BIGBREW 308 BUILD

sketch · April 25, 2017

Yup loob that sucker good for break in...how many rounds so far?

jtallen83 · April 25, 2017

My Matrix build has cratered primers like that from day one, more to do with tolerance between the bolt and firing pin than headspace I think. I also get that same dent in the neck on half my brass, my 716 really crimps them!

BIGBREW · April 25, 2017

21 hours ago, sketch said:

Yup loob that sucker good for break in...how many rounds so far?

Only 20 rounds

BIGBREW · April 26, 2017

Finally got a chance to measure a few rounds. Remington blue box. Overall length of the round got smaller by .006 to .016 of an inch.

98Z5V · April 26, 2017

Spent cases, or unfired ammo?

BIGBREW · April 26, 2017

9 hours ago, 98Z5V said:

Spent cases, or unfired ammo?

Chambered round and ejected no fire.

#1 Fresh round 2.678

After chamber 2.672

#2 Fresh round 2.676

After chamber 2.660

Edited April 26, 2017 by BIGBREW

98Z5V · April 26, 2017

Bullet setback, that's called. Not enough crimp on the casing after seating the bullet. Doesn't usually happen in bolt guns, but severe bullet setback can be disastrous in a semi. The numbers above aren't bad. Not saying it's good, but it's not severe. Severe, on a semi, is when that bullet gets shoved all the way back in the case.

Pressures would be higher in rounds that setback, over rounds that don't move in the case. I don't think there's a calculation or way to determine how much higher, without physically measuring chamber pressure, though.

BIGBREW · April 26, 2017

1 hour ago, 98Z5V said:

Bullet setback, that's called. Not enough crimp on the casing after seating the bullet. Doesn't usually happen in bolt guns, but severe bullet setback can be disastrous in a semi. The numbers above aren't bad. Not saying it's good, but it's not severe. Severe, on a semi, is when that bullet gets shoved all the way back in the case.

Pressures would be higher in rounds that setback, over rounds that don't move in the case. I don't think there's a calculation or way to determine how much higher, without physically measuring chamber pressure, though.

Next step?

98Z5V · April 26, 2017

For that, nothing, really. Pay close attention to those rounds when live-firing. Check all the brass for abnormal pressure signs. I don't think that amount of setback is enough to cause a serious situation, but based on the varience, your shot groups might suck with it.

Maybe it's a bad batch, or maybe they never crimp that brand.

I couldn't find any Remington blue box ammo - got a pic of the ammo box?

BIGBREW · April 26, 2017

26 minutes ago, 98Z5V said:

For that, nothing, really. Pay close attention to those rounds when live-firing. Check all the brass for abnormal pressure signs. I don't think that amount of setback is enough to cause a serious situation, but based on the varience, your shot groups might suck with it.

Maybe it's a bad batch, or maybe they never crimp that brand.

I couldn't find any Remington blue box ammo - got a pic of the ammo box?

My apology. It was Federal.

98Z5V · April 26, 2017

3 minutes ago, BIGBREW said:

My apology. It was Federal.

That's the Power-Shok hunting ammo. There's a whole bunch online about the crimping of that stuff.

BIGBREW · April 26, 2017

Lol great. I have another box and a half. I'll give something else a try. I might have a little more info but I have to wait till I get home from work. Thanks 98

98Z5V · April 26, 2017

4 minutes ago, BIGBREW said:

Lol great. I have another box and a half. I'll give something else a try. I might have a little more info but I have to wait till I get home from work. Thanks 98

They'll shoot, and I don't think they're gonna cause you pressure issues that would harm you or the gun - I'd just shoot 'em all up. I wouldn't use them to zero my scope, though. Try them out for accuracy and see if they shoot tight groups, or if they're all over the paper. THAT would be a decent test, and interesting results. :thumbup:

BIGBREW · April 26, 2017

20 minutes ago, 98Z5V said:

They'll shoot, and I don't think they're gonna cause you pressure issues that would harm you or the gun - I'd just shoot 'em all up. I wouldn't use them to zero my scope, though. Try them out for accuracy and see if they shoot tight groups, or if they're all over the paper. THAT would be a decent test, and interesting results.

