUZZLE. What a choke does is pretty much make a pellet into somewhat of a slug as it exits the barrel as well as help seal the passing air and blah, blah, blah, blah. This has the reverse effect when applied to a long solid bullet. The other thing is twist rate. Remember, pellets are STUBBY in comparison to bullets which are LONG. So a pellet doesn’t require fast twist rates like a bullet does. Friction is also much less compared to bullets.

    257 twist rates: In short, with the 257 in air gun form, available bullet weights cast or pre cast are roughly 65-120 grains. The 1-14 twist like on my TD257 work best with about 60-85 gr bullets and will shoot some 100+ gr bullets well. But not all. So then the 1-10 (faster twist than 14) will perform best with the 80-120+ gr bullets. Now, in the Powder Burner world the same will apply. THE HEAVIER A BULLET PER CALIBER THE FAST THE TWIST REQUIRED TO STABILIZE THAT BULLET.

    I can answer a lot of questions but I admit, response time will be slow due to my daily normal life of working and family. I’ve been reading gun magazine front to back since I was a kid and I now browse and peruse the internet for things that I don’t know. And the internet is free as opposed to buying books and cluttering up your house. Ask question, Read books, study the internet and repeat all steps to learn all you can about ballistics. Some people on the NET just have a way of explaining things. Many Youtube videos are pretty good when it comes to explaining ballistics and trajectories…etc….etc….etc….etc.

    #195213
    dougroundup
    Participant

    Thanks man! You are greatness and I have already have got a much better idea of some of the various varables that come into play with such undertakings. I am going to continue with a new posting as I start to further prepare to build my own 257. For now there is already alot that has been published of others who have proceeded with their own 257 projects and I will familiarize myself more with what is involved now that I got somwhat of a grasp of the very basic of basics involved and can ask more educated and specific questions. My next step is likely to be a .257 bullet barrel and will look towards a 1-10 twist . I will further study so I may make a informed purchase. Cool cool cool I am on my way to doing this !

    #195217
    oldgoat
    Participant

    Dougroundup, Ridetoeat and I are working on shooting our cast .257” bullets out of our formerly 25 cal R3 Matadors. We will use the Lyman 257400 and NOE molds, cut them down to around 55 grain and then have them made into hollow points by:

    http://www.hollowpointmold.com/

    I have already cut my Lyman and NOE molds down and they cast bullets that weigh 54 grain for the NOE and 55 grain for the Lyman. I’m hoping to get the HP bullets to weigh in the 45-50 grain range and see how they shoot in my Hart .257” 1 in 14” twist barrels. I need to order another TJs .257” 1 in 14” twist barrel also.

    Knifemaker has had very good results with the cut down Lyman and NOE cast bullets in a TJs barrel but: he hasn’t had them made into a HP, he is using a Condor that shoots them at around 1000 fps and he REALLY sucks at shooting at any thing over 25 yards! 😯

    Mike is only getting around 8 useful shots before he needs a refill. The Condors waste a lot of air for each shot.

    I’m thinking that I can get at least 20-22 regulated shots at 885 fps with a 45 grain HP .257” cast slug with my R3 long Matador.

    Hey Knife: it’s your turn! 😆

    #195224
    roland
    Participant

    Was just thinking about the .25 cricket with imppu’s regulated air-space increaser with a .257 barrel and cast slugs around 50 grains.
    Would the .257 diameter slugs be a problem in the .25 magazine? There is always a custom single loading tray to the rescue.

    #195228
    dyotat100
    Participant

    All sounds good but you are trying to shoot a slug that is twice as heavy as what you were shooting.

    I don’t think there is that much in them. If it does work shot count will be low just like condor because it takes that much air to more heavier slugs.

    Pellets have very low drag in a barrel compared to slugs also.

