Over All Cartridge Length

[ICEMAN]

I enjoy reading these threads....(except that I am learning how wrong I was doing my reloading before...  )

Next time I reload, I will definitely pay more attention....

[PA BEN]

OK, this is new brass. Winchester. 160 gr Nosler AccuBond, Mag. CCI Primer, 63 grs of RL22 which is max load. The Nosler books says 3058 MV. FPS. I grouped 1 1/8" at 90 yds. My O.A.L. was .013 to .02. I don't know why my die spread was that much. I'm new to reloading but it didn't mater the group w/good. The rest I was using wasn't that good, so these rounds will do for hunting. 

[PA BEN]

Without starting a new thread I thought I'd post this here.
Load Density http://www.gunnersden.com/index.htm.rifle-reloading-powder.html
I'm looking in my nosler book for my 7mm-08. I wanted to try RL19 w/150 gr Ballistic tip, but all the loads are 101% 2652 fps to 110% 2862 fps. After what I read you don't want to load over 90%. Cases that are full or compressed charges of powder will accelerate barrel wear in the rifle barrels throat area.
How many shots will it take to wear out a barrel using compressed loads?

[WDFW-SUX]

100's

[WDFW-SUX]

OK, this is new brass. Winchester. 160 gr Nosler AccuBond, Mag. CCI Primer, 63 grs of RL22 which is max load. The Nosler books says 3058 MV. FPS. I grouped 1 1/8" at 90 yds. My O.A.L. was .013 to .02. I don't know why my die spread was that much. I'm new to reloading but it didn't mater the group w/good. The rest I was using wasn't that good, so these rounds will do for hunting. 

measure your brass i bet its  not all the same length even if its new.  thats what case trimmers are for.

[PA BEN]

Isn't the bullet pushed in a certain amount? I'm just trying to under stand. Why should brass length make a difference? It seats the bullet by pushing on the bullet, not stopping on the neck rim?   

[JackOfAllTrades]

When seating, As the bullet is pushed into the neck, the neck comes up into the die and an amount of crimp is applied. -Especially with a Lee Factory crimp die. The Hornady reloading manual (and others) illustrate this very well. The objective of the motion is to have the crimp apply right as the bullet is seated/stops. There are many hunting/rifle bullets that have a canelure to crimp into but even those that don't, a correctly set die will still apply a small amount of crimp to the bullet/brass. Most rifle dies apply a taper crimp, (except the Lee Factory crimp die).  If your brass is long, more crimp will be applied. Short, less crimp. If the crimps are inconsistent, then the initial pressure build can vary across your rounds fired. That variable/inconsistent pressure spike can create harmonic as the bullet starts moving. Some loaders seat without any crimp applied, but the length of the neck, to extremes, still affects how the bullet starts when the powder explodes. Variables in crimp can account for as much as 50fps of bullet speed difference. 50fps difference down range can mean the difference of your groups of bullet holes touching or not.  It's the little things, (as I explained in my horsepower post), that build consistency for accurate cartridges.

Overall cartridge length is important. Overall CASE length is also important, if you're looking to wring the most consistency out of your reloaded rounds.

-Steve

[PA BEN]

I'm using Lee Collet Dies. Neck sizing die & Dead length bullet seater.

[WDFW-SUX]

When seating, As the bullet is pushed into the neck, the neck comes up into the die and an amount of crimp is applied. -Especially with a Lee Factory crimp die. The Hornady reloading manual (and others) illustrate this very well. The objective of the motion is to have the crimp apply right as the bullet is seated/stops. There are many hunting/rifle bullets that have a canelure to crimp into but even those that don't, a correctly set die will still apply a small amount of crimp to the bullet/brass. Most rifle dies apply a taper crimp, (except the Lee Factory crimp die).  If your brass is long, more crimp will be applied. Short, less crimp. If the crimps are inconsistent, then the initial pressure build can vary across your rounds fired. That variable/inconsistent pressure spike can create harmonic as the bullet starts moving. Some loaders seat without any crimp applied, but the length of the neck, to extremes, still affects how the bullet starts when the powder explodes. Variables in crimp can account for as much as 50fps of bullet speed difference. 50fps difference down range can mean the difference of your groups of bullet holes touching or not.  It's the little things, (as I explained in my horsepower post), that build consistency for accurate cartridges.

Overall cartridge length is important. Overall CASE length is also important, if you're looking to wring the most consistency out of your reloaded rounds.

-Steve

 

[JackOfAllTrades]

A Lee collet die is no different in concept than other premium dies.  Look at the photo, if the case is shorter, then the amount of crimp will be different than for a longer case.

[PA BEN]

OK, here's a picture of the target I just shot. I miked the brass for each round. This brass miked the same, but when I seated the bullet the 3 in the lower target were 3.35 to 3.36. The tight group was 3.31 to 3.33. My gun chamber is 3.39. It's not the brass but the die. I could have adjusted it to seat them deeper but I shot them to see what they would do. 160 gr AccuBound, 61.3 gr of RL19, CCI Mag. Primer, new Win. brass. BTW, this is a cheap rest.

[JackOfAllTrades]

So you're finding that setting the over-all length at ~3.32" provides the best groups with that powder charge? But how far from the lands is the ogive of the bullet?

Now prove it...  Load some more up identical to prove that you can  generate the same results. I'm assuming 100yds.

From the previous post/responses... Of this batch of five shots, were all the cases trimmed to the same length?

-Steve

[PA BEN]

Not trimmed but I miked them the same. W/RL22 & RL19 w/160gr AccuBond at 3.32 to 3.33 seems to be a good load. RL19 seems to be a little tighter on the group. And yes 100yds. Now, will once fired cases necked sized shoot the same.

[JackOfAllTrades]

Yes, once fired brass (from that gun's chamber), neck sized only, should shoot the same or maybe even better.  What you eliminate with that 'fireformed' brass, is the nano-second expansion that takes place with full length sized brass that can contribute to pressure fluctuation as the powder ignites. Not much, but every little variable that you can eliminate can certainly contribute to more consistent groups on target.

OK, there are even more tricks for more accuracy. We've already talked about pillar/glass bedding the action. You've floated the barrel. Could probably use a trigger job. I don't know that you need to lap the barrel.. There's truing the bolt to the breachface..

OK, I'm no gunsmith.

You could start weighing and separating your brass by weight. You could measure and separate your brass by wall thickness. Then there's the case and bullet concentricity guage.

 

I think you're doing fine for a hunting rifle though.

-Steve

[PA BEN]

It's fun now that I'm seeing results. But, I'm not into bench shooting for now. Just looking for good elk rounds for my tag I drew for my Sept. hunt. I think I'll use these 160's on deer this fall too.