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Effect of Primer Selection on Muzzle Velocity |
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Strangely Brown 
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Joined: April 05 2022 Location: Wiltshire Status: Offline Points: 645 |
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 Posted: March 02 2025 at 12:35pm |
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I don't know who's more relieved Geoff, you or me!
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Mick
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Shamu
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Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510 |
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Posted: March 02 2025 at 1:17pm |
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26 is very respectable!
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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
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britrifles
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Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404 |
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Posted: March 02 2025 at 1:41pm |
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Mick, I know you’ve been living thru the drama for a while now! Of course, I wish I had done this sooner rather than experience the frustration and expense of shooting 700 rounds over the last 2 months! The cost of reloading components spent far outweighed the cost of a new barrel! |
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britrifles
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Posted: March 02 2025 at 1:50pm |
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Yes, a huge improvement considering the last two months I’ve had ES values approaching 100 fps and vertical spreads as much as 5 MOA. I’ll continue to monitor this, I found with my other CBI barrel accuracy just got better during the first 200 rounds. Vintage Sniper Match is in just over 2 weeks… |
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DarioPirovano
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Joined: May 20 2023 Location: Italy Status: Offline Points: 219 |
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Posted: March 03 2025 at 12:22pm |
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Geoff you should try longer a longer bullet like Lapua scenar L in that barrel, if I remember correctly they make .311 bullets.
That bore looks very good!! I like it. When one of mine worn out I’m probably going to get one. |
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britrifles
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Posted: March 03 2025 at 2:22pm |
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Dario, is that the .303 Cal (.310 dia) 200 grain FMJ Boat-tail?
Although 0.10 inches is a fair bit of jump, the 174 gr SMK tangent ogive does not seem to be bothered by this. The bullet jump in the old BSA barrel on my Fulton No. 4 got up to 0.31 inches before groups started opening up. |
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Strangely Brown
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Posted: March 03 2025 at 2:32pm |
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The only .311 I can find on the Lapua website is a 123gr FMJ bullet which apart from the weight would put you much farther off the lands.
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Mick
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britrifles
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Posted: March 03 2025 at 3:00pm |
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I found the same Mick. I did see the Lapua Scenar L, but in .308, not .310 or .311. |
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Zed
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Posted: March 04 2025 at 4:06am |
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Looks like you are on to a winner with this rifle Geoff.
I bet your Father will be very proud of you can get on the podium with his old rifle! That would be a fabulous achievement! We are all looking forward to seeing the next competition!
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It's nice to be important, but it's more important to be nice!
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britrifles
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Posted: March 04 2025 at 5:15am |
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Thanks Shaun.
Our team (sniper match is shot in teams of 2) was just one point off of 1st place at the last match in November. That was with the old barrel of course. I'm hoping I don't screw it up at the spring match, which is 2 weeks from today. Then there will be the D-Day match in June too... Though winning is pretty cool, my real objective is to beat out those 1903A1 Springfields with the 8x Unertl scopes, which are generally considered the most accurate sniper rifles of WWII. And, they do shoot! |
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DarioPirovano
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Posted: March 04 2025 at 7:57am |
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I meant that bullet, i said the wrong thing.
In a new bore I believe a .310 bullet will work good |
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Shamu
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Posted: March 04 2025 at 10:35am |
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I recently gifted Doco Overboard with a couple of boxes of heavy (200 & 215) Gr bullets as he likes the single shot Martini rifles. I thought he might get better use out of them than I would. I don't know how far he got with them though.
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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
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Doco Overboard
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Posted: March 04 2025 at 1:28pm |
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Aah yes, the heavies some were inspired with some H4350 and produced quite the authority. More to come on those missiles for game taking in the upcoming months. |
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britrifles
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Posted: March 26 2025 at 3:41pm |
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I’ve recently posted a write up on the results with the rebarreled No. 4 T at last week’s sniper match on the Competition/Match Forum. I thought I would include here the data recorded on the Garmin XERO during the match.
The CBI Barrel now has 222 rounds thru it and it seems to be settling nicely. The muzzle velocity Extreme Spreads and Standard Deviations are half (or even lower) than the old barrel. This translates into much tighter vertical POI spreads at 600 yds, a very good thing if you’re shooting in matches at mid and long range. Below is the Mean Velocity (MV), Extreme Spread (ES) and Normal Distribution Standard Deviation (SD) for the two 10 shot groups, the first shot at 300 yds and the second shot at 600 yds during the Match, values in feet per second: MV ES SD 2397 27 8.2 2404 32 11.1 I never worried about ES and SD’s before. Not until I proved to myself that muzzle velocity has a direct correlation with elevation POI at the target, particularly at 600 yds and beyond. Up to 300 yds, it seems good scores can be obtained even with ES over 50 fps. Not so at 600 yds. To get elevation spreads down to 1 MOA, I needed ES values to be less than 30 fps. There is an interesting exception to this. Some No. 1 and No. 4 rifles show a characteristic to self “compensate” at the target for large muzzle velocity variation which I have written about on this Forum. Unfortunately, the T did not show positive compensation, but my No. 4 DCRA 7.62 clearly did. |
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britrifles
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Posted: April 20 2025 at 8:20am |
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Update
A member on this forum planted a seed in my brain to re-measure the barrel underturn angle on my recently CBI rebarrelled No. 4 T sniper. Although it’s been shooting quite well, it’s not as good as I had hoped. This I attributed to a longer than expected throat length. But, now I’m not so sure. So, off came the barrel this AM. I’m getting pretty quick at doing this, takes me less than an hour to fully strip the rifle and remove a barrel. This barrel came off far too easy just with a firm hit at the end of the 13” action wrench with the palm of my hand. Didn’t even have to use the 3 foot pipe extension on the wrench. My suspicions were right, this barrel has far too little underturn in the hand tight position. This time to check it, I used a digital angle gage. I first leveled the action body on a bench checking it across the top of the charger bridge and on a close fitting drill bit inserted thru the rear sight axis pin lugs, both giving the same angle. Then, with the gage sitting on the Nock’s Form, I measured just 9.6 degrees. Far too little. Reynolds states that 18.5 deg is necessary for satisfactory results. I removed the 0.037 breeching washer and fitted the 0.039” thick washer. Now have 18.5 deg underturn. Photo 1, across the charger bridge, action body leveled:  Photo two, across the chamber reinforce Knocks Form with the 0.037” thick breeching washer that was installed:  Photo 3, now with the 0.039” thick breeching washer:  Maj Reynolds would approve! I’m curious to see if this affects POI on the target and if it improves accuracy at 600 yds. |
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Strangely Brown
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Posted: April 20 2025 at 8:55am |
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Geoff, I think we would all agree on that one!
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Mick
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Strangely Brown wrote: