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Post by tisme on May 19, 2016 17:34:46 GMT
I've known for ages the bullet OAL varies some up to 8 or 9 tho. Today I was making some rounds up and wanted to to seat the bullet 5 though off the lands so measured the chamber using a hornady OAL gauge and a bullet comparator and started loading. I was surprised at how much the bullets varied from base to ogive, the bergers were 5 tho, the A max were 6 tho and SMK 9 tho. How dose anyone seat 5 tho off the lands with such bullets?
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Post by sako75varminter on May 19, 2016 18:29:40 GMT
This has always been an issue!...you need to start measuring and batching your bullets Pete!..it's a tedious job!!!
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Post by tisme on May 19, 2016 20:32:50 GMT
Batching is ok but then if you seat it in more to get the same OAL the case has a smaller volume so the pressure will be greater!
You know what learning to read the wind would make it more accurate so I might just not bother with batching etc
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Post by oaken on May 20, 2016 8:34:18 GMT
What made you decide on 5 thou?
I long ago decided to start load development at 10 thou off as I found variables in most bullets to be at least 5 thou. I didn't want any chance of a bullet touching the lands as I figured that any contact would immediately create wildly varying pressures and may be what causes the odd flyer.
Also depends on which part of the ogive is in contact with the seating die. Once you find a length that works, lock the stop ring on your die if you have a locking ring, so minimising variables when swapping out the dies.
Oal measurements are only accurate given a perfect meplat which only ever happens with trimmed bullets. And then you have differences in bearing surface (hornady seem pretty poor for this) from different batches/tooling
I agree, learning to read that wind has way more profound end result than OCD reloading :-)
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Post by c18rch on May 20, 2016 9:51:59 GMT
What made you decide on 5 thou? I long ago decided to start load development at 10 thou off as I found variables in most bullets to be at least 5 thou. I didn't want any chance of a bullet touching the lands as I figured that any contact would immediately create wildly varying pressures and may be what causes the odd flyer. Also depends on which part of the ogive is in contact with the seating die. Once you find a length that works, lock the stop ring on your die if you have a locking ring, so minimising variables when swapping out the dies. Oal measurements are only accurate given a perfect meplat which only ever happens with trimmed bullets. And then you have differences in bearing surface (hornady seem pretty poor for this) from different batches/tooling I agree, learning to read that wind has way more profound end result than OCD reloading :-) Ditto, I always seat a min of 10 thou off the lands for the same reason. However, all my rounds are loaded to mag length which keeps them well off the lands. The 75gr A-max's I used to shoot in my .223 seated to mag length were more like 0.2" off the lands, they still worked well. I don't batch anything. Life is too short.  I do however sort my rounds by OAL and feel as seated as I am reloading. It doesn't take any extra time as I check OAL anyway, and the feel is more of a wet finger in the air thing, If one feels hard or soft compared to the others, it goes to the back of the box for plinking/ short range stuff. Realistically though it makes very little difference. I've shot several groups now with the longest, shortest, hardest to seat and softest to seat etc all making up my 5 shot group, and most of the time it is the same as my 'good' loads. |
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Post by tisme on May 20, 2016 10:04:16 GMT
What made you decide on 5 thou? I long ago decided to start load development at 10 thou off as I found variables in most bullets to be at least 5 thou. I didn't want any chance of a bullet touching the lands as I figured that any contact would immediately create wildly varying pressures and may be what causes the odd flyer. Also depends on which part of the ogive is in contact with the seating die. Once you find a length that works, lock the stop ring on your die if you have a locking ring, so minimising variables when swapping out the dies. Oal measurements are only accurate given a perfect meplat which only ever happens with trimmed bullets. And then you have differences in bearing surface (hornady seem pretty poor for this) from different batches/tooling I agree, learning to read that wind has way more profound end result than OCD reloading :-) I was going to start touching but with +/-5 thou bullets its not possible. I think I've found a solution but going to have to wait as they have to come from the states, I've just applied for a licence (ITAR) to get them, see how that goes |
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Post by oaken on May 20, 2016 11:38:49 GMT
I rather like the analogy of a car butted up to a curb, it's a lot easier to get over it with a little run up. I can't help thinking that touching the lands is asking for variable pressures. I may be wrong.....
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Post by davet on May 20, 2016 11:50:14 GMT
I use the same analogy when I deliver reloading training at Dauntsey guns....makes sense.
I tell new reloaders to keep 20 thou jump as this covers bullet ogive variances and their inexperience in measuring so finitely.
I see Hornady as delivering the worst consistency and Berger pretty damned good....at least as far as the 6mm and 6.5mm that I use.
I load as close as 7 thou jump in my 6mm XLR with 115 Dtacs and have had no trouble.
The annoyance is that often as not I find best accuracy at greater than mag length for my AI mags!
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Post by tisme on May 20, 2016 16:16:59 GMT
Thanks for some good advice VLDs like to be close or toughing the lands so in car terms rev the engine first  ) Accurate mags (who make AI mags) make their own without the plate in the front given an extra 1-2mm in case you didn't know. |
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Post by davet on May 20, 2016 16:32:49 GMT
Thats worth a look Pete...cheers!
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Post by davet on May 20, 2016 16:54:21 GMT
Pete
Any knowledge of how well these work....feed problems etc......any UK stockists or is it a bloody ITAR item?
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Post by sako75varminter on May 20, 2016 17:05:55 GMT
Dave..Tier-one stock them,I've just fitted Ai bottom metal to Beau's Tikka the mags feed flawlessly
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Post by tisme on May 20, 2016 17:23:02 GMT
RPA are the importers if you can't get them I can for you but you can mod AI ones   AI mag and Accurate mag. The AI one has had the plate taken out the front by drilling out the two spot welds, removing and welding up the holes.  |
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Post by davet on May 20, 2016 20:37:22 GMT
Cheers guys...I will try to get hold of an Accurate 308 mag from RPA or Tier one.....I am not much good at metal mangling!
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Post by davet on May 20, 2016 20:39:52 GMT
Pete
If I see things right in your photos the mag will take a head-to-tip oal of 2.996?
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