Questions

[527vamint]

Before I start I'm relatively new to reloading.

 

1. bullets,if I have two bullet of the same weight, one flat Base one boat tail will there be a difference in pressure if using the same components,I'm thinking that the flat Base one would cause more due To more surface area causing more friction on the barrel.

 

2a.Will greater neck tension also cause more pressure.

 

2b.if I move the bullet out of the case closer to the lans, how will that effect pressure and speed if using the same amount of powder, will it drop. Is it more accurate further out.

 

3.Boat tail does the neck blow out more or faster than a flat base due to the shape.

 

3.twist rate does that alter the time the bullet stays in the barrel therefore effecting pressure and speed.

 

4.burn rate vit n1 powder is the powder all the same ingredients just different size kurnells ie n150 has larger kurnalls so it burns slower.

 

5. If fl sizing are you losing pressure due to the brass expanding into the chamber.

 

6. Is it better to measure weight or volume of powder,depending on powder choice. h335 meters well in my rcbs thrower less trickling and n150 is terrible more trickling.

 

I'm fl sizing throwing and trickling at the moment.

 

The questions above came from thinking to much whilst loading ammo.

Cheers Andy.

[onehole]

I will try to be brief and real world thoughts,,,

 

1 Not a pressure difference that I think you would need to consider or worry about

 

2a Aim to achieve 2 to 3 thou neck tension and again you will not need to consider this for pressure issues

 

2b Further out could produce lower pressure but in turn your moving bullet closer to lands which can raise pressures,,,,,this is fundamental as part of tuning your load and there are a few schoolsl of thought of how to best achieve this.If you can achieve the best accuracy further out then all well and good as this is also a better place to be as far as velocity potential from a greater case volume/more room for powder.Personally I like to be quite close to lands.

 

3 Not sure,,,,do not know why you would need to consider this to be honest

 

4 Burn rate more down to powder fomrulae/ ingredients,,,,stick to book recommendations for calibre and bullet weight and all should be ok.

 

5 Not sure,,,,someone else?,,,,,,,,,,

 

6 Weight,,,,,,,,,fine powders can throw very accurately,,,,,,I would never trust a thrower for the bigger kernels,,,,,I would trickle up every load unless large amounts of reloading needed.

 

You,ve only just begun thinking too much,,,,,,,there,s more,,,,,a lot more,,,,,,,O

[527vamint]

Cheers and thanks for the reply and answers.

I'm using the book thanks.

 

I have two 308s

Howa 1500 1:10 24"

Winchester p17 1:14 26"

My load for the p17 is 46g n140 and 155g amax 2.800"oal , if I use this load in the howa I get extractor marks on my brass and tight bolt lift,I was trying to work out why.

Now on 44g n150 and 168smks for the howa and slight marks on the head of the brass.

 

That made me start thinking about burn rates and kurnells.

 

Think I'm just a bit inquisitive.

[gbal]

Onehole's answers are excellent-I'd add that for your Q5,you need not be concerned-any differences between FL and neck sizing will be small.

 

It's better to use base to ogive measures,rather than COAL,and you should be using ogive if you are fine tuning sating depth.Differnt throat lengths in rifles can mean a load is into lands in one,not in another with some pressure issues-not major if loading below powde max (once nudging into the red,all the small factors come into play....safety margins are eroded).

In 'extremes' compressing powder by a deeply seated bullet will increase pressures a little-best avoided-but the throat etc on differnt rifle makes/models differs-as do chambers (within the tolerances of SAAMI or CIP,and that can be exaggerated by military chambers...

So the same load might just give pressure signs (stiff bolt lift is a fairly reliable one) in one rifle ,but not another (and increased air temperature can sometmes nudge a load into pressure signs). Extractor -plunger- marks too-something isn't as it shoud be.

 

Pressure issues are almost always relieved by reducing powder charge,within the powder manufacturers published data,with most other possible very small issues (flat base,twist rate) pretty much inconsequential for the reloader-though properly prepped brass is important too ( eg trimmed to length,as tis will increase a bit with repeated loadings....and nudge a hitherto OK load into the red)

 

AS O says,better by far to think about issues,and check them out ,than ignore pressure symptoms.

DO NOT rely on someone else's load data in your rifle (it may/not be OK in theirs; no-oe can actually measure pressure,and symptoms are not always present,or understood.)

ASK just what will another 50+ fps offer-usually nothing worth while,and no trade against accuracy for most shooters.

 

enjoy

 

gbal