Help! Case lenght before trimming

[manitou210]

I am preping New Lapua 223 rem brass for F class shooting, I trim to 1.750" with wilson Sinclair trimmer, 50% of brass is 1.750 to 1.754"The problem is 50% of brass measures 1.749",1".748 and few 1.747" I need brass all same lenght to set neck turner
Vt reloading says to trim to 1.752" Lyman says to 1.750"
To make all brass same lenght I would have to trim to 1.747"
is this to short. any dangers or problems doing this ???
Manitou

 

[bsc4444]

The 50% that is longer I would trim to 1.750. The rest I would load and fire form them to your chamber, resize and check for OAL. I bet they will be in the 1.750 range.

Brad

 

[camac]

Good suggestion by Brad, the other thing you can try is put them through your FL die a few times with expander button installed. This can stretch them a bit (sometimes depending on the taper in ball and die).
This aside thou, I have faced this many times and if your chamber is a no neck turn chamber you can just shoot the first few matches before trimming and turning the necks.
I also see no harm in trimming them all the extra 3 thou (otherwise your short ones would be "dangerous" and Lapua liable).
Cam

 

[Rust]

I have to ask, are you using a tight neck chamber where neck turning has to be done to even fit the chamber?

If you are not, why would you bother to neck turn Lapua brass?

 

[fdshuster]

Get the Sinclair chamber over all length for 22 cal., page 39, catalog# 2010-A, item #G-224, $6.95, reusable for any and all 22 centerfire chambers, and get the actual chamber length of your barrel. You may be trimming away case necks to a much shorter length than is necessary. The 223 Rem. already has a short neck. I've measured factory chambers, (and some custom also) that are as much as 1.785". And, yes, I also do not understand why you're trimming Lapua 223. I use them as is, right out of the box, for my .253" chamber necks with loaded round neck diameters of .250".

 

[gunrac]

Get the Sinclair chamber over all length for 22 cal., page 39, catalog# 2010-A, item #G-224, $6.95, reusable for any and all 22 centerfire chambers, and get the actual chamber length of your barrel. You may be trimming away case necks to a much shorter length than is necessary. The 223 Rem. already has a short neck. I've measured factory chambers, (and some custom also) that are as much as 1.785". And, yes, I also do not understand why you're trimming Lapua 223. I use them as is, right out of the box, for my .253" chamber necks with loaded round neck diameters of .250".

Agreed. Get the gauge. I think a lot of people over trim going with sammi specs because they have know way of measuring their chamber.

 

[6BRinNZ]

Without trying to change the topic, when do most people RE-TRIM for OAL? Do you do it based on a certain amount of case length growth or when its approaching chamber tolerances?

I ask on the basis - I assume everyone trims OAL on new brass so that there is a consistent OAL and the case mouths are square.

 

[camac]

I trim and minimum turn my new or once fired Lapua brass to take out the variations in wall thickness, even with no turn chambers. Some batches are very good but others not so. The biggest variation seems right near the mouth (exactly where the neck bushing or bullet seating will be affected most). I see no loss in accuracy but I do see an improvement in runout in my loading system. Other BIG reason is neck tension. For long range I like to have consistent neck tension to try and lower es. Minimum neck turning and fairly regular annealing (I am reasonably confident) are helping me with this (judged by feel for neck tension and es has definately come down with all the processes I go through). There is no doubting some fantastic results are coming from no turn necks so all this is probably not making a huge difference but neck turning and trimming (even with no turn chambers) is for those that like to do everything they can but it is a lot of work. It is a topic you will find people on both sides of the fence and with fair reason.

 

[camac]

Sorry - I would like to make a few more comments on this for discussion - I agree on the short neck of the 223 and if I still owned one would probably scrounge for every bit of length I could get. BUT there is the other side of this on runout again. If you don't trim the necks (turning aside) and get them nice and square with a good chamfer, neck bushings and bullets will not want to run in straight.

 

[fdshuster]

6BRin NZ: I let em stretch, to within .010" of chamber length. Two of my 6BR chambers are 1.570" in length, so anything over 1.560" gets trimmed off. With the tight, fitted necks and controlling headspace two other chamberings have 1.540" chambers, so that brass stays at 1.530" maximum, but trimming is seldom required since there is little stretching. When I spec a chambering reamer, chamber over-all-length is one of my requests, always .010" longer than max case length. camac: Agree with everything you say, and starting the bullet straight in the case mouth is my main reason for inside taper neck reaming using the K&M tool. Also the reason I consider the case neck the most critical portion of the case, and don't hesitate to keep it very clean, and do not use the inside neck expander with my neck bushing dies. My runout problems are minimal, all rounds are checked with the Sinclair gauge, identified, segregated, and used accordingly.

