Long Action vs Short Action.

[nralifer]

I hadn't realize that 308 brass used SRP's.

Both Peterson and Lapua make it. It's used in some competitions to stuff as much Varget in to the case without causing primer pocket expansion. Handles higher than average pressures.

 

[nralifer]

No sir, never have.

Works well. I use CCI 450 primers. SRP brass can withstand higher pressures without primer pocket expansion.

 

[Kimber7man]

I thought I would chime in and say that I bought a Defiance XM action, which I understand is a medium length action, and found an M5 bottom metal that fits it at Bugholes....and here I am months later and cant find a stock that will accommodate those components. I am new on this forum, so surely didnt want to highjack the thread by any means, but thought it might be an opportunity to get your guys' thoughts or comments on where a stock could be found. Thank you gentlemen, and if I am out of line please say so and I will back out.
Thank you

@WillELee here you go:

For Sale - Manners EH1 Defiance XM length stocks at Mountic Outdoors

Manners EH1 Defiance XM Length Stocks. There are inlet for the Hawkins XM DBM and work for the Defiance XM Length actions. Flush cups left. Sling studs bottom. Just a few left at the sale price. https://mounticoutdoors.com/products/manners-elite-carbon-eh1-defiance-xm-length-stock

www.longrangehunting.com

 

[Kimber7man]

@WillELee you can also order a stock from Manners for the XM length action. I had them make a EH-SL stock for me for an anTi XM length action with the BDL floor plate.

 

[jasent]

For those maybe not quite understanding, all 3 of these are loaded to .020" off the lands. All very close in weight (7gr spread)
Only one will mag feed

 

[nralifer]

For those maybe not quite understanding, all 3 of these are loaded to .020" off the lands. All very close in weight (7gr spread)
Only one will mag feed
View attachment 422242

Nice illustration of how ogive length influences mag feeding. Longer ogives improve BC. That is why the short magnums benefit from use in longer actions.

 

[nralifer]

Not exactly.

308 = short action ~3.0 inch COAL

30-06/300 winmag = standard (or long if you don't want to get into semantics) action ~3.4 inch COAL

300rum/375 h&h = long action (or magnum length action) 3.6+ inch COAL

You could even add mini actions on there for a 223 length action.

What point were you trying to make by 'correcting' everyone here?

#ConfidentlyIncorrect

I think the confusion stems from the imprecise definition of what is meant by a long medium and short action. This post more clearly defines these terms. Thanks for posting this.

 

[jasent]

Nice illustration of how ogive length influences mag feeding. Longer ogives improve BC. That is why the short magnums benefit from use in longer actions.

I went with the middle choice. Had to seat it .110" off to mag feed, cost me 50fps with the powder I have on hand but it's still supersonic at a mile and shoots 1/4 Moa. The other 2 can't do that. My elr and hunting bullet in one load

 

[Turpentine21]

Works well. I use CCI 450 primers. SRp brass can withstand higher pressures without primer pocket expansion.

I don't doubt it a bit. Just never really needed to try it. I was given a bucket full of LC Match and LC which has been some tough stuff. It mainly gets used in the AR 10. Winchester LRP brass has filled my bolt gun requirements

 

[nralifer]

I went with the middle choice. Had to seat it .110" off to mag feed, cost me 50fps with the powder I have on hand but it's still supersonic at a mile and shoots 1/4 Moa. The other 2 can't do that. My elr and hunting bullet in one load

What you have done is noticed the following. By extending the distance the bullet has to travel before it engages the lands you have increased the volume of combustion before the bullet hits the lands, at which point the pressure really starts to build rapidly. As this pressure forces the bullet further into the rifling, pressure is building along with resistance of the bullet to forward travel. At this stage 3 things are happening. 1) The volume of combustion is increasing as the bullet is engaging the rifling. 2) The power is continuing to burn creating ever increasing volumes of hot gas. 3) Resultant pressure is increasing because the rate of powder ignition continues to accelerate beyond the rate of volume increase as the bullet moves down the rifled barrel. It is in this time frame that you reach peak pressure. As the powder becomes fully ignited i.e. all the kernels are on fire or completely expended, the rate of hot gas formation starts to decline while the chamber volume is increasing because the bullet continues down the barrel. Finally all the powder kernels have ignited completely and there is no more burning powder to add to the gas volume, so the pressure continues to drop while still accelerating the bullet until it exits out the muzzle causing a sudden drop in pressure to atmospheric pressure and the bang we all love. You could gain back the speed you lost by increasing the powder charge a few grains or fractions thereof, and not worry about overpressure since the greater jump has increased the volume of initial powder combustion without increasing the total volume of gas produced, reducing the peak pressure. Without increasing powder charge, the result is that the average pressure that accelerates the bullet down the barrel is reduced a bit resulting in a little slower acceleration. You can make that up by increasing the total volume of gas produced by increasing the powder charge. I call this the Weatherby principle. Roy Weatherby capitalized on this trick by making chambers with longer free bore throats which allowed larger powder charges to be burned thus raising muzzle velocity, leading to the famed Weatherby magnums.

