Feedback requested on a new 6.5 wildcat design

[scottl0000]

Hey there folks,

I have spent some time working the numbers and am thinking of the design outlined below for a new,as far as I know) wild cat. From my preliminary numbers, it looks like the cartridge may fill a nitch for 1k shooters, as well as hunters like myself and possibly,though I'm not sure of the feed implications of such a design and am looking for input here too) for the AR shooters.

I focused on 4 major design constraints:

1)Case capacity approximately half way or slightly more, between the .260 Rem and 6.5x.284 Winchester
2)Had to be able to function through a short action repeater, using most 139 to 142 grain bullets seated as close as possible to the junction of the neck and shoulder. If any bullet types needed to encroach on the powder space, this was to be minimized as much as possible.
3)Needed to be formable from a case that was readily available, and of very good quality
4)Utilized a long neck to allow for greater variety of bullet weights and configurations in the 123 to 142 range if desired, while still maintaining at least .25 grip on the bullet with all desired bullets,also potential minor benefits on minimizing throat erosion)

Here are the rough numbers I come up with on paper. Any feedback would be extremely appreciated as I suspect most all up here have more experience than myself on this sort of thing plus I'm doing on-paper calculations as my copy of Load From a Disk won't arrive for several days from Texas. I'm referring to it as the 6.5 SLiC,Slick Little Cartrige) and it's based on a shortened WSM case, necks turned and reamed. I plan on using the same WSM body taper as well.

6.5 SLiC
6.5 SLiC Neck vol. 4.8503 gr.
6.5 SLiC Shld vol. 4.8053 gr.
6.5 SLiC Base vol. 52.1996 gr.
6.5 SLiC Total vol. 61.8552 gr.
Neck length 0.350
Shoulder Angle 35 degrees
Base length excl. web 1.115
Length to neck/shldr 1.475
Case OAL 1.825
Est. Cartridge OAL 2.800 ,appx. according to limited # of sample bullet measurements and depending on throating depth)
* 6.5 SLiC Usable vol. 57.00 gr.
,* Usable volume was calculated as the sum of the base volume plus the shoulder volume)

This should come out about right for my case capacity goal - my figures show the "Usable volume",capacity up to the neck/shoulder junction) of comparable cartridges as follows:
6.5 WSSM Usable vol. 49.07 gr.
.260 Rem Usable vol. 49.64 gr.
6.5x.284 W. Usable vol. 62.84 gr.
.270 WSM Usable vol. 73.34 gr.

... so the usable volume would be 5.8 grains less than the ever-popular 6.5x.284 Winchester, with the hopes it will tread quite closely on the velocities as the case is shorter/fatter; it's also anticipated that having a capacity of about 6 less grains will improve the barrel life several hundred rounds. Lastly, it should better the velocities of the .260 Rem or even the .260 Rem Ackley Improved quite noticeably.

Any feedback would be much appreciated - I'm thinking of ordering up reamers in the next couple of days so suggestions on improvements would be great! Thanks everyone for your time.

Scott L.


P.S. Editting as I just remembered one last thing... was considering a outside neck diameter of .293 similar to the 6.5x.284 Winchester and substantially neck turning&reaming accordingly - any feedback on that dimension also would be great -thanks again!

 

[CatShooter]

"... so the usable volume would be 5.8 grains less than the ever-popular 6.5x.284 Winchester, with the hopes it will tread quite closely on the velocities as the case is shorter/fatter;

Short and fat does not equal more velocities for the same amount of powder - if the case is 10% smaller, no matter what shape, and the maximum pressures are the same, it will be a slower cartridge.
If it is half way between the 260 Rem and the 6.5x284, then it's performance will be halfway between them - there are no free lunches.

"... it's also anticipated that having a capacity of about 6 less grains will improve the barrel life several hundred rounds. Lastly, it should better the velocities of the .260 Rem or even the .260 Rem Ackley Improved quite noticeably.

It will probably be equal to the 260 AI, but you won;t have the advantage of quality brass - like Lapua.

I think you are tossing good money down the toilet, while there are rounds that are equal to what you want, ready to go.

A 260 AI will do exactly what you want - and with Lapua brass, and a no turn neck, will be a joy to own.


.

 

[scottl0000]

Hi Catshooter;

Thanks for your reply! I'm not entirely following on a couple of your comments actaully and thought I'd ask.

