I decided to get another ar but i want to build it myself. i decided on the new 7.62x40 wt cartrige because i don't see

myself shooting any thing big over 200-250 yards. I wanted it for deer hunting in southern iowa and i just wanted something

bigger than 223 but wanted to use the less expensive 223 brass. The purpose here is i am going to try and get the dillon 1200b trimmer to work

with this cartridge with out the exact die. the only place to get the die is a custom one from ch4d which i will be ordering but they said it will probably take

12 months and i am going to have the gun built before that and i don't buy ammo if i can help it  


I bought the dies and case gauge from wilson combat they arrived yesterday









I also purchase a dillon 1200 trimmer and a 223 die and a 308 die from an ar15 member it should be here on monday.

i will be trying to make it work to trim the new brass.  You have to trim 5mm off each case.

here are some pics of different sizing methods. I size with and with out the expander and i also trimmed with my manual trimmer and then sized.






so now i have some cases to play with when my trimmer gets here. will post more as i work through getting the trimmer to work

Here is the upper got it assembled tonight.

waiting on my lpk and bcg to finish the lower. going to use my lmt lower to send some lead down range to test this girl out.  

Nice job on the pictures.  I use a small cut off saw when cutting down .223 brass for my 300 Whisper.

i have seen guys using the small one from harbor freight. i guess i am just lazy and wanted an excuse to buy the 1200b

then i can use it on my 223 also  

i need to see how short i can make the brass with the 223 sizing die, if i can get it to 40mm then i will size and trim with the 223 die then run them through my 7.62x40 die and see how much

they grow and adjust from there. then just deburr and chamfer

I do a preliminary trim in the drill press first (I trim them to remove most of the original neck).  Then I run the cases through the 7.62x40 sizer die.   The cases are then tumbled to remove the case lube from the sizing.  Next, the cases are then final trimmed to length and case mouths deburred.  Then I prime and load to fire form.  The case forming is all done after I first prep the once fired LC cases by depriming, primer pocket swagging, and then chemical cleaning.

Bill

Waiting to see results

Got the trimmer –– Thanks slanky

after checking things out i decided to modify the 308 die.  I cut .53 inches off it and then had to round the end so it would fit through the shellplate groove.



now when adjusted the die sits pretty low and i couldn't put the normal lock ring on. i ended up having to use the lock ring for the motor and it was interfearing with the opening for the swarf to go.

so i used my air grinder and opened up the holes. I have it adjusted so it just touches the shoulder to hold the case as it trims.



i didn't get to trim any cases yet because i don't have a nut now to lock the motor height adjustment and dill uses an odd ball thread size and pitch. 13/16-20. I ordered 2 lock rings but who knows when they will get

here. i also ordered a nut from my local parts store it will be here tomorrow. it might be thicker so i may have to grind an 1/8th inch off the thickness.

finally made some progress and got everything working here is a short video of it in action

i am making 7.62x40 wt cases out of 5.56 cases

station 1 blank

station 2 is a dillon 1200b trimmer with a modified 308 trim die because you have to have the trim die custom made and that takes a year.
the case goes into the trimmer and is necked down slightly by the 308 die and trimmed to length 1.560 inch

station 3 is blank

Station 4 is the 7.62x40 wt die with the decaping pin removed. it final sizes the case

station 5 is blank.


as easy as that other than getting the 308 die to work

as stated above i had to shorten the die to get to work but it still wouldnt trim correctly because it wouldn't hold the case and it would vibrate.

so i had an idea, fill the space in the die with something. i used silicone, i made a dummy round, filled the die with silicone, lubed the dummy round and inserted it in the die and let dry.

when dry i cleaned all excess silicone and it works like a charm.

don't know if the tubing cutter would work, the case is being cut right at the bottom of the neck where it starts its taper.

quite a few guys use this to rough cut them.

then size and then final trim with a normal trimmer. i just wanted to make it easier.


i just ordered my barrel and mag so i just need my upper and handguard. so i should be shooting in a couple of weeks.

