Test firing new 300OSSM

[Wildfowler]

I loaded up two different series of test rounds for my new upper to check for function, pressure, and chronograph readings today and to get my scope bore sighted.

Speer hotcor 150 pointed SoftPoint

Barnes 130 grain non-tipped TSX.


I only shot a total of 20 rounds between those two bullets. The speer bullets would not reliably lock the bolt back. I got a maximum velocity of about 2950 ft./s with the 150 grain bullet.

The Barnes bullet did lock the bolt back every time and I got a maximum velocity of 3064 ft./s.

My chronograph readings are right on the money with what is published by Olympic. At least for the Barnes bullet, the speer bullet I'm using was never tested. And honestly it looked like I was getting a little hot with that speer bullet before I reached maximum. I never fired the last two rounds I had loaded up.

This will definitely be a big step up in power from the 300 blackout. I can't wait to flatten a hog with it.

I'm going to have the barrel threaded for my suppressor before I do any further testing with it. So far so good!!

If anyone is interested I'll share some more info when it's available?

 

[Ratdog68]

Yeah, keep the news flowin' ! I think the .300WTF is a dieing caliber already anyhow.

 

[FrankT]

Did you have the barrel custom made as I have never seen that before on an AR?

 

[Wildfowler]

Not custom but a factory Olympic Arms chambering. I had not heard of it before about 6 weeks ago when I began looking for something different to put on top of a couple of spare lowers I've had lying around. It uses a standard ar-15 lower receiver, a modified upper and bolt, modified ar-15 magazine, rounds single stack in the magazine, allowing for approx 4, 7, & 11 round capacity depending on the size of the original 223 magazine. They call this the game stalker. This particular cartridge is based off a 243 or 25 WSSM case. Olympic does have factory ammo available. There are some other calibers available including the 22-250 and a 35 caliber version made by Dedicated Technology. I bought my complete upper directly from Olympic. It was $900 and some change. Don't remember the exact price?


I only shot it today at 25 yards. All 20 test rounds from two different bullets all went in hole the size of a quarter.

I placed an order with Olympic at the beginning of Sept and was told to expect an 8-10 month wait. Upper showed up on my doorstep three weeks later. When I called to thank them, they said my order got placed just in the nick of time because they were just getting tooled up to run a batch of this caliber. Oldest orders had been in the queue since last December.

Here's another caliber from midway:

http://www.midwayusa.com/product/57...-vented-free-float-handguard-4-round-magazine

 

[FrankT]

Certainly an interesting chambering,,,good luck with it, keep us in the loop! Thanks

 

[Itsazonik]

This is the kind of stuff I'm talking about. Now I'm sitting here looking it up and wondering if I have the parts to start ANOTHER build. I have way too many going as it is. Sounds like a really interesting round. Can't wait to hear how it performs

 

[Wildfowler]

Just a little update. I decided to use the rifle a little bit before I sent it off just in case there were any problems with it that I needed to address before I modify the barrel. Currently shooting the Barnes TSX (non-tipped) 130 bullet at 3050 fps. I've killed four hogs with it. The biggest one being about 150 lbs. This cartridge will definitely knock them on their ass, much better than my blackout. I've recovered 100% of what I have shot with the weapon, but only one dropped in its tracks. The last hog (the largest) one was evidently standing at a more severe quartering angle than I realized. I was basically shooting at the dark silhouette way past sunset last week. Shot entered right through the lower shoulder, but exited mid gut area, probably in the liver. The shot knocked the animal over, but it immediately got up and ran off before I could get a second shot off. Honestly, I have very low success rate making those running off follow up shots anyway. Ran about 75 yards.

There is one problem that I think I know what the answer is. When I extract a live round, or simply firing normally, the brass and/or bullets are getting scratched up really badly. I've never had this problem before, but I think it's the feed ramps that are too sharp and causing these scratches. If I load and unload the same round several times, it looks like I dropped the round down the garbage disposal.

 

[Afalex1]

Remington is doing more research on the 300 wtf. I have a friend who is a machinist at a Remington ammo plant. He said their ballistics lab has had him making 220 grain bullets out of zinc on a lathe. I'm thinking they are trying to develop a bullet that will expand at sub-sonic speeds.

Sorry to hi-jack the thread a little. Ratdig's comment made me think about it.

300ssm sounds interesting.

 

[TEXASLAWMAN]

Remington is doing more research on the 300 wtf. I have a friend who is a machinist at a Remington ammo plant. He said their ballistics lab has had him making 220 grain bullets out of zinc on a lathe. I'm thinking they are trying to develop a bullet that will expand at sub-sonic speeds.

Sorry to hi-jack the thread a little. Ratdig's comment made me think about it.

300ssm sounds interesting.

Good they need to.

 

[Wildfowler]

I like my black out, but I also like dropping them with authority. This might be too much gun for the smaller ones?

Shot these two this afternoon about an hour ago. Waited until they lined up and got two with one shot. It's pretty messy so please do not click on this link unless you're prepared to see a bloody mess.

http://i63.photobucket.com/albums/h121/mswildfowler/image_zps870e38f9.jpg

 

[Afalex1]

Awesomeness!

 

[Wildfowler]

I am seeking suggestions.

Regarding the barnes 130 grain non-Tip Bullet. The barnes reloading manual states something to the effect of this bullet has a short shank and they recommend using a light factory crimp.

The OAL for my magazine works best at 2.287-2.290". There is not enough neck tension in the case mouth to hold this particular bullet in place when loading the weapon. I cannot seem to put enough crimp using the Hornady seating die to hold the bullet in place. Even when I tried removing the expander ball during the sizing operation, there is still not enough tension to hold things in place. I really wanted to use these bullets, but no longer think they are suitable for the 300 OSSM.

I've never been a fan of crimping rifle bullets anyway and it looks like it will take a very heavy crimp to make this bullet useable.

I assume what I'm experiencing is this bullet is being seated into the ogive to for magazine length. Does anyone have any suggestions for keeping this bullet locked in place?

Little frustrated with that bullet.

 

[pruhdlr]

If your referring to the #30838,can't you crimp it into the upper groove ?? One thing that just might help is when you trim your brass,de-burr the outside of the mouth but leave the inside sharp. Then when you crimp it will actually cut into the bullet somewhat. In my experiences this will not effect accuracy.

Years ago I subscribed to Precision Shooter magazine. Over the years I remember reading several articles re. "to crimp or not to crimp". Most all agreed that a crimp will help accuracy,all else being equal. Reason ---> as the pressure begins to build inside the case when the primer cracks and the powder starts to burn,it is better for the inside of the case to build up more pressure and the bullet to be "spit" out than not crimped and the bullet start out "slowly".

ALSO ----> the #30838 out of my 308 Win at 2725fps is a super killer. It penetrates thru thick bone,it opens properly. Both hogs and deer have fell to this combo. --- pruhdlr

 

[Wildfowler]

Unfortunately the groove is too deep into the neck on this case.

Thanks for the suggestion.