Thought i would share some info on my new wildcat the .257 Bobcat which is the 270AR round which is produced by AR15Performance.com and necking it down to 25 caliber.

I want to start off with a big thank you to Harrison at ar15performance for helping me finish the print and for making the 800 series bolts/extensions. If not for these none of these rounds would be possible.

As stated with H's help the reamer print is done and reamer is ordered. so hopefully in a few weeks i will have a reamer and the first barrel will be made. I will be starting with a pac-nor 1-9 twist barrel. finished at 24" with rifle gas for testing. all barrels will be 24" to start out with so we can see the max potential of the round.


Intro: The .257 Bobcat is based on the 270AR made by AR15Performance. the 270AR is a 6.5x47 lapua shortened .120 and necked up to .277. It uses AR15performace's 800 series bolt and extension so it can run at 60,000 psi.
My performance goals are 100 grain bullets at 3200+ fps and the 115 bergers at 3050 fps that will make it a very flat shooter



Brass:
6.5x47 Lapua first choice will handle the pressure best and has second highest case capacity. will require neck ream and turn but will last the longest. In the 270 i have some at 10 fires and still going strong.

6.5 Creedmoor second choice has highest case capacity but brass is soft and it can't handle the pressure as well. primer pockets loosen after 2-3 fires if running toward max.

308 palma lapua brass tied for second, has almost the same capacity of the 6.5x47 lapua it also has small primer and lastly it is cheaper than the 6.5x47 brass. this brass will also require neck turning and reaming.

308 brass can also be used but most of it has really thick brass so it has reduced capacities compared to the lapua and creedmoor. it will also require neck turning and reaming.

all 308 based cases will work and all will require neck reaming and turning. the neck in the chamber is going to be 290  so loaded rounds will need the neck to be in the .282-.285 range  which gives you a neck thickness of 12-14.5 thousandths.

Lapua brass prep procedure:
.257 Bobcat Forming tools:I just did a few cases and made another video, will get it posted up a little later here is what you will need to make the bobcat cases if you are going to use the dies i am going to offer with the kits. the 6.5x47 lapua hornady bushing dies.
forster power adapter # PA1000
forster .257 neck reamer # NR1257
forster original trimmer # CT1010
forster neck turn for original trimmer # OT1010
6.5 rcbs neck reaming pilot # 98881
279 redding bushing
.257 hornady expander # 396279
Modified 6.5x47 lapua hornady bushing dies available through me or
6.5x47 lapua bushing dies with sizer modified by shortening the sizer .125 inch

rcbs case neck turner/reamer pilot 6.5 mm http://www.midwayusa.com/product/633903?cm_mmc=S_Spop-Email-_-Service_Emails-_-ShippingConf-_-ProductLink

forster neck turn kit for forster classic lathe. http://www.midwayusa.com/product/154104/forster-original-power-case-trimmer-outside-neck-turner?cm_vc=ProductFinding
or
21st century neck turn lathe part number 908-30-BR http://www.21stcenturyshooting.com/17-338_Cal_Neck_Turning_Lat.php

Forming procedure:

start with the modified bushing die with no guts in it.

lube the 6.5x47 lapua cases and run through the press pushing the shoulder back .120

neck ream and trim with forster lathe using the 257 forster reamer in the lathe so you ream and trim at the same time trim to 1.656 at this time, final trim length is 1.646 which will the the last step after final sizing.

now with the trimmed and reamed case you are ready to neck turn. install the forster neck turner on the lathe and install the 6.5 rcbs neck reaming pilot. now set the lathe to just touch at the case mouth and turn to the neck shoulder union. neck should come out at .013 give or take.

now install a 279 bushing in the die with a 257 expander and run the cases through the die. now chamfer and anneal the brass clean and they are load ready.

I made a video of my process for making .257 Bobcat brass from 6.5x47 lapua

































Dies:
you can use the redding 6.5x47 bushing die by shortening the die .125 and using the appropriate bushing it will fall in the 278-281 range.
Whidden gun works is also making the 270AR dies as custom die sets. if you get the bushing die sizer set the micrometer seater die works for seating the 25 cal bullets.
AR15Performance will have the 270AR whidden dies in stock late october early november. there again get the bushing die and use appropriate bushings

if it takes off I will be working with hornady and whidden to get custom dies made.