I ordered one of the modified lancer mags with my barrel. i will try my aluminum 20 and 30rnd mags when i get it built

Got my first sets of test loads made. my barrel and forearm should be here wed. so i will get it built next week and

get some chrono data next sunday.

updates in post 2 pics of the built upper  

Is the 7.62x40 wt another designation for the Whisper or .300 AAC blackout or something totally different?

i wanted the drawer to put the misc. stuff in.

today is the day for the range trip. so i will have a full range report tonight. picked up some more bullets and diff. powders at the fun show friday night  

yes as dryflash3 stated it is different than the 300blk. it is 5mm longer case and is designed for super sonic rounds with  bullets in the 110-130 grain range

where the blk is made for the longer bullets and subsonic rounds for suppression.

Back from an awesome day at the range.

I don't think there are many better feelings than when you build a new rifle from parts and then have to make the ammo for

it and you put your first rounds on paper, what a thrill. And man this gun shoots. these are my first ladders and they are looking

promising







24.2gn 1680 110vmax
 1)2310
 2)2322
 3)2273
 4)2295

High:2322
 Low:2273
E.S.:49
Ave.:2300
S.D.:18.3

24.gn 1680 110vmax
 1)2234
 2)2266
 3)2246
 4)2198

High:2266
 Low:2198
E.S.:68
Ave.:2236
S.D.:24.7

24.5gn 1680 110vmax
 1)2330
 2)2301
 3)2289
 4)2294
 5)2305

High:2330
 Low:2289
E.S.:41
Ave.:2303.8
S.D.:14.2

25gn 1680 110vmax
 1)2364
 2)2317
 3)2336
 4)2298
 5)2309

High:2364
 Low:2298
E.S.:66
Ave.:2324.8
S.D.:23.2

25.3gn 1680 110vmax
 1)2381
 2)2332
 3)2309
 4)2324
 5)2356

High:2381
 Low:2309
E.S.:72
Ave.:2340.4
S.D.:25.4

25.6gn 1680 110vmax
 1)2412
 2)2354
 3)2361
 4)2357
 5)2397

High:2412
 Low:2354
E.S.:58
Ave.:2376.2
S.D.:23.7

25.9gn 1680 110vmax
 1)2446
 2)2410
 3)2429
 4)2402
 5)2407

High:2446
 Low:2402
E.S.:44
Ave.:2418.8
S.D.:16.4

24gn 1680 125 sierra prohunter sp
 1)2182
 2)2155
 3)2165
 4)2178

High:2182
 Low:2155
E.S.:27
Ave.:2170
S.D.:10.7

24.3gn 1680 125 sierra prohunter sp
 1)2200
 2)2186
 3)2191
 4)2180
 5)2141

High:2200
 Low:2141
E.S.:59
Ave.:2179.6
S.D.:20.4

24.6gn 1680 125 sierra prohunter sp
 1)2235
 2)2230
 3)2231
 4)2212
 5)2214

High:2235
 Low:2212
E.S.:23
Ave.:2224.4
S.D.:9.5

24.9gn 1680 125 sierra prohunter sp
 1)2274
 2)2211
 3)2264
 4)2183
 5)2249

High:2274
 Low:2183
E.S.:91
Ave.:2236.2
S.D.:34.1

25.2gn 1680 125 sierra prohunter sp
 1)2277
 2)2256
 3)2262
 4)2258
 5)2281

High:2281
 Low:2256
E.S.:25
Ave.:2266.8
S.D.:10.2

25.5gn 1680 125 sierra prohunter sp
 1)2317
 2)2274
 3)2274
 4)2313
 5)2260

High:2317
 Low:2260
E.S.:57
Ave.:2287.6
S.D.:23

23gn 1680 130sp hornady
 1)2124
 2)2107
 3)2096
 4)2109
 5)2116

High:2124
 Low:2096
E.S.:28
Ave.:2110.4
S.D.:9.4

23.5gn 1680 130sp hornady
 1)2160
 2)2118
 3)2119
 4)2135
 5)2118

High:2160
 Low:2118
E.S.:42
Ave.:2130
S.D.:16.3

24gn 1680 130sp hornady
 1)2188
 2)2151
 3)2151
 4)2179

High:2188
 Low:2151
E.S.:37
Ave.:2167.3
S.D.:16.6

24.5gn 1680 130sp hornady
 1)2144
 2)2241
 3)2222
 4)2205

High:2241
 Low:2144
E.S.:97
Ave.:2203
S.D.:36.4

25gn 1680 130sp hornady
 1)2248
 2)2229
 3)2231
 4)2224
 5)2239

High:2248
 Low:2224
E.S.:24
Ave.:2234.2
S.D.:8.4

25.5gn 1680 130sp hornady
 1)2330
 2)2302
 3)2274
 4)2223
 5)2279

High:2330
 Low:2223
E.S.:107
Ave.:2281.6
S.D.:35.4

thanks

and yes a lot of satisfaction at the end of the day for me.

now you need to get the 300blk going.  

Very good read, thank you for the write up.

Posted Via AR15.Com Mobile

So is the extra length in the neck shoulder, both?

mostly the shoulder is higher will see if i can find the pic comparing the 2

here it is

i did some testing and standard mags work to an extent. I was using 20 rd c-products aluminum mags with an orange follower, 5-8 rounds would work ok but then they would start binding and the rounds also started to get a good tilt to them.

so for hunting and what not if you only need 5-8 rounds stock mags will work ok.

What's the advantage to making these rounds versus using 7.62x39?  Bullet weights and velocity are pretty close looks like going by your posted velocities and bullet weights.  What am I missing?  I'm sincerely curious.

for me it was the use of 556 cases and all standard ar15 parts other than barrel. stock mags also work as i stated just with diminished capacity in my case.

also for me it was because it is a wildcat round.

So, for you it was equipment, not the round in and of itself other than it being a wildcat.  No real advantage to it ballistically over the 7.62x39?

for me yes it was the equipment. i wanted a 30cal round to go dear and hog hunting with and really never even looked at the 39 because i had heard about bolt problems and i wanted to use the stock bcg.

so i focused on wildcats and chose this over the 300blk because of more velocity and i didn't need to run subsonic loads because no supressors allowed in iowa.


there is a thread in the variants section that deals with the development of the caliber. 7.62x40 thread

finally got my 5/16-32 tap to make a case for my hornady oal gauge.

drilled and taped a fireformed case and measured my bullet assortment here are my results.


the ogive measurement is to the lands and the oal is the oal with ogive on the lands

hornady 110 vmax ogive 1.693 with oal 2.261

hornady 130 soft point ogive 1.6935 with oal 2.188

sierra 125 pro hunter ogive 1.743 with oal 2.2295

nosler balistic tip ogive 1.7415 with oal 2.363


i had been loading my 110 vmax's at 2.252 and they have been my most accurate round. now i see i am only about .009 off the lands.

BIGGDAWG, what is the barrel length on your X40 ?

i went with the 18" polygonal with mid gas

Great day at the range today. getting my loads finalized

looks like 25.8 grains of aa1680, 110 vmax is my go to load.

it is averaging  2425 fps to 2450 and averaging .4 to .75 inch groups at 100 yards.

i also tried to go for max charge today. no pressure signs and i went to 26.8 grains on fire formed cases, the case is about full

26.6 shows promise  i was dealing with a wind at 9 o'clock 10-20mph

i also have it sighted in at 200yards that is why they are all high. about 2.7 inches high at 100 if sighted in at 200

thank you, yes it looks to be a winner

here are a few from last weekend. my nosler 125 load is dead on at 100 if i sight the 110 in at 200

I can only hunt predators in my area with a rifle but i am going to southern iowa in jan for a doe hunt with it.

i know if i can get one with in 200 i will get it.  

but it sure punches paper good and some great one shot kills on small squash  

Got out to the range today to test a new powder. it was 29 degrees out and i had to go to a public range so i didn't get chrono info.

the new powder is hodgon h110 with my 110 vmax bullets it looks to be a winner too i need to get chrono info but that may be a while but the groupings are good

and no pressure signs as of yet. I also shot the 25.8 load at 200yds and it still holds .590 moa group at 200 with me kinda shaking.

thanks again dryflash.

yes this gun is a keeper.  I am glad the h110 is working out because i can source it locally. i can't get 1680 locally i have to drive 120 miles to get it one way

and i refuse to pay hazmat fees. wish my slug gun shot half as good as this going deer hunting next weekend but i can't use rifle till the jan doe season and that is in the southern

counties 3-4 hr drive.