6.5-.300WSM loads

[Poper]

I've been pondering my first Wild Cat chambering for most of two years. The 6.5x55 SE, 6.5 Carcano, .260 Remmy all needed a Big Brother and I convinced my Honey it was less expensive than buying something new.

Well, I got a good buy on a new 6.5 caliber barrel and had it chambered for 6.5-.300WSM. Because of the short necks on the WSM cases and the long-for-weight 6.5 caliber bullets, I opted for the deep chamber. The new barrel is currently at the 'smithy with my Remmy 700 - .300WSM for a barrel transplant, action glass-bedded and barrel full-floated in a Classic American Walnut stock. I received my Special Order Dies (FL sizer and seater) from Huntington's last week. Over the weekend, I discovered running a .300WSM case into the FL die squashed the shoulder flat and did nothing for the neck. Goofy looking result that will not work in anything.
(The rest of the .300WSM cases will not go to waste. My A-Bolt Hunter and my brother's BAR will use 'em!)

A quick glance at the new Speer #14 revealed the dimensions of the .300WSM and .270WSM were identical except for the length of the shoulder and the diameter of the neck. Next up for trial was the .270WSM case.... .277 ID to .264 ID.... Slick! One pass and -BINGO!- A perfect case! AND one happy camper!

10 minutes and 99 6.5x.270WSM cases later, I was wishing I had bought more .270WSM cases!

My quandry: Do I use .270WSM data for starting loads or do I use .300WSM? Does it matter? Anyone have similar experience to draw on?
Reloader Fred... Can you help? From what I can gather, you've seen or tried almost everything!

Sticking with components on hand, I intend to work up loads for 120gn Sierras, 129gn Hornadys, and 140gn Sierras. Cases are Winchester, Primers are Winchester Magnum LRP or CCI-250, preferred Powder is IMR 4831 or possibly IMR 4350 or W760 for lighter bullets.

All insight is much appreciated.

Thanks in advance!

Poper

 

[dave5339]

That is what I'd love to build one of these days.

Keep us updated as how it shoots.

Semper Fi

 

[Bartkowski]

If you have a chrony, I'd love to see the speed you can get with that thing.

 

[Snapping Twig]

Try some IMR 7828. I use it for a 6.5-06 and it works well.

 

[CZ57]

Poper, have you looked at the 6.5 X 284? Not nearly as overbored, nor nearly the powder requirement. I doubt performance is worth much difference.

 

[CZ57]

My apologies, Poper. I missed that you already have the barrel. I thought you were looking for an improvement over typical 6.5mm performance, and technically, the 6.5 X 284 is no longer a Wildcat because NORMA has legitimized it. I wondered if we would see a 6.5 X 300 WSM cartridge and rifle introduced. My guess is that we won't because the 6.5, despite exceptional sectional density and ballistic coefficients, has never caught on in this country, as far as a factory chambering. I'm guessing you're out to get performance like the .264 Win Mag. It will be interesting to see if your Wildcat will do it without the associated problems (throat erosion) of the .264. You should have a great Wildcat for years to come.

 

[Poper]

Snapping Twig,
I'll give the IMR 7828 a try, but I have most of a 1lb can and all of an 8lb can of 48 31 on hand plus 1.5lbs W760, 4+lbs IMR4350, etc. I would like to use first. If none of these work out, I'll certainly try IMR 7828, tho.

CZ57:
I have 3 different 6.5 calibers I current load for - .260 Remington, 6.5x55 and 6.5 Carcano per my OP - and I find the minimal recoil coupled with their ballistic performance very interesting. I have found the 6.5x55 (CZ500 American) very tollerant and accurate with a variety of bullet weights. The .260 Remington (Kimber 84M) only wants to shoot 85 grain pills, and the old Carcano (Bubba had a good time!) doesn't want to shoot anything well.

I had (have) 2 .300WSM's (A-Bolt and 700) and I thought this would make a neat chambering to play with, so the 700 got the nod. I would like to see how well it will shoot without running at full hotrod velocities. However, a maximum load that groups less than 1moa at 100 yards would be great for the Wyoming or Montana antelope hunt I am contemplating for the future!

I do have a chronograph and will certainly utilize it during load development. Now that all of the pieces are coming together, I am looking forward to the work of developing the loads!

This is my first adventure into WildCat territory, so I am trying to be very conservative.

