OAL

[Hippy]

I shoot quite a few "Improved" rifle cartridges K-Hornet,Dashers and several Ackley . My question is OAL 1st lets use the Standard Hornet 1.403 MAX --K- said to be the SAME all of the formed Brass (Remington) struggles to be 1.385 I understand that there is NO standard for Improved cartridges especially the K-Hornet

How do I determine trim to length , Is it that important to have all of the brass the EXACT SAME OAL. ??

Thanx,
Jim

 

[Dusty Stevens]

You should do a chamber cast and measure that. I like to trim .010 shorter

 

[dkhunt14]

Sinclair has a gauge you put in your case and close the bolt and it pushes in to the chamber length. You buy it by caliber and trim a case short. Then you load it long and close the bolt. It hits on the end of where your neck is in the chamber and then you take it out and measure. Matt

 

[BillPa]

Another cheap way

Trim a sized case square, cut off a 'ring' maybe .100" long then trim the case again another 0.10 or so. Seat a bullet in the case short, just start the ring over the bullet the then chamber, extract then measure from the casehead to the forward edge of the ring. Its somewhat better method then using a generic gauge especially if the chamber is of the tight neck variety.

Of course one could make a number of these...

Same idea as the Sinclair gauges but can be made to size. For example I made two 25s, one for my .283" neck 250 Imp and one for a factory 25-06.

As far as the actual length I choose to have them a consistent length more so than a batch varying some where between the minimum and maximum.
Bill

 

[Brians356]

Or make your own adapter from a fired 22 LR case (for 22 cal) or 22 WMR case (for 6mm) for the Hornady L&L OAL tool (see my post from 03 June 2015 in this thread):

http://forum.accurateshooter.com/threads/headspace-gauge.3875237/#post-36585857

 

['Freak]

In Sinclair’s catalog it’s noted ~ that their “Chamber Length Space Gauges” won’t fit chambers cut for rounds having a thin neck wall such as factory .22 Hornet, .218 Bee, 30-30 Win., etc., or custom chambers cut for thin walled neck turned brass, except in 6mm where they make two gauges, one standard size and the other that no doubt has had its major diameter turned down a little bit more to .262" (?) for use in “Tight Neck” chambers.

 

[Brians356]

In Sinclair’s catalog it’s noted ~ that their “Chamber Length Space Gauges” won’t fit chambers cut for rounds having a thin neck wall such as factory .22 Hornet, .218 Bee, 30-30 Win., etc., or custom chambers cut for thin walled neck turned brass, except in 6mm where they make two gauges, one standard size and the other that no doubt has had its major diameter turned down just a little bit more for use in “Tight Neck” .262” chambers.

Is that .262" figure correct? That would require turning necks to only .009" to leave .001" total clearance.
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['Freak]

Is that .262" figure correct? That would require turning necks to only .009" to leave .001" total clearance.
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Says to the right of item #749-000-751 “ Tight Neck .262” “ which may well be the major diameter out on the business end of their “tight-neck 6mm chamber length gauge”, and probably/more likely NOT meaning sized specifically for 6mm chambers cut with what would be a silly tight .262” neck diameter.

 

[dkhunt14]

The bulk of the PPC guns are chambered in .262 neck. That is probably why they offer a .262. Matt

 

['Freak]

The bulk of the PPC guns are chambered in .262 neck. That is probably why they offer a .262. Matt

So, what’re the 6mm PPC, .262” chamber neck guys doing, first sorting for the bullets’ major OD then adding a thousandth clearance to it, to come up with their finished “turn to” neck wall thickness to the ten thousandth?

 

[Webster]

I shoot quite a few "Improved" rifle cartridges K-Hornet,Dashers and several Ackley . My question is OAL 1st lets use the Standard Hornet 1.403 MAX --K- said to be the SAME all of the formed Brass (Remington) struggles to be 1.385 I understand that there is NO standard for Improved cartridges especially the K-Hornet

How do I determine trim to length , Is it that important to have all of the brass the EXACT SAME OAL. ??

