Hunting Washington Forum

Equipment & Gear => Guns and Ammo => Topic started by: BULLBLASTER on April 27, 2019, 10:23:55 AM

Title: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 10:23:55 AM: I’m pretty new to the 223 game but have a savage bolt gun that craters primers very badly and pierced them now and again. I know that over pressure can cause this but I don’t think my loads are over the top hot.

I’m shooting 70 grain Rdf at 2990 FPS out of a 26 inch barrel. Using 24 grains of h4895.

Primer edges are still nice and round. I read that the firing pin could have a long taper to the point and that could make some space in the firing pin hole. Could that be an issue here?

It shoots very well with this load and bolt lift isn’t tight or anything so curious if anyone has thoughts.
I’m going to drop by a couple tenths of a grain for next time out.
Title: Re: 223 bolt gun piercing primers
Post by: b23 on April 27, 2019, 11:22:11 AM: How close to the lands are you seating your bullets? When you start getting inside of 5 thou the start pressure spikes up a fair bit and if you have a load that is already close to max, and you seat them out that close, you'll be way over max in a hurry. Although, you velocity isn't particularly high and that's usually a good indication of pressure.

You do appear to be getting a good amount of flow back into the firing pin hole which could/would indicate a bit of pressure as well as an oversized firing pin hole.

I think 24gr of H4895 w/70's is definitely the upper limit and it probably wouldn't be a bad idea to drop it down to 23gr.
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 11:26:21 AM: These are well into the lands... like .020 with higher charges I was getting primer flattening but not at this charge. Flow into the pin hole happens at starting loads also.
I did my best to measure the pin and hole and they are .005-.007 different.
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 11:33:52 AM: This one was from a few weeks ago and was clearly hot.

Piercing only happened on 2 of the 60 rounds I shot yesterday.
Title: Re: 223 bolt gun piercing primers
Post by: b23 on April 27, 2019, 11:34:36 AM: If you're using 24gr powder AND you're jamming them, I'd say you definitely need to back it down at least a grain.

FWIW, Berger and Hornady both show 23gr H4895 with their 70 grainers as max and that's not even jamming them. When you start touching the lands or jamming them like you are, you're pressures are quite a bit higher than if you were seating them 20 thou off.
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 11:46:19 AM: Those are good points. I’ve been using nosler data (24 max) and Hodgkin data (25 max) as my starting points. The nosler data is actually 5.56 data also

I’m used to seeing primer flattening or heavy bolt lift well before piercing. But I haven’t done any 223 until recently. I’ll drop it down and see how they look.
Title: Re: 223 bolt gun piercing primers
Post by: Karl Blanchard on April 27, 2019, 12:04:04 PM: You cant re-use primers so if I were you I'd go 24.5 and stop being such a sissy :chuckle:
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 12:37:28 PM: Quote from: Karl Blanchard on April 27, 2019, 12:04:04 PM
You cant re-use primers so if I were you I'd go 24.5 and stop being such a sissy :chuckle:
:chuckle:
Title: Re: 223 bolt gun piercing primers
Post by: b23 on April 27, 2019, 12:57:36 PM: Since you're jamming these things that hard into the lands it's holding the case head tight against the bolt face instead of the case slamming back into the bolt face like it would if you weren't jamming or had negative headspace.

I think you said you were jamming them 20 thou, I'll bet you really aren't jamming them that hard and instead it's just pushing the bullet back into the case when you chamber a round. I think if you were running enough neck tension to prevent this from happening it would be very difficult for you to close the bolt.

Also, when you are loading into the lands like that, you have to be VERY careful extracting a loaded round because, often, the bullet will stick in the lands and pull it right out of the case. Not only will it leave a powdery mess in the chamber, but you'll need to tap the bullet out with a cleaning rod too.
Title: Re: 223 bolt gun piercing primers
Post by: jasnt on April 27, 2019, 01:27:22 PM: 23.2gr of h4895 was my max load with 77gr ncc’s but loading at mag length
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 03:23:26 PM: Quote from: b23 on April 27, 2019, 12:57:36 PM
Since you're jamming these things that hard into the lands it's holding the case head tight against the bolt face instead of the case slamming back into the bolt face like it would if you weren't jamming or had negative headspace.

I think you said you were jamming them 20 thou, I'll bet you really aren't jamming them that hard and instead it's just pushing the bullet back into the case when you chamber a round. I think if you were running enough neck tension to prevent this from happening it would be very difficult for you to close the bolt.

Also, when you are loading into the lands like that, you have to be VERY careful extracting a loaded round because, often, the bullet will stick in the lands and pull it right out of the case. Not only will it leave a powdery mess in the chamber, but you'll need to tap the bullet out with a cleaning rod too.
I was thinking the same thing but am very non scientific with my measurements. I can load and unload loaded rounds with no change to oal and bolt closing isn’t overly tight. I measured by pushing a bullet in the barrel and measuring that with a cleaning rod and then to the bolt face.
It may be less jam or something :dunno:

I think the oal is 2.38 ish
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 03:24:09 PM: Quote from: jasnt on April 27, 2019, 01:27:22 PM
23.2gr of h4895 was my max load with 77gr ncc’s but loading at mag length
These Rdf have a short bearing surface compared to the 77 cc these are very close to bearing surface length of the 69 cc.
Title: Re: 223 bolt gun piercing primers
Post by: jasnt on April 27, 2019, 03:51:47 PM: Quote from: BULLBLASTER on April 27, 2019, 03:24:09 PM
Quote from: jasnt on April 27, 2019, 01:27:22 PM
23.2gr of h4895 was my max load with 77gr ncc’s but loading at mag length
These Rdf have a short bearing surface compared to the 77 cc these are very close to bearing surface length of the 69 cc.
i haven’t shot the 69gr. My aol is short. AR with poly mags. I think my load is 21gr that shoots the best. Wish I had gone bolt gun after the fact. Just not a fan of ar’s much. Was hoping to shoot 80gr vlds but they are too long for these mags
Title: Re: 223 bolt gun piercing primers
Post by: yorketransport on April 27, 2019, 06:08:26 PM: It has more to do with your bolt face than your loads. Savage rifles are notorious for having over sized firing pin holes which will cause the cratering that you see. Combine that with the tip profile on most Savage firing pins and you get the pierced primers. You can try recontouring the firing pin tip slightly to make it more flat and see if that helps. The other option is to either try replacing the bolt head or bushing the firing pin hole.

I'll dig through my parts drawer and see if I have a .378" bolt head. If I have one I'll send it to you, I don't have a use for a bolt head that small. :chuckle:
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 27, 2019, 08:00:35 PM: I read that on a different site about recontouring the firing pin so I had at it with some wet/dry sandpaper and precisely flattened it a bit. Hoping to try it out tomorrow.
Title: Re: 223 bolt gun piercing primers
Post by: BULLBLASTER on April 28, 2019, 04:32:54 PM: My firing pin reworking helped. Shot a handful today and not near the cratering going on. Also colored a bullet with sharpie abs chambered it Can’t see any land marks all the way around so I don’t think I’m jammed like i thought.

Thanks for the input :hello: