Possibility of getting 1.550" case length or so after FF a 6 Dasher?

[jjhall91]

The best length I've ever regularly gotten when FF a 6 dasher is 1.4555". My reamer is a JGS (6 Dasher BB - Bartlein Barrels) with a 1.5550 chamber (thank you, Frank!).

Some time ago I read a post by Jim O'hara stating he regularly realized 1.5500" to 1.5530" when he FF the dasher. Later, I found his chamber was 1.7000".

Based on the above, here is my question(s):
>Why not have a gunsmith extend the 1.5550" chamber in a FF barrel to 1.700" in an attempt to duplicate Jim's case length +-.
>What is the main benefit of a longer case neck/case in a dasher (less carbon, more accuracy, other?). In other words is it worth the effort.

I look forward to thoughts on the matter.

Thanks,
Jack

 

[Ccrider]

Better question- Does size matter?

 

[johara1]

This was beat to death for a long time Yes you can get 1.550-1.553 from blue box brass. All of this was done for a 1.560 chamber, It is a lot of work to do it right, a lot will say it doesn't matter, but they can't do it so they are content to say they are happy with short cases of all different lengths. Do a search and find out how to do it right..... jim

 

[Rset]

This was beat to death for a long time Yes you can get 1.550-1.553 from blue box brass. All of this was done for a 1.560 chamber, It is a lot of work to do it right, a lot will say it doesn't matter, but they can't do it so they are content to say they are happy with short cases of all different lengths. Do a search and find out how to do it right..... jim

Or don't worry about the neck length in the fist place since is has no bearing on the result on the target. Do not fear short necks. they work. As for the "all different lengths", you can always trim them to the same length.

 

[jjhall91]

This was beat to death for a long time Yes you can get 1.550-1.553 from blue box brass. All of this was done for a 1.560 chamber, It is a lot of work to do it right, a lot will say it doesn't matter, but they can't do it so they are content to say they are happy with short cases of all different lengths. Do a search and find out how to do it right..... jim

Thanks for the response. I will research.

Today, as a matter of fact, I had the most success, ever. I have a 100 yard range out back. I neck turned 10 Lapua brass to .0125. Used a .264 bushing to get .003 neck tension. Hard jam .030+-. (I was going to use 205 Fed primers, but forgot and used the CCI 450s.) I cleaned the chamber with brake cleaner and made sure the cases were absolutely clean.

I started with 30.0 grains of IMR 4064 (saving the H4895 and Varget)and increased by a .001 each load. By the time I got to 30.4 grains I realized 1.5485 length. Unfortunately, it started raining at that point.

Because there were zero signs of pressure, I'm going to try 30.5, tomorrow. I was thinking of "roughing" up the chamber a little to see what happens (FF barrel).

Jack

 

[jjhall91]

Or don't worry about the neck length in the fist place since is has no bearing on the result on the target. Do not fear short necks. they work. As for the "all different lengths", you can always trim them to the same length.

Thank you, Rset. Glad to hear that about accuracy not being effected. I honestly can't say I can tell the difference in accuracy to the many different case lengths I've tried. I've even shot loads that varied .005 in length and had good groups (good to my standards anyway).

I have a scope and the carbon does seem a slight bit worse when using lengths less than 1.4200 or so. But I can't say with certainty.

Could I ask you what the shortest length you'd shoot? I have some in the 1.4000 range that I've never dared to shoot. Is that too short?

Thanks for the help!

Jack

 

[Olde Man]

As my memory serves me the longer that I could make the neck the more free bore I could use which kept me out of the shoulder neck junction. The dreaded "Doughnut Area".

 

[johara1]

Or don't worry about the neck length in the fist place since is has no bearing on the result on the target. Do not fear short necks. they work. As for the "all different lengths", you can always trim them to the same length.

You just keep believing that...... BTW were do you compete and how often do you win to make those kind of statements?? ..... jim

 

[johara1]

As my memory serves me the longer that I could make the neck the more free bore I could use which kept me out of the shoulder neck junction. The dreaded "Doughnut Area".

no, the longer the neck the more bullet is in it, as you move into the lands. nothing will change the length from the end of the free bore to the neck shoulder area except throat advancement...... jim

 

[Olde Man]

Exactly, I extended my throat length to accommodate this.

 

[MTlager]

I FF 6 br cases to dasher with cream of wheat and bullseye with a false shoulder in a spare barrel and get 1.555 to 1.560. When FF with bullet they run 1.540-45. Some of my reamer prints say 1.550 but there actually 1.565 for oal

 

[NorCalMikie]

Most reamers cut the chambers "about" .020 LONGER than the Max Trim length.
I don't own or shoot a Dasher BUT, my guess is you set the brass length to YOUR measurements? It IS a wildcat right?? You and 10 other Dasher shooters will probably all have different lengths.

 

[jjhall91]

I FF 6 br cases to dasher with cream of wheat and bullseye with a false shoulder in a spare barrel and get 1.555 to 1.560. When FF with bullet they run 1.540-45. Some of my reamer prints say 1.550 but there actually 1.565 for oal

That's amazing! You are doing something(s) right. I tried FF using Red Dot and paper towel remnants, but couldn't get what I was looking for. It was sort of the same thing with hydro forming. In both cases the shoulders weren't as sharp as when using bullets and the false shoulder method or just a tight neck and hard jam.

