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Discussion Starter · #1 ·
Anyone here see a consistancy between case length and consistancy? for example, 5 cases measuring 2.010 and 5 that were 2.005?

I think im having a slight issue with this. Most of the time, if cases are under max, ill leave them alone, especially if they are under 2.010, because that is what my hand trimmer trims to, so ive got some variations here.

Thanks!

DS K.
 

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Anyone here see a consistancy between case length and consistancy? for example, 5 cases measuring 2.010 and 5 that were 2.005?

I think im having a slight issue with this. Most of the time, if cases are under max, ill leave them alone, especially if they are under 2.010, because that is what my hand trimmer trims to, so ive got some variations here.

Thanks!

DS K.
Length changes neck tension and length can also effect the support on the bullet as it begins to move into the lands as it comes out of the case. While these things are generally trivial in our "battle rifle world" they do come into play, at least theoretically, in the precision bolt gun world. No precision rifle shooter is going to shoot a match with differing case lengths. So yes there is "something" to it and I generally want all my case lengths the same for a given course of fire or match. Whether that has an "actual" effect that day, the theoretical value equates to a psychological value which means I have done everything I possibly can to make my ammunition perfect and that equates to more points To me, ammunition consistency is very important, and overall does effect how well a gun will shoot and it is something that can be measured.

Sooo, at least in theory, if your necks are different lengths of a batch you are going to shoot, the results should show up on paper.
 

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Not claiming to be the expert but I really don't think trim length variance makes any difference in accuracy that one could tell unless the rifle is an extremely fine tuned benchrest target rifle. Even then, I'm not sure. I think there are other factors that have far more impact on accuracy. As long as your cases are no longer than maximum, you're probably good to go. I remember back trying to trim cases with one of those table top hand turned jobs and the set screws working loose causing short cases.

Save buying a Giraud or Gracey, a very inexpensive way of getting good consistent trimming is the Lee system that has the case holder chucking in a drill. I set the drill between my knees with the case pointing up. Chuck in the case and hold the pilot/trimmer. It has a pin that bottoms out on the case holder preventing you from cutting too much. I think you can get the trimmer setup for less than $20 and case holder/pilot combinations for different calibers are about $5.
 

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If you have a custom chambered barrel, there could be an issue ( about a 10% chance).

If the chamber is reamed to only allow a 2005 length at the neck, anything longer will tend to crimp the case onto the bullet, forcing the pressure to increase more than normal before the bullet starts moving.

I had been fighting this problem in a Broughton barrel that Gene Barnett finished for me, so on that one I always trim to 2.005".
 

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Discussion Starter · #5 ·
Not claiming to be the expert but I really don't think trim length variance makes any difference in accuracy that one could tell unless the rifle is an extremely fine tuned benchrest target rifle. Even then, I'm not sure. I think there are other factors that have far more impact on accuracy. As long as your cases are no longer than maximum, you're probably good to go. I remember back trying to trim cases with one of those table top hand turned jobs and the set screws working loose causing short cases.

Save buying a Giraud or Gracey, a very inexpensive way of getting good consistent trimming is the Lee system that has the case holder chucking in a drill. I set the drill between my knees with the case pointing up. Chuck in the case and hold the pilot/trimmer. It has a pin that bottoms out on the case holder preventing you from cutting too much. I think you can get the trimmer setup for less than $20 and case holder/pilot combinations for different calibers are about $5.
thats one one I use. works great, and its pretty darn consistant.
 

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For case trimmers, (except the Gracie), hands down - Wilson. Do have to admit however, Lee does come up with really amazing products for amazingly low prices. Their meters are really good for the money, I mean really good.
 

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Some of the really, really obsessive-compulsive benchrest shooters worry about this; Sinclair even sells gadgets that allow you to check the real length of your chamber.

I do try to trim them all my brass to a uniform length, but there is always going to be some variation caused by brass hardness, 'dwell time' used while trimming (how long you allow the trimmer to keep turning once you think it's done cutting), phases of the moon, days of the week, etc.

IMHO, as long as the brass falls within an allowable tolerance range (say, .003" either way), that's about as close as a mere mortal is going to get it. Also probably as close as a Service Rifle shooter needs to get it.

If I were competing for money in either benchrest or long-range (1,000 yards plus) competition with a bolt gun (and hopefully using a limited number of pieces of brass), I might stress over that last .0005", and uniform bullet meplats, and 'point' my bullets again afterward, too! Me? I'd rather shoot than reload.
 

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Some of the really, really obsessive-compulsive benchrest shooters worry about this; Sinclair even sells gadgets that allow you to check the real length of your chamber.