First, definitely agree - won't likely equal the velocities of the 6.5x.284 - just stating it should be fairly close,somewhere between the .260 and 6.5x.284 to be sure, but I'd suggest it actually will be somewhere between the .260 AI and the 6.5x284 actually, right? As you said, no free lunches, and this should have more capacity than the .260 Rem AI, but without having to seat 140-class bullets down into the case to get it to function in a short action. That's the key here as to why I didn't go with the .260 Rem AI... if you want to use 140s in a .260 Rem AI,or the standard .260 Rem) in a short action repeater, you have to drop the bullets down into the boiler room and thus you actually reduce your powder capacity significantly over using the 123 to 125 grain bullets. I'd really like to get better velocities with the 140s than either of those cases offer, and still use a short action.

Also, you mentioned the question of quality brass; actually Shooters Supply sells 300 WSM Norma brass now for not much more than the 6.5x.284 Winchester Lapua brass - but if there have been problems with any of the 300 WSM Norma brass it would be very useful to hear about it as I'd rather know now than later of course

Thanks again for your thoughts and appreciate your time and feedback.

 

[CatShooter]

I understand your desire to have 140~ish bullets seated out...

I guess I've gotten old enough to look askew at projects like these.

Converting actions to feed really short fat cases is an iffy proposition.

Remington offered a 6mmBR repeater for a very short time, and found that the feeding problems could NOT be over come, so they took them off of the market - and the 6mmBR is not as radical a case design as what you are proposing.

I no longer go "Oooo ahhh" at projects that try to combine every want in the world, into one case. Too many of them are one reamer wonders...
... if you want a 55-57 grain case, and want it to feed 110% reliably, and you want to seat bullets out in a long leade, then build a 6.5x284 on a long action and load it to 45Kpsia.

I think the case you are envisioning is not a winning combination.


.

 

[Cheechako]

Scott

Kitty shooter and I disagree on a lot of things but he makes some very good points here. We're both really old cynics, BTW.

One thing I didn't see mentioned anywhere is the velocity you want to get and the type of powder you want to use. Both of these will play a big role in barrel life. Those, and the barrel length, really should be major factors in how much case capacity you need. An inch or two more barrel may result in a better cartridge and a larger capacity case could mean several hundred extra shots before your barrel becomes a tomato stake.

I'd also concentrate on ONE bullet weight so that I could choose the most-nearly correct twist. Over the years I've found that it's nice to talk about a wide range of bullet weights but I usually end up with just one in the long run.

I would take a good hard look at the quality of the brass you intend to use. "Norma" doesn't always mean the highest quality. Look at other things such as hardness,primer pockets loosening) etc.

I'm not a big fan of the WSM, WSSM, RSAUM types of cases so I'm a bit biased. That big rim size does require a unique bolt face, there is more bolt thrust, feeding,if you intend to do that) could be problematic. Things like that.

If it was me, right off the top of my head I'd take the 6.5/284 LAPUA case, shove the shoulder back to 30 degrees creating a longer neck, ending up with the same case capacity you are after while eliminating most of your bullet seating problems.

NOW, having said all that - Go for it! I'm a certified wildcatter myself and I would never want to discourage anyone from designing their own offspring.

Good Luck

Ray

 

[scottl0000]

Hi Catshooter and Ray,

Thanks for the input. Catshooter, one of the items you mentioned left me thinking... you said:
"Remington offered a 6mmBR repeater for a very short time, and found that the feeding problems could NOT be over come, so they took them off of the market - and the 6mmBR is not as radical a case design as what you are proposing."
... so this case is close to .240" longer in the body than the 6mmBR, wouldn't that make chambering actually more reliable, all things being equal? It also has a longer neck. Can you clarify what's more radical than the 6mmBR? Inquiring minds want to know

Ray, good points too! So I already have a Lilja 6.5 1-in-8 twist, 3 lands barrels ready to goSo that part is decided for me Out of this particular gun I'm trying to go for 130-grain Accubonds or 140-grain Nosler Partitions, but would definitely like to play with the 139-142 grain target bullets as I hear they are quite accurate and huntable as well. But I'm strongly, strongly hoping to stay with the short repeater action. I looked at shortening the 6.5x284, but from my preliminary figures, it looked like to meet the goals of not seating 140s past the neck/shoulder junction, I would only end up with about standard .260 velocities, which i'm trying to better by 60 to 75 fps out of a 24" barrel on this first gun,longer version to follow later if it proves worth while.) Can the 6.5x.284 be shortened enough to feed 140 grain bullets in a short action repeater and get noticeably better velocities than the .260? Thanks for your thoughts, it's very appreciated.

 

[chrisj]

The 6.5-284 can attain over 3100 fps with 139-142 bullets in kost rifles. .However...most shooters go within the 2950-3000 velocity range. A 260 Ackley throated properly will do 2950 in a 26" bbl. If you go with a longer bbl, you will be right around 3000 fps. My point is that there really is no cartridge needed that falls between the 260 AI and 6.5-284. Bbl life is a bit better with the 260 AI, but not that much from my experience.