 

[6BRinNZ]

Frank - when you re-trim do you take them back to the original trimmed length? I have wondered how many thou in neck length variation it will take before it affects things. i.e do you trim once the case meets your chambers length minus .010+ or do you just trim to maintain the case at this "max length" once they have stretched?

Manitou - sorry if I am getting this off your original question

 

[fdshuster]

6BRinNZ: .010" is the magic number, I don't let them get any closer to the end of the chamber than that. Several of my 223 chambers were cut with my reamer that has a chamber length of 1.770", so they are kept at 1.760" maximum, and if they happen to be a little shorter (-.005" or so), usually due to starting out shorter when new, they are used with all the rest. I don't like to see a gap any longer in front of the case mouth, since this area will fill up with a ring of carbon, as seen with my borescope. A similar situation when shooting 22 Shorts in a 22 Long Rifle chamber, only in that example it's wax and bits of lead that's building up.

 

[6BRinNZ]

Frank - thanks, info appreciated.

 

[camac]

Frank I agree with having them all the same length for that reason in addition to the others too. I also think the carbon is one of the reasons very low neck clearance can be an issue. Especially in the 6.5*284 - carbon gradually creeps back under the neck after repeated firings and starts to "impinge" on the bullet by not letting neck "flare" as much. Recently as I started measuring more shells out of my chamber for runout I noticed most were very good but a few had over 1.5 thou runout in neck. These came from the last few firings before cleaning.

Back to the original question though guys. Frank do you see any "isues" with him trimming them back. The only ones I see are

1) depth of seating and the corresponding neck tension, straightness etc. 3 thou difference when you are trying to seat around 200 thou plus should not have a big effect.
2) From a "flaring" and sealing the chamber point of view I don't see much issue either. It should still seal chamber well.
3) From Carbon point of view they are better off being all equal as Frank pointed out.
4) From a loading point of view they are better off being all square and chamfered.
5) From a neck turning perspective they are better off being all equal and trimmed.
6) The one downer for me and it is a bit of a clincher is I only like to partially neck size and leave a little neck unsized for alignment in chamber and seating dies. I had a lot of difficulty way back going from 222 to 223 for that reason. So I personally would chase as much neck as I could by sorting match and hunting rounds then trim and turn the match. Of course they need to be sorted by weight too as per the reason we buy a lot of shells to select a few for matches.

All that being said Manitou it is still in debate whether all this work we do helps??? Some very well respected shooters do not neck turn, and some do not bother with runout either and these guys win big events. These issues are really finally left up to the individual to decide whether they will bother doing it and do they see the benefits.

 

[fdshuster]

camac & others who may be interested: The new issue of "Precision Shooting", (May), has a very informative article by the always knowledgable Norman E. Johnson regarding the importance of case necks. He advocates neck turning in almost all circumstances for those interested in accuracy. Also considers case neck annealing to be very important, something I've never gotten involved with/ yet.

 

[manitou210]

Thanks everyone for responding, the reason i want all brass the same lenght is to set case neck turner to just meet the shoulder and not cut shoulder of case. I have done this with more than 700 Lapua cases but the last two orders have had many to short.
I would have to shorten by 30, 000 to get brass all same lenght or not use 40% of brass, have talked with dealer and he replaced 400 but same problem to short and am concerned this could be a safety problem ?
Shoot F class in Canada F/TR 308 & 223 only.
The 223rem is not hard to get to shoot well but for me uniforming primer pockets inside as well,neck turning using Hoover bullet pointer,Redding Competition dies, digital scales to within .01g this is extreemley important 1/10 gr of powder is 8"
to10" at 1000y brass sorted in 1/10gr
Have shot 90gr Bergers to low 2900fps out of 30" barrel 1/7 twist, Barnard action have shot under .600" at 300y and fellows with similar guns 28" 1/7 twist don't shoot the same small groups, I could be wrong but they do no brass prep,and they use the RCBS 1500 electronic powder measure, and they can be +- 1/10 g
All this probably doesn't mean a hoot as I am not good at reading wind
manitou

 

[camac]

Manitou, I thought in your first post the shells were 3 thou, not 30 thou short. 30 thou is a lot and should definately be sent back to Lapua.
Thanks Frank for the lead. Cheers.