100gn nosler ballistic tip, sierra 100gn sp bt, 85gn nosler ballistic tip






.257 Bobcat quickload predicted velocities with 24” barrel

100 sierra pro hunter sp  3050-3200 fps
100 sierra game king bt   3100-3250 fps
100 nosler partition          3050-3200 fps
100 nosler ballistic tip      3100-3250 fps
100 barnes ttsx                  3050-3150 fps
110 nosler accubond        2850-3000 fps
115 berger hunting vld     2825-2950 fps
115 nosler partition           2850-2975 fps
117 sierra pro hunter sp   2800-2950 fps
117 hornady sst                  2800-2925 fps
117 hornady sp                   2850-2975 fps
120 nosler partition           2750-2875 fps
120 hornady interlock sp  2800-2900 fps
120 speer grand slam        2800-2900 fps




here is everything so far, only thing missing is the reamer

Sounds like a really nice antelope round. Almost as fast as the 25 Souper.

Bigddawg,
As always, I am thoroughly impressed by your knowledge and skill at these wildcat undertakings.

Looks like an awesome round

Thank you for the kind words.

this will be the first wildcat i have designed. and it has been fun.  reamer is supposed to ship around the 31st so if it is on time i should have it in 2 weeks.

can't wait to start putting rounds down range and see the performance.

I am hoping to see velocities with in 100 fps of  25-06 factory loads performance but we will see.

should be very close and it will fit in an ar15.

my 270AR is pushing 130's at 2800 fps, the 6brx pushes 100's at 3150 and this is pretty close to a brx and being 25 caliber it should be a bit faster.

BiggDawg, with you behind the wheel of this new wildcat cartridge It will undoubtedly be a success...Best of luck with It .

Awesome.  I have a sweet spot for quarter bores.  Get this all set up and I would get one... As long as I could design my own barrel profile.

Um, this is going to be awesome.  

"TAG" as they say...

that will be a possibility.

I am hoping i am down to a week for the reamer my invoice shows a ship date of nov. 1st lets hope they are on schedule.

got the email i was waiting for. the reamer is shipping tomorrow.

won't be long now and the testing will begin.

Well it is finally here, post office misplaced it for a day but now the progress can start.

Color me interested.   Standing by for performance data.

Very Interested.  I've been waiting for a decent .25 cal AR option for a long time.

The 87gr option would be a great varmint round for the times when the Eastern Oregon afternoon wind blows a .223 varmint round into the next time zone.
This new wildcat would fill a sorely needed space in my gun cabinet between .223 AR15 and my bolt action 270.

H is one of the good guys in our world.  I've got one of his .223 5R barrels.  It's awesome.

Neat!

Totally tagged!.

My 25-06 handloads with 100 gr BT's run right at 3200 fps.  If you achieve the predicted velocities with the 257 Bobcat, you will have essentially made a high capacity, semi auto 25-06.

I would be interested in the 270 AR necked down to .264.  The long .264 bullets may take up too much case capacity, though.

H does an incredible amount of work and good will for people behind the scenes that are developing their own thing, without asking for any credit or anything in return. This sounds like another awesome round, good luck with it.

the case is too long to use bullets over 123 and if the chamber is set up for the 123 class the lighter bullets would be pushed in farther.

harrison has his 6.5 brx which fills the bill being shorter it can run up to 140's. and i think it is 2800 with the 123

thanks i hope it proves us right.

Yes Harrison is one of the good guys.

I am hoping for the 3200 with the 100 grain bullets. that is what H says it should do. I will be happy if they are 3100

we will be testing one in a savage with a 26" barrel too and see what we can max it out at.

We got the barrel made on saturday, took us most of the day but i learned a lot.

I took some measurements of the lands and they are farther out than i was expecting so i just loaded the rounds to 2.295 and went to the range with some 85 and 100 nosler bt loaded with cfe.

the gun cycled on every round but they were very light loads. I barely got up to a little pressure on the last 2 rounds of each load. could go a grain to 2 grains higher on both but i don't think it will fit with the 85's so cfe is a bit slow for them and will probably be on the edge for the 100, meaning the 100 will run with them but not at full speed. most of the cases the shoulders were not blown out on, i had them set up for the 270 at 1.330 at the shoulder with my gauge like the 270 and the last 2 loads were finally pushing the shoulders and this chamber is around 1.344  the rest of the brass was under 1.338. that shows how light the loads were.

the velocities are not bad for the light loads. the 85's are coming around and i am fairly certain i will get them to 3350-3400, and the 100's are just under 3000 now and i know i can go up 2 grains maybe a little more but case capacity will be the issue with cfe, so i will be testing with 8208 and h335 along with several others in the near future.

i started at 36 grains with the 85's and went to 39.9 and was no where near max,

With the 100 bt i started at 33.3 grains and went up to 37.2 grains, velocity was below what i wanted so the extra lead does make a difference.  I plan on going up to 39 or 40 grains once i get the pressure trace system on the barrel i think max will be around 39.5 that is my guestimate but we will see.

here is the data from today:








here are the ladder targets for them at 50 yards

85NBT



100 BT

Great looking work as usual BD, best of luck with it...

very cool! always down for another 1/4 bore

Here is my test chart for then next outing or 2, i will have the pressure trace mounted tonight so it should be a productive test session this weekend





also have more test subjects

You're on the right track by installing pressure trace equipment.  Once you get a baseline with this and that barrel length, are you considering cutting the barrel from a target length, down to a carry length?

One of my sniper partners used a .25-06 in AICS spitting the 115gr Berger VLD over 3000fps.  There was no recoil with that rifle, especially with the Brugger & Thomet suppressor.

I think we can do better than .25-06 when looking at action length, since the powder column is rather long and not so efficient with that cartridge.  Do you have any targeted operating pressures in mind for this?  It will be interesting to see what speeds you can achieve at 45,000psi.

I am running arperformance's 800 series bolt and extension and it has been tested with the brx line at sustained 60,000 psi  + so my goals are 58,000-60,000 operating threshold. I am also using Lapua 6.5x47 brass and it too can handle the pressure.

I also have Harrison's 270AR that i will be putting the pressure trace on to see where it's pressures are at my load in that with cfe and 130's runs 2700-2800 fps.

Had a productive and learning day today. I shot the 85 NBT with cfe and 8208, the 100 speer hp and 8208, 115 berger 8208, 100 sierra spbt 8208, and 87 TNT H335

here are the pressure traces and primers, the 8208 didn't lock back with any of the loads with any of the bullets. cfe locked back and cycled fine.

the highlights from sunday are
85 nosler ballistic tip 3357 fps with room to go with both 8208 and cfe but cfe is maxed out on capacity.

87 TNT 3259 fps with h335 with a lot more room to go

100 sierra spbt 3163 fps with room to go

100 speer hp 3136 fps 8208 with room to go

I hit the steel plate at 300 yards 3 or 4 times while testing and i was just guessing on hold over, was only sighted in at 50 yards.

so from the looks of it my performance goals of 3400 with 85's and 3200 with 100's will be attainable.

going to test a few more powder/bullet combo's and then work on accuracy.

Great results thus far.

One of these variants in 6.5 flavor would tickle my fancy.

Thank you, yes it is turning out as planned i am a happy camper.

i was thinking of doing a 6.5 but Harrison from arperformance is bringing back his 6.5 BRX which is the same thing but shorter so it can run the longer bullets. they get 2800 out of a 20" barrel with it.

I ran a couple of ballistic tables with the 85 nosler bt and 100 bt with the results i got on sunday and this is how they look.  I am thinking deer under 300 yards and yotes 600 yards and in have to worry.

Getting the test loads ready for sunday.
I will be testing the 85 nbt with 8208 for accuracy and the 100 nbt with cfe for accuracy.

I am also going to test the 115 berger with cfe and h4895.

If time permits i am also going to try the 75 sierra hp with aa2200 and the 87 tnt with 1200r just to get some velocity and pressure numbers.

supposed to be rain/snow sunday and in the 40's so hopefully i will get out to the shooting shack and stay out of the elements.

got out yesterday for testing it was  50 and raining. didn't get everything shot that i wanted to between the pressure trace acting up and the owner of the range stopping by for a chat i only got the accuracy tests done and the 115 bergers shot.

here is the target from the 85 nosler bt with 8208 there was a long cool down before i shot the last group it is when the owner stopped by that is why i had the high flier going to retest 38.2,38.4,38.6,38.8 also on 37.5 and 38.1 there was only 2 shots they both had a round that wouldn't chamber. not enough bump and i didn't catch it.



and the 100 nbt with cfe





here is velocity from the bergers. neither one is at max but again cfe cycled the action and locked back with 1 fail to feed and the h4895 wouldn't pick up rounds or lock back. probably going to open up the port to .084 from .082. also was having feeding issues. so i tweaked the mag lips and it got better the rounds were nose diving into the feed ramps and hanging up. i am going to tweak the front of the spring to hold the tip up more.



here is a revised drop chart with the bughole group powder charge with the 85 grainer going 3289 fps, the bullet will expand down to 1600fps

had a good day at the range today, it was cold and windy, 32 deg. with a 8-9 o'clock 10-17 mph wind and overcast.

i tested leverevolution today to compare to cfe and was pleasantly surprized it pushes the 100 speer spbt faster than cfe here is the chrono data i stopped with 2 shots left because i got a faint ejector swipe.





and here are the targets from my accuracy testing all were from bipod and rear bag, i pulled the first 85 nbt 36.9 shot

Great results thus far.

thank you yes it is. I am very pleased i have hit all my goals with it.

almost ready to put a spanking on some yotes

I am a happy camper the gun is shooting well and velocities are good what more can a guy ask for.

going to order a 1-10 twist barrel to test should be done in 6-8 weeks. also going to stretch it out to 300 with a few loads to see how it holds.