Poper

 

[CZ57]

I'm a big fan of 6.5s and CZ rifles! The custom shop will chamber the 6.5 X 284, but the 6.5 X 55 you have and 60,000 PSI data for rifles like it, make the 6.5 X 55mm, a beautiful thing! You would have to confirm this, but I'm pretty sure your 550 in 6.5 X 55 could be rechambered to 6.5 X 284. It's an extremely accurate round and getting more popular in benchrest, all the time. The twist is 1 in 9, whereas your 550 is 1 in 8.6 or 8.7 depending on when it was manufactured. Like the WSM cartridges, the 6.5 X 284 is a 65,000 PSI round. Maybe not a true magnum, but it sure maximizes the short fat concept. Keep us posted on your Wildcat project! There are many powders that are suitable like 7828 and you've probably noticed as bullet diameter decreases, powder speed requirement gets slower. Looking at .270 WSM data will give you a pretty good idea of what will work. Really, anything 4350 or slower can be used with good results, but to get 100% load density, or close to it, you'll need to go to the slower burners. RL-22 ( Made by NORMA and a variant of MRP ) gets a lot of mention. Ramshot Magnum if you like spherical powders, Accurate Mag Pro is another. Good luck!

 

[Davo]

What are the supposed ballistics?

 

[Poper]

What are the supposed ballistics?

It's a Wildcat.

I am not sure, but it should compare quite well to the .270WSM. The 6.5 caliber bullets have excellent B.C.'s and S.D. I'm interested to see how it will perform accuracy wise with the different bullet weights. Both of my .300WSM's shot groups at an inch or better with 180gn, 165gn and 150gn bullets and several different loadings. I am hoping the 6.5x.300WSM might be tollerant, too.

It is the learning experience that makes this hobby so much fun, isn't it!

Poper

 

[Snapping Twig]

OK poper, here's my IMR 4831 load for the 6.5-06



140g Nosler Partition

48.5g IMR 4831

Schweet!

 

[CZ57]

Well, I checked after my last post and the CZ Custom shop lists a twist of 1 in 8 for both .260 Rem and 6.5 X 284. Both faster than typical. Most twist the 6.5 X 284 at 1 in 9".

As far as supposed ballistics, the 6.5 WSM Wildcat should meet or exceed performance of the .264 Winchester Magnum. The .264 uses the same case as the 7mm Rem. Mag. More accurately, Remington necked up the .264 for 7mm in 1962. The .264 was introduced in 1959. I feel certain that the same comparison of 7mm WSM to 7mm Rem Mag would hold up for 6.5mm WSM to .264 Win. Mag. About 100 FPS or faster in most bullet weights.

 

[Poper]

CZ57,
Your performance data sounds about like I would expect. Now that you mention it, I too, remember reading something about the 7mm Mag. being a necked up version of Winchester's .264 Win. Mag.

I do not intend to "hotrod" this gun. That would be kind of like driving your car with your foot on the floor. Not conducive to longevity for the vehicle! loading near the top end of the scale does similar things to guns, too. I'll probably stick pretty close to the middle of the performance scale and work for maximum accuracy. This is my only custom/semi custom firearm. I will use it to hunt with, but primarily, I just want to make it shoot little groups.
This 6.5-.300WSM barrel is a 8.5" twist and should stabilize 120, 129 and 140 grain bullets quite well. I have some 155 grain Lapuas, but I think the short throat may not allow their use. I'll know more, of course, when I get it back and have the opportunity to work with it. This is my hobby gun. I'm going to work with it a lot and learn as much as I can. Like I said, this is my first Wildcat chambering. This is all new territory for me.

I stopped by the gun shop today just to check progress. The new barrel is installed, headspaced and tested. According to the gunsmith, it has a tight chamber. He gave me a chamber cast he made. It appears it to be fairly short throated. It looks like I am going to have to be very careful with bullet seating depth. I actually wanted a little more throat to accomodate longer bullets.

Poper

 

[CZ57]

Sounds like a plan to me! High end 6.5 X 55mm or 6.5 X 284 Norma loads would probably get it done for me and with a good high load density powder, I'd bet you can get that while staying 10,000 PSI or so below the pressure max. I've thought about the same type of loading with the 7mm WSM to slightly above 7mm-08 or maybe .280 Rem. loads to extend barrel life, get exceptional accuracy although you'll still burn plenty of powder! I also wonder why the 6.5mm has not been considered for the WSSM. Looking at .25 WSSM data, it looks to me like the case should achieve .260 or 6.5 X 55mm ballistics with a .264" bullet. Anything metric gets ignored for the most part, so it's great to see you taking on this Wildcat project. Should be very rewarding!

