alinwa or anybody else

N

nmibex

Guest
How far off the lands did you find your 6mmAIs shot best? I know this is a little of an open ended question and different bullets, barrels and powders respond differently and give different results. I guess a different way to ask the questions is; did you find your 6mmAIs shot better with the bullet seated closer to the lands or further back or there wasn't a trend one way or the other?

I have a 6mmAI that I've been working up a load for and I've tried several different bullets and have just about decided to use the Hornady 85 gr interbond. After reading some of the recent threads here and from my own experience I beginning to think back a little farther might be better. I'm at a point now that I just want to settle on a accurate load for long range varmint hunting and not use up barrel life trying to find that perfect load.

Dick
(still learning)
 
With Varmint guns, I've usually found..............

they want just a little jump, not much. What I typically do is to run an expander ball through the neck, gently 8-10 times to loosen up the neck just a bit, then seat the bullet out about a tenth of an inch over max. OAL. Then, you can use a kitchen match to smoke the bullet. If you have a Rem. or Win w/the Rem. type extractor, sit down and just drop the dummy in the chamber, then gently close and lock the bolt. As you open the bolt, get ready to take your finger and hold the dummy straight against the ejector pressure, so that the dummy doesn't ride against the chamber, etc. on the way out, giving you all kinds of scrapes on the blackening. When you get it out and see what you have, you can turn down the seating stem a bit at a time, cleaning, then re-blackening, until you are just shy of the lands touching the bullet. Then you can experiment up and back a bit. This takes longer to tell than to do. A friend of mine found out this way was so close to using the tools, that it just didn't pay for him to have gotten one, but he already had it. For varmints, in addition to the Sierra 85BTHP, you also might want to try their 80gr "Blitz", it should be a real performer. The Hornady IB is a good bullet, but isn't it a bit expensive for varmints?? Isn't that typically for game hunting? HTH ;)
 
Hornady IB

are more expensive but I don't shoot that much and will use the rifle antelope and barbary sheep hunting.
 
I'm no expert, but..... Until recently I was solidly a "square into the lands guy" which to me means into the lands firmly but not enough to stick. OR which means into the lands far enough to leave a square or even rectangular scuff on the bullet.

I currently have a 6X47L barrel, ONE barrel which is chambered with a 1.30 (1 and 1/2 degree) leade which I'm shooting using Euber 108's with 40thou jump. I ordered it expecting it to like a solid jam. It doesn't.

I always start with a firm seat into the lands. I jamset and then back out a thou or two. I've only played with one 6mmAI but spent quite a bit of time with .243AI and 22-250 which I class as "similar" to the 6mmAI.

I have no shorcuts nor magic formulas, just do what the gun tells you to do and in this one case I ended up 40thou out.

I believe that for short bullets like 68gr 6PPC/BR or for 112-125gr 30's there are tuning gains to be had within .005 of the lands in .001 increments....... This is often predicated on a steeper leade angle (2-3 degrees) and a blunter ogive. (7 or 8 ogive) I haven't found this to be true of VLD bullets. My thought is that this is because VLD's can be seated from .001 to .070 into the lands using conventional leade angles. In other words, the distance from "jam" to "out of the lands" on a traditional short-range bullet is very small, like 5thou total whereas for VLD's this range is much wider because of the angles involved. Lately I'm playing with trying to match the angle of the leade to the ogive of the bullet using VLD's. None of my predictions have come true in real life.

I've never tried an 85gr Interbond.

Wish I could be of more help.

al
 
Thanks for the input

I'll have to think on it a while. Right now I'll consider trying both: say .005 and .050 off.
 
I have a 6 ackley and a 243 ackley and i shot 70 gr nosler and 80 gr sierra and i just kiss the lands. And they both shot very well .They where build on a bat action.and krieger barrels with a 1x12twist
 
The advise to start at the jam point and work back is always good advise. Every barrel is not the same, every barrel chambering job is not the same. Let the barrel tell you where it wants to give it it's best. This is the only way I have ever seen it work out for the best.

You just never know for sure where a certain combination wants to work in any barrel wants to shoot, unless you test.:D
 
Well, since you're thinking, you might.............

consider this, if you're OFF the lands, and you find the best load where you are, then you can go forward, toward the lands by degrees, without worrying about increasing pressures, until you are ready to go INTO the lands, then watch for pressure. If you start out INTO the lands, then as you seat deeper, you may have to reduce your load progressively. Then, you may also have to stop at each point and fire a series of loads to determine what's working for you. Me?? I usually start where I told you, then fire a series of loads w/one powder, and not changing depth, then look for another powder if the one I'm loading doesn't pan out. While this is going on, I have decided on the bullet, primer, case I want to use, and work on different powders. HTH :)
 
Seating depth question.

My preference is for right on or a little into the lands because I think the cartridges sit in the chamber more concentric that way. However I do have two factory sporters that shoot most of their loads .2" or thereabouts off the lands and another that likes all loads kissing or just into the lands. Experiment with fine increments in the vicinity of the lands and if you are still not happy, try corse settings to get back off the lands. You could go back in fine settings but it is unnecessary and you would wear your barrel out in the process. As far as pressures are concerned I have not noticed any changes with this method as long as neck tension is normal. I blew up a 270 Winchester by seating on the lands with very light neck tension, and a near maximum load of W760.:eek:
 
murphy said:
I blew up a 270 Winchester by seating on the lands with very light neck tension, and a near maximum load of W760.:eek:
Click to expand...

