why are most long range rifles bolt action?

dmpas26 · 01-09-2009, 12:43 PM

Quote:

Originally Posted by Full MeTal Jack

What is long range? 600 yards? 1000yards?
We are still shooting 600 yards with M1 Garands, M1As and AR type semi auto rifles.
The 30 cals can have trouble staying hypersonic at 1000 yards. I've heard there is a new 90 grain .223 bullet capable of going the distance.
Harmonics play a big portion in semi-autos vs. bolts.
Bolt rifle barrels can be very thick thus reducing vibration.
Bolt rifles can and do have shorten actions there by reducing action twist as the bullet explodes down the barrel. That bullet is trying to twist the barrel off.
The semis have lots of moving parts. Lots of unnessessary vibration.

But short range you may not see a different.

bTw, Welcome to GnG. Hope to see ya around here.

Long range that I'm talking about is 1000+ yards. I would think that with the action being rigid it would increase vibration, as apposed to the semi-auto, which allows for the energy to escape. But it would also be reasonable for the action and more moving parts to cause the stability of the action to have problems. This has been very helpfull. Thank all of you for your input.

big shrek · 01-09-2009, 02:04 PM

I'm surprised nobody has mentioned the fact that some energy is taken away from the fired round to cycle the semi-auto action, resulting in LESS FORWARD POWER and you have to chart ballistics quite differently for a Semi-auto than a bolt-action.

If you fire the same ammo thru a semi & a bolt...you will find that there is a substantial difference at long ranges. The semi will hit lower on your target as there is more of a drop due to the above, how much lower depends on the round in question and the distance to the target.

At less than 200 yds you probably won't notice a serious difference, but at 600+, you definitely will.

Rimjob · 01-09-2009, 02:10 PM

Quote:

Originally Posted by big shrek

I'm surprised nobody has mentioned the fact that some energy is taken away from the fired round to cycle the semi-auto action, resulting in LESS FORWARD POWER and you have to chart ballistics quite differently for a Semi-auto than a bolt-action.

If you fire the same ammo thru a semi & a bolt...you will find that there is a substantial difference at long ranges. The semi will hit lower on your target as there is more of a drop due to the above, how much lower depends on the round in question and the distance to the target.

At less than 200 yds you probably won't notice a serious difference, but at 600+, you definitely will.

Damn Shrek, now I know why they keep you around!! LOL

Bravo · 01-09-2009, 02:33 PM

Quote:

Originally Posted by big shrek

I'm surprised nobody has mentioned the fact that some energy is taken away from the fired round to cycle the semi-auto action, resulting in LESS FORWARD POWER and you have to chart ballistics quite differently for a Semi-auto than a bolt-action.
If you fire the same ammo thru a semi & a bolt...you will find that there is a substantial difference at long ranges. The semi will hit lower on your target as there is more of a drop due to the above, how much lower depends on the round in question and the distance to the target.
At less than 200 yds you probably won't notice a serious difference, but at 600+, you definitely will.

I can understand this with semi-auto's that use a gas piston (see AK-47/SKS/M1) because gas is leaving the barrel before the bullet has left the barrel, but what about those that are strictly blow-back, like a M-16/M-4/AR-15...does velocity suffer in blow back actions as well? The reason that I ask is because to my knowledge, the bolt isn't moving backward until the bullet has left the barrel, meaning that the volume of space inside the barrel that the gas can fill isn't changing until the bullet leaves...meaning the PSI should remain the same as a bolt action. Right?

Full MeTal Jack · 01-09-2009, 03:43 PM

Quote:

Originally Posted by Bravo

I can understand this with semi-auto's that use a gas piston (see AK-47/SKS/M1) because gas is leaving the barrel before the bullet has left the barrel, but what about those that are strictly blow-back, like a M-16/M-4/AR-15...does velocity suffer in blow back actions as well? The reason that I ask is because to my knowledge, the bolt isn't moving backward until the bullet has left the barrel, meaning that the volume of space inside the barrel that the gas can fill isn't changing until the bullet leaves...meaning the PSI should remain the same as a bolt action. Right?

that not rite. The gas port from the muzzle on 4 rifles is:
The FAL is 9"
my AR is 7 "
AK is 4"
and the Garand is 1 1/2" from the muzzle.

