should i stop shooting?

Kudu101

Well-Known Member
Just testing my first loads out worked up from from start load and im now on 38grs of imr4350 with 100gr bullets.

Iv noticed that im getting a slight mark where the extractor is. No flattened primer, no difficuty extracting cartridges and bolt it easy to lift after firing.

What are your thoughts? Am i ok to contnue or shall i stop now.

Thanks

IMG_20160424_081300.jpg
 
Looks absolutely fine to me but a more effective way of measuring pressure is by measuring case expansion. Have a look on the web to find a good explanation of how to do this but in the meantime I would try to team up with a knowledgeable local reloader if you can.
 
Ok thanks. Iv read about case head swipe and it sounds like this may be what im experiencing. Everything else seems normal, primers fine, no extraction problems , no difficulty opening bolt. No excessive recoil. Well off the max load too.

Thanks
 
Kudu
Do you get the same marking when using factory ammunition? - If so you are probably still at a safe loading as the marking is not excessive.
Also have you chronographed similar factory 100 grain & your reload rounds? - That will add useful information - If both give about the same velocity you can assume you are in the right ball park. If reload velocity is the higher of the two, you may be high on load.
What make & model of 100 grain bullets are you loading & what overall length (C.O.A.L.) are you loading to? With that added info, pressure & velocity can be theoretically predicted. This will again give pointers to where you may be on the pressure scale.

Ian
 
To measure the pressure ring you really need a good micrometer one that reads 10ths and then of course you need to learn out to use it and get the feel. A Digital caliper is ok for a quick check but it is no substitute for a micrometer. Digital calipers are chep and easy to use a modern affliction of cheap, quick and good enough or "that will do" ........................... getting it right seems to be a thing of the past. I find myself wishing that I had been born 30 years earlier more and more.
 
I've found primers have different hardness to each other, federals and remington are softer than cci. So I don't go off the primers alone.
 
if its marking your brass its not good,if its marking brass how long will the brass last? perhaps the load is not worth pursuing
 
Primer 'flattening' really is not much of a guide to pressure levels at the end of the day, now a heavy bolt lift on the other hand...
 
Hi ian, the same factory ammo is unmarked when fired in the same rifle. I have a chrono so will test some factory ammo and some of the homeloads tomorrow.

They are sierra gameking 100grn sbt . Cant tell you coal off the top of my head but they were seated 20 thou off the lands.

As there were no other signs of pressure i continued and on the final load i was clover leafing which is frustrating as im going to have to drop the charge down due to the ejector recess marks which are still there (more defined at the higher charges).

Iv preped some sako brass which i will try as iv heard federal is pretty soft.

Thanks
 
Is it the same mark on all the cases? It doesn't just happen to be the one or two you had difficulty chambering, and presumably were pushing quite hard, on your last thread?

Alan

p.s. Just seen your last post which refers to the marks becoming more pronounced...

interesting that the primer in your image is much less flattened than mine ever have been whether factory or cci reloaded...
 
Last edited:
Try some decent brass Fedral brass is Toilet, and try if not using already some CCI Br2 primers harder cup than most others
 
Yes its exactly the same mark on all cases just varying in how defined they were.

Yes it didnt make sense to me as the primer was fine and the bolt lift was as easy as usual.

The primers were cci no.200 , just what i was given at the gun shop.

Thanks
 
There was an excellent photo of three fired cases side by side in an magazine article I had. It asked the reader to guess the pressures in the three handloads. A little down the article it listed the pressures taken by the pressure gun and all three were very different they then stated that they had to go all the way up to over 80,000 psi I think it was to get noticeable primer extrusion. Their point was that looking at fired primers and trying to judge the pressure is futile.

If you read Ken Waters who published a lot of handloading data when he tried a new rifle he bought fresh factory amunition and fired several rounds then measuered the expansion ring of those cases to get an average then when developing loads he measured each and every case fired at the expansion ring and noted it down. Any that expanded 0.001" more than the factory was considered excessive. I need to check that 0.001" firgure as it was a long time ago not that I read Mr Waters articles. He also had his micrometer checked for accuracy at a machine shop on slip guages to make sure it always read exactly right.

Today Mr Waters would probably use something like the Pressure Trace system to measure actual pressures that is if my understanding of this Pressure trace is correct. Must admit that have not seen much about it for the last few years.
 
Kudu
You can easily measure COAL with a vernir caliper - just measure tip of bullet point (not ogive) to bolt face end of case.
COAL means "cartridge overall length". Measure that & let us know.
SAAMI standard COAL for 243 is 2.710".

Ian
 
The COAL is now 2.650 on the latest batch of sako brass that i loaded.

I thought that perhaps i had contaminated the chamber with case lube or that it was gunked up meaning that the cartridge was prevented from gripping the chamber walls when it expanded allowing it to slam back into the bolt face causing the ejector marks.

I gave the chamber a good clean and tested 5 sako cartridges. The first four were unmarked but the last cartridge had a slight ejector mark, still no other signs of pressure.

I have been told that perhaps the chamber is worn which is not allowing the case to grip the chamber walls?

Thanks
 
Have you ever cleaned out the bolt lug locking recess?

Wonder if there is some muck in there that is sometimes getting on the bolt lugs and makign difference.
 
Back
Top