    #195280
    dougroundup
    Participant

    I keep hearing alot about the lyman bullets. I was thinking a little heavier bullet, but then again who am I to reinvent the wheel. I wasnt particularly looking forward to casting my own bullets and was hopeful that I may find a compomise in something that I may purchase. I believe that there certainly is a tradeoff between fabricating your own bullet and fine tuning as apposed to a store bought one size fits all. However there is something said about convience too.shouldnt I be able to further take a lot of bulk purchased slugs and run them through a sizing die anyways?
    As for bullets what weights do you find are commonly being used? What is your reasoning for using that modified lyman and are you selecting a hollowpoint for hunting or is it just to further trim and lean out that lyman that is in the process of your guys continued development?
    As for me and my purposes, first I suppose that like most guys starting out with PCP type of air rifles, shot count isnt intially a primary concern. I think for many getting started out, its more about the shear power above all. I am not as so concerned about max power,,, Well,,, maybe yes, velocity is nice and I appreciate having velocity for flatter trajectory , however trajectory is a major reality with shooting any distance with air rifles especially. Balance balance balance Mr.Mioggi!
    My main interest is to shoot consistiently at a minimum of 100 yrds and beyond informally at paper off the bench for fun. I want to get firearm performance out of my air rifle.
    My choice for the condor was based on the fact that this is the platform that I have seen others using, it is inexpensive, the basic mechanics are pretty simple and it’s modular design lends itself well to tinkering.
    So if I may ask what are thr pros and cons of todays avail bullet choices for 257? Who is into shooting distance beyond 100+ yards and what do they subscribe to as far bullets?
    Man I appreciate all the activity that this thread has generated and its cool to have the opprotunity to meet you all…. so far I havent been flamed or put down for such a newb…. thanks for welcoming me… you guys are some of the most hospitable and friendly group of folks . It kinda shows that greatness tend to attract greatness ….. I am far from great but I am willing to work at bettering myself and you guys are fine bunch of peers to aspire towards.
    So based on benchrest for fun purpose what are some of the opinions for bsrrel bulket choices in .257? I was almost going to throw another cal. out there too…. but I gotta narrow down the many variables and stay focused on a forward path. One other really dumb question but I am not familiar with the barrel liner concept. This is an insert or sleave that is pressed or fittted into an exsisting barrel or some sort of tubing that is bushed and shrouded? I know that it is a ignorant question but I am not ever used or am I familiar with the TJ liner or similar products.

    #195302
    knifemaker
    Participant

    Howdy Old Goat! Manuela and I were just talking about your project last night and wondering how it was comeing along.

    Doug, the liner is normally used to repair older shot out barrels. Especially in old black powder guns where the corrosive properties of black powder have really taken its toll.
    Since this is a already existing industry, and the liners are a great thickness for our AG’s, It is kinda made to order for us! Lots for cal’s and twist rates already available, and far cheaper than custom made barrels for our experimenting pleasure. 😆

    The real up side for us is that the BC is so much higher than what it is for pellets, that we have a MUCH better trajectory, even if we don’t push the bullets at a much higher speed.

    I have a small out cropping of rock that I like to shoot at that are across a bit of pasture and across a cattle pond. Apx. 175 yards. If sighted in at 50 yards, a .25 pellet will require the scope knob be turned one full turn from “0” to “0” and futher to 12 to get the job done. With the 60 grain NOE traveling at the same speed, the elevation knob needs to be turned to 12 to 13. This a HUGE difference. And as an added bonus, the .257 has much more FPE at 200 yards than the .25 JSB has at the muzzle. A real Win-Win in my mind. And this doesn’t even take into account the so much better wind drift characteristics. Here in Windy Texas, this may very well be nearly as important as the other attributes. 😀

    And about the over 25 yard thing that Old Goat spoke about. 🙄 😀 Best Group at 80 yards so far was a three shot group in 5-10 mph wind. It was .090″ ctc Just barely larger than a single hole. 😉 :8:

    knife

    Knife

    #195303
    rj-porter
    Participant

    If u want bigbore bullets check out my site. I’ve got the 257’s u want. And the guys on here will vouch for the accuracy and price. I size to your bore. Check it out here.
    http://www.accuratebigboreairgunammo.webs.com.

    #195306
    knifemaker
    Participant

    Yep! RJ does a Fine Job!!! 😉

    Knife

    #195314
    tofazfou
    Participant

    Doug,

    1st, RJ is my buddy and I took my 1st “AIRGUN” coyote with his 257 HP Spitzer bullet at 100+- grs. RJ also actually suggested that I turn my Talon into a 257 condor shortly after he got the 1st and original Jack Haley “SCANDELOUS” 257 that won the Long Range shoot in Texas. Hence its name, “SCANDELOUS”. BUY HIS BULLETS. HIS ORIGINAL LYMAN 257’s were more accurate than my 257’s SLIGHTLY (cant give that fucker too much credit….lol). You can find him here: http://www.accuratebigboreairgunammo.com. With a 1-10 twist, you can shoot the longer and higher BC 100 gr or 80 gr bullets at decent speeds for 100+ yard shooting. My puny little LYMAN 257420 70 gr HP bullets will make it ALL THE WAY OUT TO 450 yards in only 1.7 SECONDS when launched at roughly 1010 FPS muzzle fps.

    My future plans for video is too also shoot my 257 OUT TO 500 yards so I can officially join the 500 YARD SODA CAN CLUB…..lol. SERIOUSLY! The same for my new 7mm too.

