Help reading primers for pressure

slimjim

44marty wrote:

Slim, the primers in the photo definitely DO NOT show signs of excess pressure. The edges at the outside diameter of the primers are still well rounded, not flattened.

I think the machine marks from the bolt were throwing me off. Plus there may be some extra clearance around the firing pin.

slimjim

Here is my 3-shot groups for 59.0, 59.5, and 60.0 grains of H414 with the Barnes 110 TTSX. Blue = 59.0, Black = 59.5, Beige = 60.0.

I was surprized to see the 60.0 spread out horizontally. Thought it might be the rear windage screws but they are ok. I like the 59.5 but don't want to see go over the line and start impacting like the 60.0 group.

Going to load up 5-shots and shoot another group. What grain load would you recommend?

44marty

chambered221 wrote:

44marty wrote:

Even a harder to open bolt may not be a sign of high pressure. This often happens when ammo is neck-sized.

This why I mentioned the shiny markings on the case head........ I've never had them appear on neck sized brass unless the pressure was to high !!!

Exactly, Chambered. This is one of the signs I definitely look for. It can also happen, to a lesser degree, when brass is at the end of its useful life. It can be caused by brass stretching, leaving insufficient headspace. You can tell the difference since the bolt will be a bit harder to close on a round when lack of headspace is the issue.

44marty

slimjim wrote:

Here is my 3-shot groups for 59.0, 59.5, and 60.0 grains of H414 with the Barnes 110 TTSX. Blue = 59.0, Black = 59.5, Beige = 60.0.

I was surprized to see the 60.0 spread out horizontally. Thought it might be the rear windage screws but they are ok. I like the 59.5 but don't want to see go over the line and start impacting like the 60.0 group.

Going to load up 5-shots and shoot another group. What grain load would you recommend?

I would try 59.2, 59.5, and 59.7. I would expect the POI to be very close for the three loads, confirming that the 59.5 is your go-to load.

PaulS

Aloysius wrote:

Bushmaster, would you please translate your remarks to the belted magnums? A belted magnum such as the .300 WM, headspaces on the belt, not on the shoulders. In my opinion this gives less chances for case movements in the neighbourhood of the primer.

Aloysius,
The only belted magnum cartridges that are suppose to head-space on the belt are the H&H magnums. The 300 WinMag should headspace on the shoulder because if you head-space the cartridge on the belt you will experience very short case life unless :
1. you have the rifle carefully chambered so the belt fits tight
and
2. all the belts on all your cartridges are the same dimension.

From the Speer #13 manual: "Handloading for the 300 winchester is straight-forward. Like other belted cartridges, the shoulder--- not the belt--- should be usedfor headspace control."

Elvis

ok buds heres my 2 cents worth. try a heavier projectile eg 130 or 150 grn my old smoke pipe doesnt like hornady 110grn hps they group 2-3 inches every thing else is fine. they are sure devistating when they hit something small eg wallaby or goat but the 130s are heaps more accurate. my rifle has flattened primers and split cases on the 2nd load from new brass when they were loaded in a sports store for me. I dont neck size my rifle dont like it I partial resize as per the manuals. different primers are softer and flatten easier. they sure arent the be all and end all of pressure but do give you something to look at. have you delubed the rounds before fireing???

Aloysius

Thanks. It sure gives another view on headspace, overpressure and reading primers.

slimjim

PaulS wrote:

The only belted magnum cartridges that are suppose to head-space on the belt are the H&H magnums. The 300 WinMag should headspace on the shoulder.

I was reading an article in last month's Rifle Shooter about cartridge development and history. They mentioned that the public related belted cases to magnum performance. Thus when the 300 Win Mag came out, they but a belt on it even though it didn't need it because people expected a belt on a magnum cartridge.

slimjim

Elvis wrote:

try a heavier projectile eg 130 or 150 grn .... have you delubed the rounds before fireing???

.

This rifle particular rifle has not demonstrated very good accuracy. It has been shooting 2+ MOA with the premium factory 130gr bullets. The groups with the 110gr TTSX is the best this rifle has every shot.

I only neck size so don't have to worry about lube or delube.

slimjim

44marty wrote:

I would try 59.2, 59.5, and 59.7.

Good suggestion.

44marty

Aloysius wrote:

Aloysius,
The only belted magnum cartridges that are suppose to head-space on the belt are the H&H magnums. The 300 WinMag should headspace on the shoulder because if you head-space the cartridge on the belt you will experience very short case life unless :
1. you have the rifle carefully chambered so the belt fits tight
and
2. all the belts on all your cartridges are the same dimension.

From the Speer #13 manual: "Handloading for the 300 winchester is straight-forward. Like other belted cartridges, the shoulder--- not the belt--- should be usedfor headspace control."

I believe that the Weatherby magnums, at least the .300, headspace on the belt. Am I wrong?

Elvis

slimjim try some non premuim jobs or better still get some sample packs and try some other projectiles. heres my pet load 130grn projectile 54grns 2213sc any old case any old primer. yip you SHOULD use batch sorted brass bla bla bla but if it works why knock it.

Elvis

also swap the scope and try a group with another you never know it may be poked.

Grumulkin

ANY belted magnum can be reloaded to headspace on the belt. It's true that headspaceing on the belt may result in poor brass life but it's not wrong to do it that way. In addition, I haven't found rounds sized to headspace on the belt to give poor accuracy. I have, in fact, found some neck sizing techniques (specifically the Lee Collet Die) to result in poorer accuracy at times than those assembled with full length sized cases.

wncchester · Member Joined: Apr 08, 2006 Posts: 160

Obviously primers are an indicator of excessive pressure but, as Bushy says, it's also an indicator of some other things as well things so it isn't much real help unless it's found in conjunction with other signs. And, if the other signs are present it hardly matters what the primer looks like. I look at fired primers during load development but not very hard!

Highly flattened primers are mostly a great indicator that the reloader has pushed the shoulders of his resized cases back much too far. Forget about belts or rims; size cases so bottle necked shoulders are a slight crush fit and all will be well.

As Grumulkin says, many "accuracy" tips such as neck sizing of "fire formed" cases may or may not work better. Only experimention can prove the value of anything.