 

[Bartkowski]

I don't know how well the longer 6.5mm bullets would work in a wssm. I am not a reloader, and don't know much about reloading, but I am just throwing out an idea.

 

[CZ57]

Bart, you have a point as far as magazine length, and I don't have the max length in my head. I was thinking on the same plane as the PPC concept. Not likely to ever happen, but could work as a Wildcat project. The 6.5mm just gets overlooked and now that reloaders and hunters discuss Ballistic Coeffecient and Sectional Density much more than they used to, it's a bit puzzling they don't take 6.5s a bit more seriously.

When all the debate was going on a while back about our next military round, the 6.8 SPC sounded great, but ballistics fell a bit short of what was proposed. If I were the Chief of Staff, it'd be easy, I'd give the troops the .260 Rem with a 120 gr. bullet!

 

[Poper]

CZ57,
I, too, toyed with the idea of a .264 WSSM as I thought it would be an ideal mountain rifle. Imagine: 6.5x55 power in a super lightweight package!

I have gone as far as drawing up a .264 WSSM cartridge case in AutoCad. I also spoke to the fellows at Clymer about reamers for the same.
There are two obstacles to the WSSM case that stem from the same problem. The case neck is too short. As you neck a case up, the neck shortens. When you neck the .25 WSSM up to .264 caliber, you lose a little neck length. Rule of thumb is that the length of the neck needs to be a minimum as long as the bullet diameter. When you neck the .25 WSSM up to .264, you end up with very slightly more than a bullet diameter for your neck length. Most chamberings have considerably more neck. Also, such a short neck keeps you from using all of the powder capacity in the case except for the lightest bullets.
Remember, the neck grips the bullet AND helps keep it stright and true in the case. With a boat tail bullet in a minimum length neck, you lose a significant amount of that support. In a target rifle where you are probably feeding the rounds one at a time, this may not be a factor. However, my use is primarily superbly accurate hunting guns. (It tickles me where I need it most!)
Because I would have to have a reamer made to my specs anyway, I also considered having the chamber reamer configured for an extra deep neck and then forming my cases from .300 WSM brass. The drawbacks there are having to invest in case forming dies and the gawd awful case trimming chore that results.

For now, I have shelved the idea of the .264 WSSM. BUT, if I ever get another wild hair, I just might pick it up again.

Poper

 

[Gewehr98]

I'd have to add another task to that list...

Because I would have to have a reamer made to my specs anyway, I also considered having the chamber reamer configured for an extra deep neck and then forming my cases from .300 WSM brass. The drawbacks there are having to invest in case forming dies and the gawd awful case trimming chore that results.

Necking .300 WSM down to .264 means I'd do inside neck turning after trimming to length, too. Squeezing things down from .308 to .264 doesn't just make the neck longer - it gets thicker, too.

I'd be interested to hear how the 6.5-.300 WSM wildcat does.

I'm not a big fan of the ShortFats, and already have a 6.5-06 that devours 59.0gr of H4831SC each time, giving me 3200 honest fps with my tried-and-true 123gr Lapua Scenars. 6.5x284 case capacity is very similar to the 6.5-06, and depending on which guru's pressure limits you abide by, performance ranges from very similar to just a little bit better that what I'm getting with the older wildcat.

 

[Zeke Menuar]

Ran across this in "Cartridges of the World"



ZM

 

[Poper]

Zeke:
I have never seen that article, but it is very helpful. It doesn't surprise me that Carmichael as played with this one like he did with (what is now) the .260 Remington. I'll definitely print this and put it in my Project File! Thanks again!

Gewehr98:
You are absolutely correct. I did neglect to mention the thicker case necks. It would definitely slow down production of suitable brass, wouldn't it? Not to mention what it would do to my already arthritic thumbs. (All 10 of them. ) However, there is also an upside to the extra-thick case necks: It should be possible to to get perfectly centered and perfectly round case necks able to provide optimal tension, too! I guess there is no free lunch...

I am a fan of the Super Short if for no reason other than the action is approx. 1/2" shorter and 2-4 oz. lighter. I love my .243WSSM Win. Mod 70 for carrying. It is very accurate with 100gn pills. I would prefer a little more "OOMPH" in the package, though, and I think the 6.5WSSM would do that for me with possibly better terminal ballistics/performance to boot. With a Leupold 2-7x33mm, light weight sling and 22" bbl., it is the perfect ticket for us old folks that still like to get out and walk the hills with our rifle rather than sit in a stand all day. As my co-workers can attest, I can only sit still sooo long.