Thanx,
Jim

You are not shooting competition calibers. Does it really matter what the trim length is as long as the bolt closes easily? The front of the chamber where the end of the neck ends is squared off. If you were touching this area it would be a dead stop. If the cases were a little tight extracting from trying to grow longer after firing I would trim another 5 thou off. I would just measure a bunch of cases that you have and trim a few thou under what they are. I cannot think of any problem caused by doing this.

 

['Freak]

You are not shooting competition calibers. Does it really matter what the trim length is as long as the bolt closes easily? The front of the chamber where the end of the neck ends is squared off. If you were touching this area it would be a dead stop. If the cases were a little tight extracting from trying to grow longer after firing I would trim another 5 thou off. I would just measure a bunch of cases that you have and trim a few thou under what they are. I cannot think of any problem caused by doing this.

A case mouth that has been left too near the far end of the chamber’s neck can on firing effectively crimp down on the bullet impeding the bullet’s release so causing pressure to spike.

 

[Brians356]

I found reamer drawings and some are indeed .262" in the neck.

As the freebore will be ~.2433" even if you use a .262" chamber gauge in a standard .276" 6mm chamber, it will contact the short (.010") 45-deg transition ramp between the neck and the freebore in the middle somewhere, and worst case it might add an extra ~.005" to the chamber length measurement. No one should be using cases long enough that such a reading could get them in trouble.
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[dkhunt14]

So, what’re the 6mm PPC, .262” chamber neck guys doing, first sorting for the bullets’ major OD then adding a thousandth clearance to it, to come up with their finished “turn to” neck wall thickness to the ten thousandth?

Most are turning to .008 walls. Some even go a little thinner and run .004 clearance. Matt

 

[Webster]

A case mouth that has been left too near the far end of the chamber’s neck can on firing effectively crimp down on the bullet impeding the bullet’s release so causing pressure to spike.

OP statement:
I shoot quite a few "Improved" rifle cartridges K-Hornet,Dashers and several Ackley.

The OP stated that he has already fired all of these calibers many times without problems. So trim to length apparently isn't a problem in any of his rifles with his cases. It sounds like none of his cases are too long. He just wants someones opinion on a standard trim length which was probably never published. When people get custom chambers they need to ask the gunsmith for the brand and reamer number. The gunsmith must get a copy of the blueprint when he buys the reamer. It would be nice if the gunsmith made a copy of the blueprint for each customer. The gunsmith can use calipers to measure the max chamber length for the neck. A lot of non comp people don't even know what the freebore is after the gunsmith finishes the barrel.

Without much effort I found many wildcat trim lengths. Just Google for the caliber. You really need the blue print for your reamer since there may be many versions of a wildcat (shoulder angle, free bore, trim length, throat angle ect.)

Berger Reloading Manual
257 roberts IMP 2.223”
6mm Rem Ack IMP 2.220”
Standard 22 Hornet 1.393”
22 K Hornet 1.368”
17 Ackley Hornet 1.395”

http://www.6mmar.com/243_Imp_30_.php
243 Win Imp 30°

 

[Brians356]

The OP actually asked if having all case trimmed exactly the same length was critical, as his cases vary considerably in length. In order to make them all equal, he will obviously need to trim to the shortest of the set.
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[Webster]

The OP actually asked if having all case trimmed exactly the same length was critical, as his cases vary considerably in length. In order to make them all equal, he will obviously need to trim to the shortest of the set.
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His rifles are varmint hunting calibers. He is not trying to shoot 0.250" 25 shot aggregates. He will never see the difference on the target if the cases are not the same length.

 

[BillPa]

His rifles are varmint hunting calibers. He is not trying to shoot 0.250" 25 shot aggregates. He will never see the difference on the target if the cases are not the same length.

True, it may not help but it sure ain't gonna hurt none.