Fimally fired first shots of my new build! + Pics

[maroberson]

First of all, Thank you to everybody here for the generosity, all of the insight, and patience to coach a complete noob. With the exception of general stock changes and such this was my first attempt at any type of build and I'm not sure I would have got through it without the wealth of knowledge that can be found on this forum.

So my first build was a 450 Bushmaster that will be used for Indiana deer hunting.

The donor rifle was a new 11 TH XP 308
Barrel is a 17.5" 16t from Apache
Stock is the Pro Hunter model from Sharp shooter supply
Had everything metal cerakoted graphite black locally
Nikon Prostaff 5 2.5-10x40
Weaver 1 piece base/ Warne maxima rings/ Butler Creek caps
and sling made by me
http://i103.photobucket.com/albums/m147/maroberson1984/20140531_111843_zps407fa25b.jpg (http://s103.photobucket.com/user/maroberson1984/media/20140531_111843_zps407fa25b.jpg.html)
http://i103.photobucket.com/albums/m147/maroberson1984/20140531_111514_zps2b28673a.jpg (http://s103.photobucket.com/user/maroberson1984/media/20140531_111514_zps2b28673a.jpg.html)

I'm pretty happy with the way it shot. I only fired 7 shots just to get my scope in for now. I left my bipod at home and all I had as a rest was my range bag so it was less that ideal
Target on the left is 50 yards and the right is 100. The shot at the very bottom of the target was the very first shot out of the rifle
http://i103.photobucket.com/albums/m147/maroberson1984/20140531_125919_zps10ab5bbd.jpg (http://s103.photobucket.com/user/maroberson1984/media/20140531_125919_zps10ab5bbd.jpg.html)

There's only 2 concerns that I have at this point. First, when originally test fitting everything it cycled factory brass just fine. After I used the gauges to set headspace the extractor wants to hang up while closing the bolt. Also it appears that there is excessive fouling around the case mouth. No apparent bulging or anything though.
http://i103.photobucket.com/albums/m147/maroberson1984/20140531_111804_zps0f0e7403.jpg (http://s103.photobucket.com/user/maroberson1984/media/20140531_111804_zps0f0e7403.jpg.html)
Does that look normal?

[mattri]

Very interesting! Great looking rifle and good shooting too. Did you use standard go/no go gauges? Have you tried cycling either of them since putting the rifle together?

[maroberson]

Thanks
Actually I had a problem with the standard gauges. The case rim diameter was slightly too big and would not seat all of the way to the bolt face. They sent me the AR version go/no go which has the same length but no rim. They fit fine but they wont extract obviously.

[mattri]

That's interesting, isn't the 450 rim diameter smaller than a standard 308 rim of .473?

ALSO CAUTION -- The rim diameter is different too. 284 brass is .473 inches. 450 bushmaster is .470 inches. In addition, the rim "groove" diameter is larger. I think Hoot has the dimensions.

From here:

http://450bushmaster.net/viewtopic.php?f=5&t=4817

Hopefully some folks more experienced than me will reply, I think this project is an awesome idea and would love to see it perfected.

[maroberson]

They had an explanation as to why the gauges were slightly oversized but it didn't really make all that much sense to me. When comparing the gauge to the factory ammo I had it was obviously larger than the brass. The brass seats against the bolt face fine. FWIW I'm shooting factory Hornady ammo and I don't reload so that's probably all that I will shoot.

The only thing I find odd was when I originally mocked everything up I used factory brass and some shims to get it close. I function tested everything and it the bolt closed fine. When I got the gauges I had to loosen the barrel about 1/4 turn to get the go gauge to close all of the way. I didn't function test it again until I went to shoot this morning. Now like I said it hesitates a little when the extractor is engaging the cartridge.

The extractor appears to be put back together correctly

[Texas Solo]

There appears to be a split case neck on the 2nd case down from the top in your pic.

[maroberson]

There appears to be a split case neck on the 2nd case down from the top in your pic.

It's a scratch

[mattri]

Shims? Where, what, why? Sounds like we're narrowing down the what of the problem, just need to sort out the why/how.

As it stands can you feed-chamber extract a factory round?

[maroberson]

Shims? Where, what, why? Sounds like we're narrowing down the what of the problem, just need to sort out the why/how.

As it stands can you feed-chamber extract a factory round?

I initially set it up with factory brass and using brass shim stock on the case head for a no go. I essentially wanted to get it as close as possible while waiting for the gauges while I worked on the stock. The shims have nothing to do with how it is set up now.

Yes I can feed and extract a factory round. It just sticks a little at the start of dropping the bolt when the extractor is engaging the case.

[bootsmcguire]

I have had mine together now for some time, and can't say I have had any of those issues. The carbon/colors you are getting on your cases seems normal to me as mine does it a bit too. As to your extractor, I would just bet you have a stiffer than normal extractor. Mine has the SSS kit in the bolt head and it works perfectly. FWIW it also worked perfectly with the factory parts too.

I set my headspace using a pc off brass of nominal length and it works great. Feeds and functions flawlessly.

[bootsmcguire]

Here is an excerpt from a message I received from Jim earlier explaining why we are getting the carbon colors on the 450BM brass.