 

[jjhall91]

Most reamers cut the chambers "about" .020 LONGER than the Max Trim length.
I don't own or shoot a Dasher BUT, my guess is you set the brass length to YOUR measurements? It IS a wildcat right?? You and 10 other Dasher shooters will probably all have different lengths.

I've no doubt you're correct, at least to a certain degree. Magnify that by comparing a 1.5000 to a chamber to a 1.7000 chamber and there has to be a difference in FF length (my opinion/theory). If one could get a length he/she sought after simply by extending the chamber in a FF barrel it would make things so much easier.

I had the 6ppc barrel that came on the action chambered with the same new dasher 1.5555 reamer. I now have a second barrel that's lost its pinpoint accuracy and will be used for FF. I'll have the chamber pushed out to say 1.5700 and see what happens when using the identical loads used in the 1.555 chamber.

If nothing else it should prove or disprove my theory.

 

[Ccrider]

I will research.

Well. If you have researched, like me several months ago, your head spun so fast that it popped off and landed on the floor.
Put your head back on your shoulders, clean up the mess, and rest assured with the conclusion that there is no definitive right answer. There are guys on here that are top notch that insist on shooting with longer Dasher brass, and those that have set records shooting shorter brass.

You will have to find what works for you in your barrel and ride with it.

 

[tom]

Look for consistency in the lengths, and make changes as necessary to get them as consistent as possible. That leads to more consistent volumes and just better overall brass. I was always coming up with brass that were very consistent, but always on the short side. I've had good luck with short brass in long chambers as well, but never was that brass ever inconsistent in it's "blow lengths" .

Tom

 

[jjhall91]

Well. If you have researched, like me several months ago, your head spun so fast that it popped off and landed on the floor.
Put your head back on your shoulders, clean up the mess, and rest assured with the conclusion that there is no definitive right answer. There are guys on here that are top notch that insist on shooting with longer Dasher brass, and those that have set records shooting shorter brass.

You will have to find what works for you in your barrel and ride with it.

Uhm... How can I do that without experimentation?

I'm not questioning the accuracy factor as much as the carbon situation as I posted, above. My bore scope seems to indicate a more difficult carbon ring and more carbon in the grooves closer to the chamber when using short brass.

If one can find a simple and cost effective manner to "potentially" increase accuracy and limit carbon, why not use it!?

 

[jjhall91]

Look for consistency in the lengths, and make changes as necessary to get them as convenient as possible. That leads to more consistent volumes and just better overall brass. I was always coming up with brass that were very consistent, but always on the short side. I've had good luck with short brass in long chambers as well, but never was that brass ever inconsistent in it's "blow lengths" .

Tom

Tom, as you say "...consistency and convenience...". That's what I'm looking for. These combine to create a better experience.

While I have no proof longer cases are more accurate or even prevent more carbon (although it does make sense) I agree consistency is what it's all about. It will cost me $80 dollars to have my FF barrel chamber moved from 1.5555 or so, to 1.7000+- One would have to agree this cost is less than negligible.

As I see it: while there are some who say shorter can result in less accuracy and more carbon, I've heard no one say that longer has potential for detriment. It may not be better, but it seems there are no risks/questions as there is to short. Therefore, logic maintains a longer case poses no assumed risk, only potential benefit, and should be the obvious choice.

Tom, this is just my theory/opinion, but I see it making sense until someone dispels it.

Thanks for your input.

Jack

 

[tom]

Tom, as you say "...consistency and convenience...". That's what I'm looking for. These combine to create a better experience.

While I have no proof longer cases are more accurate or even prevent more carbon (although it does make sense) I agree consistency is what it's all about. It will cost me $80 dollars to have my FF barrel chamber moved from 1.5555 or so, to 1.7000+- One would have to agree this cost is less than negligible.

As I see it: while there are some who say shorter can result in less accuracy and more carbon, I've heard no one say that longer has potential for detriment. It may not be better, but it seems there are no risks/questions as there is to short. Therefore, logic maintains a longer case poses no assumed risk, only potential benefit, and should be the obvious choice.

Tom, this is just my theory/opinion, but I see it making sense until someone dispels it.

Thanks for your input.

Jack

While it's not proof by any stretch. At a time I shortened up my reamers on purpose for this very reason. I struggled with a handful of barrels. I concluded, without proof, that chamber length was the only change I made to cause those struggles. I went back to the longer chambers and wound up back to great barrels one after another again. This was years ago, and not scientifically proven, but is my experience. I also had those same thoughts/theories back then, and is why I tried it.

Tom

 

[DJSBRS]

IMO, to get to 1.570 AOL on a Dasher, it will thin the side walls each time you fire it in your chamber. The brass has to flow forward to get there. Depending on your chamber and condition of your chamber wall, is where the brass will grip upon firing and how much flows forward. Lapua brass comes out of the box approximately 1.555. Fire form it and it will be around 1.545 or hydro-form with 50,000 psi and it will form back to 1.535 to 1.540. Why would you ever want to buy a new reamer neck length 1.570? 1.570 provides more room for carbon rings.

There is plenty of neck at 1.540 to use provided you throat the reamer to maintain the bearing of the bullet at just above the neck shoulder junction. You will wear out the throat for the best accuracy duration of the barrel before you run out of neck to seat your bullet.

No need for a 1.570 chamber.

DJ
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