I do try to trim them all my brass to a uniform length, but there is always going to be some variation caused by brass hardness, 'dwell time' used while trimming (how long you allow the trimmer to keep turning once you think it's done cutting), phases of the moon, days of the week, etc.

IMHO, as long as the brass falls within an allowable tolerance range (say, .003" either way), that's about as close as a mere mortal is going to get it. Also probably as close as a Service Rifle shooter needs to get it.

If I were competing for money in either benchrest or long-range (1,000 yards plus) competition with a bolt gun (and hopefully using a limited number of pieces of brass), I might stress over that last .0005", and uniform bullet meplats, and 'point' my bullets again afterward, too! Me? I'd rather shoot than reload.
Yes - in our gas gun world, its stretching what one will actually benefit from just little too far. Most cant hold good enough to actually see the difference any of this would make, and most would be hard pressed to see a difference from the bench. The act of trimming (besides keeping cases in spec dimensions) squares the case mouths and that probably has more of an effect than any minute differences in length, but whose going to trim cases a bunch of different lengths...?
 

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Discussion Starter · #9 ·
Excellent answers gentlemen, and I thank you.

I had some suspicions about it since I seem to get better accuracy when I trim the whole batch at once, rather than (if the cases are under spec) just resizing them. I was beginning to wonder.

Probably just need to go ahead and bed and shim the ol girl.
 

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Having checked a fair number of FGMM cases over the years, it seems Federal doesn't particularly worry about case length either. I've seen 0.015" variations in the same box of 20, never mind a 500rd case. Not particularly worried about case mouth chamfers, either, they aren't. Still it shoots very well out of both bolt guns and self-loaders.

That said, I still trim 'em and fret in all sorts of more or less stupid ways in order to make the best loads as possible. Does it help? Danged if I know. Don't shoot benchrest style often enough to do a "scientific" test.
 

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I use a Forster trimmer with a 3-in-1 outside/inside chamfer and length trimming tool. Donno if the length precision makes a big difference, but I'd do it anyway for the chamfering convenience.
 

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I size and trim after the first firing. From then on I use an X die, when I check them they run from 2.003 to 2010. Works for me.
 

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I always trimmed my 308 cases to 2.000, even when we shot the Hunter BR with full blown 308 in the 80s. The Giraud trimmer makes it too easy these days.
 

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Not claiming to be the expert but I really don't think trim length variance makes any difference in accuracy that one could tell unless the rifle is an extremely fine tuned benchrest target rifle. Even then, I'm not sure. I think there are other factors that have far more impact on accuracy.
I agree 100%!
 

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I have used (2) types of trimmers over the past couple of years, one was a Possum Hollow and the other was a Lyman rotary with pilot and although these are wonderful products and do a fairly excellent job my Giraud wins hands down (The Mrs. said buy it and save those hands and time)
I still have both if the electricity goes out MCORPS1

 

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Just one note on the trimmers mentioned above. I have a couple Graceys set up for my two main calibers (.308, .223). They are pricey but well worth the cost, especially if you go through a high volume of cases. The Graceys are a real pain to set up for different calibers, so I use a Wilson for the others that are low volume guns.

The Lee trimmer is cheap and it works great - for a while. The problem I kept having was that the index pin that sets the length kept digging a divot in the base piece. Then all my cases were short by the depth of the divot, and kept getting shorter as the divot got deeper. Probably not a problem if you don't prep a high volume of cases but it's something to watch for over time. After replacing the base piece several times, I gave up and spent some more money for a better tool.

EDIT: The Gracey is a lot less than the Giraud - around $280 pre-set for your stated caliber. http://www.matchprep.com/trimmer.htm
 

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The Giraud is pricey but I thank Doug everyday for designing and building this I sized and trimmed approx 750 cases a few weeks ago and I think it took me approx 2hrs, I don't do a ton of shooting but after getting the Giraud all I do now is load up all my brass and shoot till it's gone then do the brass prep thing all at once which starts off by tumbling for a few hours then size,deprime,trim,debur, chamfer and inspect after it come out out the tumbler to get the lube off and I can easily do a thousand or so over the weekend and not dread it.
As far as trimming I go with 2.007" +/- .001" and I don't think accuracy is affected by this as much a sizing is, my Springer is HS at 1.632" and I size my brass at 1.628" and this keeps things tight as far as movement in the chamber plus extends brass life by not over working it, awhile back I did some testing on sizing this way and got 10 reloads out of LC cases before I tossed them in the scrap bucket this is not something for the faint hearted but I was developing a load and wanted to use the same brass till I was done and I was amazed and the brass life I got, I posted up my results here along with pics so if you run a search you can find it. YMMV
 
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