Saw the 450 BM post on the new build that maroberson did.........The brass isn't sealing the chamber completely when it is fired. Nearly any load pulled off the net for the 450 BM will be loaded to function out of an AR......at AR pressures. One of the ways it was cured in the AR platform was to use heavy crimps which (in theory) caused the cartridge to develop enough pressure to seal the chamber before releasing the bullet to proceed down the barrel........personally, I'm not sure I buy into that theory. But whether it's true are not it did seem to help the problem with the AR platform. Care had to be taken when crimping because the case mouth is what it is headspaced on.....too much crimp....and you can guess what happens from there.

The pressures of AR loads are well below that of what the Savage can handle. The little 450 BM can be a very powerful cartridge in a bolt gun for no bigger than it is. Especially with heavy for caliber slugs.....which is why I used the faster twist barrels for it. Higher pressures will seal the chamber properly. Be sure to use rifle primers and not pistol primers when driving the pressures up in a bolt gun. DO NOT UNDER ANY CIRCUMSTANCES PUT A ROUND THAT HAS BEEN DEVELOPED FOR A BOLT GUN IN AN AR PLATFORM. IT WILL DESTROY THE AR AND MAY EVEN TAKE YOU WITH IT.

You may want to try it a bit and see what I'm talking about..... Just use the same precautions as when reloading any other round. ;)

Sounds like great tips direct from the barrel's maker himself.

[maroberson]

Thanks for the info boots. As far as the extractor goes, it's so minor I'm hoping it will wear in. If not then I might polish the extractor a little or send it to Fred and see what he can do with it.

What Jim said is interesting. I noticed that the crimp on the bullets that I have are pretty weak. I actually inadvertently pushed the bullet down pretty far into one of the cases.
I went to bed last night thinking that I might take it apart today and headspace to the factory cartridge and see if it cured both problems but after reading that I'm just going to leave it as is.
I've never really been that interested in handloading but this rifle may be the tipping point that gets me started on that path. I'm not really looking for pinpoint accuracy and I won't be shooting this rifle on a regular basis but as Jim's comments prove I know I could get more (both performance and function) of the 450 than what I'm getting from factory ammo.

[emtrescue6]

Great looking build! Must be nice to have the additional "modern" rifle options to hunt with now. I probably woulda chose the 450 BM as my caliber to build on as well....

[FW Conch]

" The gauges being oversize makes no sense to me either" ? :-((. If we know anything at all about installing a barrel, too little

headspace is a "non issue". "We won't be able to chamber a round"! Too "much" headspace is where "problems" arise!

If I find out that the gauge I head spaced off of is bigger than the rounds I am shooting, "guess what I'm going to headspace off of"?

The best and safest headspace is "0" headspace! JMHO :))

That's why I quit buying headspace gauges years ago. "But", I do reload. I see the dilemma for someone who only wants to shoot factory loads?

"I really want to know why a standardized headspace gauge would be noticeably larger than the rounds expected to be shot in that chamber. More than .004". :((

maroberson, as for me, I think you did it right the first time! :)) JMHO Good Luck-Good Shooting......Jim

[maroberson]

EMTrescue6
thanks for the compliment. I'm glad Indiana decided to allow certain "modern" calibers. Now that I built this I'm sure they'll open it up to bigger calibers but oh well.

FW Conch
The original gauge itself presumably wasn't larger, it was just the rim that was larger. I just finished checking the headspace with the shims and the fired brass and I'm showing .009" (bolt would barely close on .009 and wouldn't on .010) so I think I'm going to ditch the gauges and go back to square one with the cartridge and shims. I'm sure that will take care of at least some of the fouling.

Also I found the culprit for the sticking extractor. It was a bur right on the edge, I buffed it out with some emery cloth and now it function flawlessly.

[FW Conch]

Good deal on the extractor !

The way I see it, your cases headspace on the case mouth, so if you have calipers, I would find the longest fired one. If you don't have calipers, line the fired cases up on the kitchen table and pick the one that looks the longest. Chances are they will all look the same. Set your headspace with that case. Turn the barrel down ever so slightly until it touches the case, then just back it off slightly(.002"). Without moving the barrel or the action, snug up the barrel nut. When you tighten the nut, you will take up a little thread slack and get another .001" of headspace or so. Then, in a safe place, the range, etc., with the muzzle pointed in a safe direction, cycle your un fired cases through the chamber. My bet is they will all go.

Some will disagree with this, but to me, this is much safer than trying to set headspace with a gauge that is different than the ammo you will be using. And with this chambering, there is some confusion.

The "sooting" on the cases, I have noticed, happens with some powders, and not with others. Perhaps it is because some powders produce enough internal pressure to insure adequate seal and others do not. At any rate, it's not been a problem for me.

JMHO ! Good Luck.......Jim

[maroberson]

Thanks Jim

As much as I hate to tear it all apart I'm not sure I feel too comfortable with >.009. Especially since that is probably the only round that I'll ever use. I'm going to be pretty busy this week and I'm not sure I'll get to it until the weekend. In the mean time I'll read a little more and maybe some more people will weigh in.

[FW Conch]

The more who weigh in the better :))