Don357 · 01-10-2009, 08:16 AM

Quote:

Originally Posted by Bravo

I can understand this with semi-auto's that use a gas piston (see AK-47/SKS/M1) because gas is leaving the barrel before the bullet has left the barrel, but what about those that are strictly blow-back, like a M-16/M-4/AR-15...does velocity suffer in blow back actions as well? The reason that I ask is because to my knowledge, the bolt isn't moving backward until the bullet has left the barrel, meaning that the volume of space inside the barrel that the gas can fill isn't changing until the bullet leaves...meaning the PSI should remain the same as a bolt action. Right?

When did they change M-16/M-4/AR-15's to a "blow-back" action? Everyone I ever fired was either gas or gas-piston operated. How well I remember the hours cleaning and re-cleaning those worn out M-16 A1's. RBC, hot water and a pipe cleaner or 10.LOL

TargetGunFan · 01-10-2009, 09:28 AM

I am pretty sure my bushmaster ar-15 is a delayed blow back bolt. They sell a gas piston conversion kit for it that I think NATO uses.

BattleRifleG3 · 01-11-2009, 10:16 AM

The term "blowback" is used to refer to being recoil operated. The AR-15 in standard caliber is NOT blowback operated. It is gas operated, but instead of using a piston it uses a tube inside another tube. Sort of like an inverse piston. The term is "impingement".

NATO uses a variety of arms in 5.56x45mm caliber. NATO is comprised of many member nations. Some use the M16 with impingement system, some use HK's piston driven version of the M4, some use the HK G36, some use the Steyr Aug, some use the FNC, etc. I'm not aware of the HK M4 being adopted by a major military yet.

Piston conversions for AR-16 are growing in popularity in the US. Bushmaster's version is one of them.

mosin warrior · 01-11-2009, 08:56 PM

The Barret .416 that I saw on Future Weapons was a bolt gun. I didn't know that they made a semi auto version

BattleRifleG3 · 01-12-2009, 11:34 AM

The Barrett 416 cartridge, as far as I am aware, was based on the 50 BMG case but intended for citizens of states that banned the 50 BMG. Barrett's policy as I understand it is that he won't sell anything to CA government agencies.

TargetGunFan · 01-12-2009, 12:45 PM

Future weapons was talking about the 416 being a better sniper rifle than the 50 bmg against low armor targets because it shoots flatter. I believe that on that episode he shot a steel plate at 1.5 miles.

johnnyskid · 01-12-2009, 09:43 PM

All right.. Barret 416...next project. Don't own any bolt actions. yet.

Great thread!

samuel · 01-14-2009, 09:58 AM

A properly tuned gas operated self loader will shoot exactly like a breech-locked fierarm such as a bolt because the bolt is locked and the action doesn't actuate until the bullet has left the muzzle and is at least 8",s from the barrel.This is also true on blow-back,s with delayed release,which most are,even .22lr,s in rifles.On the chrony,I got no more difference between auto,s and bolts than you might get between one firearm and another.This can easily be substantiated by getting a chronigraph out and doing a little shooting.I have seen cases with slide,lever,bolts,that were smoking cases up that an auto/loader actually had more fps than the locked breech.(actually 'locked breech' is a misnomer,as they are all locked for the firing period, if right.) sam.

TargetGunFan · 01-14-2009, 10:46 AM

Here you go Johnny Barret 416 on future weapons.
2500 yards = 1.42 miles

You Tube

Edwan Wolfhause · 01-23-2009, 10:43 PM

Aside from the designs in the action, think about brass/chamber in semi vs. bolt. In a bolt, you can use neck-sizing dies to maintain tight-fitting brass and better bullet to bore alignment; the stronger cam action of a bolt allows it to chamber. In a semi, you must full length size, otherwise, it will probably jam every shot, and you cannot keep the optimal bullet-bore alignment because the smaller case is laying in the bottom of the chamber (exaggeration).

Intuition tells me that this would not matter as much in a smaller caliber though.