    Man, I feel as sexy as HOOT looks :hoot:

    And Mike (knifemaker) is dead on. I set my gun up PURPOSELY. My 257 is sighted in for 75 yards and has a Simmons Mil Dot scope. About 4-5 MD’s IIRC! That gun is good for about 175 yards using all the dots and 200 using the lower post. My 7mm is sighted in for the same yardage and its good for OVER 215 yards using all the MRAD hash marks. My 257 shoots about 1010 fps with a .129 BC bullet and my 7mm shoots at 870 fps with a bullet that has a BC of .305. So one uses SPEED and BC to get there and the other uses BC strictly to achieve its trajectory. And yeah, I haven’t even began to push the 7mm….lol. SO far, I’ve seen over 905 fps with it new spring and a 3500 psi fill. If I fill to over 3800 or 4000 psi, you can expect so damned high or UPPER 900 FPS…..lol. You talking “FLAT FOR AN AIRGUN”……lol

    #195319
    dougroundup
    Participant

    Oh right on thats what I am talking about!!!! Hell yeah , now where do I sign up?
    Oh and RJ I have already been reading up on you! It all is very positive. I will be contacting you as I continue to proceed and make my final selection for barrel. I am leaning towards the one in ten from TJ’s ….. One more question with the liners….. For air rifle use you are jyst using them as barrel themselves and arent pressing them into or sleeving any other exsisting barrel. In the condor the frame kinda just shrouds it all on its own? Because its not seeing the kind of pressures that would be encountered within the chamber of a firearm its all good on its own? Pretty stout and not alot of flex from what it seems by how you guys are shooting.
    And … oh yeah DUH…… I finally located the Dedicated .257 Reference Page by ToFazfou…..
    Doh doh doh doh 😳
    I am suprised nobody chased me off to do more research before asking so many questions, I did take note of RL’s services over there and I also noted that someone had mentioned the idea of a group buy to get the tooling for TJ to offer a 1-12 barrel. Nothing came of that huh?
    Well I do have one slight setback today … just found out that we are going to be slowing down and outta work for at least the next two or three weeks! I already was trying to squeak all this shooting stuff past the Ol’ Lady….. but I gotta couple of other of my own jobs I am currently working on or soon to be rolling….. and ready to be paid on another, just a minor hiccup .. Baby just will have to get by with a little smaller down payment on that new car she is shopping and I will have to put the shooting out on front street! :rofl:
    I will have to wait a few days or a week or so before callling TJs for that barrel, so that I can rathole more of that lunch money away! :rofl:

    #195333
    oldgoat
    Participant

    Hi Doug. I have got my .257′ Hart barrel to shoot my 44 grain cast .257″ LBT bullets in the 850 fps range so far. I still need to open up the transfer port In the front breech block to match the OD of the transfer port in the 30 cal R3 air valve. I think that I will be able to shoot a 46-48 grain cut down HP 257420 and NOE bullet in the 880 fps range and get around 20-22 regulated shots per fill.

    IIRC, I got 27 regulated 850 fps shots with the gun when I tried the 44 grain LBT bullets. I will lose some regulated shots by increasing the speed 30 fps and bullet weight by 3-5 grains. I hope to still get 20-22 regulated shots.

    I might not get there with the Hart .257 barrels as they have more drag than the TJ .257″ barrel does. I’m not looking for a lot of power, long and heavy cast bullets or being able to shoot 500 yards.

    I would be very happy with consistent 1/2″ 100 yard groups 1 1/2″ 200 yard groups. Very!

    #195334
    knifemaker
    Participant

    Tedd, what makes for the higher drag, or friction in the Hart Barrel?

    Knife

    #195341
    oldgoat
    Participant

    Hi Mike!

    This is just an oldgoat’s opinion but; the .257”Hart barrels have the rifling cut and the .257” TJs barrels are hammer forged.

    Cut rifling and the sharp edges produce more drag than a hammer forged barrel does.

    At least the cut barrels have done that in my findings; then again, I am a dumb ass oldgoat that might not have a clue.

    I have noticed the same thing between my stock 25 cal R2.5 and R3s barrels and my BSA 25 cal (.243”) barrels that I have fitted to them.

    The BSA (25 cal) barrels are actually .243”. There is more force required to seat a 25 cal JSB pellet in the BSA barrel than is required to seat one in the stock 25 cal LW barrel. DUH!

    The BSA barrel needs a more tapered and polished lead in to get the same pellet seating force than the LW barrel needs. I am basically resizing the pellets as they are being pushed into the barrel. Once the BSA barrel has a proper lead in cut and polished, the pellets will just “snick” into the barrel.

    When I get the lead in cut and polished, the .243” BSA barrels have less drag when I push a pellet thru the barrel.

    I have found out that once I get the lead in right, the BSA barrels shoot a little better than the stock barrels.

    I think that I am finding the same thing on my .257” barrels.

    I currently have over $900 in Hart .257” barrels here. I don’t have any TJs .257” barrels here and I need to order a couple of them in 26 and 28” lengths.

    I sent my only .257” TJ barrel to somebody: I can’t remember who I sent it to!

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