At what point is cratering an issue?

[Cerwinski]

My Bergara HMR in 6.5 Creed has done nothing but please me since I bought it in early May. For this newb to attempting precision shooting I am amazed how well it shoots. So impressed that I decided to try some "good" brass. I bought 100 Lapua cases and loaded them up with the gun's favorite load, which is 41.6 grains H4350 under a 140 grain ELD-M. I used CCI 450 primers for this. The very first group of five produced the tightest group I've ever seen this gun produce. Easily sub 1/2 MOA. As expected (from research) the primers were definately more cratered than the same load with the Hornady brass I had been loading. I had zero issues with bolt lift, etc. Just super accurate shooting.

This is admittedly a pretty mild load (avg 2690 FPS) but I'm very happy with it. Is the cratering a potential issue down the road as far as wear on the bolt? Or anything for that matter?

Interesting to me was the avg FPS was nearly identical to between the two different types of brass. I kinda expected the Lapua to be a little faster...

I was thinking I may have to send the bolt off for a bush job but if I don't have to all the better. Opinions welcome.

 

[Steel head]

My last savage cratered anything and everything.

With realistic loads it never popped any primers.

It was a non issue for me.

 

[trob_205]

In my AI I went through 150ish rounds of cratered Lapua brass without issues. Then like a faucet was turned on it pierced 1 out of every 10. I’ll be sending my bolt to LRI to be bushed when life settles down a bit.

 

[antithesis]

What elevation and barrel? <2700 seems rather slow for that load/bullet.

IMO if the crater is uniform and the lip is not sharp than likely a non-issue. I start looking for answers if I see an uneven splash or sharp edges.

 

[Cerwinski]

'Bout 13 feet ASL. 22" barrel.

 

[Hawk in WY]

In my AI I went through 150ish rounds of cratered Lapua brass without issues. Then like a faucet was turned on it pierced 1 out of every 10. I’ll be sending my bolt to LRI to be bushed when life settles down a bit.

What caliber? Small or large primer?

 

[Lunchbox27]

my factory 223 will crater any primer I feed it. Factory ammo, mild charge hand loads... doesn't matter.

 

[garandman]

My Rem 700 in 6.5 CM 41.5 H4350 140 Berger....

 

[Jake the dog]

My B14 Bergara cratered everything. When I started using Lapua SRP with Fed 205M, it started piercing primers. I swapped into a bolt from the Premier series, which has a small fp. No cratering or piercing. Having the bolt bushed is slightly cheaper, but takes longer. Replacing the bolt took a day for shipping, but I live in Georgia, fairly close to Bergara.

 

[trob_205]

What caliber? Small or large primer?

Small Rifle Primer 6.5 Creed

 

[47guy]

drop the pin with the bolt out of the gun and look at the pin compared to the pin hole in the bolt...id be willing to bet its a sloppy fit...its pretty common.
if it really bothers you have the bolt bushed other wise just shoot it.

 

[JMcBurn]

My Bergara HMR in 6.5 Creed has done nothing but please me since I bought it in early May. For this newb to attempting precision shooting I am amazed how well it shoots. So impressed that I decided to try some "good" brass. I bought 100 Lapua cases and loaded them up with the gun's favorite load, which is 41.6 grains H4350 under a 140 grain ELD-M. I used CCI 450 primers for this. The very first group of five produced the tightest group I've ever seen this gun produce. Easily sub 1/2 MOA. As expected (from research) the primers were definately more cratered than the same load with the Hornady brass I had been loading. I had zero issues with bolt lift, etc. Just super accurate shooting.

This is admittedly a pretty mild load (avg 2690 FPS) but I'm very happy with it. Is the cratering a potential issue down the road as far as wear on the bolt? Or anything for that matter?

Interesting to me was the avg FPS was nearly identical to between the two different types of brass. I kinda expected the Lapua to be a little faster...

I was thinking I may have to send the bolt off for a bush job but if I don't have to all the better. Opinions welcome.

If you send it out to be bushed you won't have to worry about it anymore, but as long as it isn't piercing and you don't see any wear on the pin you should be fine. As long as your pin doesn't wear or the hole doesn't wear till it starts popping primers.

 

[6brshooter]

Lapua is fairly thicker brass than hornady. In my aiat, keeping everything the same except brass, the rds in lapua brass was 70fps faster than horn brass. Did you actually chrono these loads or just going by previous data?

 

[bogey]

My buddies bergera would shoot dang tight..... and throw fliers and pierce primers. Had bolt bushed and both have stopped

 

[Cerwinski]

Lapua is fairly thicker brass than hornady. In my aiat, keeping everything the same except brass, the rds in lapua brass was 70fps faster than horn brass. Did you actually chrono these loads or just going by previous data?

Numbers obtained yesterday with my Magnetospeed V3.

 

[TheGerman]

As far as primers go; unless there is like 0 space between the primer and case or the primer is pierced, I dont even care.

It's the extractor/ejector marks and overall case I'm looking at.

 

[psubond]

My 700 craters EVERYTHING. I just watch for ejector marks, flat primers (havent pierced or popped any primers either), sticky bolt etc.

 

[LawnMM]

When it pierced the primer it's a problem

 

[Dale264]

It an issue once primers become pierced.

 

[stevenlgts]

What exactly is cratering? Are we talking about the firing pin impression on the primer or the primer metal flow into the firing pin channel, which makes the concentric raised ring around the fp impression, or both? Apologies for the fuzzy pics, notice the flattened primer too!

 

[6brshooter]

The ridge around impact, where primer flow goes in between fp and fp aperature. Its usually a indicator of pressure, as most factory actions are sloppy around the FP. I normally dont pay attention to cratering, looking for fully flattened edges are a more true indicator of pressure, followed by ejector swipe, then pierced primers.

 

[stevenlgts]

The ridge around impact, where primer flow goes in between fp and fp aperature. Its usually a indicator of pressure, as most factory actions are sloppy around the FP. I normally dont pay attention to cratering, looking for fully flattened edges are a more true indicator of pressure, followed by ejector swipe, then pierced primers.

Thanks for the reply. I do notice that most of my rifles produce some sort of cratering so I follow a similar process for pressure signs but also include ejected primers.

 

[6brshooter]

Flattened primers is my max sign, ejector swipes are " back up", pierced primers is "oh shit". I guess blown out primers is "duck and cover", lol.

 

[stevenlgts]

Flattened primers is my max sign, ejector swipes are " back up", pierced primers is "oh shit". I guess blown out primers is "duck and cover", lol.

I have had everything but pierced primers. Only one blown primer though care of my 308 gas gun ... thankfully!

 

[CJS-6.5]

I have a 22-250 Hmr that craters every load. Factory, mild and hot loads. But it doesn't pierce and it shoots good so who cares? I just wish it was 1:8 twist instead of 1:9.

 

[6brshooter]

Yep, sounds like a sloppy fp aperature. My aiae was like that till lri worked there magic. That 9 tw should do fine with a 77gr smk.