01-09-2009, 02:04 PM	#22
big shrek Senior Member Join Date: Mar 2008 Location: Northwest, FL Posts: 3,769	I'm surprised nobody has mentioned the fact that some energy is taken away from the fired round to cycle the semi-auto action, resulting in LESS FORWARD POWER and you have to chart ballistics quite differently for a Semi-auto than a bolt-action. If you fire the same ammo thru a semi & a bolt...you will find that there is a substantial difference at long ranges. The semi will hit lower on your target as there is more of a drop due to the above, how much lower depends on the round in question and the distance to the target. At less than 200 yds you probably won't notice a serious difference, but at 600+, you definitely will. __________________ Marlin Specialist, Calico Specialist

01-11-2009, 10:16 AM	#28
BattleRifleG3 Retired Moderator Join Date: Mar 2002 Location: Western PA Posts: 11,721	The term "blowback" is used to refer to being recoil operated. The AR-15 in standard caliber is NOT blowback operated. It is gas operated, but instead of using a piston it uses a tube inside another tube. Sort of like an inverse piston. The term is "impingement". NATO uses a variety of arms in 5.56x45mm caliber. NATO is comprised of many member nations. Some use the M16 with impingement system, some use HK's piston driven version of the M4, some use the HK G36, some use the Steyr Aug, some use the FNC, etc. I'm not aware of the HK M4 being adopted by a major military yet. Piston conversions for AR-16 are growing in popularity in the US. Bushmaster's version is one of them. __________________ Trust is earned, not... GIVEN away. - Worf

01-12-2009, 11:34 AM	#30
BattleRifleG3 Retired Moderator Join Date: Mar 2002 Location: Western PA Posts: 11,721	The Barrett 416 cartridge, as far as I am aware, was based on the 50 BMG case but intended for citizens of states that banned the 50 BMG. Barrett's policy as I understand it is that he won't sell anything to CA government agencies. __________________ Trust is earned, not... GIVEN away. - Worf

01-10-2009, 09:28 AM	#27
TargetGunFan Cardinal Richlieu Join Date: Dec 2008 Location: Omaha, NE Posts: 2,847 Blog Entries: 2	I am pretty sure my bushmaster ar-15 is a delayed blow back bolt. They sell a gas piston conversion kit for it that I think NATO uses.

01-11-2009, 08:56 PM	#29
mosin warrior Senior Member Join Date: Oct 2008 Location: Carlisle, PA Posts: 482	The Barret .416 that I saw on Future Weapons was a bolt gun. I didn't know that they made a semi auto version

01-12-2009, 12:45 PM	#31
TargetGunFan Cardinal Richlieu Join Date: Dec 2008 Location: Omaha, NE Posts: 2,847 Blog Entries: 2	Future weapons was talking about the 416 being a better sniper rifle than the 50 bmg against low armor targets because it shoots flatter. I believe that on that episode he shot a steel plate at 1.5 miles.

01-12-2009, 09:43 PM	#32
johnnyskid Member Join Date: Jan 2009 Location: ozark MO Posts: 62	All right.. Barret 416...next project. Don't own any bolt actions. yet. Great thread!

01-14-2009, 09:58 AM	#33
samuel Senior Member Join Date: Dec 2006 Posts: 12,459	A properly tuned gas operated self loader will shoot exactly like a breech-locked fierarm such as a bolt because the bolt is locked and the action doesn't actuate until the bullet has left the muzzle and is at least 8",s from the barrel.This is also true on blow-back,s with delayed release,which most are,even .22lr,s in rifles.On the chrony,I got no more difference between auto,s and bolts than you might get between one firearm and another.This can easily be substantiated by getting a chronigraph out and doing a little shooting.I have seen cases with slide,lever,bolts,that were smoking cases up that an auto/loader actually had more fps than the locked breech.(actually 'locked breech' is a misnomer,as they are all locked for the firing period, if right.) sam.

01-23-2009, 10:43 PM	#35
Edwan Wolfhause Member Join Date: Aug 2008 Posts: 31	Aside from the designs in the action, think about brass/chamber in semi vs. bolt. In a bolt, you can use neck-sizing dies to maintain tight-fitting brass and better bullet to bore alignment; the stronger cam action of a bolt allows it to chamber. In a semi, you must full length size, otherwise, it will probably jam every shot, and you cannot keep the optimal bullet-bore alignment because the smaller case is laying in the bottom of the chamber (exaggeration). Intuition tells me that this would not matter as much in a smaller caliber though.