Please tell us more. I have trouble believing that this is the whole story.

You were "near maximum" in a load manual and because of "light neck tension" and "on the lands" you blew up a gun?

really?

al
 
alinwa said:
Please tell us more. I have trouble believing that this is the whole story.

You were "near maximum" in a load manual and because of "light neck tension" and "on the lands" you blew up a gun?

really?

al
Click to expand...


Sounds like a myth, that is believed without the practical experience to know better. I guess it comes from the myth that freebore reduces pressure? This is 1940's thinking.

Hard in the lands and light neck tension is how I start all target barrels. What is new about that?
 
More information on ""The Myth"

Here is a photo of the 270 cartridge case that came out of my Marlin Mr7 and here is the story of how it got that way. Bought the rifle near new second hand and a heap of reloading components. The gun shop did not have a neck sizing die or fls die, but they did have a bullet seater which I bought. I found that Lake City 30/06 brass when passed through the bullet seater would grip a 270 bullet "just right". I assembled some loads with 130g Rem Corelokt bullets CCI250 primers and Win 760 powder. started 5g below max and worked up in 1/2g increments with the bullets seated to to touch the lands. Trouble was that as the powder charge increased the accuracy just kept getting better. I carefully watched for pressure signs and things proceeded normally up to 55.5g where slight cratering occurred but no tight bolt lift or other signs of trouble. My next session at the range started well with excellent accuracy,then on about the 18th round all hell broke loose. I was enveloped in a cloud of smoke and my face peppered with blood spots. The bolt would not open and I bashed it open with a block of wood and the cartridge case stuck fast in the bolt face. The case was removed with a pair of pliers and the primer was completly gone, vaporised I suspect. The extractor was wrecked and the bolt face burned but it could have been a lot worse. Exactly what caused this accident I will leave for you learned people to decide. Maybe there was a problem with the throating on MR7s as I did hear of another one getting blown up but exactly what happned to it I don't know. Have a look at the next window for the photo:confused:
 
Photo of Blown 270 Win cartridge case

Here it is.
 

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OK,

The gun didn't blow up. :)

The case failed, probably due to an overload, but many factors could have been at work..... none of them having to do with "throating" IMO. Were you weighing each charge or throwing from a measure?

al
 
To Alinwa

All charges were carefully weighed and the remaining rounds were pulled and checked but nothing unusual was found. How blown up have they got to be to qualify?:(
 
remember one thing if you are going to hunt with this gun Don't do what i did i work up a load for a gun and it shot real well then i tried to put one in the magazine and they did not fit to long. so i had to start all over or shot it as a single shot.
 
murphy said:
All charges were carefully weighed and the remaining rounds were pulled and checked but nothing unusual was found. How blown up have they got to be to qualify?:(
Click to expand...

Hey Murph,

There's a big difference between blowing out case and blowing up a rifle.

Your original post says you "blew up a 270 Winchester" which led me and possible others to believe that you'd unzipped a model 70 with a load from a reloading manual.

This forum is read all over the world.

Your clarification sheds a different light on the thing.

I'm not minimizing what happened, in fact were it me I'd be very concerned with WHY. So concerned that I'd not reload any more until I got to the bottom of it. The idea that I could be walking around with a bomb in my pocket would put me right off!

al
 
As with anything in shooting, you got to know the ambient temperature your shooting in. I do not shoot in a higher temperature than the load was developed in. What works fine in the 50-60 degree outside temps may be a little strong at 70-80 degree temp range.:D


Who knows what happened, if you follow that all brass is equal formula, there in lies trouble. Same with lots of components. Few people follow some basic rules about developing loads. Not having all the components for a couple of thousand rounds. Not staying with the same lot number for all your loading of that round is a big no, no. Lots of ways to get in trouble with many of the assumed things reloaders do."Oh gosh, I ran out of 43??, I'll just run down to the store and pick up another pound and assume it just like the one I was loading with". No thought to variance to lot numbers, what is the problem?:confused:
 
To nmibex and others

Sorry mate, I really didn't mean to hijack your thread or decieve anyone, but it seems my 270 story has got a few people upset or a least very curious. Since that incident I have been very wary of light neck tension as I have analysed this mishap from every angle. I have come to the conclusion that with the light neck tension and magnum primer, the primer explosion may have forced the projectile into the rifeling making a lot of room in the case and thereby upset the combustion process. In all honesty I don't think that a 270 case stuffed to the brim with W760 powder(and this one certainly was not) could create as much pressure as this one had. Have a good look at that case and the distance my eye would have been away from it when it went off! It may only happen every 10,000 rounds but some of you guys might be getting up there.:eek:
 
Murphy

I don't think you hijacked the thread. I appreciate the information flow whether it's somebody questioning a post or asking for a better explanation or more information, I think there is an opportunity to learn. I take a lot away from reading these forums. As an example; I used to believe IMR 4350 was the same from one can to the next until I learned different from my gunsmith. So now I started buying it 8 pounds at a time rather than one pound at a time. Had I not known that, I would have got a clue from post #18 in this thread.

So thanks for participating.

Dick
 
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