Chris

 

[CatShooter]

Hi Catshooter and Ray,

Thanks for the input. Catshooter, one of the items you mentioned left me thinking... you said:
"Remington offered a 6mmBR repeater for a very short time, and found that the feeding problems could NOT be over come, so they took them off of the market - and the 6mmBR is not as radical a case design as what you are proposing."
... so this case is close to .240" longer in the body than the 6mmBR, wouldn't that make chambering actually more reliable, all things being equal? It also has a longer neck. Can you clarify what's more radical than the 6mmBR? Inquiring minds want to know

The case you are proposing in more fatterer, so even though it's 0.25" longer, it will have feeding problems.

What is often overlooked in these projects is that cartridges like the 300 H&H, the 270, and the 30-06 NEVER had feeding problems - they slipped into the chambers like greased owl poop.

As cases get shorter and fatter, getting them off the rails and into the chamber gets to be tougher and tougher.

Little fatties like the WSSM family are pigs to get to feed - they work,sorta OK), but only in an action that was designed and manufactured to feed them... conversions to the WSSM family are notorious for being in the shop more than they are in the field.


And I too, am a "wildcatter",in remission - 12 steep program) - my most infamous was the "224 longneck"... it was a one reamer wonder. You could have hidden a 224 75gr A-Max in the neck


.

 

[scottl0000]

Hi ChrisJ,

The problem is that I cannot fit the 6.5x.284 into the desired short action... and the .260 Rem AI is very close to what I'm looking for,and the most likely non-new wildcat I'd go with), but still requires that for a short action I would need to seat the 140s deep into the case, right?

Catshooter - very funny and good points, thanks! I have heard that many times these feeding problems can be solved with going to a HS Precision pro center feed box magazine. By any chance of you,or otheres reading the thread) had experience using these? If so, did they correct any feed problems you may have had?

Thanks again,
Scott

 

[CatShooter]

Hi ChrisJ,

The problem is that I cannot fit the 6.5x.284 into the desired short action...

Thanks again,
Scott

I know this is a dumb question, but why do you have your little heart set on a short action.

Hell... If I was building a fast twist 243, I would put it in a long action.


.

 

[Cheechako]

. . .If I was building a fast twist 243, I would put it in a long action. . .

Scott

Once again I find myself agreeing with CatShooter. A long action would certainly be a lot more versatile. If the longer bolt throw bothers you there are ways to shorten it to the "just right" length ,the bolt throw, not the action).

Also, why not consider a single shot? Then you needn't worry about a lot of things and it's surprising how quickly you'll get used to it.

Cat Shooter - Somewhere in my collection of wildcats I have a 224 Long Neck. Could it be one of yours?? What case is it made from?? I'll have to dig around and see if I can find it.

Ray

 

[CatShooter]

. . .If I was building a fast twist 243, I would put it in a long action. . .

Scott

Once again I find myself agreeing with CatShooter.

Oh God - Cheech, this has to stop - people are going to start talking

Cat Shooter - Somewhere in my collection of wildcats I have a 224 Long Neck. Could it be one of yours??

I don't know - I hope not - it would mean that someone else was dumb enuff to make one!

What case is it made from?? I'll have to dig around and see if I can find it.

It was from a 22-250, that progressed to a 6mm Walker international, which then progressed to - Ta-ta, the silly "224 Long neck".

The 22-250 was set back so the capacity was ~28 grains,about like a 222 Mag) w/ a 30 degree shoulder - the neck was about 1 inch long. I made it back in the dark days when people thought that accuracy of the 222 Rem was from the "long neck" of the 222 - so I figured that if some was good, more was more better

I made one up, and everyone laughed when I took it to a match... including ME!

Shot fer shit!


.

 

[scottl0000]

Hi ChrisJ,

The problem is that I cannot fit the 6.5x.284 into the desired short action...

Thanks again,
Scott

I know this is a dumb question, but why do you have your little heart set on a short action.

Hell... If I was building a fast twist 243, I would put it in a long action.


.

My reason for preferring the short action over the long action is that this will be my "walking rifle" for hunting as well, and frankly as a smaller framed shooter,12 3/4" pull) it just swings up for me a lot more naturally than the longer action, with less weight as well. I actually have no aversion at all to going with a single shot, the only problem is the time for the gun smith to acquire one, and the fact that he had gotten a really, really outstanding reputation as one of the most outstanding smiths in the area for building 700s in particular. I have several friends with his rifles that have been shooting rifles from other smiths for decades and I'm told these are the best they have ever had. I'd share his name but I was essentially sworn to secrecy over threat of life and limb I'd also like a short action over at least a long action as I'd like my 2 kids to be able to shoot it, and at ages 10 and 13, they are much more comfortable with a lighter rifle that a short action gets you, and the shorter action also favors smaller framed users as the entire wieght of the barrel is that much closer to your body, vs. farther out there away from you. The result is a package that's quicker to shoulder and easier to handle, especially for my kids.