Poper

 

[CZ57]

Poper, As far as magazine length, a 6.5 WSSM might work best with bullets from 100 - 120 grains. If the 125 gr. Partition, or the 129 gr. Hornady's could be used, that would be a bonus. I don't see the neck length as a problem if it's at .264". There are several cartridges with necks slightly shorter than bullet diameter, i.e. 7mm Rem Mag. .308 Win. No problems there.

I remember seeing reports on the 6.5mm Leopard. That was an excellent addition to the thread, Zeke. I'm thinking there is also a 6.5mm by Lazzeroni.

The 6.5-06 is definitely a great option as well.

 

[GooseGestapo]

I like the direction you are going. Before Winchester came out with the .270wssm, I had a discussion with one of the engineers. I (along with a number of others) suggested a 6.5 instead. Because of the poor experience they had (Winchester) with the .264winmag, they were reluctant. It does turn out that the .270wssm is the best of the bunch. I'd probably have just gotten a .270 and forgot about the few thousandths' difference. (Of course I'd use .277" bullets..............).

I think that for starting data, you should use .270wssm "start load" data reduced an additional 10%. With each step downward in bore diameter, you decrease the amount of powder that it will take to generate an equivalent pressure. Look closely at the 7mm-08 vs .260Rem data and use an equivalent percentage in reduction. Obviously, not an exact "grain for grain", but a percentage reduction. Also, compare the internal volumn with that of the .264winmag and possibly use .264 data as a starting point.

Or, get someone with a computer program to develop some data based on cartridge parameters.

I've found that with my .257wbymag and .300RemUltMag that I'm getting best performance with some mil-surp .50BMG powder. WC-860 to be specific. At $50.00 for 16lbs, how could I have gone wrong ?????????????
Turns out to give top velocity AND top accuracy.

I was able to work up my loads for both, and still have 15+lbs of power left.........

 

[Poper]

GooseGestapo,
Thank you for the info for starter loads tips. I will definitely use one of the methods you outline. I am new to the Wildcat game, but I DO find it fascinating and educational. I am not intimidated as I have worked up loads for several calibers and many different rifles. Using a micrometer and Ken Waters' .001" case head expansion as maximum is the rule I usually follow, and it has never let me down. (I figure he knows far more about this game than I do.)

Early on in my handloading experience, I found myself very surprised at just how different the tollerance of a load can be from gun to gun. I used to have a Ruger 77R in .270 that showed no signs of excessive pressure at maximum loads of AA3100, but my brother's Parker-Hale .270 showed cratered primers at 1.5 gn before max. published loads and .001" case head expansion at 1gn before max. published load. You just never know...

Thanks again for the tips. I will put them to good use.

Poper

 

[Poper]

Ok, time for an update...

So I thought I might resurrect this thread. Besides, it’s my first semi-custom project rifle...

I retrieved my 6.5 x .300 S. Mag. project rifle from the gunsmith last Saturday. The Remington 700 had the .300 WSM barrel swapped for a new 6.5 x .300 WSM Montana Rifleman barrel. The barreled action was re-blued. A Remington 700 “Classic” wood stock had the action pillar bedded and glass bedded, too. A Timney trigger was installed and adjusted to 2.5 lbs. The Nikon 4.5-18 x 40 scope is mounted with Leupold bases and rings.

I spent most of Saturday afternoon cleaning the barreled action of the vaseline/bondbreaker the bore. Good grief there is a lot of gunk in a new barrel’s bore!

Sunday I assembled 70 rounds of handloads. Cases were Winchester .270 WSM’s necked down with necks trimmed and all the preparations. Bullets are 129 gn Hornadys, primers are CCI-250’s and the powder is IMR 4350. I selected the starting load reduced 10% (thanks Goosegestapo!) published in the latest Hodgdon update (magazine style) as my barrel break-in load. I will be using the barrel manufacturer’s break in procedure.

In a week or two, I intend to begin load development with 120gn & 140gn Sierras, 129gn & 140gn Hornady’s. Depending on the results, I may consider developing a 85gn Sierra varmint load, too.

Let the fun begin!

Poper

 

[Howard Roark]

It looks like you have an interesting project Poper. I hope it shoots well. It appears that you will be getting about the same performance as my 6.5x284 in a shorter case.

A local shooter/gunsmith necked down the 300 RUM to 6.5 and used it for a 1K rifle. It shot great but he only got 800 rounds out of it before the barrel went out!

Good luck and keep us posted.