Wow, awesome round. I'm very interested in this.
Please allow me to ask a few simple/obvious questions just so there's no doubt in my mind, I am a simple guy after all. This round can be made with .308 brass correct, so with that being said because it is shortened I can use an AR 15 lower instead of an AR 10, correct? So I can use my existing lower and just build another upper with dedicated bolt and mags for this round, correct?

yes it is ar15 based so all ar15 lowers will work just mags and barrel with bolt. the barrels will come with bolt. and grendel mags or pri 6.8 ,mags  it is designed around an oal of 2.295. I have a long lead to help with pressure so i can run it hard and it seems to be working quite well. think of it as a 556 throat.

308 brass works but is a little harder to work with than lapua 6.5x47, the 308 cases are thicker and require a little more reaming and turning to get just right.

Thanks. Do you expect "ready made brass becoming available? I watched your video on the first page and that's a lot to do before it can be necked down to .25 cal.

I will be making brass for it and including it in a kit.

it does take some work but the brass lasts i have well over 10 fires on it in my 270ar and i am up to 5 fires on some of the bobcat brass all is going strong. I am annealing at 3-4 fires.

Thanks, I'm new to reloading so I'd prefer to just buy prepared brass.
I have a .300 BLK and very interested in this round.

I just made a new video for making the brass using the modified 6.5x47 hornady bushing die. here is the new procedure also

Lapua brass prep procedure:

.257 Bobcat Forming tools:I just did a few cases and made another video, will get it posted up a little later here is what you will need to make the bobcat cases if you are going to use the dies i am going to offer with the kits. the 6.5x47 lapua hornady bushing dies.
forster power adapter # PA1000
forster .257 neck reamer # NR1257
forster original trimmer # CT1010
forster neck turn for original trimmer # OT1010
6.5 rcbs neck reaming pilot # 98881
279 redding bushing
.257 hornady expander # 396279
Modified 6.5x47 lapua hornady bushing dies available through me or
6.5x47 lapua bushing dies with sizer modified by shortening the sizer .125 inch

rcbs case neck turner/reamer pilot 6.5 mm http://www.midwayusa.com/product/633903?cm_mmc=S_Spop-Email-_-Service_Emails-_-ShippingConf-_-ProductLink

forster neck turn kit for forster classic lathe. http://www.midwayusa.com/product/154104/forster-original-power-case-trimmer-outside-neck-turner?cm_vc=ProductFinding
or
21st century neck turn lathe part number 908-30-BR http://www.21stcenturyshooting.com/17-338_Cal_Neck_Turning_Lat.php

Forming procedure:

start with the modified bushing die with no guts in it.

lube the 6.5x47 lapua cases and run through the press pushing the shoulder back .120

neck ream and trim with forster lathe using the 257 forster reamer in the lathe so you ream and trim at the same time trim to 1.656 at this time, final trim length is 1.646 which will the the last step after final sizing.

now with the trimmed and reamed case you are ready to neck turn. install the forster neck turner on the lathe and install the 6.5 rcbs neck reaming pilot. now set the lathe to just touch at the case mouth and turn to the neck shoulder union. neck should come out at .013 give or take.

now install a 279 bushing in the die with a 257 expander and run the cases through the die. now chamfer and anneal the brass clean and they are load ready.

I couldn't get your video link to work

ETA: never mind, works now

yes when i first posted it i messed up but i caught it almost right away and fixed it. you must have tried it in that short time.

Updates DAWG?

Yes I decided to have the throat modified on the reamer to shorten it a little  .050. the gun was shooting very good but I did't like the jump to the lands so I sent some dummy rounds in to JGS along with the reamer.

Cary got back with me friday with a revised print and i ok'ed it so they will be regrinding the reamer and i should have it back in a couple weeks.  I already have a blank ready to chamber -- i am going to build a savage bolt gun to go along with the ar so i can test them both side by side -- new throat - old throat

if all goes well testing i think i will order some barrels in mid to late feb I have a few guys that want one.

also i have got a load done for the 87 tnt and h335 for the original barrel

I shot 3 3 shot groups and it looks to be a winner at 37.4




and the 100 nosler ballistic tip with lever looks very promising also

 " the .257 Bobcat which is the 270AR round which is produced by AR15Performance.com and necking it down to 25 caliber."  

So in otherwords a 6mm BR necked up to .257?  

no it isn't a br necked up. the br cases are 1.58 inches long the case for the bobcat is 1.646 so the br cases won't work, i gained case capacity not pushing the shoulder back and keeping the case longer.