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Boat tail projectiles

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Category: Reloading
Forum Name: Reloading .303 British
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URL: http://www.enfield-rifles.com/forum_posts.asp?TID=9168
Printed Date: December 02 2020 at 2:22pm
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Topic: Boat tail projectiles
Posted By: Honkytonk
Subject: Boat tail projectiles
Date Posted: August 31 2018 at 11:50am
I've been doing some reading and understand the principle of why a boat tail projectiles should fly more efficient. Does projectile speed make a difference? I wonder as I bought those Prvi 174 gr FMJBT's. By my loading manual, maybe 2300 ft/sec tops. I've ordered some 150 FMJBT's, and a middle of the road powder load of H335 will produce about 2600/ft sec. Well below maximum load. I will be interested to see how they work, as the above 174 gr performed excellent!



Replies:
Posted By: Shamu
Date Posted: August 31 2018 at 12:35pm
Watch out for that H335 in .303 Brit I had major problems with it!
click-BANGs, misfires, partially burnt charges giving squib loads & so on.
It was so bad I absolutely refuse to use it in .303.



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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: Honkytonk
Date Posted: August 31 2018 at 2:18pm
Roger. Good advice. Will work up a load with my favorite H4895.


Posted By: Goosic
Date Posted: August 31 2018 at 6:18pm
Honkytonk. If you ever get a chance to try this load,I guarantee you will not be disappointed.

The minimum powder load is 39.0 grains, maximum is 41.0 grains. Split the difference and load it at 40.0 grains. You'll get and honest 2550 fps. The ballistic coefficient of the Hornady 174grn BTHP is 0,496 OAL should be maxed out to 3,075" This particular load will out perform the 7.62x51mm with the same subsequent load...


Posted By: Honkytonk
Date Posted: August 31 2018 at 6:52pm
Goosic. I'm curious as to why the magnum load primers?


Posted By: Goosic
Date Posted: August 31 2018 at 7:26pm
The Holy Bible tells me so.


Posted By: Goosic
Date Posted: August 31 2018 at 8:55pm
The Magnum primers have a faster burn rate. Combine that with the fast burning Norma powder. The C.U.P. pressures are reduced and allow for higher velocities. The Norma 202 powder is excellent for medium calibers like .308, .303, 22-250, 7mm, .220 Swift, 30-338...


Posted By: britrifles
Date Posted: September 01 2018 at 4:45am
Your question about boat tails: due to the shape, they have less aerodynamic drag than a flat base bullet of the same diameter and weight. The BT bullet will generally be longer and more aerodynamically efficient retaining its velocity for a longer range than a flat base.

You will see this in the ballistic coefficient tables comparing flat base to boat tails at the same weight. Yes, BC is a function of velocity, some bullet shapes more than others.


Posted By: Pukka Bundook
Date Posted: September 01 2018 at 5:01am
Goosic,
 
I too have been a long term fan of Norma #202 for the .303!
(Same as Norma # 204 for the Swedish Mauser, ....can't be beat!)
 
Re boat-tails;
Some number 4's do not like them and shoot very badly.   Evidenced by tippling seen on target.
These same rifles can perform beautifully with flat base projectiles.
Yes, we mostly all know this, but worth repeating unless some of us with the wrong rifle get too caught up with boat-tails!  LOL!
 


Posted By: Honkytonk
Date Posted: September 01 2018 at 5:12am
Agree! As primarily a hunter, not a target shooter, my go to and favourite projectiles for my Enfields are Sierra ProHunters. Both the 150's and 180's. Very consistent at the range and the 150's are devastating in the field. I've never hunted with the 180's. I started loading them this year for my sniper clone and No5. Found out I got drawn for elk/moose so hopefully I'll be able to report they are equally devastating in the field!


Posted By: Shamu
Date Posted: September 04 2018 at 8:43am
Here ya go, a picture.



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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: Honkytonk
Date Posted: September 04 2018 at 9:32am
Thanks once again Shamu!


Posted By: britrifles
Date Posted: September 04 2018 at 10:30am
I'm curious if anyone who has had poor accuracy with BT bullets in their LE had slugged the bore. The reduced bearing area of the BT bullet could conceivably result in yawing of the bullet within the barrel, especially if the groove diameter is oversize.  I would imagine that a large bore diameter wouldn't be good either. There is a large variation of bore and groove diameters in service barrels.
 
My No. 4 with BSA barrel measured 0.303 bore and if I remember right 0.314 groove diameter.  And it shoots the SMK and Hornady Match BT bullets very well. 


Posted By: Stanforth
Date Posted: September 04 2018 at 11:19am
I understand that Enfield No.4 1* can have problems with Boat Tail bullets. I believe it is the rifles with 2 groove rifling and is caused by propellant gasses escaping around the base of the projectile.
 
I have a Savage No.4 1* with 2 groove rifling and find no problems up to 500 yards, I don't use that rifle at longer ranges. However the bore in my rifle is in mint condition with little trough it.
I have a standby plan for the time things deteriorate and that is to use a wooden 3/8 inch wad behind the bullet.


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Life.. a sexually transmitted condition that is invariably fatal.


Posted By: Shamu
Date Posted: September 04 2018 at 1:38pm
Yes it seems to be limited to worn 2-groove barrels.


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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: Goosic
Date Posted: September 04 2018 at 2:45pm
Another, sometimes overlooked factor is speed. Benchrest shooters will most often max a round out for better accuracy. The slower the speed the bullet is turning once it has left the confines of the barrel greatly affects accuracy and will sometimes cause the bullet to lose its spin causing it to tumble. You won't look for this in a heavy round nose bullet you intend to use for hunting however,when target shooting you can get a heavy bullet to outperform a lighter more aerodynamic if you are using the same powder charge and primers for both rounds. The powder charge for a FMJBT or BTHP when reloading should be a fast burning powder ignited by a fast burning Magnum primer at almost to but not exceeding maximum pressures. Keeping the speed and spin of the bullet at it's maximum insures accuracy. When that Boattail slows down enough the leading edge of the bullet will lift causing a negative flight instability. I ran a series of test in regards to surface contact lengths of individual bullets to see if accuracy is affected using a five groove barrel and a two groove barrel. Accuracy was only affected when the powder charge was reduced to a minimum in the FMJBT and BTHP. I could only achieve a maximum FPS of 2466 whereas I maintained a maximum FPS of 2608 with a 174gr RN using the same powder charge and primers. A 215gr RN maxed out at 2310 fps and a 150gr SP maxed out at 2779. All four rounds we're tested using Magnum primers and exactly 40.0 grains of Norma powder with a C.O.L. of 3.075. The end result from most accurate to not accurate is,
#1- 150gr SP
#2- 174gr RN
#3- 174gr BTHP
#4- 215gr RNSN


The rifling of both barrels played no factor in this test other then the two groove produced high pressures due to tighter tolerances. Nor did mean contact surface of each round.


Posted By: Ranch Dog
Date Posted: September 09 2018 at 7:36am
I'm using the PPU B125 180-grain BTSP. My interest is that of a hunter. It has been accurate and deadly on feral hogs.



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