 

[jasent]

What you have done is noticed the following. By extending the distance the bullet has to travel before it engages the lands you have increased the volume of combustion before the bullet hits the lands, at which point the pressure really starts to build rapidly. As this pressure forces the bullet further into the rifling, pressure is building along with resistance of the bullet to forward travel. At this stage 3 things are happening. 1) The volume of combustion is increasing as the bullet is engaging the rifling. 2) The power is continuing to burn creating ever increasing volumes of hot gas. 3) Resultant pressure is increasing because the rate of powder ignition continues to accelerate beyond the rate of volume increase as the bullet moves down the rifled barrel. It is in this time frame that you reach peak pressure. As the powder becomes fully ignited i.e. all the kernels are on fire or completely expended, the rate of hot gas formation starts to decline while the chamber volume is increasing because the bullet continues down the barrel. Finally all the powder kernels have ignited completely and there is no more burning powder to add to the gas volume, so the pressure continues to drop while still accelerating the bullet until it exits out the muzzle causing a sudden drop in pressure to atmospheric pressure and the bang we all love. You could gain back the speed you lost by increasing the powder charge a few grains or fractions thereof, and not worry about overpressure since the greater jump has increased the volume of initial powder combustion without increasing the total volume of gas produced, reducing the peak pressure. Without increasing powder charge, the result is that the average pressure that accelerates the bullet down the barrel is reduced a bit resulting in a little slower acceleration. You can make that up by increasing the total volume of gas produced by increasing the powder charge. I call this the Weatherby principle. Roy Weatherby capitalized on this trick by making chambers with longer free bore throats which allowed larger powder charges to be burned thus raising muzzle velocity, leading to the famed Weatherby magnums.

I was able to gain that speed back but it opened up to 1/2 Moa. So I just stuck with the original load. With g7 of .402 2960 is plenty for my needs. I'm already compressed as it is. I'm well into the life of this barrel now (720rds) so I'll stick with this load for the rest of this barrel.

 

[Buck Fever]

Well, if you like a project, look at a cheap Savage Axis. They are all the same action length with different bolt head baffles to limit bolt stroke for short action cartridges.

It's a tube style action so more rigid than open top.

With some simple machining you can face off the front of the action to use a standard 110 style recoil lug.

I used a .30-06 donor action with an Accu-trigger and used parts from Glades to build up my bolt with a fluted sleeve and extended knob. A spring mod and some shims made the trigger pretty nice for just a few bucks.

For a barrel I bought a 110 style prefit chambered in 284 Winchester.

I put that in a MDT LSS chassis and use their mags.

284 Winchester is technically a short action chambering but it never really fit right. Bench rest shooters win championships with 284 Winchester frequently with 175-190 grain high BC bullets which they single load. They don't use magazines but 284 Winchester loaded long has no chance fitting in a short action magazine.

It will fit in my magazine though. It's a pretty low budget project (my gen1 LSS was clearance priced). I could have saved money skipping the Glades parts for the bolt but I like them.

A Tikka build is similar but not quite as cheap. A Remington 700 build isn't as DIY friendly.

 

[nralifer]

Well, if you like a project, look at a cheap Savage Axis. They are all the same action length with different bolt head baffles to limit bolt stroke for short action cartridges.

It's a tube style action so more rigid than open top.

With some simple machining you can face off the front of the action to use a standard 110 style recoil lug.

I used a .30-06 donor action with an Accu-trigger and used parts from Glades to build up my bolt with a fluted sleeve and extended knob. A spring mod and some shims made the trigger pretty nice for just a few bucks.

For a barrel I bought a 110 style prefit chambered in 284 Winchester.

I put that in a MDT LSS chassis and use their mags.

284 Winchester is technically a short action chambering but it never really fit right. Bench rest shooters win championships with 284 Winchester frequently with 175-190 grain high BC bullets which they single load. They don't use magazines but 284 Winchester loaded long has no chance fitting in a short action magazine.

It will fit in my magazine though. It's a pretty low budget project (my gen1 LSS was clearance priced). I could have saved money skipping the Glades parts for the bolt but I like them.

A Tikka build is similar but not quite as cheap. A Remington 700 build isn't as DIY friendly.

Thanks for the information. I already have 2 110 actions and 3 mod 10 actions as well as a mod 12 action in a WSM. The test rifle I am using to test the 308Win came from a Stevens 270Win i used as the donor rifle. Interesting to hear that Savage is going to a fixed length action with variable bolt stops. Similar to Tikka and Sako like you said.

 

[Buck Fever]

The Axis is Savage's budget rifle but oddly I like a lot of the features. I believe their higher end offerings are still long and short action.

I would rather build up a custom action than a Savage (beside the Axis)...