We did get some odd results when we were playing with the scope when giving it it's test run. Just when we thought we were dead nuts we were across the paper.

In other news, I bought a new scope. The other one needed two mounts to get it off the barrel. I threw the new scope on with the old mount set up. Taking it apart last night i can take off the 1/2 inch riser that i needed for the first scope and get this one down a bit.

98Z5V · April 26, 2017

That Vortex isn't gonna give you any issues, that's for sure - but I'd be interested, now, to see if you get some weird groups. It will be from velocity differences from the ammo, with the projectiles seated to various depths, after chambering.

Jetdoc · May 5, 2017

Brew ....Ive used this technique when using a bipod and it works great. Installing your bipod with the legs folding back is not a option to properly pre load the bipod.

Great looking Rifle and awesome color! :fullauto:

jtallen83 · May 6, 2017

9 hours ago, Jetdoc said:

Installing your bipod with the legs folding back is not a option to properly pre load the bipod.

Atlas bi-pods are an exception to that, they fold both ways no matter which way you install them.

survivalshop · May 6, 2017

What manufacturer is you Bolt /BCG ? Cratered primers can also be a sign that the Firing Pin Hole in the Bolt face is too large , may not be a safety issue , just cosmetic as far as what your primers will look like . Just ask anyone with a DPMS G2 . Or it could be ammo is a little hot .

BIGBREW · May 8, 2017

On 5/6/2017 at 7:08 AM, survivalshop said:

What manufacturer is you Bolt /BCG ? Cratered primers can also be a sign that the Firing Pin Hole in the Bolt face is too large , may not be a safety issue , just cosmetic as far as what your primers will look like . Just ask anyone with a DPMS G2 . Or it could be ammo is a little hot .

Bolt and carrier are from DWilson on the page here.

Haven't had time to shoot it again have stuff going on the next couple weekends did i sent the rings out to be painted to match. Hopefully I have them back later this week or early next week. Ill probably get a chance to shoot again in a couple weeks.

BIGBREW · May 8, 2017

On 5/5/2017 at 7:59 PM, Jetdoc said:

Brew ....Ive used this technique when using a bipod and it works great. Installing your bipod with the legs folding back is not a option to properly pre load the bipod.

Great looking Rifle and awesome color!

I mounted them facing forward.

BIGBREW · May 8, 2017

So i see the new MA top loaders, think I might pre order one, when I get it fix the magazine. Not having a grip to hold onto is making me nuts. This stupid removable magazine/ pistol grip law here blows.

I can tolerate three rest of the law, 10 round mag doesn't bother me, no holes at the end of the barrel doesn't bother me.

Not having a good grip on the firearm in my hand..... bothers me.

Edited May 8, 2017 by BIGBREW

survivalshop · May 8, 2017

10 hours ago, BIGBREW said:

Bolt and carrier are from DWilson on the page here.

I don't see an issue with that brand , I have several of his & no issues with firing pin holes .

BIGBREW · May 8, 2017

18 minutes ago, survivalshop said:

I don't see an issue with that brand , I have several of his & no issues with firing pin holes .

Thank you. You are always very helpful.

jtallen83 · May 8, 2017

4 hours ago, survivalshop said:

I don't see an issue with that brand , I have several of his & no issues with firing pin holes .

My D Wilson bolt in my Matrix build has a bit of a crater effect from the hole being a touch big but it has not been an issue, never had a rupture. I'm pretty sure it is not a pressure issue as it does it with everything including the ZQ1 and other underpowered ammo. It is the only one of several D Wilson BCG's I have that do this, haven't tried swapping a firing pin from the extra parts kit yet..............

survivalshop · May 8, 2017

Just so its known , there is more to Primer cratering then just what we have talked about here , the Chamber holding onto the case a little longer then normal , can also show these signs as does some Primer brands & some Military crimping .

If they are not showing signs of puncture or the case is not showing pressure rings , I don't think its a cause of concern .