So yes, I do agree putting it on a short action is a compromise, however the longer action doesn't fit my build and the single shot is not as quickly available and we leave in 4 months for Africa; less actually. The smith is confident he can have reamers and dies from his source in 2 weeks, and though I wouldn't mind a single shot, it's not available as quickly as far as acquiring an action.

So I guess the net result of all this is
1) my goofball cartridge idea has the inherent design capabilities of, if nothing else, bringing consensus to the masses,catshooter and cheechako notwithstanding)
2) I'm left with the question of what is the best beltless existing case that will fit in a short action repeater, will feed well and get top velocities with a 140 grain bullets? I'm getting the feeling there may not be any - at least at this point.

Thanks all,
Scott

 

[constructor]

Rsaum- 123gr lapuas at 3320fps and 139s at 3190fps.
Regular short action with mag bolt face.

6.5 Reaper has a 20 degree shoulder for use in AR10s, Kiff makes the reamer and Hornady makes the dies. If just for a bolt gun I would change it to a 30 degree shoulder.

 

[longlowdog]

Scott,
if you are dead set on a light rifle, won't it kick the kids if your wildcat has most of the attributes of a 6.5-284? Maybe a little weight would be no bad thing. All depends how familiar they are with recoil.
Just my tuppence worth, I envy anybody with the smarts to come up with a new shell.
Best of luck, Longlowdog

 

[Ackman]

It's been done. A riflebuilder in Idaho started doing them a couple years ago. It's called 6.5TRS, uses the .243WSSM necked to 6.5mm. The shoulder is 40* and blown forward quite a bit giving it a shorter neck. A friend shoots highpower with one.....56.5gr/ WMR powder and a 142gr Sierra gets 3200fps with a 24" barrel. He says it's very accurate.

 

[scottl0000]

Thanks, sounds similar but somewhat different, would be interested in knowing the length from base to the body/shoulder junction - now the latest from my side.

The smith and I decided to lengthen the case an additional .126, I worked up a great load and went off to Africa. However I forgot to file my 4457 customs form for it. So when I got to Africa, they held that rifle in customs for the whole 12 days we were there. Apparently that gave them plenty of time to find a buyer...

We picked up the rifle from customs, put it in the case with the other, checked it in with Delta, unbeknownst to us they then gave it to their courier,a company called Bid Air), and the rifle,plus my daughter's rifle, the case, cleaning kit and various curios we put in the case) were never seen again. Apparently Delta says they were stolen... and all only covered up to a $2800 max.

So after all that work, the rifle never made it to the field and now is stolen. We're working through all the red tape with both Delta and my home owners insurance as I type this... the saga continues.

For the ballistics data though, I had found a very accurate load of RL-22 that was poking a 130 grain Barnes TSX out very accurately with no pressure signs at a bit over 3k fps. Unfortunately I hadn't had time to push it though before the gun was stolen to figure out where the optimal accuracy/max velocity was.

Once all the insurance paperwork nightmare is out of the way, I plan on building another back up immediately and should have some more complete data. Smith is already checking on barrel availability.

On the plus side, the little ol' .260,downloaded for my daughters to a mere 2580 fps with a 120-grain Barnes TSX BT) whacked 16 animals total, including a black wildebeest at 299 yds with about a 25 mph cross wind - so much so I had to hold at the top of the shoulder and slightly up the neck as he faced me broadside. Out of 22 shots I believe it was to bring down the 16 animals, 3 included single shot kills on zebra under a hundred yards, with 2 being the herd mares,large.) The farthest one went about 50 yards, while the shortest went 29. Impressive little bullet, at least on African game,no experience with it here at home yet...) All of the 22 shots, all but 5 were pass throughs, with 3 bullets recovered. 2 were perfect 4-petal mushrooms, while the 3rd, a frontal shot at close quarters on a Nyala, sheared 3 out of 4 petals off passing through the sternum, bent the bullet shank actually, then lodged just behind the right shoulder. Nyala dropped in his tracks. All that to say, so the trip was far from all bad anyway, even with the rifles being stolen. Other species taken with the .260 included 2 bush buck,one an exceedingly rare 3-horn bush buck), a gemsbok, 4 impala, springbok, and a good waterbuck. Almost all scoreable species made SCI book except for I think 1 impala and one other, I think it was the springbok. Fun trip, and that .260 really suprised me with it's lethality on those tough African animals,and I've long been a fan already of the .260...)

Thanks,