7mm and or 30cal Bushmaster?

The forum is for discussions about calibers whose parent is the 450B.

Moderators: MudBug, Hoot

Re: 7mm and or 30cal Bushmaster?

Postby IceAxe » Thu Jan 14, 2016 8:31 pm

I think finding the right bullet will probably be key. I cleaned it good today, and time permitting I will measure the distance to the lands tomorrow. If it has a long jump I may try a round nose. I will see what kind of assortment Sportsman's has available.
NRA Life
User avatar
IceAxe
 
Posts: 68
Joined: Fri Aug 15, 2014 9:43 pm
Location: Colorado Springs, CO

Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Thu Jan 14, 2016 9:28 pm

I ordered a 5/16-36 tap to make a DIY case to go with my Stoney Creek Overall Length Gauge since Hornady, who took that product over, doesn't sell one for the 30 RAR. The tap is good for more than one case, so if anyone wants me to make one for them, send me a clean, resized case and return postage. If interested, contact me for my address. The tap should be here next week.

For typical tangent ogive bullets like we will be seeing, it may take a long one to reach to the lands without falling out of the case. Probably going to need a 168-180gr 30 cal bullet to measure it. There's an old trick to establish the absolute leade length. Turn a flat base bullet around backwards and measure where it stops at the lands. That will show the absolute leade length since the flat base it precisely at the diameter where the ogive ends. The impact it has upon a spitzer or round nose COL will not be reflected by the absolute distance unless you will be loading wad cutters however. IIRC and I may not, my original 450b barrel had something like a .32 absolute leade, which is a little "roomy". Then again, the entire chamber was "roomy". I could actually load 300gr Hornady XTP Mag bullets to the lands without exceeding 2.26 COL since it is so blunt on the end. Since you're more concerned with how a particular bullet measures, the absolute lead is just an esoteric measurement. It would be interesting to see what different leades are out there for the 450b since there are a lot more barrel makers since back when I measured my original Bushmaster barrel. I do recall measuring a Trident barrel and it was spot on with the SAAMI spec.

Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.
User avatar
Hoot
 
Posts: 5083
Joined: Tue Feb 09, 2010 9:34 am
Location: Minnesota

Re: 7mm and or 30cal Bushmaster?

Postby IceAxe » Fri Jan 15, 2016 9:55 am

I measured the case volume on five of my spent cases from the 30 RAR. They averaged 44.8 grains of water. That is a bit more than QuickLoad referenced at 44. I am thinking I might be able to use some of the 3031 I have on hand with a slight compression.
NRA Life
User avatar
IceAxe
 
Posts: 68
Joined: Fri Aug 15, 2014 9:43 pm
Location: Colorado Springs, CO

Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Fri Jan 15, 2016 10:21 am

IceAxe wrote:I measured the case volume on five of my spent cases from the 30 RAR. They averaged 44.8 grains of water. That is a bit more than QuickLoad referenced at 44. I am thinking I might be able to use some of the 3031 I have on hand with a slight compression.


Interesting idea. I have an old tin of 3031 but it's got to be something like 15+ years old. Here's a clue. The faded sticker on it says $9.88 :lol:

Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.
User avatar
Hoot
 
Posts: 5083
Joined: Tue Feb 09, 2010 9:34 am
Location: Minnesota

Re: 7mm and or 30cal Bushmaster?

Postby IceAxe » Fri Jan 15, 2016 7:55 pm

Well now maybe we should check lot numbers!
Attachments
image.jpeg
image.jpeg (58.39 KiB) Viewed 37817 times
NRA Life
User avatar
IceAxe
 
Posts: 68
Joined: Fri Aug 15, 2014 9:43 pm
Location: Colorado Springs, CO

Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Fri Jan 15, 2016 8:22 pm

My dies arrived from Midway and fate being the cruel mistress of the universe, they're the wrong dies. The sent me 30 Remington, not 30 Remington AR. I open the box and look at the resizing die and my mind's eye goes "That hole's too small!". I then looked at the side of the box and no AR in the name. So, I have to box them back up and send them back. Went ack to the Midway site and of course, the 30 Rem AR FL sets are sold out, past due, kiss-of-death. :|

Gotta look around and see who else actually has them in stock for a reasonable price.

Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.
User avatar
Hoot
 
Posts: 5083
Joined: Tue Feb 09, 2010 9:34 am
Location: Minnesota

Re: 7mm and or 30cal Bushmaster?

Postby IceAxe » Sat Jan 16, 2016 6:21 pm

I hate when I get the wrong part! Though in most cases I was in too much of a hurry, and ordered the wrong part.

I tried two bullets I had on hand and think the SST looks the most promising of the two.
Attachments
image.jpeg
150gr SST
image.jpeg (52.9 KiB) Viewed 37797 times
image.jpeg
150gr FN
image.jpeg (46.88 KiB) Viewed 37797 times
NRA Life
User avatar
IceAxe
 
Posts: 68
Joined: Fri Aug 15, 2014 9:43 pm
Location: Colorado Springs, CO

Re: 7mm and or 30cal Bushmaster?

Postby Hoot » Sun Jan 17, 2016 11:21 pm

IMHO and I saw this as well in the 300 OSSM, the 150 gr bullets while being a weight we commonly think of as minimum for deer sized game, do not take advantage of the geometry limited by having to fit the rounds in an AR 15 magazine. I will know for sure soon enough, but I'd bet that your best results will come from 110gr-130gr bullets. I doubt that a deer will feel the 20-30gr difference in weight when your shot placement is ethical. A lot of folks are hanging venison using 110gr Barnes bullets shot out of 300 BO, 7.62x40 and the 30 HRT as well as 125 and 130 grainers. Your results do serve as a baseline to compare to using different form factor but same weight bullets and either or both, different powder charges or different distance to lands seating depth. Those variables can be experimented with within a given bullet weight, to find what your chamber and barrel prefer. To save on losing powder capacity from seating depth, it also helps to stick with flat bottom bullets as opposed to ones with boat tails when loading the heavier bullets. The boat tails do not add to the neck retention amount since they are less diameter than the bearing surface of the bullets but they do take up valuable powder space.

Hoot
In Theory, there is no difference between theory and practice. In Practice, there is.
User avatar
Hoot
 
Posts: 5083
Joined: Tue Feb 09, 2010 9:34 am
Location: Minnesota

Re: 7mm and or 30cal Bushmaster?

Postby IceAxe » Mon Jan 18, 2016 10:33 am

I agree, I had those bullets on hand so wanted to see how a home load compared to my earlier factory load results. Also, my fear was that the chamber might have a long lead or throat causing the mediocre accuracy and therefore might benefit from a longer bullet. I will probably have to order something online in the 130 range and hopefully without getting into a varmint bullet.
NRA Life
User avatar
IceAxe
 
Posts: 68
Joined: Fri Aug 15, 2014 9:43 pm
Location: Colorado Springs, CO

Re: 7mm and or 30cal Bushmaster?

Postby m113103 » Mon Jan 18, 2016 1:04 pm

Before you get too hung up on bullet weight. Check out the Barnes and u tube video's on ballistic gel impact. Barnes marketed a 30-06 130gr load that wasn't popular. Not because it didn't perform well, but it wasn't a conventional weight. Barnes has a 110gr flat base that has killed a lot of deer. The AR platform for hunting isn't the go to gun for 500yd to 1000+yd hunting IMHO. :P :D :D
m113103
 
Posts: 148
Joined: Fri Sep 26, 2014 8:42 pm
Location: Thumb of Michigan

PreviousNext

Return to 450B Children

Who is online

Users browsing this forum: No registered users and 7 guests

cron